COMPUTER HARDWARE TERMS by SRIKANTHKAJUBOJU316

02/3/2016

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COMPUTER HARD WARE TERMS

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Adapter An adapter is a device that allows a specific type of hardware to work with another device that would otherwise be incompatible. Examples of adapters include electrical adapters, video adapters, audio adapters, and network adapters. An electrical adapter, for instance, may convert the incoming voltage from 120V to 12V, which is suitable for a radio or other small electronic device. Without regulating voltage through an adapter, the incoming electrical surge could literally fry the internal components of the device. Most consumer electronics have adapters attached to the plug at the end of the electrical cord. Whenever you see an plug surrounded by a large box, it is most likely an electrical adapter. You can typically find the input and outputvoltage printed directly on the adapter. A device that does not have an adapter on the end of its electrical

cable

typically

has

built-in

voltage

adapter.

For

example, desktop computers typically have the adapter built into the internal power supply. Video adapters and audio adapters adapt one type of interface to another type of connector. For example, a DVI to VGA adapter allows you to connect theDVI output of alaptop to the VGA input of a projector. Most professional audio devices use 1/4" audio jacks, while most computers have 1/8" "minijacks" for audio input and output. Therefore, 1/4" to 1/8" audio adapters are often used to import audio into computers. Likewise, an 1/8" to 1/4" adapter can used to output 2

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audio from a computer to a professional audio system. Since a large number of audio and video interfaces exist, there are hundreds of audio and video adapters available. Network cards, or NICs, are also called network adapters. These include Ethernet cards,

internal Wi-Fi chips,

external wireless transmitters. While

these

devices

and don't

convert

connections like audio or video adapters, they enable computers to connect tonetwork. Since the network card makes it possible to connect to an otherwise incompatible network, the card serves as an adapter. Similarly, video cards are sometimes called video adapters because they convert a video signal to an image that can be displayed on a monitor.

ADC Stands

for

"Analog-to-Digital

Converter."

Since

computers

only

process digital information, they require digital input. Therefore, if an analog input is sent to a computer, an analog-to-digital converter (ADC) is required. This device can take an analog signal, such as an electrical current, and digitize it into a binaryformat that the computer can understand. A common use for an ADC is to convert analog video to a digital format. For example, video recorded on 8mm film or a VHS tape is stored in an analog format. In order to transfer the video to a computer, the video must be converted to a digital format. This can be done using an ADC video conversion box, which typically has composite video inputs and a Firewire output. Some digital camcorders 3

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that have analog inputs can also be used to convert video from analog to digital. ADCs may also be used to convert analog audio streams. For example, if you want to record sounds from a microphone, the audio must be converted from the microphone's analog signal into a digital signal that the computer can understand. This is why allsound cards that have an analog audio input also require an ADC that converts the incoming audio signal to a digital format. The accuracy of the audio conversion depends on the sampling rate used in the conversion process. Higher sampling rates provide a better estimation of the analog signal, and therefore produce a higher-quality sound. While ADCs convert analog inputs into a digital format that computers can recognize, sometimes a computer must output an analog signal. For this type of conversion, a digital-to-analog converter (DAC) is used. NOTE: ADC can also stand for "Apple Display Connector," which was a proprietary video connector developed by Apple. It combined DVI, USB, and AC power into a single cable. Apple stopped producing computers with ADC ports in 2004 in favor of the standard DVI connection.

ADF Stands for "Automatic Document Feeder." An ADF is used in copiers and scanners to feed pages into the machine. It allows multiple pages to be copied or scanned at one time without the need to place each individual page in the copier or scanner.

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A flatbed scanner, on the other hand, requires each page to be individually placed on the scanning surface. While this is convenient for single pages, copying 80 pages would require a lot of manual page-loading! Some copy machines include both an automatic document feeder and a flatbed scanning surface so that either method can be used.

ADSL Stands for "Asymmetric Digital Subscriber Line." ADSL is a type of DSL, which is a method of transferring data over copper telephone lines. While symmetrical DSL (SDSL)uploads and downloads data at the same speed, ADSL has different maximum data transfer rates for uploading and downloading data. For example, an ADSL connection may allow download rates of 1.5Mbps, while upload speeds may only reach 256Kbps. Since most users download much more data than they upload, this difference usually does not make a noticeable impact on Internet access speeds. However, for Web servers or other computers that send a lot of data upstream, ADSL would be an inefficient choice.

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AGP Stands for "Accelerated Graphics Port." AGP is a type of expansion slot designed specifically for graphics cards. It was developed in 1996 as an alternative to the PCI standard. Since the AGP interface provides a dedicated busfor graphics data, AGP cards are able to render graphics faster than comparable PCI graphics cards. Like PCI slots, AGP slots are built into a computer's motherboard. They have a similar form factor to PCI slots, but can only be used for graphics cards. Additionally, several AGP specifications exist, including AGP 1.0, 2.0, and 3.0, which each use a different voltage. Therefore, AGP cards must be compatible with the specification of the AGP slot they are installed in. Since AGP cards require an expansion slot, they can only be used in desktop computers. While AGP was popular for about a decade, the technology has been superseded by PCI Express, which was introduced in 2004. For a few years, many desktop computers included both AGP and PCI Express slots, but eventually AGP slots were removed completely. Therefore, most desktop computers manufactured after 2006 do not include an AGP slot.

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ALU Stands

for

circuit within

"Arithmetic

Logic

a CPU or GPU that

Unit."

performs

ALU

arithmetic

an integrated and

logic

operations. Arithmetic instructions include addition, subtraction, and shifting

operations,

while

logic

instructions

include booleancomparisons, such as AND, OR, XOR, and NOT operations. ALUs are designed to perform integercalculations. Therefore, besides adding and subtracting numbers, ALUs often handle the multiplication of two integers, since the result is also an integer. However, ALUs typically do not perform division operations, since the result may be a fraction, or a "floating point" number. Instead, division operations are usually handled by the floating-point unit (FPU), which also performs other non-integer calculations. While the ALU is a fundamental component of all processors, the design and function of an ALU may vary between different processor models. For example, some ALUs only perform integer calculations, while others are designed to handle floating point operations as well. Some processors contain a single ALU, while others include several arithmetic logic units that work together to perform calculations. Regardless of the way an ALU is designed, its primary job is to handle integer operations. Therefore, a computer's integer performance is tied directly to the processing speed of the ALU.

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Architecture The word "architecture" typically refers to building design and construction. In the computing world, "architecture" also refers to design, but instead of buildings, it describes the design of computer systems. Computer architecture is a broad topic that includes everything from the relationship between multiple computers (such as a "client-server" model) to specific components inside a computer. The

most

important

type

computer's processor architecture.

of hardware design The

design

the

processor

determines what software can run on the computer and what other hardware

components

are

supported.

For

example,

Intel's x86 processor architecture is the standard architecture used by most PCs. By using this design, computer manufacturers can create machines that include different hardware components, but run the same software. Several years ago, Apple switched from the PowerPC architecture to the x86 architecture to make the Macintosh platform more compatible with Windows PCs. The architecture of the motherboard is also important in determining what hardware and software a computer system will support. The motherboard design is often called the "chipset" and defines what processor

models

and

other

components

will

work

with

the

motherboard. For example, while two motherboards may both support x86 processors, one may only work with newer processor models. A newer chipset may also require faster RAM and a different type of video card than an older model. 8

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NOTE: Most modern computers have 64-bit processors and chipsets, while earlier computers used a 32-bit architecture. A computer with a 64-bit chipset supports far more memory than one with a 32-bit chipset and can run software designed specifically for 64-bit processors.

ATA Stands for "Advanced Technology Attachment." It is a type of disk drive that integrates the drive controller directly on the drive itself. Computers can use ATA hard drives without a specific controller to support the drive. The motherboard must still support an ATA connection, but a separate card (such as a SCSI card for a SCSI hard drive) is not needed. Some different types of ATA standards include ATA-1, ATA-2 (a.k.a. Fast ATA), ATA-3, Ultra ATA (33 MBps maximum transfer rate), ATA/66 (66 MBps), and ATA/100 (100 MBps). The term IDE, or "Integrated Drive Electronics," is also used to refer to ATA drives. Sometimes (to add extra confusion to people buying hard drives), ATA drives are labeled as "IDE/ATA." Technically, ATA uses IDE technology, but the important thing to know is that they refer to the same thing.

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ATX Stands

for

"Advanced

a motherboard specification

Technology that

defines

eXtended." the

board's

ATX

physical

dimensions, connector placement, I/O ports, and supported power supplies. It was introduced by Intel in 1995 and was designed to replace the previous "AT" standard for desktop PCs. Since then, many variations of the original ATX standard have been developed and some are still used in today's desktop computers. There are several distinct differences between ATX and the AT form factor it superseded. For example, ATX has an I/O panel that is twice the height of the AT panel and allows for flexible interface layouts. It also has different processor, memory, anddrive I/O locations. These changes provide the following benefits: 

Fewer cables



Improved reliability



Support for modern I/O standards like USB



Support for integrated graphics



Larger expansion slots



Easier processor and memory upgrades



Reduced cost

A full size ATX motherboard is 12 inches wide and 9.6 inches deep (305 x 244 mm). There are also several variants of ATX, which have slightly different form factors. This include the following:



FlexATX – 9 × 7.5 in (229 × 191 mm)



MicroATX – 9.6 × 9.6 in (244 × 244 mm) COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU



Mini ATX – 11.2 × 8.2 in (284 × 208 mm)



Extended ATX (EATX) – 12 × 13 in (305 × 330 mm)



Workstation ATX (WTX) – 14 × 16.75 in (356 × 425 mm)

The ATX specification defines the mounting hole locations, which means any standard ATX motherboard can be attached to any standard ATX case. Smaller boards (such as FlexATX, MicroATX, and Mini ATX) have several of the same mounting hole locations, so they can be placed in a standard ATX case as well. The universal compatibility of ATX boards and components make them a popular choice for hobbyists who build their ownPCs.

Backside Bus There are two types of buses that carry data to and from a computer's CPU.

They

are

thefrontside

bus and

backside

bus.

Surprisingly, there is no correlation between these and the backside and frontside airs that snowboarders talk about. While the frontside bus carries data between the CPU and memory, the backside

bus

transfers

data

and

from

the

computer's

secondary cache. The secondary, or L2 cache stores frequently used functions and other data close to the processor. This allows the computer's CPU to work more efficiently since it can repeat processes faster. When the processor needs information from the L2 cache, it is sent over the backside bus. Because this process needs to be extremely fast, the clock speed of the backside bus cannot afford to lag behind. For this reason, the backside bus is often as fast as the processor. The 11

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frontside bus, on the other hand, is typically half the speed of the processor or slower

Bare Metal A bare metal system is a computer that does not include any software. This means the user must install an operating system in order for the hardware to be functional. The term "bare metal" is commonly used to refer to custombuilt PCs and barebonessystems. These types of computers are ideal for PC enthusiasts, who may prefer to install their own software rather than paying extra for pre-loaded programs. A bare metal system also allows advanced users to choose a non-mainstream OS, such as a specific Linuxdistribution. Web hosting companies may also offer bare metal systems to clients who wish to customize their web server from the ground up. For instance, a client may purchase a dedicated or co-located server with a specific

hardware

configuration.

The

server

administrator

can

then install a specific operating system and web server software on the computer. NOTE: Bare metal is sometimes used to refer to a "bare metal restore," which refers to restoring a complete computer software configuration.

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Barebones A barebones PC is a computer that has minimal components. A typical barebones system includes a case, motherboard, CPU,hard drive, RAM, and power supply. Most barebones systems are sold as kits, in which the components must be assembled by the user. Since barebones PCs usually do not come preassembled, they are not designed for the average computer user. Instead, barebones kits are aimed at computer enthusiasts and users who prefer to build their own PCs. By purchasing only specific components, a user can fully customize his computer system and avoid paying for unwanted extras. For example, if you buy a barebones kit, you can choose your own keyboard and mouse, since they are not included. Also, no software is bundled with barebones systems, so you avoid paying for software you don't need. Additionally, most barebones systems do not come with an operating system, so you can choose to install any operating system that is compatible with the hardware. Nearly all barebones PCs are desktop computers since they are the most

customizable.

However,

some

companies

also

offer

barebone laptop systems, or "barebooks," which can be homebuilt. While Macintosh computers now use most of the same components as PCs, the Mac OS X operating system requires proprietary hardware to run. Therefore, barebones systems are generally built to run either Windows or Linux.

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Base Station The term "base station" was first used to refer to the towers you see on the side of the road that relay cell phone calls. These stations handle all cellular calls made within their area, receiving information from one end of the call and transmitting it to the other. In the computer world, however, a base station refers to the wireless access point for computers with wireless cards. It is basically a router that communicates with devices based on the Wi-Fi standard. Some common Wi-Fi configurations include 802.11b and 802.11g. Wireless base stations are made by companies such as Netgear, Linksys, D-Link, Apple Computer, and other manufacturers. Fortunately, as long as the hardware is based on the Wi-Fi standard, all wireless cards can communicate with base stations from any manufacturer.

Bezel The term "bezel" comes from the jewelry industry, in which case a bezel is a groove that holds a gemstone or watch crystal in place. The term is also used to describe the rim around gauges, such as the speedometer in a car. In the computer industry, a bezel may refer to either

the

edge

around

a monitor or

the

front

a desktop

computer case. 14

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A monitor bezel, or screen bezel, is the area of a display that surrounds the screen. For example, if a monitor has a one inch bezel, the screen is surrounded by one inch of plastic or metal. If a monitor's bezel width is different on the sides than the top and bottom of the screen, the bezel specification will include individual measurements for each side. As displays have evolved, bezel widths have generally gotten smaller. For example, old CRT monitors often had bezel widths of two inches or more, while modernLCD displays often have bezels that are less than one inch thick. Thinner bezels help maximize the screen real estate of a laptops and make multiple desktop displays look more like a single screen when placed side by side. A computer bezel is the front face of a system unit or "tower." Most PC bezels include have openings for one or more drive bays. These slots allow you to add devices such as an optical drive or an additional internal hard drive. When extra drives are not installed, these bays are usually covered by plates that are the same color as the bezel, but are not technically part of the bezel.

Blu-ray Blu-ray is an optical disc format such as CD and DVD. It was developed for recording and playing back high-definition (HD) video and for storing large amounts of data. While a CD can hold 700 MB of data and a basic DVD can hold 4.7 GB of data, a single Blu-ray disc can hold up 15 COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

to 25 GB of data. Even a double sided, dual layer DVD (which are not common) can only hold 17 GB of data. Dual-layer Blu-ray discs will be able to store 50 GB of data. That is equivalent to 4 hours of HDTV. Blu-ray discs can hold more information than other optical media because of the blue lasers the drives use. The laser is actually blueviolet, but "Blu-ray" rolls off the tounge a little easier than "Blu-violetray." The blue-violet laser has a shorter wavelength than the red lasers used for CDs and DVDs (405nm compared to 650nm). This allows the laser to focus on a smaller area, which makes it possible to cram significantly more data on a disc the same size as a CD or DVD. Proponents of the Blu-ray format say they expect Blu-ray devices to replace VCRs (thank goodness) and DVD recorders as more people make the transition to HDTV. For the latest Blu-ray news, check out Blu-ray.com.

Boot Disk A boot disk is actually not a computer disk in the shape of a boot. If it was, most disk drives would have a difficult time reading it. Instead, a boot disk is a disk that a computer can start up or "boot" from. The most common type of boot disk is an internal hard drive, which most computers use to start up from. The operating system installed on the hard drive is loaded during the boot process. However, most computers allow you to boot from other disks, including external Firewire hard drives, CD-ROMs, DVD-ROMs, and floppy disks. In order to function as boot disks, these disks need to 16

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have an operating system installed that is understandable by the computer. This can either be a full-blown operating system like Windows or Mac OS X, or a small utility operating system, such as Norton Utilities or DiskWarrior. CD and DVD boot disks are often used to start up a computer when the operating system on the internal hard drive won't load. This can happen when bad data blocks or other errors occur on the disk. By running a disk repair utility from the CD or DVD, you can often fix the hard drive and restart from it, using the full operating system

Bridge When a road needs to extend across a river or valley, a bridge is built to connect the two land masses. Since the average car cannot swim or fly, the bridge makes it possible for automobiles to continue driving from one land mass to another. In computer networking, a bridge serves the same purpose. It connects two or more local area networks (LANs) together. The cars, or the data in this case, use the bridge to travel to and from different areas of the network. The device is similar to a router, but it does not analyze the data being forwarded. Because of this, bridges are typically fast at transferring data, but not as versatile as a router. For example, a bridge cannot be used as a firewall like most routers can. A bridge can transfer data between different protocols (i.e. a Token Ring and Ethernet network) and operates at the "data link layer" or level 2 of the OSI (Open Systems Interconnection) networking reference model 17

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Brouter A brouter is a device that functions as both abridge and a router. It can forward data between networks (serving as a bridge), but can also route data to individual systems within a network (serving as a router). The main purpose of a bridge is to connect two separate networks. It simply forwards the incoming packets from one network to the next. A router, on the other hand, is more advanced since it can route packets to specific systems connected to the router. A brouter combines these two functions by routing some incoming data to the correct systems, while forwarding other data to another network. In other words, a brouter functions as a filter that lets some data into the local network, while redirecting unrecognized data to another network. While the term "brouter" is used to describe bridge/router device, actual brouters are pretty rare. Instead, most brouters are simply routers that have been configured to also function as a bridge. This functionality

can

often

implemented

using

the

router'ssoftware interface. For example, you may configure a router to only accept data from specific protocols and data sources, while forwarding other data to another network. NOTE: Since routers are more complex than bridges, it is more likely for router than a bridge to function as a brouter. Therefore, brouters are also called bridging routers.

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Bus While the wheels on the bus may go "round and round," data on a computer's bus goes up and down. Each bus inside a computer consists of set of wires that allow data to be passed back and forth. Most computers have several buses that transmit data to different parts of the machine. Each bus has a certain size, measured in bits (such as 32-bit or 64-bit), that determines how much data can travel across the bus at one time. Buses also have a certain speed, measured in megahertz, which determines how fast the data can travel. The computer's primary bus is called the frontside bus and connects the CPU to the rest of the components on the motherboard. Expansion buses, such as PCI and AGP, allow data to move to and from expansion cards, including video cards and other I/O devices. While there are several buses inside a computer, the speed of the frontside bus is the most important, as it determines how fast data can move in and out of the processor.

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Cable Modem A cable modem is a peripheral device used to connect to the Internet. It operates over coaxcable TV lines and provides high-speed Internet access. Since cable modems offer an always-on connection and fast data transfer rates, they are considered broadband devices. Dial-up modems, which were popular in the early years of the Internet, offered

speeds

56 Kbps over

analog

telephone

lines.

Eventually, DSL and cable modems replaced dial-up modems since they offered

much

faster

speeds.

Early

cable

modems

provideddownload and upload speeds of 1 to 3 Mbps, 20 to 60 times faster than the fastest dial-up modems. Today, standard cable Internet access speeds range from 25 to 50 Mbps. On the high end, Comcast offers an "Xfinity Extreme" service with speeds up to 505 Mbps. Most cable modems include a standard RJ45 port that connects to the Ethernet port on your computer or router. Since most homes now have several Internet-enabled devices, cable modems are typically connected to home router, allowing multiple devices to access the Internet. Some cable modems even include a built-in wireless router, eliminating the need for a second device. NOTE: While "cable modem" includes the word "modem," it does not function

traditional

"modulator/demodulator").

modem

Cable

(which

modems

send

short and

for

receive

information digitally, so there is no need to modulate an analog signal.

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Card Reader "Card reader" is the generic term for an input device that reads flash memory cards. It can be a standalone device that connects to a computer via USB or it may be integrated into a computer, printer, or multifunction

device.

fact,

most

multifunction

printer/scanner/copiers now have built-in card readers. Most

card

readers

multiple

memory

card

formats,

including compact flash (CF),secure digital (SD), and Sony's Memory Stick. Some card readers accept various other formats such as XD, SmartMedia, Microdrive, and Memory Stick Pro Duo cards. The purpose of a card reader is, not surprisingly, to read the data from a memory card. When you place a memory card into a card reader, it will often show up on your computer as a mounted disk. You can then view the contents of the memory card by double-clicking the card's icon.

This

icon

typically

of Macintoshcomputers

appears inside

on "My

the

desktop Computer"

on Windows machines. Since memory cards most often contain pictures from digital cameras, a photo organization program may automatically open when you insert a memory card into you card reader. This provides an easy way of importing your pictures into your photo album. If you don't want to import photos using the program, you can simply close the program and the card will still be mounted on your computer.

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Once you decide to remove the card, make sure you unmount or "eject" the disk before physically removing the card. This will help prevent the data on the card from becoming corrupted.

CCD Stands for "Charged Coupled Device." CCDs are sensors used in digital cameras and video cameras to record still and moving images. The CCD captures light and converts it to digital data that is recorded by the camera. For this reason, a CCD is often considered the digital version of film. The

quality

image

captured

CCD

depends

the resolution of the sensor. In digital cameras, the resolution is measured in Megapixels (or thousands of or pixels. Therefore, an 8MP digital camera can capture twice as much information as a 4MP camera. The result is a larger photo with more detail. CCDs in video cameras are usually measured by physical size. For example, most consumer digital cameras use a CCD around 1/6 or 1/5 of an inch in size. More expensive cameras may have CCDs 1/3 of an inch in size or larger. The larger the sensor, the more light it can capture, meaning it will produce better video in low light settings. Professional digital video cameras often have three sensors, referred to as "3CCD," which use separate CCDs for capturing red, green, and blue hues.

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CD Stands for "Compact Disc." CDs are circular discs that are 4.75 in (12 cm) in diameter. The CD standard was proposed by Sony and Philips in 1980 and the technology was introduced to the U.S. market in 1983. CDs can hold up to 700 MB of data or 80 minutes of audio. The data on a CD is stored as small notches on the disc and is read by a laser from an optical drive. The drives translate the notches (which represent 1's and 0's) into usable data. The first CDs were audio CDs, which eventually replaced audio tapes (which earlier replaced records). Audio CDs have the advantage of allowing the user to jump to different places on the disc. CDs can also be listened to an unlimited number of times without losing quality. Audio tapes can start to lose quality after listening to them as few as ten times. This is because the laser that reads the data on a CD doesn't put pressure on the disc, whereas the playheads on a tape deck slowly wear away the magnetic strip on the tape. In 1985, CD-ROMs hit the computer market. Because they could store far more information than floppy discs (700 MB compared to 1.4 MB), CDs soon became the most common software format. In 1988, the CDR (CD-Recordable) technology was introduced, allowing computer users to burn their own CDs. However, this technology did not become 23

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mainstream until the late 1990s. A smaller 3" CD, called "CD-3" is also available and is readable by most tray-loading CD-ROM drives. For a timeline of the history of the CD, visit OneOff Media, Inc.

CD-R Stands for "Compact Disc Recordable." CD-R discs are blank CDs that can record data written by a CD burner. The word "recordable" is used because CD-Rs are often used to record audio, which can be played back by most CD players. However, many other kinds of data can also be written to a CD-R, so the discs are also referred to as "writable CDs." The data burned onto a CD-R disc is permanent, meaning it can not be altered or erased like the data on a hard drive. Typically, once a CD has been burned, it will not be able to record any more data. Some CD burning programs can record data as "sessions," allowing a disc to be written to mulitple times until it is full. Each session creates a new partition on the disc, meaning a computer will read a disc with multiple sessions as multiple discs. CD-RWs, on the other hand, can be erased and completely re-recorded. Like CDs, the data on CD-RWs cannot be altered, meaning the disc has to be completely erased each time you want to add new data.

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CD-ROM Stands for "Compact Disc Read-Only Memory." A CD-ROM is a CD that can be read by a computer with an optical drive. The "ROM" part of the term means the data on the disc is "read-only," or cannot be altered or erased. Because of this feature and their large capacity, CD-ROMs are a great media format for retail software. The first CD-ROMs could hold about 600 MB of data, but now they can hold up to 700 MB. CD-ROMs share the same technology as audio CDs, but they are formatted differently, allowing them to store many types of data.

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CD-RW Stands for "Compact Disc Re-Writable." A CD-RW is a blank CD that can be written to by a CD burner. Unlike a CD-R (CD-Recordable), a CD-RW can be written to multiple times. The data burned on a CD-RW cannot be changed, but it can be erased. Therefore, you have to completely erase a CD-RW every time you want to change the files or add new data. While it may be somewhat inconvenient, this capability makes CD-RWs a good choice for making frequent backups. However, because CD-RWs can be erased, they don't store data reliably for as long as CDRs do. Therefore, you should use regular CD-Rs for long-term backups.

Chip Technically speaking, a computer chip is a piece of silicon with an electronic circuit embedded in it. However, the word "chip" is often used as a slang term that refers to various components inside a computer. It typically describes an integrated circuit, or IC, such as a central processor or a graphics chip, but may also refer to other components such as a memory module. While "chip" is a somewhat ambiguous term, it should not be confused with the term "card." For example, a laptop might have a graphics chip embedded in the motherboard, while a desktop computer may contain 26

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a graphics card connected to a PCI or AGP slot. A graphics card may contain a chip, but the chip cannot contain a card. Similarly, a CPU may contain a chip (the processor), but it may also contain several other components. Therefore, the term "chip" can be used to refer to specific components, but should not be used describe multiple components that are grouped together.

Chipset A chipset is a group of integrated circuits that work together. It may refer to the design of a single component or may describe the relationship of multiple components within a computer system. For example, the chipset ofvideo card describes the design of the card, while a motherboard chipset describes its layout and the different components it supports. Diagrams are often used to illustrate chipset designs. For example, a diagram of a video card chipset may contain the GPU, video RAM, and the PCI bus. It may also include lines and arrows that represent the circuitry between the components. Together, the components and circuitry make up the overall design of the chipset, and may also be called the architecture of the video card. A motherboard chipset diagram may include components such as the CPU, RAM, video card, and I/O ports. A detailed diagram may also include

lesser-known

components,

such

the northbridge, southbridge and frontside bus. Regardless of level of detail, all motherboard chipset diagrams include lines and arrows that 27

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visually

describe

the

way

data

flows

between

the

different

components. Most internal computer components are designed for a specific chipset. Therefore, if you decide to upgrade any internal hardware, it is important to know what type of chipset your computer uses. In many cases, a computer's chipset is synonymous with the chipset of the motherboard. Once you find out what chipset your motherboard uses, you can determine what components are compatible with your machine.

Chromebook A Chromebook is a laptop that runs Google's Chrome OS operating system.

While

Google

sells

its

own

Chromebook

model,

the

Chromebook Pixel, many other manufacturers offer Chromebooks as well. Examples include Dell, HP, Toshiba, Samsung, ASUS, and Acer. Chromebooks are designed to be inexpensive and highly portable. They are considered thin clients since they have minimal internal storage. Unlike traditional laptops, Chromebooks are designed to run cloud-basedapplications and store data online. While the Chrome OS and some applications can runoffline, Chromebooks work best when used with an Internet connection. The Chrome OS includes several Google apps, such as the Chrome web browser, Gmail, Google+, and YouTube applications. It also runs the Google Drive office suite and related apps such as Google Docs, Google Drawings, and Google Forms. Third partyapplications can 28

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be downloaded from the Chrome Web Store. Some Android apps can also run on Chrome OS via Google's App Runtime for Chrome (ARC). Since Chromebooks do not run Windows or OS X, they do not natively support many traditional applications, such as Microsoft Office. However, you can run online versions of Word, Excel, and other common applications from the Chrome OS or through the Chrome web browser. These applications run on a remote server, but look and function like traditional desktop applications. Chromebooks also support remote accesssoftware, which allows you operate Windows or OS X computers from a Chromebook.

CISC Stands for "Complex Instruction Set Computing." This is a type of microprocessor design. The CISC architecture contains a large set of computer instructions that range from very simple to very complex and specialized. Though the design was intended to compute complex instructions in the most efficient way, it was later found that many small, short instructions could compute complex instructions more efficiently. This led to a design called Reduced Instruction Set Computing

(RISC),

which

now

the

other

major

kind

microprocessor architecture. Intel Pentium processors are mainly CISCbased, with some RISC facilities built into them, whereas the PowerPC processors are completely RISC-based

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Clone What do sheep, droids, and computers all have in common? They can all be cloned! Of the three, computer clones are by far the most common. The term "clone" arose in the mid-1980s to describe DOS or Windowsbased computers made by companies other than IBM. The machines were often referred to as "IBM clones," or "IBM compatible" computers. They were called clones because the computers functioned exactly the same way as the ones made by IBM. They used similar hardware and ran the same software. PC clones are still around today. In fact there are dozens more manufacturers of Windows-based computers now than there were in the 1980s. Companies like Dell, Gateway, HP, Compaq, and Sony all make

Windows-based

computers,

well

many

other

manufacturers. Today, the term "PC," which technically stands for "Personal Computer," is often used to refer to IBM clones. Macintosh clones were made for a few years in the late 1990s, but Apple forced the end of their production by making the Macintosh operating system only run on the Apple-branded machines. "Clone" can also be used to refer to software that serves the same purpose as another more mainstream software program. It can also refer to electronic devices other than computers that are similar to other electronics.

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Cluster In computing, a cluster may refer to two different things: 1) a group of sectors in a storage device, or 2) a group of connected computers.

1) A group of sectors A sector is the smallest unit that can be accessed on a storage device like an HDD orSSD. A cluster, or allocation unit, is a group of sectors that make up the smallest unit of disk allocation for a file within a file system. In other words, a file system's cluster size is the smallest amount of space a file can take up on a computer. A common sector size is 512 bytes. A common cluster size is 8 sectors. Therefore, many file systems have a minimum cluster size of 4kibibytes (8 x 512 bytes). Most files require a large number of clusters, which means the file contents are spread across multiple clusters on the drive. Often the data can be written in contiguous blocks so that the file contents are stored in one physical location. However, when a hard drivebegins to fill up, there may not be enough contiguous clusters available to save large files in a single area. Instead, they must be written in multiple locations on the disk. This is called fragmentation and can slow down the hard drive's read and write speeds.

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2) A group of connected computers A cluster can also refer to a group of machines that work together that perform a similar function. Unlike grid computing, a computer cluster is controlled by a singlesoftware program that manages all the computers or "nodes" within the cluster. The nodes work together to complete a single task. This process is called "parallel computing" since the nodes perform operations in tandem. Computer clusters can range from two machines to hundreds of connected computers. Small clusters are often used to improve the performance of web and online gaming services by handling multiple incoming requests in parallel. A web farm, for example, is a type of cluster that provides low latency access to websites. Large clusters can be used to perform scientific calculations or to run a large number of complex algorithms. For example, a large cluster may be used to apply textures and lighting effects to 3D models in each frame of an animated movie.

CMOS Stands

for

technology

"Complementary is

typically

Metal

used

Oxide

Semiconductor."

making

transistors.

This The

"complementary" part of the term unfortunately does not mean these semiconductors are free. Instead, it refers to how they produce either a positive or negative charge. Because CMOS-based transistors only use one charge at a time, they run efficiently, using up very little power. This is because the charges can stay in one state for a long period of 32

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time, allowing the transistor to use little or no power except when needed. Because of their wonderful efficiency, processors that use CMOS-based transistors can run at extremely high speeds without getting too hot and going up in flames. You may also find CMOS memory in your computer, which holds the date and time and other basic system settings. The low power consumption of CMOS allows the memory to be powered by a simple Lithium battery for many years.

Coaxial Cable Coaxial (or “coax”) cable is a common type of cable used for transmitting data over

long

distances.

can

carry

either

an analog ordigital signal. While coax cables have many applications, they are most commonly used to transmit cable TV and Internet signals. Coax cables that run underground are typically thicker and more heavily insulated than the cables that connect your cable box or cable modem to the wall outlet. However, they all transmit data via a thin copper line in the middle of the cable. This wire is surrounded by a layer of insulation comprised of non-conductive or “dielectric” material. The dielectric layer is covered with one or more metallic shields that provides additional protection from signal interference. Finally, a protective plastic outer layer surrounds the entire cable. The heavy duty design of coaxial cables is what allows them to carry data over long distances with minimum signal degradation. In many cases, coax cables laid by cable companies several decades ago are sufficient 33

provide HDTV and

high-speed

Internet

access

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simultaneously. However, certain coax cables (such as RG-59 cables) are designed for low bandwidth applications, like connecting a VCR to a TV, and may not provide enough bandwidth to carry a full HDTV signal. Coax cables labeled as â&#x20AC;&#x153;RG-6â&#x20AC;? are a better choice for HDTV and cable Internet service.

Compact Flash Often abbreviated as simply "CF," Compact Flash is a type of flash memory. Compact flash cards are most commonly used for storing pictures in digital cameras, but are also used in devices such as PDAs and portable music players. There are two types of Compact Flash cards, creatively named "Type I" and "Type II." Type I cards are 3.3 mm thick, while Type II are 5 mm thick. IBM makes a "MicroDrive" card that has the same dimensions as a Type II CF card, but uses an actual hard drive construction rather than flash memory. Compact Flash cards originally could only store a few megabyes of data, but now can store several gigabytes. The new CF+ standard can store a possible 137 GB of data. I don't know about you, but I'd think about backing up that information before throwing the card in my pocket.

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Component Computers

are

made

many

different

parts,

such

a motherboard, CPU, RAM, andhard drive. Each of these parts are made up of smaller parts, called components. For example, a motherboard includes electrical connectors, a printed circuit board (PCB), capacitors, resistors, and transformers. All these components work together to make the motherboard function with the other parts of the computer. The CPU includes components such as integrated circuits, switches, and extremely small transistors. These components process information and perform calculations. Generally speaking, a component is a element of a larger group. Therefore, the larger parts of a computer, such as the CPU and hard drive, can also be referred to as computer components. Technically, however, the components are the smaller parts that make up these devices. Component may also refer to component video, which is a type of high-quality video connection. A component connection sends the video signal through three separate cables â&#x20AC;&#x201D; one for red, green, and blue. This provides better color accuracy than composite video (typically a yellow connector), which combines all the color signals into a single cable.

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Computer Technically, a computer is a programmable machine. This means it can execute a programmed list of instructions and respond to new instructions that it is given. Today, however, the term is most often used to refer to the desktop and laptop computers that most people use. When referring to a desktop model, the term "computer" technically only refers to the computer itself -- not the monitor, keyboard, and mouse. Still, it is acceptable to refer to everything together as the computer. If you want to be really technical, the box that holds the computer is called the "system unit." Some of the major parts of a personal computer (or PC) include the motherboard, CPU, memory (or RAM), hard drive, and video card. While personal computers are by far the most common type of computers today, there are several other types of computers. For example, a "minicomputer" is a powerful computer that can support many users at once. A "mainframe" is a large, high-powered computer that can perform billions of calculations from multiple sources at one time. Finally, a "supercomputer" is a machine that can process billions of instructions a second and is used to calculate extremely complex calculations.

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Console A console is the combination of a monitor andkeyboard. It is a rudimentary interface in which the monitor provides the output and the keyboard is used for input. While any computer with a monitor and keyboard may be considered a console, the term most often refers to a system used to control one or more servers. Early consoles in the 1970s and 1980s provided a textonly "command line" interface, in which a network admin could type commands at a command prompt. Modern consoles often provide a graphical interface that can be used to control machines on a local network (LAN) or provide remote access to remote systems. These consoles typically include a mouse for navigating graphical interfaces. The terms "console" and "terminal" are often used synonymously. However, "terminal" may also be used to describe the software that runs on a console, such as a command line interface or remote access program. Mac OS X includes both a Terminal program that provides a command line interface, and a Console utility that displays system logs and diagnostic reports. NOTE: A console may also refer to other types of hardware besides computer interfaces. For example, gaming systems such as the PlayStation, Xbox, and Wii, are called video game consoles, while multichannel audio mixing boards are called mixing consoles.

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Controller Card The controller card, or simply "controller," is a piece of hardware that acts as the interface between the motherboard and the other components of the computer. For example, hard drives, optical drives, printers, keyboards, and mice all require controllers to work. Most computers have all the necessary controllers built in the motherboard as chips, not full-sized cards. However, if you add additional components such as a SCSI hard drive, you may need to add a controller card as well. Controller cards are typically installed in one of the computer's PCI slots.

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CPU Stands

for

"Central

Processing

Unit."

The

CPU

the

primary component of a computer that processes instructions. It runs the operating system and applications, constantly receivinginput from the user or active software programs. It processes the data and producesoutput, which may stored by an application or displayed on the screen. The CPU contains at least one processor, which is the actual chip inside the CPU that performs calculations. For many years, most CPUs only had one processor, but now it is common for a single CPU to have at least two processors or "processing cores." A CPU with two processing cores is called a dual-core CPU and models with four cores are called quad-core CPUs. High-end CPUs may have six (hexa-core) or even eight (octo-core) processors. A computer may also have more than one CPU, which each have multiple cores. For example, a server with two hexa-core CPUs has a total of 12 processors. While processor architectures differ between models, each processor within a CPU typically has its own ALU, FPU, register, and L1 cache. In some cases, individual processing cores may have their own L2 cache, though they can also share the same L2 cache. A single frontside bus routes data between the CPU and the system memory. NOTE: The

terms

"CPU"

and

"processor"

are

often

used

interchangeably. Some technical diagrams even label individual processors as CPUs. While this verbiage is not incorrect, it is more

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accurate (and less confusing) to describe each processing unit as a CPU, while each processor within a CPU is a processing core

CRT Stands for "Cathode Ray Tube." CRT is the technology used in traditional computer monitors and televisions. The image on a CRT display is created by firing electrons from the back of the tube to phosphors located towards the front of the display. Once the electrons hit the phosphors, they light up and are projected on the screen. The color you see on the screen is produced by a blend of red, blue, and green light, often referred to asRGB. The stream of electrons is guiding by magnetic charges, which is why you may get interference with unshielded speakers or other magnetic devices that are placed close to a CRT monitor. Flat screen or LCD displays don't have this problem, since they don't require a magnetic charge. LCD monitors also don't use a tube, which is what enables them to be much thinner than CRT monitors. While CRT displays are still used by graphics professionals because of their vibrant and accurate color, LCD displays now nearly match the quality of CRT monitors. Therefore, flat screen displays are well on their way to replacing CRT monitors in both the consumer and professional markets.

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DAC Stands for "Digital-to-Analog Converter" and is often pronounced "dac." Since

computers

only

recognize digital information,

the outputproduced by computers is typically in digital format. However, some output devices only accept analog input, which means a digital-to-analog converter, or DAC, must be used. The most common use for a DAC is to convert digital audio to an analog signal. This conversion typically takes place in the sound card, which has a built-in DAC. The digital signal, which is basically a stream of ones and zeros, is transformed into an analog signal that might take the form of an electrical charge. This electrical charge is recognized by most speaker inputs and therefore can be output to a speaker system. DACs are also used for converting video signals. Historically, most video displays, such as TVs and computer monitors used analog inputs. Only in the last couple of years have digital displays with DVI and HDMI connections become commonplace. Therefore, in order for a computer to output to an analog display, the digital video signal must be converted to an analog signal. This is why all video cards with an analog output (such as a VGA connection) also include a DAC. Any time a signal is converted from one format to another, there is a potential loss of quality. Therefore, it is important to have a highquality DAC whether you are converting audio or video signals. The same holds true when performing the opposite conversion, which requires an analog-to-digital converter, or ADC. 41

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DAS Stands for "Direct Attached Storage." DAS refers to any storage device connected directly to a computer. Examples includeHDDs, SSDs, and optical drives. While DAS can refer to internal storage devices, it is most often describes external devices, such as anexternal hard drive. The term "DAS" was created to differentiate between network-attached storage (NAS) and direct-attached storage. Before NAS and storage area networks (SANs) were available, direct-attached storage was the the only option. While DAS is still the most common type of storage used in personal computing,network and server administrators often need to choose between DAS and NAS for a storage solution. The primary benefit of DAS vs NAS is the simplicity of the setup. You can simply connect a device to a computer and, as long as the necessary drivers are available, it will show up as an additional storage device. There is no need to configure network settings or set up permissions for individual computers. The main drawback of DAS is that a direct-attached device is only accessible via the computer to which it is attached. Therefore, a computer must be configured as a file server in order for other systems to access any connected DAS devices.

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DDR Stands for "Double Data Rate." It is an advanced version of SDRAM, a type of computer memory. DDR-SDRAM, sometimes called "SDRAM II," can transfer data twice as fast as regular SDRAM chips. This is because DDR memory can send and receive signals twice per clock cycle. The efficient operation of DDR-SDRAM makes the memory great for notebook computers since it uses up less power.

DDR2 Stands for "Double Data Rate 2." DDR2 RAM is an improved version of DDR memory that is faster and more efficient. Like standard DDR memory, DDR2 memory can send data on both the rising and falling edges of the processor's clock cycles. This nearly doubles the amount of work the RAM can do in a given amount of time. DDR and DDR2 are also both types of SDRAM, which allows them to run faster than conventional memory. While DDR and DDR2 have many similarities, DDR2 RAM uses a different design than DDR memory. The improved design allows DDR2 RAM to run faster than standard DDR memory. The modified design also gives the RAM more bandwidth, which means more data can be 43

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

passed through the RAM chip at one time. This increases the efficiency of the memory. Since DDR2 runs more efficiently than standard DDR memory, it actually uses less power than DDR memory, even though it runs faster. The only downside of DDR2 memory is that it is not compatible with standard DDR slots. So make sure your computer supports DDR2 RAM before upgrading your memory.

DDR3 Stands for "Double Data Rate Type 3." DDR3 is a type of SDRAM that is used

for

systemmemory.

available

both DIMM andSO-

DIMM form factors. DDR3 RAM is similar to DDR2 RAM, but uses roughly 30% less power and can transfer data twice as fast. While DDR2 memory can transfer data at up to 3200 MBps (megabytes per second), DDR3 memory supports maximum data transfer rates of 6400 MBps. This means computers with DDR3 memory can transfer data to and from the CPU much faster than systems with DDR2 RAM. The faster memory speed prevents bottlenecks, especially when processing large amounts of data. Therefore, if two computers have the same processor clock speed, but different types of memory, the computer with DDR3 memory may perform faster than the computer with DDR2 memory. DDR3 memory modules look similar to DDR and DDR2 chips, but the gap that separates the two sets of pins on the bottom of each module is in a different location. This prevents the RAM chip from being 44

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

installed in a slot that does not support DDR3 RAM. Therefore, when upgrading

your

computer's

memory,

make

sure

you get

the

appropriate type of memory for your computer.

Degauss Degaussing is the process of reducing a magnetic field. It can be used to reset the magnetic field of a CRT monitor or to destroy the data on a magnetic storage device. A CRT monitor displays images by firing electrons through a cathode ray tube (CRT) onto the screen. The electron beams are focused by a plate near the screen called a shadow mask. If this plate becomes unevenly magnetized by surrounding objects or simply the earth's magnetic field, it can cause discoloration on the screen. Therefore, CRT monitors often include a "Degauss" command that resets the magnetic field when run. Since it is impossible to eliminate the magnetic charge inside the monitor, the degaussing process realigns or randomizes the magnetic field, which provides consistent colors across the screen. Degaussing

may

also

used

destroy

the

data

magnetic storage device, such as a hard drive or tape drive. A hard drive degausser, for example, includes a chamber where you can insert a hard drive. When you run the degausser, it uses a process called capacitative discharge to decrease the drive's magnetic field, making any data on the drive unreadable. The cycle time, which is the time it takes for the data to be erased, varies between degaussers, but is usually between ten seconds and one minute. Companies and 45

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

government organizations may use degaussers to eliminate the data on storage devices before reprovisioning or discarding them

Desktop Computer A desktop computer (or desktop PC) is acomputer that is designed to stay in a single location. It may be a tower (also known as asystem unit) or an all-in-one machine, such as an iMac. Unlike laptops and other portable devices, desktop computers cannot be powered from an internal battery and therefore must remain connected to a wall outlet. In the early age of computers, desktop computers were the only personal computers available. Since laptops and tablets did not exist, all home PCs were desktop computers. Still, the term "desktop computer" was used back then to differentiate between personal PCs and larger computers, such asmainframes and supercomputers. While desktop computers were the most popular type of personal computer for several decades, in recent years, laptop sales have surpassed those of desktop PCs. Because of the rise in mobile computing, this trend is likely to continue. However, desktop computers

remain

the

most

popular

choice

for

business workstations and family computers.

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Digital Camera A digital camera is a similar to a traditional film-based camera, but it captures imagesdigitally. When you take a picture with a digital camera, the image is recorded by a sensor, called a "charged coupled device" orCCD. Instead of saving the picture on analogfilm like traditional cameras, digital cameras save photos in digital memory. Some

digital

cameras

have

built-in

memory,

but

most

use

an SD or Compact Flash card. Digital

cameras

have

several

advantages

over

their

analog

counterparts. While film rolls typically hold about 24 pictures, memory cards have the capacity to store several hundred or even several thousand pictures on a single card. Therefore, photographers can be much more liberal in the shots they take. Since the images are captured digitally, unwanted images can be deleted directly on the camera. Most digital cameras also include a small LCD screen that shows a live preview of the image, which makes it easier to capture the perfect picture. These cameras usually include an option to record video as well. In the past, people would need to drop off their film at a photo processing location in order to get their pictures developed. With digital cameras, you can simply import the pictures to your computer via a USB cable. Once the digital photos have been imported, you can publish them online or e-mail them to friends. You can also edit them using photo editing software. If you want to print hard copies of your photos, you can use a home printer or an online printing service. 47

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Digital cameras range greatly in size in quality. On the low end are portable electronic devices such as as cell phones and iPods that have digital

cameras

built

into

them.

the

mid

range

are

are standalone point-and-shoot cameras that have additional features and picture taking modes. On the high end are digital SLR (single lens reflex) cameras, which support interchangeable lenses. These cameras are

used

photography

professionals

and

capture

high resolution images with accurate color. While early digital cameras did not perform as well as their film-based counterparts, modern digital cameras can now capture even higher quality images. Today's point-and-shoot cameras now have resolutions in excess of 10 megapixels, which allows them to capture crystal clear images. They also focus and capture images much faster than before, which gives them the responsiveness of analog cameras. These improvements,

along

with

the

many

advantages

digital

photography, are why nearly all photographers have gone digital.

DIMM Stands for "Dual In-Line Memory Module." It is a type of computer memory. A DIMM is a small circuit board that holds memory chips. It uses a 64-bit bus to the memory, whereas a single in-line memory module (SIMM) only has a 32-bit path. This allows DIMMs to transfer more data at once. Because DIMMs have faster data transfer capabilities than SIMMs, they have pretty much replaced SIMMs. 48

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Disk Drive A disk drive is a device that reads and/or writes data to a disk. The most common type of disk drive is a hard drive (or "hard disk drive"), but several other types of disk drives exist as well. Some examples include removable storage devices, floppy drives, and optical drives, which read optical media, such as CDs and DVDs. While there are multiple types of disk drives, they all work in a similar fashion. Each drive operates by spinning a disk and reading data from it using a small component called a drive head. Hard drives and removable disk drives use a magnetic head, while optical drives use a laser. CD and DVD burners include a high-powered laser that can imprint data onto discs. Since hard drives are now available in such large capacities, there is little need for removable disk drives. Instead of expanding a system's storage capacity with removable media, most people now use external hard drives instead. While CD and DVD drives are still common, they have become less used since software, movies, and music can now often

be downloaded from

the

Internet.

Therefore, internal

hard

drives and external hard drives are the most common types of disk drives used today

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DMA Stands for "Direct Memory Access." DMA is a method of transferring data from the computer's RAM to another part of the computer without processing it using theCPU. While most data that is input or output from your computer is processed by the CPU, some data does not require processing, or can be processed by another device. In these situations, DMA can save processing time and is a more efficient way to move data from the computer's memory to other devices. For example, a sound card may need to access data stored in the computer's RAM, but since it can process the data itself, it may use DMA to bypass the CPU. Video cards that support DMA can also access the system memory and process graphics without needing the CPU. Ultra DMA hard drives use DMA to transfer data faster than previous hard drives that required the data to first be run through the CPU. In order for devices to use direct memory access, they must be assigned to a DMA channel. Each type of port on a computer has a set of DMA channels that can be assigned to each connected device. For example, a PCI controller and a hard drivecontroller each have their own set of DMA channels.

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Docking Station A docking station, or dock, is a device that connects a laptop to multiple peripherals. It provides a single connection point that allows a laptop to use a connected monitor, printer, keyboard, and mouse. This allows a laptop to function like a desktop computer. Laptop manufacturers often build custom docking stations for their laptops. These docks usually have a proprietary input port that connects to a matching port on specific laptop models. Early docks, such as those built in the 1990s, included serial ports for connecting input devices, parallel ports for connecting printers and scanners, and VGAports for connecting monitors. In recent years, laptop docking stations

have

become

standardized,

with USB ports

for

connecting most peripherals and DVI ports for connecting displays. While modern docks provide standardized I/O ports, many docking stations still use a proprietary dock connector, which means when you buy a new laptop, you may need to buy a new dock. Fortunately, the Thunderbolt connector, first used in Apple's MacBook laptops, eliminates the need for a docking station. A single Thunderbolt connection

can

support

USB, FireWire, Ethernet,

and

DisplayPort

connections. Therefore, a Thunderbolt hub serves the same purpose as a laptop dock and is compatible with any computer that has a standard Thunderbolt connection. NOTE: Docking

stations

may

also

refer

hardware

used

connect tablets,smartphones, and other portable devices to one or more peripherals. However, these devices are generally called "docks" and typically have fewer I/O connections than a laptop dock. 51

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Dongle A dongle is a small device, typically about the size of a flash drive, that plugs in to acomputer. Some dongles act as security keys while others serve as adapters. While early dongles connected to parallel ports on PCs and ADB ports on Macs, modern versions typically connect to a USB port.

Security Keys Security dongles are used for copy protection are designed to prevent software piracy. For example, some high-end softwareapplications, such as professional audio and video production programs, require a dongle in order to run. The dongle, which is included with the software, must be plugged in when you open the software program. If the correct dongle is not detected, the application will produce an error message saying a dongle is required in order to use the software.

Adapters Certain types of adapters are also called dongles. For instance, a dongle may provide alaptop with different types of wired connections. Previous

generations

laptops

had

expansion

slots

called PCMCIA ports that were too skinny to include an Ethernet jack. Therefore, a dongle was required. These types of dongles were typically one to three inch cables that connected to the card on one end and had an Ethernet jack on the other. Modern Ethernet dongles 52

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

have a similar appearance, but they usually connect to a USB or Thunderbolt port. Today, many dongles provide wireless capabilities. For example, USB Wi-Fi adapters are often called dongles. Since most computers now have

built-in

Wi-Fi

chips,

cellular

data

adapters,

such

as 3G and 4G dongles, are more prevalent. These types of dongles allow you to connect to the Internet via a cellular carrier like Verizon or AT&T even when Wi-Fi is not available.

Dot Pitch Dot pitch, or "pixel pitch," is a measurement that defines the sharpness of a display. It measures the distance between the dots used to display the image on the screen. This distance is very small and is typically measured in fractions of millimeters. The smaller the dot pitch, the sharper the picture. Dot pitch applies to both CRT monitors and flat-screen displays. While some large-screen CRTs have dot-pitches as high as 0.51 mm, most computer displays have a dot pitch between 0.25 and 0.28 mm. Similarly, mostLCD displays have a dot pitch between 0.20 and 0.28 mm. Some high-end displays used for scientific or medical imagery have dot pitches as low as 0.15 mm. These displays usually cost several times as much as consumer displays of the same size. While the terms "dot pitch" and "resolution" are related, they have different

meanings.

display's

resolution

refers

how

many pixels can be displayed on the screen. For example, a 20" 53

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

monitor may have a maximum resolution of 1680 x 1050 pixels. When a display is set to its native resolution (typically the maximum resolution), it may display exactly one pixel per dot. However, if the resolution is reduced, the pixels will be larger than the dots used to display the image on the screen. In this case, each pixel is mapped onto multiple dots.

DRAM Stands for "Dynamic Random Access Memory." DRAM is a type of RAM that stores each bit of data on a separate capacitor. This is an efficient way to store data in memory, because it requires less physical space to store the same amount of data than if it was stored statically. Therefore, a DRAM chip can hold more data than an SRAM (static RAM) chip of the same size can. However, the capacitors in DRAM need to constantly be refreshed to keep their charge, so DRAM requires more power than SRAM. Still, because DRAM can hold more data than SRAM and because it is significantly less expensive to manufacture, DRAM is the most common type of memory found in personal computer systems. While there are many types of DRAM available, the most common type is synchronous DRAM SDRAM, which is a faster version of standard DRAM. This is the type of memory most computers use for their main system memory. If you choose to upgrade your computer's SDRAM, check your machine's requirements to see if the memory modules must be 54

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

installed in pairs. If so, you will need to replace two modules at once and they must be the same size (i.e. two 1GB SDRAM memory modules).

Drive A drive is a computer component used to store data. It may be a static storage device or may use removable media. All drives store nonvolatile data, meaning the data is not erased when the power is turned off. Over the past several decades, drives have evolved along with other computer technologies. Below is a list of different types of computer drives. 1. 5.25 inch floppy drive - uses flexible removable media drive, stores up to 800 KB per floppy disk, popular in the 1980s 2. 3.5 inch floppy drive - uses more rigid removable media, stores up to 1.44 MB per disk, popular in the 1990s 3. Optical drive - uses removable optical media such as CDs (800 MB), DVDs (4.7 - 17 GB), and Blu-ray discs (25-50 GB), available in both read-only and writable models, popular in the 2000s 4. Flash drive - a small, highly portable storage device that uses flash memory and connects directly to a USB port 5. HDD (hard disk drive) - the most common internal storage device used by computers over the past several decades, can store several terabytes (TB) of data 55

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6. SSD (solid state drive) - serves the same purpose as a hard drive but contains no moving parts; uses flash memory and provides faster performance than a hard drive While there are many different types of drives, they are all considered secondary memory since they are not accessed directly by the CPU. Instead, when a computer reads data from a drive, the data first gets sent to the RAM so that it can be accessed more quickly. Even the fastest drives, likes SSDs, have much slower read/write speeds than RAM.

Why are computer drives called "drives?" While an official answer remains elusive, a compelling reason is that early drives required a rotating device that would spin or "drive" the disk. While some modern drives have no moving parts, the legacy term "drive" seems to have stuck

DSL Stands for "Digital Subscriber Line." DSL is a communications medium used to transferdigital signals over standard telephone lines. Along with

cable

Internet,

DSL

one

the

most

popular

ways ISPs provide broadbandInternet access. When you make a telephone call using a landline, the voice signal is transmitted using low frequencies from 0 Hz to 4 kHz. This range, called the "voiceband," only uses a small part of the frequency range supported by copper phone lines. Therefore, DSL makes use of the 56

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

higher frequencies to transmit digital signals, in the range of 25 kHz to 1.5 MHz. While these frequencies are higher than the highest audible frequency (20 kHz), then can still cause interference during phone conversations. Therefore, DSL filters or splitters are used to make sure the high frequencies do not interfere with phone calls. Symmetric DSL (SDSL) splits the upstream and downstream frequencies evenly, providing equal speeds for both sending and receiving data. However, since most usersdownload more data than they upload, ISPs typically offer asymmetric DSL (ADSL) service. ADSL provides a wider frequency range for downstream transfers, which offers several times faster downstream speeds. For example, an SDSL connection may provide 2 Mbps upstream and downstream, while an ASDL connection may offer 20 Mbps downstream and 1.5 Mbps upstream. In order to access the Internet using DSL, you must connect to a DSL Internet service provider (ISP). The ISP will provide you with a DSL modem, which you can connect to either a router or a computer. Some DSL modems now have built-in wireless routers, which allows you to connect to your DSL modem via Wi-Fi. A DSL kit may also include a splitter and filters that you can connect to landline phones. NOTE: Since DSL signals have a limited range, you must live within a specific distance of an ISP in order to be eligible for DSL Internet service. While most urban locations now have access to DSL, it is not available in many rural areas.

DSLAM 57

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Stands for "Digital Subscriber Line Access Multiplexer." A DSLAM is a device

used

Internet

Service

Providers

(ISPs)

route

incoming DSL connections to the Internet. Since a "multiplexer" combines multiple signals into one, a DSLAM combines a group of subscribers' connections into one aggregate Internet connection. For example, a DSL access multiplier may receive signals from all the DSL modems in a certain neighborhood and patch them through to the Internet backbone. The DSLAM processes each incoming connection and may limit the bandwidth of certain DSL lines. Most DSL service providers use multiple DSLAMs to help route incoming and outgoing traffic in the most efficient way possible.

Dual-Core A dual-core processor is a CPU with two processors or "execution cores"

the

sameintegrated

circuit.

Each

processor

has

its

owncache and controller, which enables it to function as efficiently as a single processor. However, because the two processors are linked together, they can perform operations up to twice as fast as a single processor can. The Intel Core Duo, the AMD X2, and the dual-core PowerPC G5 are all examples of CPUs that use dual-core technologies. These CPUs each combine two processor cores on a single silicon chip. This is different than a "dual processor" configuration, in which two physically separate CPUs work together. However, some high-end machines, such as the

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PowerPC G5 Quad, use two separate dual-core processors together, providing up to four times the performance of a single processor. While a dual-core system has twice the processing power of a singleprocessor machine, it does not always perform twice as fast. This is because the software running on the machine may not be able to take full advantage or both processors. Some operating systems and programs are optimized for multiprocessing, while others are not. Though programs that have been optimized for multiple processors will run especially fast on dual-core systems, most programs will see at least some benefit from multiple processors as well.

DVD Stands for "Digital Versatile Disc." A DVD is a type of optical media used for storing digitaldata. It is the same size as a CD, but has a larger storage capacity. Some DVDs are formatted specifically for video playback, while others may contain different types ofdata, such as software programs and computer files. The original "DVD-Video" format was standardized in 1995 by consortium of electronics companies, including Sony, Panasonic, Toshiba, and Philips. It

provided a number of

improvements

over analog VHS tapes, including higher quality video, widescreen aspect ratios, custom menus, and chapter markers, which allow you to jump to different sections within a video. DVDs can also be watched repeatedly without reducing the quality of the video and of course they don't need to be rewound. A standard video DVD can store 4.7 GB of 59

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

data,

which

enough

hold

over

hours

video

720p resolution, using MPEG-2 compression. DVDs

are

also

used

distribute

software programs.

Since

some applications and other software (such as clip art collections) are too large to fit on a single 700 MB CD, DVDs provide a way to distribute large programs on a single disc. Writable DVDs also provide a way to store a large number of files and back up data. The writable DVD

formats

include DVD-R, DVD+R, DVD-RW, DVD+RW,

and DVD-

RAM. While the different writable DVD formats caused a lot of confusion and incompatibility issues in the early 2000s, most DVD drives now support all formats besides DVD-RAM. A standard DVD can hold 4.7 GB of data, but variations of the original DVD format have greater capacities. For example, a dual-layer DVD (which has two layers of data on a single side of the disc) can store 8.5 GB of data. A dual-sided DVD can store 9.4 GB of data (4.7 x 2). A duallayer, dual-sided DVD can store 17.1 GB of data. The larger capacity formats are not supported by most standalone DVD players, but they can be used with many computer-based DVD drives

DVD+R Stands for "Digital Versatile Disc Recordable." DVD+R discs look the same as regular DVDs, but can be used to record data. Single-sided, single-layer DVD+R discs can store 4.7GB of data, while double-layer discs can store 8.5GB and double-sided DVD-Rs can store 9.4GB. The DVD+R format is not quite as common as the DVD-R format, but is still supported by most current DVD players and DVD-ROM drives. Drives 60

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

that can read both DVD+R and DVD-R discs are often referred to as DVD?R drives.

DVD+RW Stands for "Digital Versatile Disk Rewritable." A DVD+RW is like a DVD+R, but can be erased and rewritten. DVD+RWs must be completely erased in order for new data to be added. DVD+RW discs can hold 4.7GB of data and do not come in double-sided or doublelayer versions like DVD+Rs do. Still, 4.7GB of data is a lot of storage space. Combined with their ability to be re-recorded, DVD+RWs are a great choice for making frequent backups of your data. To record data onto a DVD+RW disc, you'll need a DVD burner that supports the DVD+RW format.

DVI Stands for "Digital Video Interface." DVI is a video connection standard created by the Digital Display Working Group (DDWG). Most DVI ports support both analog and digital displays. If the display is analog, the DVI connection converts the digital signal to an analog signal. If the display is digital, no conversion is necessary. There are three types of DVI connections: 1) DVI-A (for analog), 2) DVID (for digital), and 3) DVI-I (integrated, for both analog and digital). 61

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The digital video interface supports high bandwidth signals, over 160 MHz, which means it can be used for high resolution displays such as UXGA and HDTV. You may find DVI ports on video cards in computers as well as on high-end televisions.

Dvorak Keyboard The Dvorak keyboard is a keyboard layout named after its designer, Dr. August Dvorak. He designed the keyboard as alternative to the standard QWERTY keyboard

layout,

with

the

goal

improving

typing ergonomics. Dvorak developed the new keyboard layout after studying common typing patterns. He determined the QWERTY layout, which was designed for telegraph operators and early typewriters, was inefficient. It required awkward motions, didn't use the home row (ASDF) enough, and required many common key patterns to be typed with one hand. To improve typing efficiency, Dvorak designed his keyboard layout to alternate keystrokes between left and right hands. He also placed the most common letters in the home row. For example, since nearly all words have vowels, the home row on the Dvorak keyboard begins with the letters AOEUI. The vowel keys are placed next to each other since vowels often alternate with consonants. Dvorak patented his keyboard layout in 1936, claiming layout offered the faster typing speeds, greater accuracy, and less fatigue than the QWERTY keyboard. Despite these benefits, the Dvorak keyboard has 62

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

never achieved the popularity of the QWERTY layout. Most people still learn to type on a QWERTY keyboard and simply do not want to relearn a

new

keyboard

layout.

Therefore,

nearly

all desktop

computers and laptops sold in Western countries come with QWERTY keyboards. NOTE: The original version of the Dvorak keyboard is also known as the Dvorak Simplified Keyboard (DSK). In 1982, ANSI standardized a slight variation of the Dvorak keyboard layout, called the American Simplified Keyboard (ASK).

DVR Stands for "Digital Video Recorder." A DVR is basically a VCR that uses a hard drive instead of video tapes. It can be used to record, save, and play back television programs. Unlike a VCR, however, a DVR can also pause live TV by recording the current show in real time. The user can choose to fast forward (often during commercials) to return to live television. Most satellite and cable TV companies offer a DVR as an option with their digital television packages. Since cable boxes already provide program listings through some kind of TV guide interface, most DVRs allow users to use the guide to schedule recordings. For example, a user can use the remote to search through the guide's program listings for the current week and select the shows he would like to record. TiVo, the "brand name" DVR, performs the same functions as a DVR offered directly from a cable company. However, TiVo users can 63

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choose to buy the DVR box instead of renting it. Since TiVo is a standalone box, it does not require cable or satellite TV. While TiVo users who buy their own TiVo boxes may avoid the monthly rental fees, they must pay a monthly fee for program listings if they want to schedule recordings. DVRs conveniently save shows in an list that the user can access at any time. Since the shows are stored on DVR's hard drive, there is no need to rewind or fast forward to play a certain show, like a VCR requires. While DVRs make it even easier to record your favorite shows every week or even every day, it also makes it easier to watch more TV. And an excuse to watch more TV is something most of us don't need

E-reader An e-reader, or "e-book reader," is a portablehardware device designed for reading digitalpublications. These include e-books, electronic magazines, and digital versions of newspapers. Since textual data does not require a lot of storage space, most e-readers can store thousands of books and other publications. Just like an iPod can store an entire music library, a single e-reader can store a large collection of books. Dozens of different e-readers are available, but some of the most popular ones include the Amazon Kindle, the Barnes and Noble Nook, and the Sony Reader. These devices all support a wide range of eBook formats and can download content over a wirelessnetwork. Many ereaders have a monochrome display, often called "electronic paper," while others have a full-color backlit display. While the electronic paper 64

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displays do not provide color images, the screen appears more like a paper page from a book, and it can be easily viewed in bright sunlight. Tablets, such as the Apple iPad, the BlackBerry PlayBook, and the Amazon Kindle Fire are often considered e-readers, since they can be used for reading digital publications. However, it is more accurate to refer to these devices as tablets that can be used as e-readers since they are not designed primarily as digital readers. Tablets offer more capabilities than e-readers, but e-readers are often better suited for just reading e-books.

ECC Stands for "Error Correction Code." ECC is used to verify data transmissions by locating and correcting transmission errors. It is commonly used by RAM chips that include forward error correction (FEC), which ensures all the data being sent to and from the RAM is transmitted correctly. ECC RAM or memory is similar to parity RAM, which includes a parity bit

that

validates

the

data

being

sent.

The

parity

bit

redundantbinary value of 1 or 0 that is sent along with the data. If the parity bit does not match the value of the data it represents, it indicates an error in the transmission and the data may need to be resent. ECC works in a similar way, but uses a more advanced error correction system that can correct data transmission errors on the fly. Since ECC memory requires more processing, it can be slower than non-ECC RAM and basic parity RAM. However, ECC RAM provides more reliable data transfers, which results is greater system stability. 65

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Therefore, high-end servers and workstations may use ECC memory to minimize crashes and system downtime.

EIDE Stands for "Enhanced Integrated Drive Electronics." EIDE is an improved version of the IDE drive interface that provides faster data transfer rates than the original standard. While the original IDE drive controllers supported transfer rates of 8.3 Mbps, EIDE can transfer data up to 16.6 Mbps, which is twice as fast. The term EIDE can be a bit ambiguous, since it technically refers to an ATA standard known as ATA-2 or Fast ATA. Therefore, the terms EIDE, ATA-2, and Fast ATA may be used synonymously. To add to the confusion, EIDE may also refer to the ATA-3 standard, which is similar to ATA-2, but includes additional features. ATA-3 supports the same maximum data transfer rate as ATA-2, but has SMART support and uses a 44 pin connector. While EIDE was the most common drive controller used for many years, it has since been replaced by updated versions of the ATA standard that support Ultra DMA. These include the ATA-4 through ATA-7 standards, which provide data throughput rates from 33 to 133 Mbps. Most modern computers use a completely new standard called "Serial ATA," or SATA, which supports even faster transfer rates.

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eSATA Stands for "External Serial Advanced Technology Attachment." eSATA is a variation of the SATA interface that supports externalstorage devices. It

was

standardized

2004

and

uses

the

same

pins

and

same protocolsas internal SATA. However, it provides a slightly different, more rugged connector. The eSATA standard also supports a cable length of two meters compared to the one meter cable length supported by SATA. Since eSATA uses the same protocols as SATA, an eSATA drive offers the same high-speed data transfer rates as and internal SATA drive. For example, an eSATA 3.0 drive can transfer data at 6 Gbps or 4.8 Gbps, taking into account the data encoding process. This is significantly faster than Firewire 800 (800 Mbps) and USB 2.0 (480 Mbps) and is on par with USB 3.0 (5 Gbps). Because eSATA offers such fast transfer rates, it has been a popular external hard driveinterface used by video editors, audio producers, and other media professionals. While eSATA is one of the fastest interfaces available, it is surpassed by both Thunderbolt (10 Gbps) and Thunderbolt 2.0 (20 Gbps), which are alternatives to eSATA.

eSATAp Unlike Firewire, USB, and Thunderbolt, the eSATA interface does not provide power to connected devices. Therefore, all drives connected via eSATA must include a separate power connector to provide electricity to the device. A variation of eSATA, called eSATAp or eSATA 67

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

USB Hybrid Port (EUHP), combines four USB pins and two 12-volt power pins into the eSATA connector. An eSATAp port supports both eSATA and USB connectors. It allows connected devices to draw power from the computer's power supply, eliminating the need for a separate power cable.

Ethernet Ethernet, pronounced "E-thernet" (with a long "e"), is the standard way to connect computers on a network over a wiredconnection. It provides a

simple interface and

for

connecting

multiple

devices,

such

computers, routers, and switches. With a single router and a few Ethernet cables, you can create a LAN, which allows all connected devices to communicate with each other. A standard Ethernet cable is slightly thicker than a phone cable and has an RJ45 connector on each end. Ethernet ports look similar to telephone jacks, but are slightly wider. You can plug or unplug devices on an Ethernet network while they are powered on without harming them. Like USB, Ethernet has multiple standards that all use the same interface. These include: 

10BASE-T - supports up to 10 Mbps



100BASE-T - supports up to 100 Mbps



1000BASE-T (also called "Gigabit Ethernet") - supports up to 1,000 Mbps

Most Ethernet devices are backwards compatible with lower-speed Ethernet cables and devices. However, the connection will only be as 68

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

fast as the lowest common denominator. For example, if you connect a computer with a 10BASE-T NIC to a 100BASE-T network, the computer will only be able to send and receive data at 10 Mbps. If you have a Gigabit Ethernet router and connect devices to it using 100BASE-T cables, the maximum data transfer rate will be 100 Mbps. While Ethernet is still the standard for wired networking, it has been replaced in many areas by wireless networks. Wi-Fi allows you to connect

your laptop or smartphone to

network

without

being

tethered to the wall by a cable. The 802.11ac Wi-Fi standard even provides faster maximum data transfer rates than Gigabit Ethernet. Still, wired connections are less prone to interference and are more secure than wireless ones, which is why many businesses and organizations still use Ethernet. NOTE: Ethernet is also known by its technical name, "IEEE 802.3."

Expansion Card An expansion card is a printed circuit boardthat can be installed in computer to add functionality to it. For example, a user may add a new graphics card to his computer to give it more 3D graphics processing power. An audio engineer may add a professional sound card to his machine to increase the computer's audio input and output connections. Users that need more Firewireor USB ports can add Firewire or USB expansion cards, which provide additional connections. Most expansion cards are installed in PCI slots. This includes variations of PCI, such asPCI-X and PCI Express. Graphics cards may also be installed in an AGP slot, which is designed specifically for video cards. 69

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Since expansion cards require open slots, they can only be installed in computers that have available expansion slots. Therefore, computers like the Apple iMac and other all-in-one machines cannot accept expansion cards. Computer towers, however, often have two or three open expansion slots, and can accept multiple cards. Laptops don't use traditional expansion cards because of their small form

factor.

However,

some

models

can

removable PCMCIA cards that add extra ports or other functionality to the computer.

External Hard Drive Nearly all personal computers come with an internal hard drive. This drive stores the computer's operating system, programs, and other files. For most users, the internal hard drive provides enough disk space to store all the programs and files. However, if the internal hard drive becomes full or if the user wants to back up the data on the internal hard drive, and external hard drive may be useful. External

hard

drives

typically

have

one

two

interfaces

USB or Firewire. USB hard drives commonly use the USB 2.0 interface because it supports data transfer rates of up to 480 Mbps. USB 1.1 only supports transfers of up to 12 Mbps, which would make the hard drive seem slow to even the most patient people. Firewire drives may use either Firewire 400 or Firewire 800, which support data transfer rates of up to 400 and 800Mbps respectively.

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

The most likely users to need external hard drives are those who do audio and video editing. This is because high-quality media files can fill up even the largest hard drives. Fortunately, external hard drives can be daisy chained, which means they can be connected one after the other and be used at the same time. This allows for virtually unlimited amounts storage. Users who do not require extra storage may still find external hard drives useful for backing up their main hard drive. External hard drives are a great backup solution because they can store an exact copy of another hard drive and can be stored in a safe location. Using the drive to restore data or perform another backup is as simple as connecting it to the computer and dragging the necessary files from one drive to another. While most external hard drives come in heavy, protective cases, some hard drives are designed primarily for portability. These drives usually don't hold as much data as their larger desktop counterparts, but they have a sleek form factor and can easily be transported with a laptop computer. Some portable drives also include security features such as fingerprint recognition that prevent other people from accessing data on the drive in case it is lost.

Fiber Optic Cable Fiber optic cable is a high-speed datatransmission medium. It contains tiny glass or plastic filaments that carry light beams. Digitaldata is transmitted through the cable via rapid pulses of light. The receiving 71

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end of a fiber optic transmission translates the light pulses into binary values, which can be read by a computer. Because fiber optic cables transmit data via light waves, they can transfer information at the speed of light. Not surprisingly, fiber optic cables provide the fastest data transfer rates of any data transmission medium. They are also less susceptible to noise and interference compared to copper wires or telephone lines. However, fiber optic cables are more fragile than their metallic counterparts and therefore require more protective shielding. While copper wires can be spliced and mended as many times as needed, broken fiber optic cables often need to be replaced. Since

fiber

optic

large bandwidth, Internet backbone.

cables

they

are

provide used For

fast for

transfer a

large

example,

speeds part

and the most

transatlantictelecommunications cables between the U.S. and Europe are fiber optic. In recent years, fiber optic technology has become increasingly popular for local Internet connections as well. For example, some ISPs now offer "fiber Internet," which provides Internet access via a fiber optic line. Fiber connections can provide homes and businesses with data transfer speeds of 1 Gbps.

File Server As the name implies, a file server is a serverthat provides access to files. It acts as a central file storage location that can be accessed by multiple systems. File servers are commonly found in enterprise 72

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

settings, such as company networks, but they are also used in schools, small organizations, and even home networks. A file server may be a dedicated system, such as network attached storage (NAS) device, or it may simply be a computer that hosts shared files.

Dedicated

file

servers

are

typically

used

for

enterprise

applications, since they provide faster data access and offer more storage capacity than non-dedicated systems. In home networks, personal computers are often used as file servers. However, personal NAS devices are also available for home users that require more storage capacity and faster performance than a non-dedicated file server would allow. File servers can be configured in multiple ways. For example, in a home setting, a file server may be set to automatically allow access to all computers on the local network (LAN). In a business setting where security is important, a file server may require allclient systems to log in before accessing the server. Others may only grant access to a specific list of machines, which can be defined by MAC address or IP address. Internet file servers, which provide access to files over the Internet, often require an FTP login before users can download files. NOTE: When you connect to a file server on a local network, it usually appears as a hard disk on your computer. You can double-click the hard disk icon to view the contents and browse through directories on the server, just like local folders. If you want to copy a file from the server to your computer, simply drag the file to your desktop or another folder on your local disk. If the file server has write permissions enabled, you can also copy local files to the server by dragging them to a directory on the server. When you copy files to or from the file server, it may appear that they are simply being

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

transferred from one local folder to another. However, the files are actually being transferred across the network.

Firewire FireWire is an I/O interface developed by Apple Computer. It is also known as IEEE 1394, which is the technical name standardized by the IEEE. Other names for IEEE 1394 include Sony i.Link and Yamaha mLAN, but Apple's FireWire name the most commonly used. There are two primary versions of the FireWire interface â&#x20AC;&#x201C; FireWire 400 (IEEE 1394a) and FireWire 800 (IEEE 1394b). FireWire 400 uses a 6-pin connector and supports data transfer rates of up to 400 Mbps. FireWire 800 uses a 9-pin connector and can transfer data at up to 800 Mbps.

The

FireWire

800

interface,

which

was

introduced

on Macintosh computers in 2003, is backwards compatible with FireWire 400 devices using an adapter. Both interfaces support daisy chaining and can provide up to 30 volts of power to connected devices. FireWire is considered a high-speed interface, and therefore can be used for connectingperipheral devices that require fast data transfer speeds. Examples include external hard drives, video cameras, and audio interfaces. On Macintosh computers, FireWire can be used to boot a computer in target disk mode, which allows the hard drive to show up as an external drive on another computer. Mac OS X also supports networking two computers via a FireWire cable. While FireWire has never been as popular as USB, it has remained a popular choice for audio and video professionals. Since FireWire 74

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

supports speeds up to 800 Mbps, it is faster than USB 2.0, which maxes out at 480 Mbps. In fact, even FireWire 400 provides faster sustained read and write speeds than USB 2.0, which is important for recording audio and video in real-time. Future versions of IEEE 1394, such as FireWire 1600 and 3200, were designed to support even faster data transfer speeds. However, the FireWire interface has been superseded by Thunderbolt, which can transfer data at up to 10,000 Mbps (10 Gbps) and is backwards compatible with multiple interfaces

Flash Drive Flash drives have many names â&#x20AC;&#x201D; jump drives, thumb drives, pen drives, and USB keychain drives. Regardless of what you call them, they all refer to the same thing, which is a small data storage device that uses flash memoryand has a built-in USB connection. Flash drives are typically no more than two to three inches in length and less than an inch in width. Their size and shape may resemble a thumb or a small pen (which is where the names "thumb drive" and "pen drive" come from). Flash drives are also very thin, often having a depth of less than a centimeter. Because of their small form factor, they are highly portable and can easily fit in a pocket or on a keychain (hence the name "keychain drive"). Early flash drives could store only a few megabytes of data, but modern flash drives can store several gigabytes of information. Since they are small in size but have large storage capacities, flash drives have replaced most previous portable data storage mediums such 75

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

as floppy disks and removable hard disks like Zip disks. Because they have a built-in USB connection, flash drives also don't require a special disk drive to be used. Instead, they can be used on any computer with a USB port, which nearly all modern computers have.

Flash Memory Flash memory is a type of electrically erasable programmable read-only memory (EEPROM). Whew, that's a mouthful. The name comes from how the memory is designed -- a section of memory cells can be erased in a single action or in a "flash." A common use of flash memory is to store the BIOS settings in a computer's ROM. When the BIOS needs to be changed, the flash memory can be written in blocks, rather than bytes, making it easy to update. Most modems use flash memory for the same reason. Though flash memory was orginally used inside computers, it has invaded many other areas outside the box. Flash memory cards used for digital cameras, cellular phones, networking hardware, and PC cards. Though the memory's read/write speed is not lightning fast, it is nice to be able to tote around a little card rather than a cumbersome hard drive.

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Flatbed A flatbed is a type of scanner or copier that uses a flat, glass surface for scanning documents or other objects. Most flatbed scanners have an adjustable lid that can be raised to allow magazines, books, and other thick objects to be scanned. This is a significant benefit over sheet-fed scanners or copiers (sometimes referred to as automatic document feeders, which can only accept paper documents. Flatbed scanners and copy machines range in size from standard letter size (8.5"x11") to legal size and beyond. For example, a scanner used to scan architectural blueprints may be the size of several letter-size scanners. Because of their large size capacity and ability to scan thick objects, flatbed scanners are more versatile than sheet-fed scanners. However, they cannot automatically feed pages into the scanner, which means scanning multiple pages can be a time-consuming process. For this reason, some scanners and copy machines include both a flatbed scanning surface for large or thick objects, and an ADF for feeding multiple pages at once.

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Floppy Disk Floppy disks have an interesting name, considering they do not appear to be "floppy." However, if you take the actual disk out of the protective casing, you will discover that the disk is, in fact, rather flexible. It is coated with iron oxide and stores data magnetically, just like a hard disk. The first floppy disks were created in 1969, the same year the Internet had its origin. These disks were 8 inches in diameter and were read-only, like a CD-ROM, meaning no data could be written to them by the user. The first 8 inch disks only held 80KB of data, but later versions could hold as much as 800KB. In 1978, a 5.25 inch disk was introduced, which could hold a whopping 360KB of data. Later revisions of the 5.25 inch floppy disk could store 1.2MB. These disks were used in early desktop PCs, such as the Apple IIe. In 1987, the 3.5 inch HD (high density) floppy disk was released, which could hold 1.44MB after being formatted. These disks were a little more durable than the 5.25 inch disks and were also more portable. For the next decade, the 3.5 inch floppy disk became the standard means of distributing commercial software titles and backing up personal data. In the late 1990s, CD-ROMs began to replace floppy disks as the standard means of distributing software. A few years later, consumers began migrating to recordable CDsfor backing up their data. Apple's original iMac, released in 1998, was the first mainstream computer to 78

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not even include a floppy disk drive. While it took several years, many PC manufacturers eventually followed suit. Now most software is distributed on CDs and DVDs and most people back up their data either on recordable CDs or USB flash drives. Floppy disks are finally becoming a thing of the past, which is good, considering they are notorious for losing data. Still, the floppy disk will always have a special place in the hearts and minds of veteran computer users as it was the data storage medium many people grew up with

FPGA Stands for "Field-Programmable Gate Array." An FPGA is an integrated circuit that can be customized for a specific application. Unlike traditional CPUs, FGPAs are "field-programmable," meaning they can be configured by the user after manufacturing. FPGAs contain programmable logic blocks that can be wired in different configurations. These blocks create a physical array of logic gates that can be used to perform different operations. Because the gates are customizable, FPGAs can be optimized for any computing task. This gives FPGAs the potential to perform operations several times faster than a hard-wired processor. Field-programmable gate arrays are typically customized using a hardware description language, or HDL. A programmer can use HDL commands to configure the gate interconnects (how the gates connect to each other) as well as the gates themselves. For example, a gate may be assigned a boolean operator, such as AND, OR, or XOR. By 79

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linking several gates together, it is possible to perform advanced logic operations. Since FPGAs are designed to be programmed for specific applications, they are not suitable for personal computers. However, they have a wide

variety

field

applications.

Examples

include telecommunications, data centers, scientific computing, and audio/video processing. Besides being used in servers and highend computers, they can also be implemented in electronic devices, such as TVs, radios, and medical equipment.

FPU Stands for "Floating Point Unit." An FPU is aprocessor or part of a processor that performs floating point calculations. While early FPUs were standalone processors, most are now integrated inside a computer's CPU. Even without an floating point unit, a CPU can handle both integer and floating point (non-integer) calculations. However, integer operations use significantly different logic than floating point operations, which makes it inefficient to use the same processor to handle both types of operations. An FPU provides a faster way to handle calculations with non-integer numbers. Any

mathematical

operation,

such

addition,

subtraction,

multiplication, or division can be performed by either the integer processing unit or the FPU. When a CPU receives an instruction, it automatically sends it to the corresponding processor. For example, 12 + 5 would be processed as an integer calculation, 80

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while 1.0023 x 5.789 would get sent to the FPU. While it is possible for a programmer to write an instruction specifically for either processing unit, it is usually unnecessary. Since integer and floating point performance can vary significantly, most processor benchmarks include both types of operations. Integer calculation speed is typically listed as "integer performance" and is labeled "SPECint" in SPEC benchmarks. FPU calculation speed is often listed as "floating point performance" and can be measured inFLOPS.

FSB Stands for "frontside bus." The FSB connects the computer's processor to the system memory (RAM) and other components on the motherboard. These components include the system chipset, AGP card, PCI devices, and other peripherals. Because the FSB serves as the main path from the processor to the rest of the motherboard, it is also called the "system bus." The speed of the frontside bus is measured in Megahertz or Gigahertz, just like the processor. Most computers' processors run faster than their system buses, so the FSB speed is typically a ratio of the processor speed. For example, a Pentium 4 processor that runs at 2.4 GHz may have an FSB speed of only 400 MHz. The CPU to FSB ratio would be 6:1. A Power Mac G5, however, with a 2.0 GHz processor, has a 1.0 GHz frontside bus. Therefore, its CPU to FSB ratio is 2:1. The smaller the ratio, the more efficiently the processor can work. Therefore, 81

faster

frontside

bus

speeds

lead

faster

overall

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

performance. When the CPU to FSB ratio is high, the processor often has to wait for data to be sent out over the system bus before getting new data to process. For this reason, the FSB can be a bottleneck in a computer's performance. So if you are looking for a fast computer, don't just check the processor speed, but find out what the frontside bus speed is as well.

Gateway A gateway is a hardware device that acts as a "gate" between two networks. It may be arouter, firewall, server, or other device that enables traffic to flow in and out of the network. While a gateway protects the nodes within network, it also a node itself. The gateway node is considered to be on the "edge" of the network as all data must flow through it before coming in or going out of the network. It may also translate data received from outside networks into a format or protocolrecognized by devices within the internal network. A router is a common type of gateway used in home networks. It allows computers within the local network to send and receive data over the Internet. A firewall is a more advanced type of gateway, which filters inbound and outbound traffic, disallowing incoming data from suspicious or unauthorized sources. A proxy server is another type of gateway that uses a combination of hardware and software to filter traffic between two networks. For example, a proxy server may only allow local computers to access a list of authorized websites. 82

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NOTE: Gateway is also the name of a computer hardware company founded in the United States in 1985. The company was acquired by Acer in 2007 but still sells computers under the Gateway name

GPU Stands for "Graphics Processing Unit." Like the CPU (Central Processing Unit), it is a single-chip processor. However, the GPU is used primarily for computing 3D functions. This includes things such as lighting effects, object transformations, and 3D motion. Because these types of calculations are rather taxing on the CPU, the GPU can help the computer run more effienciently. The first company to develop the GPU was NVidia, Inc. Its GeForce 256 GPU can process 10 million polygons per second and has over 22 million transistors. Compare that to the 9 million transistors found on the Pentium III chip. Wow -- that's a lot of processing power. There is also a workstation version of the chip called the Quadro, designed for CAD applications. This chip can process over 200 billion operations a second and deliver up to 17 million polygons per second. If only you could think that fast during those darn Calculus tests..

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Hard Disk When you save data or install programs on your computer, the information is typically written to your hard disk. The hard disk is a spindle of magnetic disks, called platters, that record and store information. Because the data is stored magnetically, information recorded to the hard disk remains intact after you turn your computer off. This is an important distinction between the hard disk and RAM, or memory, which is reset when the computer's power is turned off. The hard disk is housed inside the hard drive, which reads and writes data to the disk. The hard drive also transmits data back and forth between the CPU and the disk. When you save data on your hard disk, the hard drive has to write thousands, if not millions, of ones and zeros to the hard disk. It is an amazing process to think about, but may also be a good incentive to keep a backup of your data.

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Hard Drive The hard drive is what stores all your data. It houses the hard disk, where all your files and folders are physically located. A typical hard drive is only slightly larger than your hand, yet can hold over 100 GB of data. The data is stored on a stack of disks that are mounted inside a solid encasement. These disks spin extremely fast (typically at either 5400 or 7200 RPM) so that data can be accessed immediately from anywhere on the drive. The data is stored on the hard drive magnetically, so it stays on the drive even after the power supply is turned off. The term "hard drive" is actually short for "hard disk drive." The term "hard disk" refers to the actual disks inside the drive. However, all three of these terms are usually seen as referring to the same thing -the place where your data is stored. Since I use the term "hard drive" most often, that is the correct one to use.

HDD Stands for "Hard Disk Drive." "HDD" is often used interchangeably with the terms "hard drive" and "hard disk." However, the term "hard disk drive" is technically the most accurate, since "hard drive" is short for "hard disk drive" and the "hard disk" is actually contained within the hard disk drive. 85

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The HDD is the most common storage deviceused to store data. Most computers made in the 1980s, 1990s, and 2000s include an internal hard disk drive. The first PCs had hard drives that were less than one megabytein

size,

while

modern

hard

drives

may

contain

several terabytes of data. Some desktop computers have multiple internal hard drives, and external hard drives are often used for additional storage or backup purposes. HDDs are non-volatile, meaning they do not need electrical power to maintain their data. They store data magnetically using a series of spinning platters, or magnetic discs, which record individual bits as ones and zeroes. Data is recorded using a write head that writes bits onto the disk. A read head is used to read data from the disk. Both of these heads are located at the end of a tapered metal component called an actuator arm. The appearance is similar to a turntable, but the hard disk spins hundreds of times faster than a record. Additionally, an HDD reads data digitally, while a record player captures an analog signal. Hard disk drives come in many shapes and sizes, but 3.5 inch models are most common in desktop computers, and 2.5 inch models are usually found in laptops. A typical consumer HDD has a rotational speed of 7200 RPM, but some high-end hard disk drives run as fast as 15,000 RPM. Laptop HDDs typically run at either 4800 or 5400 RPM. Even at the fastest rotational speed, hard drives are still limited by the "seek time" of the drive head. Therefore, SSDs, which do not have a drive head, have become a popular high-performance alternative to HDDs in recent years

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HDMI Stands for "High-Definition Multimedia Interface." HDMI is a digital interface for transmitting audio and video data in a single cable. It is supported

most HDTVs and

components,

such

as DVD and Blu-rayplayers, cable boxes, and video game systems. While other types of A/V connections require separate cables for audio and video data, HDMI carries the audio and video streams together, greatly eliminating cable clutter. For example, a component cable connection requires three cables for video and two for audio, totaling five cables in all. The same information can be transmitted using one HDMI cable. Because HDMI is a digital connection, HDMI cables are less prone to interference and signal noise than analog cables. Also, since most components, such as DVD players and digital cable boxes process information digitally, using HDMI eliminates the analog to digital conversion other interfaces require. Therefore, HDMI often produces the best quality picture and sound compared to other types of connections. HDMI cables are typically more expensive than analog cables, largely because they cost more to manufacture. But it is important to remember that with HDMI, you don't need to buy separate audio and video cables. Besides, the single all-purpose connection may alone be worth the difference to those who don't like dealing with confusing cables and connections. Just remember that before you buy an HDMI 87

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

cable, make sure the devices you are connecting have HDMI connections available.

Heat Sink A computer's CPU may perform millions of calculations every second. As the processor continues to work at a rapid pace, it begins to generate heat. If this heat is not kept in check, the processor could overheat and eventually destroy itself. Fortunately, CPUs include a heat sink, which dissipates the heat from the processor, preventing it from overheating. The heat sink is made out of metal, such as a zinc or copper alloy, and is attached to the processor with a thermal material that draws the heat from away the processor towards the heat sink. Heat sinks can range in size from barely covering the processor to several times the size of the processor if the CPU requires it. Most heat sinks also have "fins," which are thin slices of metal that are connected to the base of the heat sink. These additional pieces of metal further dissipate the heat by spreading it over a much larger area. A fan is often used to cool the air surrounding the heat sink, which prevents the heat sink from getting too hot. This configuration is referred to as a heat sink and fan or HSF combination. While heat sinks are used in nearly all computer CPUs, they have become commonplace in video card processors, orGPUs, as well.

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Host A host is a computer that is accessible over anetwork. It can be a client, server, or any other type of computer. Each host has a unique identifier called a hostname that allows other computers to access it. Depending on the network protocol, a computer's hostname may be a domain name, IP address, or simply a unique textstring. For example, the hostname of a computer on a local network might be Tech-Terms.local, while an Internet hostname might be techterms.com. A host can access its own data over a network protocol using the hostname "localhost."

Host vs Server The terms host and server are often used interchangeably, but they are two different things. All servers are hosts, but not all hosts are servers. To avoid confusion, servers are often defined as a specific type of host, such as a web host or mail host. For instance, a mail host and mail server may refer to the same thing. While a server refers to a specific machine, a host may also refer to an organization that provides a service over the Internet. For example, a web host (or web hosting company) maintains multiple web servers and provides web hosting services for clients. A file host may provide online storage using multiple file servers. In other words, a hosting company hosts multiple servers that serve data to clients.

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Hot Swappable In electronics terminology, the word "hot" is often used to mean "active" or "powered on." Therefore, a hot swappable device is aperipheral or component that can be removed or added while a computer is running. Replacing a device while a computer is powered on is called "hot swapping." Most early I/O devices were not hot swappable. This is because early ports, such as parallel ports and SCSI ports did not support connecting or removing devices while the computer was powered on. In fact, removing devices from these older ports while the computer was running could cause damage to them or the computer. Since it was hassle for users to turn off their computers each time they needed to connect or reconnect a device, newer I/O ports were designed to be hot

swappable.

Modern

ports

that

support

hot

swapping

includeUSB, FireWire, and Thunderbolt. Most modern PCs include only hot swappable ports. Therefore, the term is now used most often to describe internal components that can be replaced while the computer is running. A common example is a server hard drive. Since servers need to run constantly to avoid downtime, they typically support hot swappable hard drives. Rackbased servers often provide easy access to one or more hard drives on the front face of the rack unit. This allows server administrators to quickly add more storage or replace old hard drives without powering down the server. NOTE: Except for rare exceptions, RAM is generally not hot swappable. 90

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HSF Stands for "Heat Sink and Fan." Nearly all computers have heat sinks, which help keep the CPU cool and prevent it from overheating. But sometimes the heat sink itself can become too hot. This can happen if the CPU is running at full capacity for an extended period of time or if the air surrounding the computer is simply too hot. Therefore, a fan is often used in combination with the heat sink to keep both the CPU and heat sink at an acceptable temperature. This combination is creatively called a "heat sink and fan," or HSF. The fan moves cool air across the heat sink, pushing hot air away from the computer. Each CPU has a thermometer built in that keeps track of the processor's temperature. If the temperature becomes to hot, the fan or fans near the CPU may speed up to help cool the processor and heat sink

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Hub There are two primary types of hubs in the computing world: 1) network hubs and 2) USB hubs.

1. Network hub A network hub is a

device that allows

communicate

each

with

other

over

multiple computers to a

network.

has

several Ethernet ports that are used to connect two or more network devices together. Each computer or device connected to the hub can communicate with any other device connected to one of the hub's Ethernet ports. Hubs are similar to switches, but are not as "smart." While switches send incoming datato a specific port, hubs broadcast all incoming data to all active ports. For example, if five devices are connected to an 8port hub, all data received by the hub is relayed to the five active ports. While this ensures the data gets to the right port, it also leads to inefficient use of the network bandwidth. For this reason, switches are much more commonly used than hubs.

2. USB hub A USB hub is a device that allows multiple peripherals to connect through a single USBport. It is designed to increase the number of USB devices you can connect to a computer. For example, if your computer has two USB ports, but you want to connect five USB devices, you can 92

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connect a 4-port USB hub to one of the ports. The hub will create four ports out of one, giving you five total ports. The USB interface allows you to daisy chain USB hubs together and connect up to 127 devices to a single computer. Some USB hubs include a power supply, while others do not. If you're connecting basic devices like a mouse, keyboard, and USB flash drive, an unpowered or "passive" USB hub should work fine. However, some peripherals,

like external

hard

drives and

backlitkeyboards,

require additional electrical power. In order for these types of devices to function through a USB hub, you may need use a powered or "active" hub that provides 5 volts of power to connected devices.

I/O Address Each I/O device connected to your computer is mapped to a unique I/O (Input/Output) address. These addresses are assigned to every I/O port

your

computer,

includingUSB, Firewire, Ethernet, VGA,

and DVI ports, as well as any other ports your computer might have. Having a unique address assigned to each port allows your computer to easily recognize and locate devices attached to your computer. Whether it is a keyboard, mouse, monitor, printer, or any other device, the computer can locate it by its I/O address. Because I/O addresses are controlled by the computer's motherboard, they do not use up any system memory, or RAM.

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IBM Compatible The personal computer market in the early 1980's consisted primarily of Apple and IBM computers. Apple's systems ran a proprietary operating system developed by Apple, while IBM machines primarily ran PC-DOS. As the demand for personal computers began to grow, IBM

decided

license

the DOSoperating

system

other

manufacturers. These companies began producing personal computers that were called PC clones or IBM compatibles. As several other manufacturers began producing PCs, supplies grew and costs began to drop. This enabled more people to afford PCs and sales of IBM compatibles began to dominate the personal computer market. It wasn't long until the new manufacturers' PC sales surpassed the number of computers sold directly by IBM. The Apple Macintosh also gained substantial market share when it was introduced in 1984, but the low cost and wide availability of IBM compatibles kept their sales strong. Sales of IBM compatibles surged again in 1995, when Microsoft introduced the Windows 95 operating system. However, by that time, the term "IBM compatible" had become almost irrelevant, since most PCs used Microsoft Windows as the primary operating system. Also, PC manufacturers had been building their own computers for many years, and there were few similarities between IBM's own PCs and IBM compatibles.

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In 2005, IBM stopped manufacturing personal computers. The company that started the PC revolution is no longer in the market. Therefore, the term "IBM compatible" is a bit outdated, though it can still be used to describe Windows-based computers. The term "PC" is more appropriate, albeit a bit ambiguous, since Macs are technically PCs too. Therefore, the term "Windows computer" seems to be the best way to describe a modern day IBM compatible.

IDE IDE stands for both "Integrated Device Electronics" and "Integrated Development Environment." The first is a hardware term, while the second is related to softwareprogramming.

1. Integrated Device Electronics IDE was the most widely-used type of hard drive from the mid 1990s to the late 2000s. The "integrated" aspect of the name describes how the controller is integrated into thedrive itself. IDE and ATA are often used synonymously since they both refer to the same type of hard drive. However, ATA describes the interface while IDE describes the actual hard drive. The

first

IDE

standard

(ATA-1)

was

released

1994

and

supported data transfer rates of 8.3 Mbps in DMA mode. Enhanced IDE (ATA-2) was standardized in 1996 and supported data transfer rates up to 16.7 Mbps â&#x20AC;&#x201C; twice the rate of the original standard. The next several IDE standards were labeled using ATA versions (up to ATA-7), 95

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

maxing out at 133 Mbps. The IDE interface was eventually superseded by SATA, an even faster interface.

2. Integrated Development Environment A

software

IDE

an application that developers use

create

computer programs. In this case, "integrated" refers to the way multiple development tools are combined into a single program. For example, a typical IDE includes a source code editor, debugger, andcompiler. Most IDEs also provide a project interface that allows programmers to keep track of all files related to a project. Many support version control as well. Some IDEs provide a runtime environment (RTE) for testing software programs. When aprogram is run within the RTE, the developer can track each event that takes place within the application being tested. This can be useful for finding and fixing bugs and locating the source of memory leaks. Because IDEs provide a centralized user interfacefor writing code and testing programs, a programmer can make a quick change, recompile the program, and run the program again. Programming is still hard work, but IDE software helps streamline the development process.

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IGP Stands for "Integrated Graphics Processor." An IGP is a graphics chip that is integrated into a computer's motherboard. The IGP serves the same purpose as a video card, which is to process the graphics displayed on the computer. Integrated graphics processors take the graphcis portion of the processing load off the main CPU. However, because IGPs are soldered onto the motherboard, their size is limited and they cannot use a dedicated fan to cool them, like some video cards do. For this reason, IGPs typically do not have the same performance as video cards, which may

attached

the

computer's PCI or AGP slots.

Because

integrated graphics processors cannot be removed, they also cannot be upgraded like video cards can. However, because of their small size, IGPs are a good solution for laptop computers and entry-level desktop PCs.

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IMAP Stands for "Internet Message Access Protocol" and is pronounced "eyemap." It is a method of accessing e-mail messages on a server without having to download them to your local hard drive. This is the main difference between IMAP and another popular e-mail protocol called "POP3." POP3 requires users to download messages to their hard drive before reading them. The advantage of using an IMAP mail server is that users can check their mail from multiple computers and always see the same messages. This is because the messages stay on the server until the user chooses to download them to his or her local drive. Most webmail systems are IMAP based, which allows people to access to both their sent and received messages no matter what computer they use to check their mail. Most e-mail client programs such as Microsoft Outlook and Mac OS X Mail allow you to specify what kind of protocol your mail server uses. If you use your ISP's mail service, you should check with them to find out if their mail server uses IMAP or POP3 mail. If you enter the wrong protocol setting, your e-mail program will not be able to send or receive mail.

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Impact Printer An impact printer is a type of printer that operates by striking a metal or plastic head against an ink ribbon. The ink ribbon is pressed against the paper, marking the page with the appropriate character, dot, line, or symbol. Common examples of impact printers include dot matrix, daisy-wheel printers, and ball printers. Dot matrix printers work by striking a grid of pins against a ribbon. Different characters are printed by using different pin combinations. Daisy-wheel printers use a circular wheel with "petals" that each have a different character or symbol on the end. In order to print each character, the wheel spins to the appropriate petal and a hammer strikes the petal against the ribbon and the page. Similarly, ball printers use a spherical ball with raised characters on the outside. The ball spins to each character before printing it on the page. While impact printers still have some uses (such as printing carbon copies), most printers are now non-impact printers. These printers, such as laser and inkjet printers are much quieter than impact printers and can print more detailed images.

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Inkjet Inkjet printers are the most common type of consumer printers. The inkjet technology works by spraying very fine drops of ink on a sheet of paper. These droplets are "ionized" which allows them to be directed by magnetic plates in the ink's path. As the paper is fed through the printer, the print head moves back and forth, spraying thousands of these small droplets on the page. While inkjet printers used to lack the quality and speed of laser printers, they have become almost as fast as laser printers and some can even produce higher-quality images. Even low-budget inkjet printers can now print high-resolution photos. The amazing thing is, as the quality of inkjet printers has improved, the prices have continued to drop. However, for most people, refilling the inkjet cartridges a few times will often cost more than the printer.

100

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Input Device An input device is any device that providesinput to a computer. There are dozens of possible input devices, but the two most common ones are a keyboard and mouse. Every key you press on the keyboard and every movement or click you make with the mouse sends a specific input signal to the computer. These commands allow you to open programs, type messages, drag objects, and perform many other functions on your computer. Since the job of a computer is primarily to process input, computers are pretty useless without input devices. Just imagine how much fun you would have using your computer without a keyboard or mouse. Not very much. Therefore, input devices are a vital part of every computer system. While most computers come with a keyboard and mouse, other input devices may also be used to send information to the computer. Some examples include joysticks, MIDIkeyboards, microphones, scanners, digital cameras, webcams, card readers, UPC scanners, and scientific measuring equipment. All these devices send information to the computer

and

therefore

devices. Peripherals that

output

are

categorized

data

from

the

as computer

input are

called output devices

101

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Integrated Circuit An integrated circuit, or IC, is small chip that can function as an amplifier, oscillator, timer,microprocessor, or even computer memory. An IC is a small wafer, usually made of silicon, that can hold anywhere from hundreds to millions of transistors, resistors, and capacitors. These extremely small electronics can perform calculations and store data using either digital or analog technology. Digital ICs use logic gates, which work only with values of ones and zeros. A low signal sent to to a component on a digital IC will result in a value of 0, while a high signal creates a value of 1. Digital ICs are the kind you will usually find in computers, networking equipment, and most consumer electronics. Analog, or linear ICs work with continuous values. This means a component on a linear IC can take a value of any kind and output another value. The term "linear" is used since the output value is a linear function of the input. For example, a component on a linear IC may multiple an incoming value by a factor of 2.5 and output the result. Linear ICs are typically used in audio and radio frequency amplification.

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Interface The term "interface" can refer to either a hardware connection or a user interface. It can also be used as a verb, describing how two devices connect to each other. A hardware interface is used to connect two or more electronic devices together. For example, a printer typically connects to a computer via a USB interface. Therefore, the USB port on the computer is considered the hardware interface. The printer itself also has a USB interface, which is where the other end of the USB cable connects. Several common peripherals connect to a computer via USB, while other devices

use

a Firewireconnection

other

interface. Ethernet connections are commonly used for networking, which is why most cable modems and routers have an Ethernet interface. Many other electronic devices besides computers use some type of interface to connect to other equipment. For example, a TV may connect to a Blu-ray player via an HDMIcable and may connect to a cable box using component cables. Audio devices may have either analog or digital audio connections and may include a MIDI interface, which is used to transfer MIDI data. iPods have a proprietary "dock connector" interface, which allows them to connect to a power source and transfer data via USB. Since there are many different types of electronic devices, there are also a lot of hardware interfaces. Fortunately, standards like USB, Firewire, HDMI, and MIDI have helped consolidate the number of 103

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interfaces into a manageable number. After all, it would be pretty difficult if each digital camera, printer, keyboard, and mouse used a different interface. Computers would need a lot more ports on the back!

Internal Hard Drive An internal hard drive is a hard drive that resides inside the computer. Most computers come with a single internal hard drive, which includes the operating

system and

pre-installed applications.

While

laptop

computers only have room for one internal hard drive, some desktop computers have multiple hard drive bays, which allows for multiple internal hard drives. Internal hard drives have two main connections â&#x20AC;&#x201C; one for data and another for power. The data port may have an ATA or aSATA interface. This interface connects to the computer's hard drive controller, which enables the drive to communicate with the motherboard. The power connector attaches to an electrical cable, which provides power from the computer's main power supply. The internal hard drive is a key component of a computer since it stores the user's software and personal files. While the rest of a computer's components can be easily replaced, if a hard drive fails, the data may not be able to be recovered. Therefore, it is wise to regularly back up the data stored on an internal hard drive using an external hard drive or an online backup service.

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iPad The iPad is a tablet computer developed by Apple. It is smaller than a typical laptop, but significantly larger than the averagesmartphone. The iPad does not include akeyboard or a trackpad, but instead has atouchscreen interface, which is used to control the device. Like the iPhone, the iPad runs Apple's iOS operating system. This allows the iPad to runthird-party apps, which can downloaded from Apple's App Store. While apps designed for the iPhone can also be installed and run on the iPad, many iOS apps are developed specifically for the iPad. Since the iPad's screen is much larger than the iPhone's screen, iPad apps can include more user interfacefeatures that would not fit within an iPhone app. Therefore, productivity, graphics, and video-editing apps are often developed specifically for the iPad rather than the iPhone. The iPad's 9.7 in screen size also makes it ideal as an e-reader. The iBooks app allows you to download electronic versions of books from the iBookstore and read them on your iPad. Since the iPad has a full color screen, it supports novels as well as art books and illustrated children's stories. Books can be read one page at a time in portrait mode or with pages side by side in landscape mode. All versions of the iPad include Wi-Fi capability, which can be used for surfing the Web, checking email, and downloading apps directly to the device. Some versions of the iPad also include 3G support for transferring data over a cellular connection, though this capability requires a monthly cellular service contract. While the original iPad did 105

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not include a camera, the iPad 2 includes both rear-facing and frontfacing cameras. These cameras can be used for video conferencing with other iPad, iPhone, or Mac users via the FaceTime feature.

iPhone The iPhone is a smartphone developed by Apple. The first iPhone was released in June, 2007 and an updated version has been released roughly every year since then. While the iPhone was originally only available to AT&T customers, the iPhone 4 was released on the Verizon network in February, 2010. The iPhone has a sleek, minimalist design, and differs from other smartphones in its lack of buttons. Most operations on the iPhone are performed using the touch screen display. The only physical buttons include a sleep/wake button, a mute switch, volume up/down buttons, and a home button. All versions of the iPhone have a rear-facing camera, but the iPhone 4 introduced a front-facing camera, which can be used for video calls made using the FaceTime feature. The iPhone 4 also includes a 960 x 640 pixel "retina display," which has double theresolution of previous iPhone displays. Internally, the iPhone runs the iOS, an operating system developed by Apple for portable devices. This allows the iPhone to run "apps," or applications developed

specifically

for

the

iPhone.

Apps

can

be downloaded from Apple's App Store, which can be accessed through iTunes or directly from the iPhone's built-in App Store app. There are hundreds of thousands of apps available from the App Store, which provide the iPhone with limitless functionality. 106

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An example of an iPhone app is the ChatSlang.com app, which provides meanings of chat abbreviations and emoticons.

iPod The iPod is a portable music player developed by Apple Computer. Though it is an Apple product, the iPod can be used with both Macs and PCs. The iTunes software, also created by Apple, is used to organize and transfer songs and playlists to the iPod. Both iTunes and the iPod support a wide variety of audio formats, including MP3, AAC, WAV, and AIFF. MP3 is the most common audio compression format, while AAC is the format used by the iTunes Music Store. WAV and AIFF are nearly identical formats that store CD-quality audio. Since introducing the iPod in 2001, Apple has released several new versions of the popular device. These include iPod, iPod mini, iPod Special Edition, iPod photo, and iPod shuffle. iPod mini is a smaller version of the iPod that comes in various colors and stores fewer songs. iPod Special Edition is a variation of the basic iPod (the first being a black U2 iPod with the signatures of the band members on the back). iPod photo is an iPod with a color screen that allows users to store and view a library of photos as well as play music. iPod shuffle is an extra small iPod that only holds a couple hundred songs and does not have a screen. All iPods store data on an internal hard drive, except the iPod Shuffle, which uses flash memory. This means each iPod, including the shuffle, can also be used as a hard drive. Aside from being a music player, the 107

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iPod can serve as a backup device, a basic organizer, and an alarm clock. To transfer files to the iPod, you must first connect it to your computer using a USB or Firewire cable. iTunes can automatically transfer your playlists and songs or you can change the program's preferences to manually update the iPod. Because of its superb interface and unmatched ease of use, the iPod has become the staple product of the portable music player market. Granted, the "cool factor" of owning an iPod has certainly helped it gain popularity as well.

IRQ Stands for "Interrupt Request." PCs use interrupt requests to manage various hardware operations. Devices such as sound cards, modems, and keyboards can all send interrupt requests to the processor. For example, when the modem needs to run a process, it sends an interrupt request to the CPU saying, "Hey, hold up, let me do my thing!" The CPU then interrupts its current job to let the modem run its process. It is important to assign different IRQ addresses to different hardware devices is because the interrupt request signals run along single IRQ lines to a controller. This interrupt controller assigns priorities to incoming IRQs and sends them to the CPU. It's kind of like taking a number at the local deli, except the hardware usually only has to wait a couple of nanoseconds instead of like twenty minutes). Since the interrupt controller can control only one device per IRQ line, if you 108

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assign the same IRQ address to multiple devices, you are likely to get an IRQ conflict. This can cause a range of errors from not allowing network connections to crashing your computer. So make sure you assign unique IRQs to new hardware you install and avoid the frustration and keyboard throwing that conflicts can cause.

ISA Stands for "Industry Standard Architecture." ISA is a type of bus used in PCs for adding expansion cards. For example, an ISA slot may be used to add a video card, a network card, or an extra serial port. The original 8-bit version of PCI uses a 62 pin connection and supports clock speeds of 8 and 33 MHz. 16-bit PCI uses 98 pins and supports the same clock speeds. The original 8-bit version of ISA was introduced in 1981 but the technology did not become widely used until 1984, when the 16-bit version was released. Two competing technologies -- MCA and VLB -were also used by some manufacturers, but ISA remained the most common expansion bus for most of the 1980s and 1990s. However, by the end of the twentieth century, ISA ports were beginning to be replaced by faster PCI and AGP slots. Today, most computers only support PCI and AGP expansion cards.

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Joystick A joystick is an input device commonly used to control video games. Joysticks consist of a base and a stick that can be moved in any direction. The stick can be moved slowly or quickly and in different amounts. Some joysticks have sticks that can also be rotated to the left or right. Because of the flexible movements a joystick allows, it can provide much greater control than the keys on a keyboard. Joysticks typically include several buttons as well. Most joysticks have at least one button on the top of the stick and another button in the front of the stick for the trigger. Many joysticks also include other buttons on the base that can be pressed using the hand that is not guiding the stick. Joysticks typically connect to your computer using a basic USB or serial port connection and often come with software that allows you to assign the function of each button. Since joysticks emulate the controls of planes and other aircraft, they are best suited for flight simulators and flying action games. However, some gamers like to use joysticks for other types of video games, such as first-person shooters and fighting games. Others prefer using the basic keyboard and mouse, with which they are already accustomed to.

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Jumper This is a small metal connector that acts as an on/off switch and is used to alter hardware configurations. A jumper is typically made of two wires and a small piece of metal. When the wires are connected by the metal piece, the jumper is turned on, completing the circuit. When the wires are disconnected, the jumper is turned off. Mulitple jumpers, referred to collectively as a jumper block, are often used to tell the computer how a certain device, such as a hard drive or a modem, is configured. They can be found on motherboards, sound cards, graphics cards, I/O cards, CD-ROM interface boards, modems, and hard drive controller boards, and others. Manually setting jumpers can be a confusing process, so most hardware usually comes with the necessary jumpers preset. If they are not preset, there should be documentation with a clear diagram of the jumper settings included with the hardware. Fortunately, a lot of plugand-play equipment available today does not require any jumpers. These devices can be configured through a user-friendly interface on your computer.

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Keyboard As the name implies, a keyboard is basically a board of keys. Along with the mouse, the keyboard is one of the primary input devices used with a computer. The keyboard's design comes from the original typewriter keyboards, which arranged letters and numbers in a way that prevented the type-bars from getting jammed when typing quickly. This keyboard layout is known as the QWERTY design, which gets its name from the first six letters across in the upper-left-hand corner of the keyboard. While the design of computer keyboards may have come from typewriters, today's keyboards have many other keys as well. Modifier keys, such as Control, Alt/Option, and Command (Mac) or the Windows key (Windows) can be used in conjunction with other keys as "shortcuts" to perform certain operations. For example, pressing Command-S (Mac), or Control-S (Windows) typically saves a document or project you are working on. Most of today's computer keyboards also have a row of function keys (F1 through F16) along the top of the keyboard, arrow keys arranged in an upside-down T, and a numeric keypad on the right-hand side. Some keyboards have even more buttons, allowing you to change the system volume, eject a CD, or open programs such as your e-mail or Web browser.

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Kindle The Kindle is a portable e-reader developed by Amazon.com. It allows you to downloadand read digital books, newspapers, magazines, and other electronic publications. The Kindle also includes a built-in speaker

and

headphone

jack

for

listening

audiobooks

background music. The first Kindle was released in November 2007 and several updated versions have been released since then. Each Kindle, except for the Kindle Fire, uses special type of display called "E Ink" or electronic paper. Unlike a typical laptop screen or computer monitor, the E Ink display is monochrome and has no backlight. Instead, it has a lightcolored background and text and images are displayed in grayscale. The result is a paper-like display that can be easily viewed in bright sunlight. You can download content to a Kindle using the built-in WiFi connection (available in Kindles released in 2010 or later) or Amazon's

proprietary 3G Whispernet

network. This Whispernet

network is a free service provided by Amazon.com to Kindle users and does not require a wireless subscription. Amazon.com also provides a "Whispersync" that allows users to wirelessly sync data between multiple Kindle devices. While the Kindle was originally designed as a basic e-reader, each iteration has provided more functionality. For example, recent versions of the Kindle include a web browser, which allows you to view websites. The Kindle Fire, which was introduced in September 2011, is as much as tablet as an e-reader, since it has a color touchscreen and 113

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runs theAndroid operating system. Kindle Fire users can also download apps directly from the Amazon.com Appstore. NOTE: Kindle eBook files are saved with an .AZW file extension.

KVM Switch Stands for "Keyboard, Video, and Mouse switch." As the name implies, a KVM switch allows you to used multiple computers with the same keyboard, video display, and mouse. Now, most of us don't need to use two computers at once. In fact, using one computer at a time can sometimes be a challenge. However, there are situations where using a single keyboard, mouse, and display with multiple machines can be very practical. For example, software programmers may use a KVM switch to alternate between two or more computers with different operating systems. This allows them to test their software on multiple platforms when developing a crossplatform application. Network administrators often use KVM switches to monitor and control multiple servers at a time. These KVM switches may support eight or more computers at once. By simply pressing a button on the KVM switch, the administrator can view the display of any machine connected to the switch and control it with a single keyboard and mouse. Of course, KVM switches can also be used by the everyday home user. Some people may find it useful to have two computers at their desk, such as a home and work computer, or a Mac and a PC. In these situations, a KVM switch can accommodate both machines, allowing 114

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them to share the same monitor, keyboard, and mouse. Because only one of each is needed, the result is far less clutter on the desk. This leaves room for stacks of papers, mail, and other objects to clutter up the rest of the desk. Since most keyboards and mice use a USB connection, most KVM switches include USB ports. Older models may include PS/2 or serial ports. The connection for the monitor may be a VGA or DVI port, or both. If you plan on using a KVM switch for your computer setup, make sure the ports match the display and input devices you are going to use with it.

Laptop Laptop computers, also known as notebooks, are portable computers that you can take with you and use in different environments. They include a screen, keyboard, and a trackpad or trackball, which serves as themouse. Because laptops are meant to be used on the go, they have a battery which allows them to operate without being plugged into a power outlet. Laptops also include a power adapter that allows them to use power from an outlet and recharges the battery. While portable computers used to be significantly slower and less capable

than

desktop

computers,

advances

manufacturing

technology have enabled laptops to perform nearly as well as their desktop counterparts. In fact, high-end laptops often perform better than low or even mid-range desktop systems. Most laptops also include severalI/O ports, such as USB ports, that allow standard 115

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keyboards and mice to be used with the laptop. Modern laptops often include a wireless networking adapter as well, allowing users to access the Internet without requiring any wires. While laptops can be powerful and convenient, the convenience often comes at a price. Most laptops cost several hundred dollars more than a similarly equipped desktop model with a monitor, keyboard, and mouse. Furthermore, working long hours on a laptop with a small screen and keyboard may be more fatiguing than working on a desktop system. Therefore, if portability is not a requirement for your computer, you may find better value in a desktop model.

Laser Printer A laser printer is a printer that uses a focused beam or light to transfer text and images onto paper. Though contrary to popular belief, the laser does not actually burn the images onto the paper. Instead, as paper passes through the printer, the laser beam fires at the surface of a cylindrical drum called a photoreceptor. This drum has an electrical charge (typically positive), that is reversed in areas where the laser beam hits it. By reversing the charge in certain areas of the drum, the laser beam can print patterns (such as text and pictures) onto the photoreceptor. Once the pattern has been created on the drum, it is coated with toner from a toner cartridge. The toner is black in most cartridges, but may be cyan, magenta, and yellow in color laser printers. The positively charged toner clings to areas of the drum that have been negatively 116

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charged by the laser. When the paper passes through the printer, the drum is given a strong negative charge, which allows the toner to transfer and stick to the paper. The result is a clean copy of the image written on the paper. Because laser printers do not use ink, they have less image smearing problems thaninkjet printers and are able to print pages faster. While laser printers and toner cartridges typically cost more than inkjet printers and ink cartridges, most laser toner cartridges last several times longer than ink cartridges, which makes their cost per page about equal. For this reason, businesses tend to use laser printers, while consumers are more likely to use inkjet printers. Laser printers typically have a resolution of 600 dpi (dots per inch) or higher.

LCD Stands for "Liquid Crystal Display." LCDs are super-thin displays that are used in laptop computer screens and flat panel monitors. Smaller LCDs are used in handheld TVs, PDAs, and portable video game devices. The image on an LCD screen is created by sandwiching an electrically reactive substance between two electrodes. This color of this substance can be changed by increasing or reducing the electrical current. Since LCD screens are based on the principle of blocking light (rather than emitting it), they use up much less power than standard CRT (Cathode-Ray Tube) monitors.

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LED Stands for "Light-Emitting Diode." An LED is an electronic device that emits light when an electrical current is passed through it. Early LEDs produced only red light, but modern LEDs can produce several different colors, including red, green, and blue (RGB) light. Recent advances in LED technology have made it possible for LEDs to produce white light as well. LEDs are commonly used for indicator lights (such as power on/off lights) on electronic devices. They also have several other applications, including electronic signs, clock displays, and flashlights. Since LEDs are energy efficient and have a long lifespan (often more than 100,000 hours), they have begun to replace traditional light bulbs in several areas. Some examples include street lights, the red lights on cars, and various types of decorative lighting. You can typically identify LEDs by a series of small lights that make up a larger display. For example, if you look closely at a street light, you can tell it is an LED light if each circle is comprised of a series of dots. The energy efficient nature of LEDs allows them to produce brighter light than other types of bulbs while using less energy. For this reason, traditional flat screen LCDdisplays have started to be replaced by LED displays,

which

use

LEDs

for

the

backlight.

LED

TVs

and

computer monitors are typically brighter and thinner than their LCD counterparts.

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Lightning Lightning is a proprietary I/O interface designed by Apple for its mobile devices, such as the iPhone, iPad, and iPod. It was first introduced in September, 2012, with the iPhone 5 and new iPod models. It was later added to iPads, beginning with the 4th generation iPad and the first generation iPad mini. The Lightning interface replaced the the previous "dock connector," which Apple products used since 2003. The Lightning connector has eight pins and is about one third the size of the 30-pin dock connector it supersedes. Instead of having mobile latches on the sides, the Lightning connector has small divots on each side that allow it to snap into place. Even without magnets or clips, the Lightning connection is designed to be strong enough to hold a device upside down by the cable without the cable detaching. Unlike most other I/O interfaces, such as USB, Firewire, and the previous dock connector, the Lightning connector is reversible. The connection is fully symmetrical and the connector can be inserted either way into a Lightning port. This means it is impossible to insert the cable upside down, which makes it easier to plug in and reduces wear and tear on the interface. The order of the pins are recognized dynamically by the device when the connection is made, allowing power and data to flow through the correct channels. The name "Lightning" is correlated with Thunderbolt, another I/O port Apple began using around the same time the Lightning interface was introduced. However, unlike Thunderbolt, Lightning is proprietary and 119

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is only used in Apple products. While most mobile devices (such as Android phones) have standard mini-USB or micro-USB ports, if you have an Apple device, you will need a Lightning cable to charge it and transfer data.

MAC Address Stands for "Media Access Control Address," and no, it is not related Apple

Macintosh

computers.

MAC

address

hardware

identification number that uniquely identifies each device on a network. The MAC address is manufactured into every network card, such as an Ethernet card or Wi-Fi card, and therefore cannot be changed. Because there are millions of networkable devices in existence, and each device needs to have a unique MAC address, there must be a very wide range of possible addresses. For this reason, MAC addresses are made up of six two-digit hexadecimal numbers, separated by colons. For example, an Ethernet card may have a MAC address of 00:0d:83:b1:c0:8e. Fortunately, you do not need to know this address, since it is automatically recognized by most networks.

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Mainframe A mainframe is an ultra high-performance computer made for highvolume, processor-intensive computing. They are typically used by large businesses and for scientific purposes. You probably won't find a mainframe in any household.

In the hierarchy of

computers,

mainframes are right below supercomputers, the most powerful computers in the world. (Which is why they are aptly named "supercomputers.") Yet a mainframe can usually execute many programs simultaneously at a high speed, whereas supercomputers are designed for a single process. Currently, the largest manufacturers of mainframes are IBM and Unisys.

MCA Stands for "Micro Channel Architecture." It is an expansion bus created by IBM that was used in the company's PS/2 desktop computers. An expansion bus allows additional cards to be connected to the computer's motherboard, expanding the number of I/O ports. These include SCSI, USB, Firewire, AGP, and DVI connections, as well as many others.

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The MCA standard was designed to take the place of the AT and ISA buses used in previous IBM PC/AT compatible computers. While the MCA bus architecture was an improvement in both size and speed over AT and ISA, it was kept as a proprietary standard by IBM. This discouraged other manufacturers from adopting the standard, since the MCA architecture was not compatible with other standards. Most PC companies incorporated the more universal PCI and AGP expansion buses into their computers, which are both widely used today.

Media In general, "media" refers to various means of communication. For example, television, radio, and the newspaper are different types of media. The term can also be used as a collective noun for the press or news reporting agencies. In the computer world, "media" is also used as a collective noun, but refers to different types of data storage options. Computer media can be hard drives, removable drives (such as Zip disks), CD-ROM or CD-R discs, DVDs, flash memory, USB drives, and yes, floppy disks. For example, if you want to bring your pictures from your digital camera into a photo processing store, they might ask you what kind of media your pictures are stored on. Are they on the flash memory card inside your camera or are they on a CD or USB drive? For this and many other reasons, it is helpful to have a basic understanding of what the different types of media are.

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Memory Just like humans, computers rely a lot on memory. They need to process and store data, just like we do. However, computers store data in digital format, which means the information can always be called up exactly the way it was stored. Also, unlike our memory, the computer's memory doesn't get worse over time. While memory can refer to any medium of data storage, it usually refers to RAM, or random access memory. When your computer boots up, it loads the operating system into its memory, or RAM. This allows your computer to access system functions, such as handling mouse clicks and keystrokes, since the event handlers are all loaded into RAM. Whenever you open a program, the interface and functions used by that program are also loaded into RAM. RAM is a very high-speed type of memory, which makes it ideal for storing active programs and system processes. It is different than hard disk space in that RAM is made up of physical memory chips, while hard disks are magnetic disks that spin inside a hard drive. Accessing RAM is much faster than accessing the hard disk because RAM access is based on electric charges, while the hard drive needs to seek to the correct part of the disk before accessing data. However, all the information stored in RAM is erased when the computer's power is turned off. The hard disk, on the other hand, stores data magnetically without requiring any electrical power. For more information on the difference between RAM and hard disk space, view this Help Center article. 123

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Another common type of memory is flash memory, which is typically used for small devices such as digital cameras, USB keychain drives, and portable music players like the iPod nano. This kind of memory, known as "electrically erasable programmable read-only memory" (EEPROM),

convenient

for

portable

devices,

since

stores

information even when its power source is turned off, but is smaller and more resilient than a hard drive. To summarize, memory is a vital part of the way computers and many electronic devices function. While memory and RAM can often be used synonymously, it is good to know about other types of memory as well. Hopefully you will be able to store the information you've learned in your own memory.

Memory Module A memory module is another name for a RAMchip. It is often used as a general term used to describe SIMM, DIMM, and SO-DIMMmemory. While there are several different types of memory modules available, they all serve the same purpose, which is to store temporary data while the computer is running. Memory modules come in different sizes and have several different pin configurations. For example, the original SIMMs had 30 pins (which are metal contacts that connect to themotherboard). However, newer SIMM chips have 72 pins. DIMMs commonly come in 168-pin configurations, but some DIMMs have as many as 240 pins. SO-DIMMs have a smaller

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form factor than standard DIMM chips, and come in 72-pin, 144-pin, and 200-pin configurations. While "memory module" is the technical term used to describe computer memory, the terms "RAM," "memory," and "RAM chip" are just as acceptable. But remember, while memory terms may be interchangeable, the memory itself is not. This is because most computers only accept one type of memory. Therefore, if you decide to upgrade you computer's RAM, make sure the memory modules you buy are compatible with your machine.

Memory Stick Memory Stick is a type of flash memorydeveloped by Sony. It is used to store data for digital cameras, camcorders, and other kinds of electronics. Because Memory Stick is a proprietary Sony product, it is used by nearly all of Sony's products that use flash media. Unfortunately, this also means Memory Stick cards are incompatible with most products not developed by Sony. Memory Stick cards are available in two versions: Memory Stick PRO and Memory Stick PRO Duo. Memory Stick PRO cards are 50mm long by 21.5mm wide and are 2.8mm thick. Memory Stick PRO Duo cards are 31mm long by 20mm wide and are only 1.6mm thick. High-speed versions of Memory Stick media support data transfer rates up to 80Mbps, or 10 MB/sec, which is fast enough record high-quality digital video.

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Microcomputer A microcomputer is a computer designed for individual use. The term was introduced in the 1970s to differentiate desktop computer systems from larger minicomputers. It is often used synonymously with

the

term

"desktop

computer,"

but

may

refer

a server orlaptop as well. In the 1960s and 1970s, computers were much larger than today, often taking up several cubic feet of space. Some mainframecomputers could even fill a large room. Therefore, the first computers that could fit on a desktop were appropriately labeled "microcomputers" in comparison to these larger machines. The first microcomputers became available in the 1970s and were used primarily by businesses. As they became cheaper, individuals were able to buy their own microcomputer systems. This lead to the personal computer revolution of the 1980s, in which microcomputers became a mainstream consumer product. As microcomputers grew in popularity, the name "microcomputer" faded and was replaced with other more specific terms. For example, computers

purchased

for

business

purposes

were

labeled

as workstations, while computers bought for home use became known as personal computers, or PCs. Eventually, computer manufacturers developed portable computers, which were called laptops. While

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computers have evolved a lot over the past few decades, these same terms are still used today.

Microphone A microphone is a device that captures audio by converting sound waves into an electrical signal. This signal can be amplified as ananalog signal or may be converted to a digitalsignal, which can be processed by a computeror other digital audio device. While all microphones (or "mics") serve the same basic function, they can capture audio in several different ways. Therefore, multiple classes of microphones exist. The three most common types are described below. 1. Dynamic - Dynamic microphones are the most widely used microphones. They have a simple design that includes a magnet wrapped by a metal coil. A thin sheet called a diaphragm is placed on the front end of the magnet and transmits vibrations from sound waves to the coil. The coil then transfers these vibrations to electrical wires that transmit the sound as an electrical signal. Since dynamic microphones use a simple design, they are typically very durable and do not require electrical power. 2. Condenser - Condenser microphones are commonly used for audio recording purposes. They are known for their sensitivity and

flat frequency response.

Each

condenser

microphone

includes a front plate (the diaphragm) and a back plate that is 127

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parallel to the front plate. When sound waves hit the diaphragm, it vibrates and alters the distance between the two plates. This change is transmitted as an electrical signal. Unlike dynamic microphones, condensers require electrical power. This current may be provided by an internal battery, but is most often provided as 48 volt "phantom power" from an external preamp or mixing console. 3. Ribbon - Ribbon microphones are also known for their high fidelity. They contain a thin ribbon made of a aluminum, duraluminum, or nanofilm, which is suspended in a magnetic field.

Incoming

sound

waves

make

the

ribbon

vibrate,

generating voltage proportional to the velocity of the vibration. This voltage is transmitted as an electrical signal. While early ribbon microphones required a transformer to increase the output voltage, modern ribbon mics have improved magnets that provide a stronger signal â&#x20AC;&#x201C; in some cases even stronger than dynamic microphones. Though ribbon mics have been largely replaced by condensers, several models are still manufactured and used today. Not only do microphones come in several different classes, they also use several types of directional patterns to capture audio. Some microphones are designed with a single "polar pattern," while others have switches that allow you to select the appropriate pattern for a specific recording purpose. Some of the most common patterns include: 1. Cardioid - a heart or bean-shaped pattern that captures audio from one direction; commonly used for recording vocals or a single instrument. 128

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2. Bidirectional - a figure 8 pattern that captures audio from two separate directions; may be used for recoding audio from two different sources or to capture reverb. 3. Omnidirectional - a circular pattern that captures audio from all directions; often used to capture groups of vocalists or ambient sounds. NOTE: Microphones perform the opposite action of speakers, which convert electrical signals into sound waves.

Minicomputer While a minicomputer sounds like a smallcomputer, the name can be a bit misleading. In fact, minicomputers are several times the size of desktop PCs and are only one step below mainframes in the hierarchy of computer classes. The term "minicomputer" was introduced in the 1960s to describe powerful computers that were not as large as mainframes, which sometimes could fill an entire room. Instead, most minicomputers were a few feet wide and several feet tall. They were primarily used by large businesses during the 1960s and 1970s to process large amounts of data. Some minicomputers also functioned as servers, allowing multiple users to access them from connected terminals. As

computer processors became

smaller

and

powerful, microcomputers began to rival minicomputers in processing power. Therefore, in the 1980s, minicomputers started becoming less relevant and eventually became obsolete. Today, rack-based servers perform similar functions to minicomputers 129

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Mirrored Volume A mirrored volume is a hard drive or other form of storage media that stores an exact copy of the data from another volume. It is used for fault tolerance, which means mirrored volume serves as a backup device in case the primary device fails. Companies and organizations that store critical information typically "mirror" the data on another drive. Using a mirrored volume decreases the chance of losing data exponentially. For example, if the odds of a hard drive going bad is 1 out of 200, the odds of two drives going bad at the same time is 1 out of 40,000. Mirroring data can be done using various backup software programs or may be enabled within operating systems that support disk mirroring. While using a mirrored volume helps keep data safe, it also slows down data transfers because the data must always be written twice. It also costs more, since mirroring data requires twice as much disk storage than what would otherwise be required. However, the cost of an extra hard drive is usually well worth the security of having important data backed up. Mirroring may also be referred to as "duplexing" or RAID 1.

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Modem The word modem is actually short for Modulator/Demodulator. (There's something you can really impress your friends with). A modem is a communications device that can be either internal or external to your computer. It allows one computer to connect another computer and transfer data over telephone lines. The original dial-up modems are becoming obsolete because of their slow speeds and are being replaced by the much faster cable and DSL modems.

Modifier Key A modifier key modifies the action of another key when the keys are pressed at the same time. Common modifier keys include Shift, Function, Control, Alt, Command, and Option. The Shift key is found on all keyboards, while the other keys may be exclusive to laptops or Windows or Macintosh computers. Below is a list of the common modifier keys and their primary uses. ď&#x201A;ˇ

Shift - used for capitalizing letters and entering different types of symbols.

ď&#x201A;ˇ

Function (Fn) - commonly found on laptop computers and used to enter the F1 - F15 commands if the function keys also have other functions (such as brightness and volume controls).

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

Control (Ctrl) - a Windows key used for entering keyboard shortcuts, such as Ctrl+S for saving a file or Ctrl+P for printing a document.



Alt - a Windows key that is also called the Alternate or Alternative key; used in combination with the numeric keypad for entering "Alt codes," which outputspecial characters; may also be used in combination with the Control key for entering keyboard shortcuts.



Command (Cmd) - a Macintosh key (similar to the Windows Control key) used for entering keyboard shortcuts; may have a four leaf clover or Apple icon printed on the key.



Option - A Macintosh key (similar to the Windows Alt key) used for

entering

special

characters;

may

also

used

combination with the Command key for entering keyboard shortcuts. To enter a key combination that requires a modifier key, first press the modifier key, then the other key in the combination. For example, to save a document using the common "Ctrl+S" shortcut, first press and hold the Control key. Then press and release the "S" key to perform the command. Finally, release the Ctrl key. While most key combinations require only one modifier key, some require multiple modifier keys. For example, in Mac OS X, Cmd+Shift+3 takes a screenshot of the screen. In this case, either modifier key can be pressed first, as long as both keys are held when the "3" key is pressed.

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Molex Connector A Molex connector is a common type of connector used to power internal computercomponents. The name comes from the Molex Connector

Company,

which

pioneered

the

two-piece

electrical

connectors that became standard in computers and other electronics. Since Molex makes dozens of different connectors, there is no single connector technically called a "Molex connector." However, the term "Molex connector" has become a generic way to describe the Molex 4pin 8981 power connector used to power hard drives, optical drives, and other storage devices. It contains four pins (colored yellow, black, black, and red) encased in a white plastic connector. The connector snaps into a receptacle attached to the power supply and locks into place, ensuring a reliable connection. The 8981 connector's simple and inexpensive design helped it become the standard power connector in desktop computers for several decades. While the Molex 8981 connector is still used in many PCs, modern storage devices, such as SSDs and SATA drives often use newer types of connectors. However, other products from the Molex family are still used in many electronic devices. These connectors are not generically referred to as "Molex connectors," but instead have proprietary names. Examples include the "Mini-Fit Jr." motherboard connector and the "PanelMate" connector used for powering flat panel displays.

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Monitor The term "monitor" is often used synonymously with "computer screen" or "display." The monitor displays the computer's user interface and open programs, allowing the user to interact with the computer, typically using the keyboardand mouse. Older computer monitors were built using cathode ray tubes (CRTs), which made them rather heavy and caused them to take up a lot of desk space. Most modern monitors are built using LCD technology and are commonly referred to as flat screen displays. These thin monitors take up much less space than the older CRT displays. This means people with LCD monitors have more desk space to clutter up with stacks of papers, pens, and other objects. "Monitor" can also be used as a verb. A network administrator may monitor network traffic, which means he watches the traffic to make sure the bandwidth usage is within a certain limit and checks to see what external sources may be attempting to access the network. Software programs may monitor the system's CPU performance as well asRAM and hard disk usage. Finally, monitors also refer to speakers used for monitoring sound. Audio engineers typically use "studio monitors" to listen to recordings. These high-end speakers allow the engineers to accurately mix and master audio tracks. So a sound mixer could be monitoring a recording visually using a computer monitor, while monitoring the sound using audio monitors at the same. As you can tell, "monitor" serves as a rather multipurpose word. 134

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Motherboard The motherboard is the main circuit board of your computer and is also known as the mainboard or logic board. If you ever open your computer, the biggest piece of silicon you see is the motherboard. Attached

the

motherboard,

you'll

find

the CPU, ROM,

memory RAM expansion slots, PCI slots, andUSB ports. It also includes controllers for devices like the hard drive, DVD drive, keyboard, and mouse. Basically, the motherboard is what makes everything in your computer work together. Each motherboard has a collection of chips and controllers known as the chipset. When new motherboards are developed, they often use new chipsets. The good news is that these boards are typically more efficient and faster than their predecessors. The bad news is that older components often do not work with new chipsets. Of course, if you are planning on upgrading multiple components, it may be more cost-effective to just buy a new computer.

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Mouse While most people don't want to see a mouse running around in their home, they typically don't have a problem seeing one sitting by their computer. This is because, along with the keyboard, the mouse is one of the primary input devices used with today's computers. The name comes from the small shape of the mouse, which you can move quickly back and forth on the mouse pad, and the cord, which represents the mouse's tail. Of course, if you are using a wireless mouse, the analogy does not work so well. All mice have at least one button, though most mice have two or three. Some also have additional buttons on the sides, which can be assigned to different commands. Most mice also have a scroll-wheel, which lets you scroll up and down documents and Web pages by just rolling the wheel with your index finger. Early mice tracked movement using a ball in the bottom of the mouse. This "mouse ball" pushed against different rollers as it moved, measuring the mouse's speed and direction. However, now most mice use optical technology, which uses a beam of light to track the mouse's motion. Optical mice are more accurate than roller-based mice and they have the added bonus of not getting dirty inside. A plurality of plurals When you refer to more than one mouse, you can call them either "mice" or "mouses," since both terms are acceptable. However, "mouses" is technically the correct version since "mice" is the plural 136

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

form designated for living creatures. Still, most people have a hard time saying "mouses," which is why "mice" is more commonly used.

Mouse Pad A mouse pad, or "mousing surface," is a surface designed for tracking the motion of a computer mouse. Early mouse pads were literally "pads," which had soft surfaces. The slight cushion allowed the mouse ball to roll smoothly in any direction. Modern mouse pads typically have harder surfaces, designed to track the motion of optical mice. Mouse pads come in many shapes and sizes. Most are rectangular, though are some are circular or oval shaped. While the majority of mouse pads are less than a foot wide or long, graphic artists and CAD designers sometimes use mouse pads that are much larger. These super-sized mousing surfaces allow them to use a slow, precise mouse speed without needing to lift up the mouse very often. Computer gamers also prefer larger mouse pads, because they offer more desktop real estate for making long, fast motions. Since optical mice track motion by detecting small changes in the surface below the mouse, the mouse pad's surface affects how accurately the mouse responds to movement. Lighter colored mouse pads typically produce the best results since they reflect the most light. Some highly reflective mouse pads even claim to have "battery saving" capabilities for wireless mice. The improvement in battery life most likely comes from how quickly the mouse enters low-power mode when it stops moving. 137

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Since optical mice work on just about any opaque surface, you typically do not even need a mouse pad to use a mouse. However, a good mouse pad can provide smooth, accurate motion, which is beneficial if cursor accuracy is important for your work. When choosing a mouse pad, make sure you get one large enough for your needs, but not so large that it won't fit on your desk. If possible, choose a mouse pad with a built-in wrist rest or buy a separate wrist rest if necessary. This small ergonomic addition will relieve a lot of strain on your wrist no matter what mouse pad you use.

Multi-Core Multi-core technology refers to CPUs that contain two or more processing cores. These cores operate as separate processors within a single chip. By using multiple cores, processor manufacturers can increase the performance of a CPU without raising the processor clock speed. Since the upper threshold of clock speeds has leveled out during recent years, multi-core processors have become a common means to improve computing performance. Most modern computers have at least two cores, or a dualcore processor. Some high-end machines have four core (quad-core), six core (hexa-core), or eight core (octo-core) processors. While adding more cores does not increase the overall computing performance by a proportional amount (two cores do not equal twice the speed), multicore processors do provide a substantial performance boost over a single-core CPUs. Additionally, a multi-core processor can run more efficiently than a single processor, since not all cores need to be active 138

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unless needed. For example, Intel's "Turbo Boost Technology" can turn off power to entire cores when they are not being used. It is important to understand that multiple cores are different than multiple CPUs. While a multi-core computer may contain two processing cores on a single chip, amultiprocessor computer may have two CPUs, each with a single processing core. Since multi-core computing is more energy and cost efficient, multi-core computers have become more popular than multiprocessor computers. However, some high-end machines combine the two technologies and include multiple CPUs, each with multiple cores.

Multiprocessing For many years, the speed of computerprocessors increased through improvements in the architecture and clock speed of processors. However, in recent years, chip manufacturers have reached a limit in how small they can make the transistors insideCPUs without them overheating. Therefore, using multiple processors, or multiprocessing, has become the next step in increasing computing performance. Multiprocessing can be implemented in two different ways: 1) using more than one physical processor, or 2) using a processor with multiple cores. For example, early Power Mac G5 computers had multiple

physical

processors,

each

with

their

own heat

sink and frontside bus. When Apple switched to using Intel processors in 2006, they began using dual-core processors. These chips look like a single processor, but act as two. Now, some machines like the Mac Pro, have quad-core processors, which include four processing cores. 139

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Some Mac Pros even have two physical quad-core processors, giving the computer a total of eight processors. Most Windows and Linuxbased PCs now use multi-core processors as well. While multiprocessing sounds like a logical choice for improving computing

performance,

must

supported

the

computer's operating system in order to work correctly. Fortunately, current

versions

both Windows and Mac

X fully

support

multiprocessing. This means they can manage multiple processors as one CPU, dividing the processing load between them. Still, not all tasks can be split equally between two or more processors. Therefore, while multiprocessing may increase a computer's speed, it does not typically improve performance by the exact factor of processors in the machine.

NAS Stands for "Network Attached Storage." A typical computer stores data using internal and external hard drives. If the computer is connected to a network, it can share data on its connected hard drives with other systems on the network. While this allows multiple computers to send data back and forth, it requires that each computer share its files individually. Therefore, if a computer is turned off or disconnected from the network, its files will not be available to the other systems. By using NAS, computers can store and access data using a centralized storage location. Instead of each computer sharing its own files, the shared data is stored on a single NASserver. This provides a simpler and more reliable way of sharing files on a network. Once an NAS server connected to a network (typically via Ethernet), it can be 140

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

configured to share files with multiple computers on the network. It may allow access to all systems or may provide access to a limited number of authenticated machines. NAS servers typically contain multiple hard drives, providing a large amount of shared disk space for connected systems to save data. They are often used in business networks, but have become increasing more common

home

networks

well.

Since

NAS

uses

centralized storage device, it can be a simple way for family members to share and backup their data.

NIC Stands for "Network Interface Card." Pronounced "nick," this is the card that physically makes the connection between the computer and the network cable. These cards typically use an Ethernet connection and are available in 10, 100, and 1000 Base-T configurations. A 100 Base-T card can transfer data at 100 Mbps. The cards come in ISA and PCI versions and are made by companies like 3Com and LinkSys. So if you want to connect your computer to a network, you better get yourself a NIC.

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Node Any system or device connected to a network is also called a node. For example, if a network connects a file server, five computers, and two printers, there are eight nodes on the network. Each device on the network has a network address, such as aMAC address, which uniquely identifies each device. This helps keep track of where data is being transferred to and from on the network. A node can also refer to a leaf, which is a folder or file on your hard disk. In physics, a node, or nodal point, is a point of minimum displacement or where multiple waves converge, creating a net amplitude of zero.

Non-Impact Printer Early printers, such as dot matrix and daisywheel printers were called impact printers, since they operated by striking an ink ribbon against the paper. Most modern printers, including inkjet and laser printers, don't include an ink ribbon and are considered to be nonimpact printers. Non-impact printers are generally much quieter than impact printers since they don't physically strike the page. For example, inkjet printers spray tiny drops of ink onto the page, while laser printers use a cylindrical drum that rolls electrically charged ink onto the paper. Both 142

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

of these methods are non-impact and provide an efficient printing process that produces little sound. The low impact nature of inkjet and laser printers also means they are less likely to need maintenance or repairs than earlier impact printers.

Northbridge The northbridge is a chip inside a computer that connects the central processing unit (CPU) to other primary components in the system. These components include RAM(a.k.a. system memory), the frontside bus (FSB), PCI Express cards, and the AGP card. The northbridge also connects to thesouthbridge, which controls the remaining components of the computer. While the CPU is the main processor inside the computer, the northbridge is the primary controller. It acts like a traffic cop directing data to and from the CPU. Therefore, the performance of the northbridge chip affects the overall performance of the computer. On Intel systems, the northbridge is also called the Memory Controller Hub (MCH), since it controls the data flow to and from the system memory.

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NVRAM Stands for "Non-Volatile Random Access Memory." NVRAM is a type of RAM that retains data after the host device's power is turned off. Two common types of NVRAM include SRAM and EEPROM. SRAM (pronounced "s-ram") retains data by using an alternative source of power such as a battery. SRAM is often used to store computer hardware settings that need to be maintained when the computer is shut down. Common examples include the BIOS settings on Windows computers or the PRAM settings on Macintosh systems. Since SRAM typically uses a battery to retain memory, if the battery dies or is disconnected, the data stored in the SRAM will be lost. Therefore, if BIOS or PRAM settings are not retained after a computer is restarted, it is likely the computer's battery has lost its charge and needs to be replaced. EEPROM (pronounced "e-e-p-rom") stores data using electrical charges that maintain their state without electrical power. Therefore, EEPROM does not need a battery or other power source to retain data. The most common

type

EEPROM

is flash

memory,

which

used

for USB keychain drives and other portable electronic devices.

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OLED Stands for "Organic Light Emitting Diode" and is pronounced "oh-led." OLED is a type of flat screen display similar to an LCD that does not require a backlight. Instead, each LED within an OLED panel lights up individually. An OLED screen has six layers that work together to produce color images. These layers include the following, from bottom to top: 1. Substrate - the foundational structure that supports the panel; typically made out of glass or plastic 2. Anode - a transparent layer that removes electrons when electrical current flows through it 3. Conductive Layer - contains organic molecules or polymers such as polyaniline that transfer current to the emissive layer 4. Emissive Layer - contains organic molecules or polymers such as polyfluorene that light up when current is passed through them 5. Cathode - injects electrons into the other layers when current flows through it 6. Cover - the top protective layer of the screen; typically made out of glass or plastic

How does an OLED work? OLEDs display light using a process called electrophosphorescence. While this may sound like an intimidating term, the process is 145

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

relatively simple. Electrical current flows from the cathode (negatively charged) to the anode (positively charged), causing electrons to move to the emissive layer. These electrons find "holes" (where atoms missing electrons) in the conductive layer and produce light when they fill these holes. The color of the light depends on the organic molecule that the current passed through in the emissive layer. Since the diodes in OLED displays light up individually, there is no need for a backlight. This means OLEDs can have darker blacks than LED/LCD displays and use less electricity. The are also thinner and may be curved or even bendable. While OLEDs have many advantages over LED/LCD displays, it has been expensive to produce large, reliable OLED screens. Therefore, OLEDs have been more common in small electronics, such as smartphones and tablets. As OLED production costs decrease and reliability increases, the technology will become more commonly used in larger screens, such as televisions and computer monitors.

Optical Drive In the real world, "optical" refers to vision, or the ability to see. In the computer world, however, "optical" refers to lasers, which can "see" and read data on optical discs. These discs include CDs and DVDs, which are made up of millions of small bumps and dips. Optical drives have lasers that read these bumps and dips as ones and zeros, which the computer can understand.

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Some common types of optical drives include CD-ROM, CD-RW, DVDROM, DVD-RW, and Blu-ray drives. CD and DVD writers, such as CD-R and DVD-R drives use a laser to both read and write data on the discs. The laser used for writing the data is much more powerful than the laser that reads the data, as it "burns" the bumps and dips into the disc. While optical drives can spin discs at very high speeds, they are still

significantly

slower

than

hard

drives,

which

store

data

magnetically. However, because optical media is inexpensive and removable, it is the most common format used for distributing computer software

Optical Media Media, in the computer world, refers to various types of data storage. For example,hard drives, CDs, DVDs, and USB drives are all different types of media. Optical media refers to discs that are read by a laser. This includes CD-ROMs, DVD-ROMs, and all the variations of the two formats -- CD-R, CD-RW, DVD-R, DVD+R, Blu-ray, and many others. Optical media typically does not have as fast of a seek time as hard drives (the time it takes to access information on different parts of the disk), but it has many other advantages. Because optical discs are not based on magnetic charges like hard drives are, the discs are less likely to lose their data and have a longer shelf life -- around seven times longer than magnetic media. The discs are also more durable than hard drives and are much cheaper to produce, making them great

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for backups and for transferring small amounts of data between different computers.

OSD Stands for "On Screen Display." Mostmonitors include an on screen menu for making adjustments to the display. This menu, called the OSD, may be activated by pressing the Menu button located on the side or front of your monitor. Once the OSD appears on the screen, you can navigate through the menu and make adjustments using the Plus (+) and Minus (-) buttons, which are usually located right next to the menu button. On screen displays vary between monitors, but most include the basic brightness and contrast controls. Some include more advanced color controls, allowing you to calibrate individual red, green, and blue (RGB) settings. Many monitors also support positioning adjustments, which can be used to make slight modifications to the position and tilt of the screen. Monitors that include built-in speakers may include audio adjustments as well. Most CRT and flat screen monitors, such as LCD and LED displays, include OSDs. However, flat screen displays typically have less adjustment options since their screen position is more consistent than older CRT monitors. Some newer monitors also allow users to make adjustments through a software interface rather than using the standard on screen display. Regardless of what monitor you have, it is good to be familiar with the OSD so you know how to adjust the display settings 148

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Output Device Any device that outputs information from a computer is called, not surprisingly, an output device. Since most information from a computer is output in either a visual or auditory format, the most common output devices are the monitor and speakers. These two devices provide instant feedback to the user's input, such as displaying characters as they are typed or playing a song selected from a playlist. While monitors and speakers are the most common output devices, there are many others. Some examples include headphones, printers, projectors, lighting control systems, audio recording devices, and robotic machines. A computer without an output device connected to it is pretty useless, since the output is what we interact with. Anyone who has ever had a monitor or printer stop working knows just how true this is. Of course, it is also important to be able to send information to the computer, which requires an input device.

Overclocking For some people, fast is never fast enough. In the world of computers, a

fast processor can

Overclocking

involves

made even faster by overclocking increasing

the clock

speed of

it. the

computer's CPU past the rate at which it was originally designed to run. 149

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

Some ways to overclock a processor include increasing the CPU's operating

speed

the

system BIOS or

changing

the

hardwarejumper settings for the processor. Modifying these settings may allow the processor to run faster than set by the manufacturer, which may increase the overall performance of the computer. However, since

other

settings,

such

the

memory

speed, frontside and backside bus speeds, and other components are fixed, there may not be a significant increase in performance. Regardless of how overclocking is done, it potentially may cause problems with the computer. After all, when you overclock a computer, you are altering the manufacturer's design of the machine. For example, if there is not enough electrical current to to power the processor at the new rate, it may slow down or stop running completely. Also, if theheat sink cannot sufficiently cool the processor running at the faster rate, it may overheat, causing your computer to freeze or crash. This is actually a preventive measure, since the computer stops functioning when the CPU gets too hot. Otherwise, the CPU may literally fry itself and your overclocked processor may become an overcooked processor. In summary, overclocking a processor can be a risky endeavor. It is best left to computer enthusiasts who understand their hardware and are willing to accept the risks associated with it. Since overclocking voids your computer's warranty, don't expect the manufacturer to replace your cooked CPU for free. If you want a fast machine that is supported by the manufacturer, buying a fast processor to begin with is your best bet.

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Parallel Port This interface is found on the back of older PCs and is used for connecting external devices such as printers or a scanners. It uses a 25-pin connector (DB-25) and is rather large compared to most new interfaces. The parallel port is sometimes called a Centronics interface, since Centronics was the company that designed the original parallel port standard. It is sometimes also referred to as a printer port because the printer is the device most commonly attached to the parallel port. The latest parallel port standard, which supports the same connectors as the Centronics interface, is called the Enhanced Parallel

Port

(EPP).

This

standard

supports

bi-directional

communication and can transfer data up to ten times faster than the original Centronics port. However, since the parallel port is a rather dated technology, don't be surprised to see USB or Firewire interfaces completely replace parallel ports in the future.

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Passive-Matrix Passive-matrix is an LCD technology that uses a grid of vertical and horizontal wires to display an image on the screen. Each pixel is controlled by an intersection of two wires in the grid. By altering the electrical charge at a given intersection, the color and brightness of the corresponding pixel can be changed. While passive-matrix displays are relatively simple and inexpensive to produce, they have a few drawbacks. Since the charge of two wires (both vertical and horizontal) must be altered in order to change a single pixel, the response time of passive-matrix displays is relatively slow. This means fast movement on a passive-matrix display may appear blurry or faded, since the electrical charges cannot keep up with the motion. On some passive-matrix displays, you may experience "ghosting" if you move the cursor quickly across the screen. Since passive-matrix monitors do not display fast motion well, most modern flat screen displays use active-matrix technology. Instead of managing pixels through intersections of wires, active-matrix displays control each pixel using individual capacitors. This allows pixels to change brightness and color states much more rapidly. While most of today's computer monitors and flat screen televisions have activematrix screens, passive-matrix displays are still used in some smaller devices, since they are less expensive to produce.

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PC Stands for "Personal computer." PCs are are what most of us use on a daily basis for work or personal use. A typical PC includes asystem unit, monitor, keyboard, and mouse. Most PCs today also have a network

Internet

connection,

connecting peripheral devices,

such as

well

digital

ports

cameras,

for

printers,

scanners, speakers, external hard drives, and other components. Personal computers allow us to write papers, create spreadsheets, track our finances, play games, and do many other things. If a PC is connected to the Internet, it can be used to browse the Web, check email, communicate with friends via instant messaging programs, and download files. PCs have become such an integral part of our lives that it can be difficult to imagine life without them! While PC stands for "personal computer," the term can be a bit ambiguous. This is because Macintosh computers are often contrasted with PCs, even though Macs are also technically PCs. However, Apple itself has used the term "PC" to refer to Windows-based machines, as opposed to its own computers, which are called "Macs." While the Mac/PC dilemma remains, PCs can always contrasted with other types of computers, such as mainframes and server computers, such as Web servers and network file servers. In other words, if you use a computer at home or at work, you can safely call it a PC.

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PCB Stands for "Printed Circuit Board." A PCB is a thin board made of fiberglass, composite epoxy, or other laminate material. Conductive pathways are etched or "printed" onto board, connecting different components on the PCB, such as transistors, resistors, and integrated circuits. PCBs are used in both desktop and laptop computers. They serve as the foundation for many internal computer components, such asvideo cards, controller cards, network interface cards, and expansion cards. These components all connect to the motherboard, which is also a printed circuit board. While PCBs are often associated with computers, they are used in many other electronic devices besides PCs. Most TVs, radios, digital cameras, cellphones, and tablets include one or more printed circuit boards. While the PCBs found in mobile devices look similar to those found in desktop computers and large electronics, they are typically thinner and contain finer circuitry. NOTE: PCB may also stand for "Process Control Block," a data structure in a systemkernel that stores information about a process. In order for a process to run, the operating system must first register information about the process in the PCB.

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PCI Stands for "Peripheral Component Interconnect." It is a hardware bus designed by Intel and used in both PCs and Macs. Most add-on cards such as SCSI, Firewire, and USB controllers, use a PCI connection. Some graphics cards use PCI, but most new graphics cards connect to the AGP slot. PCI slots are found in the back of your computer and are about 3.5" long and about 0.5" high. So before you go buy that Firewire expansion card, make sure you have at least one PCI slot available.

PCI Express First came PCI, then PCI-X, then PCI Express. PCI Express can be abbreviated as PCIe or, less commonly and more confusingly, PCX. Unlike

earlier

PCI

standards,

PCI

Express

does

not

use

parallel bus structure, but instead is a network of serial connections controlled by a hub on the computer's motherboard. This enables PCI Express cards to run significantly faster than previous PCI cards. Because the PCI Express interface is a serial connection, it does not have a speed measured in Megahertz, like PCI or PCI-X. Instead, its performance is measured in data throughput speeds, which are several times faster than PCI-X. Furthermore, PCI Express is available in x1, x4, x8, and x16 implementations, which increases the bandwidth by the 155

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corresponding amount. However, larger implementations require longer PCI Express slots. For example, a x4 slot is larger than a x1 slot and a x16 slot is larger than a x8 slot. A PCI Express card can be inserted in any slot that is large enough for it. For example, a x8 card could be inserted into a x16 slot, but a not a x1 or x4 slot. Since PCI Express connections can support such fast data transfer rates, they can be used to connect high-speed devices such as Gigabit Ethernet cards and high-end video cards. For this reason, PCI Express is expected to replace both PCI and AGP connections. Fortunately, PCI Express was designed to be backwards compatible with both PCI hardware and software. However, to use a PCI Express card, your computer must have at least one available PCI Express slot.

PCI-X Stands for "Peripheral Component Interconnect Extended." Once again, "Ex" is abbreviated with an "X" instead of an "E." Most desktop computers

include

one

morePCI slots

for

expanding

the

computer's I/Ocapabilities. Common PCI cards include network cards, sound cards, and video cards. In the early 1990s, when PCI was first introduced, the 66 MHz speed of PCI was more than sufficient for PCI cards available at the time. However, a decade later, expansion cards supported much faster data transfer rates and therefore became faster than the PCI bus would support. To prevent the interface from becoming a bottleneck, PCI-X was introduced. The first version of PCI-X supported data transfer rates of 133 MHz, which is more than twice as fast as the original PCI standard. Then 156

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along came PCI-X 2.0, which can run at speeds of 266 or 533 MHz. These speeds are fast enough to support Gigabit Ethernetcards and video capture devices without slowing them down. PCI-X cards can only be installed in PCI-X slots, but the slots themselves are backwards compatible with PCI cards.

PCMCIA Stands

for

"Personal

Computer

Memory

Card

International

Association." It can also mean, perhaps more appropriately, "People Can't Memorize Computer Industry Acronyms." This way-to-long acronym stands for an association founded in 1989 which develops standards for expansion cards for portable computers. However, the term is most commonly associated with the actual cards standardized by the organization. These cards are referred to as "PCMCIA cards," or simply "PC cards." There are three types of PCMCIA cards, all of which are rectangular and measure 8.56 by 5.4 cm., but have different widths: 

Type I: up to 3.3 mm. thick, mainly used to add additional ROM or RAM.



Type II: up to 5.5 mm. thick, typically used for fax/modem cards.



Type III: up to 10.5 mm. thick, often used to attach portable disk drives.

PCMCIA slots also come in three sizes -- a Type I slot can hold one Type I card, a Type II slot can hold one Type II card or two Type I 157

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cards, and a Type III slot can hold one Type III card or one Type I and one Type II card. PC Cards can be removed or inserted "on the fly," which means you don't have to turn your computer off to exchange them and you don't have to restart for your computer to recognize them.

PDA Stands for "Personal Digital Assistant." These are the little electronic devices you see people jotting stuff down on in public. Usually, when you see someone with a PDA, they will be holding it out far front of them for everyone to see. Fortunately, as PDAs become more common, more people will have them and we won't have to deal with the people who make sure everyone else sees that they have one. The first PDA, called the Newton, was created by Apple in 1993. Since then, numerous other companies have jumped on the bandwagon and have added many new designs and options to the PDA market. The Palm Pilot, Handspring Visor, HP Jordana, Compaq Aero, Sharp Mobilon, and Sony Cli? are all common PDAs. Ironically, Apple's Newton was discontinued when the company was having financial difficulties in 1998. Today's PDAs allow you to organize your schedule, take notes, do math calculations, play games, write memos, and even surf the Internet and send e-mail. They are cool things to have, but if you decide to get one, please do us all a favor and don't show it off in public.

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PDA also stands for "Public Display of Affection," and though this term is all too relevant at college campuses, it has nothing to do with this definition

Peripheral A computer peripheral is any external device that provides input and output for the computer. For example, a keyboard and mouse are input peripherals, while a monitor and printer are output peripherals. Computer peripherals, or peripheral devices, are sometimes called "I/O devices" because they provide input and output for the computer. Some peripherals, such as external hard drives, provide both input and output for the computer. For an extended list of various peripheral devices, view this Help Center article

Pipeline Computer processors can handle millions of instructions each second. Once one instruction is processed, the next one in line is processed, and so on. A pipeline allows multiple instructions to be processed at the same time. While one stage of an instruction is being processed, other instructions may be undergoing processing at a different stage.

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Without a pipeline, each instruction would have to wait for the previous one to finish before it could even be accessed. To understand the benefit of a pipeline, imagine that a car manufacturing plant had to wait for each car to be fully completed before starting on the next one. That would be horribly inefficient, right? It makes much more sense to work on many cars at once, completing them one stage at a time. This is what a pipeline in a computer allows. Pipelining, as it is called, often keeps around six instructions at once in the processor at different stages of processing. Pipelines can be used for the CPU as well as for accessing memory (DRAM).

Plotter A plotter is a printer designed for printingvector graphics. Instead of printing individual dots on the paper, plotters draw continuous lines. This makes plotters ideal for printing architectural blueprints, engineering designs, and other CAD drawings. There are two main types of plotters â&#x20AC;&#x201C; drum and flatbed plotters. Drum plotters (also called roller plotters) spin the paper back and forth on a cylindrical drum while the ink pens move left and right. By combining these two directions, lines can be drawn in any direction. Flatbed plotters have a large horizontal surface on which the paper is placed. A traveling bar draws lines on the paper as it moves across the surface.

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Most drum and flatbed plotters provide output sizes that are much larger than standardinkjet and laser printers. For example, a typical inkjet printer creates documents that are 8.5 inches wide. A drum plotter may produce documents that are 44 inches wide. The length of a document printed by a drum plotter is only limited by the size of the paper. Documents printed by flatbed plotters are constrained to the length and width of the printing surface. NOTE: While pen plotters are still used today, most models have been replaced by wide-format inkjet printers.

Plug and Play Plug and Play, sometimes, abbreviated PnP, is a catchy phrase used to describe devices that work with a computer system as soon as they are connected. The user does not have to manually install drivers for the device or even tell the computer that a new device has been added. Instead the computer automatically recognizes the device, loads new drivers for the hardware if needed, and begins to work with the newly connected device. For example, if you connect a Plug-and-Play mouse to the USB port on your computer, it will begin to work within a few seconds of being plugged in. A non plug-and-play device would require you to go through several steps of installing drivers and setting up the device before it would work. While Plug and Play usually refers to computer peripheral devices, such as keyboards and mice, it can also be used to describe internal 161

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hardware. For example, a video cardor hard drive may be a Plug and Play device, meaning the computer will recognize it as soon as it is installed. The only difference is that internal components usually require the computer to be turned off when they are installed, while external devices can typically be installed while the computer is running.

PMU Stands for "Power Management Unit." The PMU is a microcontroller, or integrated circuit, that controls the power functions of Macintosh computers. Though it is not a large component, the PMU contains several parts, including memory, software, firmware, and its own CPU. Some responsibilities of the PMU include: 

Telling the computer when to turn on, turn off, go to sleep, and wake up.



Maintaining the system's PRAM (Parameter Random Access Memory).



Managing system resets from various types of commands.



Managing the real-time clock (date and time).

Because every function the computer performs requires electrical power,

the

power

management

unit

essential

part

every Macintosh computer. Therefore, it is important that the PMU functions correctly. In the rare case that the PMU stops functioning or behaves erratically, it can be reset, which should fix any problems caused by the PMU. 162

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The method for resetting the PMU depends on the type of Macintosh computer. Some Macs have a small reset button on the logic board that can be pressed when the computer is off. Other models include a reset button on the outside of the computer. These buttons typically have an icon of a triangle pointing to the left, indicating it is a reset button. The PMU on some PowerBook G4 models can be reset by turning off the computer, removing the battery and power supply, and pressing Shift-Control-Option-Power. Since different machines require different methods for resetting the PMU, it is best to check your manual or Apple's Support website to find out the proper way to reset your Mac's PMU. In newer Macs, such as the MacBook and MacBook Pro, the PMU is referred to as the System Management Controller, or SMC.

POST Stands for "Power On Self Test." POST (or P.O.S.T.) is a series of system checks run bycomputers and other electronic devices when they are turned on. The results of the test may be displayed on a screen, output through flashing LEDs, or simply recorded internally. On computer systems, the POST operation runs at the beginning of the boot sequence. If all the tests pass, the rest of the startup process continues automatically. Both Macs and Windows PCs run a POST each time the computer is booted up or restarted. The scan checks the hardware and makes sure the processor, RAM, andstorage devices are all functioning correctly. If 163

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an error is encountered during the POST, the startup process may pause or halt completely and the error may be displayed on the monitor.

PCs,

POST

errors

are

often

displayed

the BIOS information screen. They may be output as cryptic codes, such as "08" for bad memory, or as a system message, such as "System RAM failed at offset." On Macs, POST errors are often indicated by a simple graphic, such as a broken folder icon that indicates no bootable device was found. In some cases, the computer screen may not even turn on before POST errors take place. If this happens, error codes may be output through flashing LED lights or audible tones. For example, an Apple iMac will sound three successive tones, followed by a five second pause, then repeat the tones when bad RAM is encountered during startup. Most PCs also emit beeps when POST errors are detected, though each manufacturer uses its own codes. POST is rather technical term that only computer technicians use on a regular basis. However, it is a good acronym to know, since it will help you better understand error messages that may pop up on computers or other electronic devices. If your computer won't start up because of a POST error, you can use a different device to look up the meaning and cause of the error, possibly from the manufacturer's website. Then you can take the appropriate action, such as removing a memory module or reseating thevideo card, then you can try starting up your computer again. NOTE: "POST" is also a method for passing HTML form variables from one webpage to another without displaying them in the address bar. The alternative method is "GET," which appends the values to the URL.

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Power Cycle While the phrase "power cycle" appears to be a noun, it is actually more commonly used as a verb. In simple terms, to power cycle a device means to turn it off and turn it back on again. For example, the user manual of arouter may ask you to power cycle the router if it stops responding. This may mean switching the power to OFF and then ON again or may require physically unplugging the device and then plugging it back in again. Power cycling is often synonymous with resetting a device. As we all know, computer equipment can be rather finicky at times. A device that was working fine ten minutes ago may begin acting strangely or may not be responding at all. Often the low-tech solution of simply turning off the device and turning it back on again will fix the

problem.

This

because

information

stored

the

device's RAM may have gotten corrupted and caused the device to hang up or stall on a certain instruction. Power cycling the device erases the RAM and allows it to boot up with fresh information. Typically it is a good idea to wait 5 to 10 seconds before turning the device back on to make sure it has chance to fully reset. Of course, if you need to power cycle your computer, you should save any work you currently have open, since it will be erased from the RAM once the system is restarted

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Power Supply A power supply is a hardware component that supplies power to an electrical device. It receives power from an electrical outlet and converts the current from AC (alternating current) to DC (direct current), which is what the computer requires. It also regulates the voltage to an adequate amount, which allows the computer to run smoothly without overheating. The power supply an integral part of any computer and must function correctly for the rest of the components to work. You can locate the power supply on a system unit by simply finding the input where the power cord is plugged in. Without opening your computer, this is typically the only part of the power supply you will see. If you were to remove the power supply, it would look like a metal box with a fan inside and some cables attached to it. Of course, you should never have to remove the power supply, so it's best to leave it in the case. While most computers have internal power supplies, many electronic devices use external ones. For example, some monitors and external hard drives have power supplies that reside outside the main unit. These power supplies are connected directly to the cable that plugs into the wall. They often include another cable that connects the device to the power supply. Some power supplies, often called "AC adaptors," are connected directly to the plug (which can make them difficult to plug in where space is limited). Both of these designs allow the main device to be smaller or sleeker by moving the power supply outside the unit. 166

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Since the power supply is the first place an electronic device receives electricity, it is also the most vulnerable to power surges and spikes. Therefore, power supplies are designed to handle fluctuations in electrical current and still provide a regulated or consistent power output. Some include fuses that will blow if the surge is too great, protecting the rest of the equipment. After all, it is much cheaper to replace a power supply than an entire computer. Still, it is wise to connect all electronics to a surge protector or UPS to keep them from being damaged by electrical surges.

PPGA Stands for "Plastic Pin Grid Array" (not the Pretty People Golfer's Association). PPGA is a type of processor design or "form factor" used by the Intel Celeron processor. The design allows the heat generated by the chip to dissipate more quickly. This enables the processor to use more transistors and run at higher speeds without burning a hole in the side of your computer. If you'd like to know more about PPGA, check out Intel's own documention.

PRAM Stands for "Parameter Random Access Memory," and is pronounced "Pram." PRAM is a type of memory found in Macintoshcomputers that stores system settings. These settings include display settings (like 167 COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

screen resolution and color depth), the time zone setting, speaker volume, and the startup volume choice. The system settings that are stored in the computer's PRAM differ from Mac to Mac, but the purpose of the memory remains the same. If your Macintosh is behaving erratically or is not booting up all the way, you may want to try resetting the PRAM. You can reset or "zap" the PRAM on a Mac by pressing and holding the Command, Option, P, and R keys right as you turn the computer on. Yes, there are four keys you need to hold down at the same time. Once your hear the startup chime a second time, the PRAM has been reset and you can release the keys. Note that if you choose to zap your PRAM, you may need to set your display, time zone, startup volume, and other affected settings using System Preferences. Some firmware updates may reset your PRAM as part of their installation process, which will means you will have to reset the affected settings after the installation.

Primary Memory Primary memory is computer memory that is accessed directly by the CPU. This includes several types of memory, such as the processor cache and system ROM. However, in most cases, primary memory refers to system RAM. RAM, or random access memory, consists of one or more memory modules that temporarily store data while a computer is running. RAM is volatile memory, meaning it is erased when the power is turned off. 168

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Therefore, each time you start up your computer, the operating system must be loaded from secondary memory (such as ahard drive) into the primary memory, or RAM. Similarly, whenever you launch anapplication on your computer, it is loaded into RAM. The operating system and applications are loaded into primary memory, since RAM can be accessed much faster than storage devices. In fact, the data can be transferred between CPU and RAM more than a hundred times faster than between the CPU and the hard drive. By loading data into RAM, programs can run significantly faster and are much more responsive than if than constantly accessed data from secondary memory. NOTE: Primary memory may be called "primary storage" as well. However, this term is somewhat more ambiguous since, depending on the context, primary storage may also refer to internal storage devices, such as internal hard drives.

Print Server A print server is a device that allows you to share a printer with multiple computers. It may be a standalone adapter or may be integrated within a printer or a router. When activated, the print server allows a printer to connect to a local network rather than a single computer. The printer can then be accessed by multiple devices (including both Mac and Windows computers) as a "network printer." Standalone print servers come in several varieties. Most have a USB port, which connects directly to the USB port of the printer. 169

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

However,

some

servers

can

connect

printer's Ethernet or parallel port as well. Wired print servers include an

Ethernet

port

for

connecting

directly

router,

while wireless versions are able to connect to a Wi-Fi network. Printers that include a built-in print server are often called "network printers" or "wireless printers." These printers may have an Ethernet port for connecting directly to a LAN or a built-in Wi-Fi card, which enables the printer to show up on a wireless network. Since many homes and businesses now have wireless networks, wireless printers have become a popular way to share a printer with multiple computers. Some routers can also function as print servers. Besides the typical Ethernet ports, they also include a USB port for connecting a printer. When you connect a printer to the router, the printer becomes a network device and can be accessed by other devices on the network.

Printer A printer is an output device that prints paper documents. This includes text documents, images, or a combination of both. The two most common types of printers are inkjet andlaser printers. Inkjet printers are commonly used by consumers, while laser printers are a typical choice for businesses. Dot matrixprinters, which have become increasingly rare, are still used for basic text printing. The printed output produced by a printer is often called a hard copy, which is the physical version of an electronic document. While some printers can only print black and white hard copies, most printers 170

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today can produce color prints. In fact, many home printers can now produce high-quality photo prints that rival professionally developed photos. This is because modern printers have a high DPI (dots per inch) setting, which allows documents to printed with a very fineresolution. In order to print a document, the electronic data must be sent from the computer to the printer. Many software programs, such as word processors and image editing programs, include a "Print..." option in the File menu. When you select "Print," you will typically presented with a Print dialog box. This box allows you to select the print output settings before sending the document to the printer. After choosing the appropriate settings, you can hit the Print button, which will send the document to the printer. Of course for the document to print, the printer must be turned on and connected to the computer. Most modern printers are connected using a standard USB cable. However, some printers can be wirelessly connected to one or more computers over aWi-Fi network. You can also use more than one printer on a single computer, as long as the correct drivers are installed. While printers are notorious for breaking down at inopportune times, modern printers are fortunately more reliable than the printers of the past. Of course, keeping extra ink or toner cartridges on hand is still your responsibility

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A processor, or "microprocessor," is a small chip that resides in computers and other electronic devices. Its basic job is to receiveinput and provide the appropriate output. While this may seem like a simple task, modern processors can handle trillions of calculations per second. The central processor of a computer is also known as the CPU, or "central processing unit." This processor handles all the basic system instructions,

such

runningapplications. developed

processing mouse and keyboard input

Most desktop

either

Intel

the x86 processor architecture.

computers contain AMD, Mobile

both

CPU

which

devices,

and use such

as laptops andtablets may use Intel and AMD CPUs, but can also use specific mobile processors developed by companies like ARM or Apple. Modern CPUs often include multiple processing cores, which work together to process instructions. While these "cores" are contained in one physical unit, they are actually individual processors. In fact, if you view

your

computer's

performance

with

system

monitoring utility like Windows Task Manager (Windows) or Activity Monitor (Mac OS X), you will see separate graphs for each processor. Processors that include two cores are called dual-core processors, while those with four cores are called quad-coreprocessors. Some highend workstations contain multiple CPUs with multiple cores, allowing a single machine to have eight, twelve, or even more processing cores. Besides the central processing unit, most desktop and laptop computers also include aGPU. This processor is specifically designed for rendering graphics that are output on amonitor. Desktop computers often have a video card that contains the GPU, while mobile devices usually contain a graphics chip that is integrated into the motherboard. By using separate processors for system and 172

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

graphics processing, computers are able to handle graphic-intensive applications more efficiently.

Processor Core A processor core (or simply “core”) is an individual processor within a CPU. Many computers today have multi-core processors, meaning the CPU contains more than one core. For many years, computer CPUs only had a single core. In the early 2000s,

processorclock

speeds began

plateauing,

CPU

manufacturers needed to find other ways to increase processing performance.

Initially,

they

achieved

this

putting

multiple

processors in high-end computers. While this was effective, it added significant cost to the computers and the multiprocessingperformance was limited by the bus speed between the CPUs. By combining processors on a single chip, CPU manufactures were able to increase performance more efficiently at a lower cost. The individual processing units became known as “cores” rather than processors. In the mid-2000s, dual-core and quad-coreCPUs began replacing multiprocessor configurations. While initially only high-end computers contained

multiple

cores,

today

nearly

all PCs have

multi-core

processors. NOTE: “Core” is also the name of Intel’s processor line, which replaced the Pentium lineup in 2006. Examples of Intel Core processors include the Core Duo, Core 2, Core i3, Core i5, and Core i7.

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PROM Stands for "Programmable Read-Only Memory," and is pronounced "prom," not "prom" like the high school dance. PROM is a type of ROM that is programmed after the memory is constructed. PROM chips have several different applications, including cell phones, video game consoles, RFID tags, medical devices, and other electronics. They provide a simple means of programming electronic devices. Standard PROM can only be programmed once. This is because PROM chips are manufactured with a series of fuses. The chip is programmed by burning fuses, which is an irreversible process. The open fuses are read as ones, while the burned fuses are read as zeros. By burning specific fuses, a binary pattern of ones and zeros is imprinted on the chip. This pattern represents the program applied to the ROM. While PROM cannot be erased, two other versions of PROM have been developed that can be erased and reprogrammed. One type is called EPROM, or Erasable Programmable Read-Only Memory. This type of memory uses floating-gate transistors and can be erased by strong ultraviolet light. The other type is EEPROM, or Electrically Erasable Programmable Read-Only Memory. EEPROM can be erased with an electrical charge and is used in flash memory.

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PS/2 PS/2 is a type of port used by older computers for connecting input devices such askeyboards and mice. The port was introduced with IBM's Personal System/2 computer in 1987 (which was abbreviated "PS/2"). In the following years, the PS/2 port became the standard connection for keyboards and mice in all IBM compatible computers. The PS/2 port has six pins and is roughly circular in shape. Since each PS/2 port is designed to accept a specific input, the keyboard and mouse connections are typically color-coded. For example, the keyboard port on the back of the computer is often purple, while the mouse port is usually green. Similarly, the connector on the end of the keyboard cord is purple and the mouse cord connector is green. This makes it easy for all users to know where to plug the cables into the computer. The concept is similar to the color-coded composite audio/video connections on the back of a TV, which use red, white, and yellow connectors. While the PS/2 port enjoyed a good run for almost two decades, now most keyboards and mice use USB connectors. Unlike PS/2 ports, USB devices can be plugged into any USB port or even a USB hub and the computer will automatically determine what the device is. USB is also "hot swappable," meaning the connections can be removed while the computer is running. If you remove a PS/2 device while the computer is on, it may potentially cause damage to the hardware. Therefore, if you are using a PS/2 device, it is best to turn off the computer before connecting or unplugging a keyboard or mouse. 175

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NOTE: The term "PS2" is also a common abbreviation for Sony's PlayStation 2 game console.

Quad-Core A quad-core CPU has four processing cores in a single chip. It is similar to a dual-core CPU, but has four separate processors (rather than two), which can process instructions at the same time. Quad-core CPUs have become more popular in recent years as the clock speeds of processors have plateaued. By including multiple cores in a single CPU, chip manufacturers can generate higher performance

without

boosting

the

clock

speed.

However,

the

performance gain can only be realized if the computer's software supports multiprocessing. This allows the software to split the processing load between multiple processors (or "cores") instead of only using one processor at a time. Fortunately, most modern operating

systems

and

many

programs

provide

support

for

multiprocessing. Some examples of quad-core CPUs include the Intel Core 2 Quad, Intel Nehalem, and AMD Phenom X4 processors. The Intel processors are used in Mac, Windows, and Linux systems, while the AMD processors are only used in Windows and Linux systems. While four cores may seems impressive, some high end computers have two quad-core CPUs, giving them a total of eight processing cores. Now that is some core power!

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RAM Stands for "Random Access Memory," and is pronounced like the male sheep. RAM is made up of small memory chips that form amemory module.

These

modules

are

installed

the

RAM

slots

the motherboard of your computer. Every time you open a program, it gets loaded from the hard drive into the RAM. This is because reading data from the RAM is much faster than reading data from the hard drive. Running programs from the RAM of the computer allows them to function without any lag time. The more RAM your computer has, the more data can be loaded from the hard drive into the RAM, which can effectively speed up your computer. In fact, adding RAM can be more beneficial to your computer's performance than upgrading the CPU. To check how much RAM a Windows computer has, open the "System" Control Panel. This can be done by right-clicking "My Computer" and selecting "Properties..." To view how much RAM is installed in a Macintosh computer, select "About This Mac" from the Apple Menu.

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RDRAM Stands for "Rambus Dynamic Random Access Memory." It is a type of RAM made by Rambus (big surprise) and is the fastest type of computer memory available. Typical SDRAM can transfer data at speeds up to 133 MHz, while standard RDRAM can crank it up over 1 GHz. Though some motherboards can use RDRAM as system memory, it is so fast, most boards cannot fully benefit from the speed. Because of this, RDRAM is typically used for video memory on graphics acclerator cards, for cache memory (located on the CPU), and for system memory in high-performance workstations and servers. An improvement to RDRAM called Direct Rambus (DRDRAM) allows for even faster data transfer rates. DRDRAM uses a 16-bit bus rather than the 8-bit bus DRAM uses, which means it can handle 8 operations at once and can transfer data at a speeds of 1.6 GHz. Now that's fast.

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Repeater A repeater is an electronic device that relays a transmitted signal. It receives a

signal

on a specific frequency, then amplifies and

rebroadcasts it. By amplifying the signal, a repeater increases the transmission range of the original signal. Repeaters have many applications, but in computing they are most commonly used inwireless networks. For example, a Wi-Finetwork in a large home may benefit from using one or more repeaters to relay the signal to different areas of the house. Homes that have brick walls or cement floors may also benefit from having a repeater relay the signal around the obstacle. Businesses often use a series of repeaters to create a single wireless network within a large building. While repeaters all serve the same purpose, they come in many forms. Some wireless devices, often called "range extenders" are designed to be

used

specifically

repeaters.

Other

devices,

such

as hubs, switches, and routers can all be configured as repeaters using a software utility or web interface that controls the wireless device. NOTE: Since repeaters only relay an incoming signal, using a router as a repeater does not make use of its signal routing capability. Therefore, it make more sense to use a range extender as a repeater if possible

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Retina Display The term "retina display" is a hardware term coined by Apple in June, 2010. It describes a display that has a resolution of over 300 dpi. The iPhone 4, which was also announced in June, 2010, has a screen resolution of 326 dpi and was the first Apple product to include a retina display. The name "retina display" refers to way the high-resolution display appears to the human eye. When a display has a resolution over 300 dpi, most humans cannot recognize individual pixels when viewing the screen from a distance of about 12 inches. Therefore, the pixels seem to run together, creating a smooth appearance. This is similar to digital audio that is recorded with a high sampling rate. Since the audio samples are so close together, we perceive the sound as a smoothanalog signal. Since some people have better vision than others, there is no scientifically accurate number that defines a retina display. In fact, some people may in fact be able to identify individual pixels in a retina display. Still, compared to a typical computer monitors, which has a resolution of 72 dpi, a retina display will look noticeably sharper to all users. Retina displays are especially useful for reading text on a small screen, such as an iPhone or iPod Touch. The increased resolution makes small text legible and medium-sized text easier to read. As display technology continues to evolve, retina displays are expected to be made available in larger devices, such as the iPad and HiDPI monitors 180

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RFID Stands for "Radio-Frequency Identification." RFID is a system used to track objects, people, or animals using tags that respond to radio waves. RFID tags are integrated circuits that include a small antenna. The are typically small enough that they are not easily noticeable and therefore can be placed on many types of objects. Like UPC labels, RFID tags are often used to uniquely identify the object they are attached to. However, unlike UPCs, RFID tags don't need to be scanned directly with a laser scanner. Instead, they can be recorded by simply placing the tag within the range of an RFID radio transmitter. This makes it possible to quickly scan several items or to locate a specific product surrounded by many other items. RFID tags have many different uses. Some examples include: 

Merchandise tags - These tags are attached to clothing, electronics, and other products to prevent theft from retail stores. These tags are typically deactivated at the place of checkout. Tags that have not been deactivated will sound the alarm system near the store's exit.



Inventory management - Products stored in warehouses may be given RFID tags so they can be located more easily.



Airplane luggage - RFID tags may be placed on checked bags so they can be easily tracked and located.



Toll booth passes - E-ZPass and I-Pass receivers may be placed in automobiles, allowing cars and trucks to pass through toll

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booths without needing to stop. This enables drivers to make toll payments automatically. ď&#x201A;ˇ

Credit cards - Some credit cards have built-in RFIDs so they can be "waved" rather than "swiped" near compatible readers. The SpeedPass wand is an example of an RFID-only payment device.

ď&#x201A;ˇ

Animal tags - RFID tags can be placed pet collars to make help identify pets if they are lost. Tags may also be placed on birds

and other animals to help track them for research purposes. The above list includes just a few of the applications of radiofrequency identification. There are many other existing and potential applications for RFID tags as well.

RISC Stands for "Reduced Instruction Set Computing,"and is pronounced "risk." It is arguably the fastest and most effiecient microprocessor technology available today. The RISC architechture is an improvement upon the CISC (Complex Instruction Set Computing) architecture used in the original Intel Pentium chips. In 1974, John Cocke of IBM Research was working on making a faster version of the CISC chip and came up with a design that significantly reduced the number of instructions need for performing computations. The new design was not only faster than the CISC architecture, but the chips were also smaller and less expensive to manufacture. Motorola's PowerPC chips (such as the G4 in Power Macs) are the most widely used RISC-based 182

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chips. Intel has slowly been integrating RISC technology into its chips, but they still are mostly CISC-based.

ROM Stands for "Read-Only Memory." Please do not confuse this term with RAM or a hard drive, as many people already do. ROM is memory containing hardwired instructions that the computer uses when it boots up, before the system software loads. In PCs, the instructions are read from a small program in the ROM, called the BIOS (Basic Input/Output System).

Router This is a hardware device that routes data (hence the name) from a local area network (LAN) to another network connection. A router acts like a coin sorting machine, allowing only authorized machines to connect to other computer systems. Most routers also keep log files about the local network activity.

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SAN Stands for "Storage Area Network." A SAN is anetwork of storage devices that can be accessed by multiple computers. Each computer on the network can access hard drives in the SAN as if they were local disks connected directly to the computer. This allows individual hard drives to be used by multiple computers, making it easy to share information between different machines. While a single server can provide a shared hard drive to multiple machines, large networks may require more storage than a single server

can

offer.

For

example,

large

business

may

have

several terabytes of data that needs to be accessible by multiple machines on a local area network (LAN). In this situation, a SAN could be setup instead of adding additional servers. Since only hard drives need to be added instead of complete computer systems, SANs are an efficient way to increase network storage.

SATA Stands for "Serial Advanced Technology Attachment," or "Serial ATA." It is an interface used to connect ATA hard drives to a computer's motherboard. SATA transfer rates start at 150MBps, which is significantly faster than even the fastest 100MBps ATA/100 drives. For

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this and other reasons, Serial ATA is likely to replace the previous standard, Parallel ATA (PATA), which has been around since the 1980s. Besides

faster

transfer

rates,

the

SATA

interface

has

several

advantages over the PATA interface. For one, SATA drives each have their own independent bus, so there is no competition for bandwidth like there is with Parallel ATA. They also use smaller, thinner cables, which allows for better airflow inside the computer. SATA cables can be as long as one meter, while PATA cables max out at 40cm. This gives manufacturers more liberty when designing the internal layout of their computers. Finally, Serial ATA uses only 7 conductors, while Parallel ATA uses 40. This means there is less likely to be electromagnetic interference with SATA devices. In summary, Serial ATA is a better, more efficient interface than the dated PATA standard. If you are looking to buy a computer that will support fast hard drives for years to come, make sure it comes with a SATA interface.

Scanner A

scanner

an input

device that

scans

documents

such

photographs and pages of text. When a document is scanned, it is converted into a digital format. This creates an electronic version of the document that can be viewed and edited on a computer. Most scanners are flatbed devices, which means they have a flat scanning surface. This is ideal for photographs, magazines, and various documents. Most flatbed scanners have a cover that lifts up so 185

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that books and other bulky objects can also be scanned. Another type of scanner is a sheet-fed scanner, which can only accept paper documents. While sheet-fed scanners cannot scan books, some models include an automatic document feeder, or ADF, which allows multiple pages to be scanned in sequence. Scanners work in conjunction with computer software programs, which import data from the scanner. Most scanners include basic scanning software that allows the user to configure, initiate, and import scans. Scanning plug-ins can also be installed, which allow various software programs to import scanned images directly. For example, if a scanner plug-in is installed for Adobe Photoshop, a user can create new images in Photoshop directly from the connected scanner. While Photoshop can edit scanned images, some programs like Acrobat and OmniPage can actually recognize scanned text. This technology is called optical character recognition, or OCR. Scanning software that includes OCR can turn a scanned text document into a digital text file that can be opened and edited by a word processor. Some OCR programs even capture page and text formatting, making it possible to create electronic copies of physical documents.

Scroll Wheel Computer windows are often not large enough to display the entire contents of the window at one time. Therefore, you may need to scroll through the window to view all the contents. Traditionally, this has been done by clicking and dragging the slider within thescroll 186

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bar. However, many mice now come with scroll wheels that make the scrolling process even easier. The scroll wheel typically sits between the left and right buttons on the top of a mouse. It is raised slightly, which allows the user to easily drag the wheel up or down using the index finger. Pulling the scroll wheel towards you scrolls down the window, while pushing it away scrolls up. Most modern mice include a scroll wheel, since it eliminates the need to move the cursor to the scroll bar in order to scroll through the window. Therefore, once you get accustomed to using a scroll wheel, it can be pretty difficult to live without. Most scroll wheels only allow the user to scroll up and down. However, some programs allow the user to use a modifier key, such as Control or Shift, to change the scrolling input to left and right. Some mice even have a tilting scroll wheel that allows the user to scroll left and right. The Apple Mighty Mouse has a spherical scrolling mechanism (called a scroll ball) that allows the user to also scroll left and right and even diagonally. Whatever the case, any type of scroll wheel is certainly better than nothing.

SCSI Stands for "Small Computer System Interface," and is pronounced "scuzzy." SCSI is a computer interface used primarily for highspeed hard drives. This is because SCSI can support faster data transfer rates than the commonly used IDE storage interface. SCSI also supports daisy-chaining devices, which means several SCSI hard drives 187

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can be connected to single a SCSI interface, with little to no decrease in performance. The different types of SCSI interfaces are listed below: 

SCSI-1: Uses an 8-bit bus, supports data transfer speeds of 4 MBps.



SCSI-2: Uses a 50-pin connector instead of a 25-pin connector, and supports multiple devices. It is one of the most commonly used SCSI standards. Data transfer speeds are typically around 5 MBps.



Wide SCSI: Uses a wider cable (168 cable lines to 68 pins) to support 16-bit data transfers.



Fast SCSI: Uses an 8-bit bus, but doubles the clock rate to support data transfer speeds of 10 MBps.



Fast Wide SCSI: Uses a 16-bit bus and supports data transfer speeds of 20 MBps.



Ultra SCSI: Uses an 8-bit bus, supports data rates of 20 MBps.



SCSI-3: Uses a 16-bit bus, supports data rates of 40 MBps. Also called Ultra Wide SCSI.



Ultra2 SCSI: Uses an 8-bit bus, supports data transfer speeds of 40 MBps.



Wide Ultra2 SCSI: Uses a 16-bit bus, supports data transfer speeds of 80 MBps.



Ultra3 SCSI: Uses a 16-bit bus, supports data transfer rates of 160 MBps. Also known as Ultra-160.



Ultra-320 SCSI: Uses a 16-bit bus, supports data transfer speeds of 320 MBps.



Ultra-640 SCSI: Uses a 16-bit bus, supports data transfer speeds of 640 MBps.

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While SCSI is still used for some high-performance equipment, newer interfaces have largely replaced SCSI in certain applications. For example, Firewire and USB 2.0

have

become

commonly

used

for

connecting external hard drives. Serial ATA, or SATA, is now used as a fast interface for internal hard drives.

SD Stands for "Secure Digital." It is a type of memory card used for storing data in devices such as digital cameras, PDAs, mobile phones, portable music players, and digital voice recorders. The card is one of the smaller memory card formats, measuring 24mm wide by 32mm long and is just 2.1mm thick. To give the cards some orientation, the toprght corner of each SD card is slanted. Even though the cards are extremely small, as of late 2004, they can hold up to 8GB of data. Part of the reason the cards are called "Secure Digital" cards is because the cards have a copyright protection feature built in. The security feature, called "key revocation" means protected data on the card can only be read by specific devices. The cards can have both secured and unsecured areas on them for copyrighted and non-copyrighted data. For more information on SD cards, visit the SD Card Association.

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SDRAM Stands for "Synchronous Dynamic Random Access Memory." Yeah, it's a mouthful, but if you memorize it, you can really impress your friends. SDRAM is an improvement to standard DRAM because it retrieves data alternately between two sets of memory. This eliminates the delay caused when one bank of memory addresses is shut down while another is prepared for reading. It is called "Synchronous" DRAM because the memory is synchronized with the clock speed that the computer's CPU bus speed is optimized for. The faster the bus speed, the faster the SDRAM can be. SDRAM speed is measured in Megahertz, which makes it easy to compare the processor's bus speed to the speed of the memory.

Secondary Memory Secondary

memory

refers

to storage

devices,

such

as hard

drives and solid state drives. It may also refer to removable storage media, such as USB flash drives, CDs, and DVDs. Unlike primary memory, secondary memory is not accessed directly by the CPU. Instead,data accessed from secondary memory is first loaded into RAM and is then sent to theprocessor. The RAM plays an important intermediate role, since it provides much faster data access speeds 190

than

secondary

memory.

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

software programs andfiles into

primary

memory,

computers

can

process data much more quickly. While secondary memory is much slower than primary memory, it typically offers far greater storage capacity. For example, a computer may have a one terabyte hard drive, but only 16 gigabytes of RAM. That means the computer has roughly 64 times more secondary memory than primary memory. Additionally, secondary memory is non-volatile, meaning it retains its data with or without electrical power. RAM, on the other hand, is erased when a computer is shut down or restarted. Therefore, secondary memory is used to store "permanent data," such as the operating system, applications, and user files. NOTE: Secondary memory may also be called "secondary storage." However, this term is a bit more ambiguous, since internal storage devices are sometimes called "primary storage devices" as well.

Secondary Storage Secondary storage technology refers tostorage devices and storage media that are not always directly accessible by a computer. This differs from primary storage technology, such as an internal hard drive, which is constantly available. Examples of secondary storage devices include external hard drives, USB flash drives, and tape drives. These devices must be connected to a computer's external I/O ports in order to be accessed by the system. They may or may not require their own power supply. 191

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Examples

secondary

storage

media

include

recordable CDs and DVDs, floppy disks, and removable disks, such as Zip disks and Jaz disks. Each one of these types of media must be inserted into the appropriate drive in order to be read by the computer. While floppy disks and removable disks are rarely used anymore, CDs and DVDs are still a popular way to save and transfer data. Because secondary storage technology is not always accessible by a computer, it is commonly used for archival and backup purposes. If a computer stops functioning, a secondary storage device may be used to restore a recent backup to a new system. Therefore, if you use a secondary storage device to backup your data, make sure you run frequent backups and test the data on a regular basis.

Sector A sector is the smallest unit that can be accessed on a hard disk. Each platter, or circular disk of a hard disk is divided into tracks, which run around the disk. These tracks get longer as they move from the middle towards the outside of the disk, so there are more sectors along the tracks near the outside of the disk than the ones towards the center of disk. This variance in sectors per track is referred to as "zoned-bit recording." Large files can take up thousands of sectors on a disk. Even if one of these sectors becomes corrupted, the file will most likely be unreadable. While a disk utility program may be able to fix corrupted 192

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data, it cannot fix physical damage. Physically damaged sectors are called "bad sectors." While your computer may recognize and bypass bad sectors on your hard disk, certain bad sectors may prevent your disk from operating properly. Yet another good reason to always back up your data!

Serial Port The serial port is a type of connection on PCs that is used for peripherals such as mice, gaming controllers, modems, and older printers. It is sometimes called a COM port or an RS-232 port, which is its technical name. If that's not enough to confuse you, there are two types of serial ports -- DB9 and DB25. DB9 is a 9-pin connection, and DB25 is, you guessed it, a 25-pin connection. A serial port can only transmit one bit of data at a time, whereas a parallel port can transmit many bits at once. The serial port is typically the slowest port you'll find on a PC, if you find one at all. Most newer computers have replaced serial ports with much faster and more compatible USB ports.

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A server is a computer that provides data to other computers. It may serve data to systems on a local area network (LAN) or a wide area network (WAN) over the Internet. Many types of servers exist, including web servers, mail servers, and file servers. Each type runs software specific to the purpose of the server. For example, a Web server may run Apache HTTP Server or Microsoft IIS, which both provide access to websites over the Internet. A mail server may run a program like Exim or iMail, which provides SMTPservices for sending and receiving email. A file server might use Samba or the operating system's built-in file sharing services to share files over a network. While server software is specific to the type of server, the hardware is not as important. In fact, a regular desktop computers can be turned into a server by adding the appropriate software. For example, a computer connected to a home network can be designated as a file server, print server, or both. While any computer can be configured as a server, most large businesses use rack-mountable hardware designed specifically for server functionality. These systems, often1U in size, take up minimal space and often have useful features such as LED status lights and hotswappable hard drive bays. Multiple rack-mountable servers can be placed in a single rack and often share the same monitor and input devices.

Most

servers

are

accessed

remotely

using remote

access software, so input devices are often not even necessary. While servers can run on different types of computers, it is important that the hardware is sufficient to support the demands of the server. For instance, a web server that runs lots of web scripts in real-time should have a fast processor and enough RAM to handle the "load" without slowing down. A file server should have one or more fast hard 194

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drives or SSDs that can read and write data quickly. Regardless of the type of server, a fast network connection is critical, since all data flows through that connection

Shift Key The Shift key is a modifier key on thekeyboard. Its primary purpose is to capitalize lowercase letters. When the Shift key is not being pressed, letters are entered as lowercase by default (unless Caps Lock has been activated). When a user holds down the Shift key while typing a letter, the capitalized version of the letter is entered. The Shift key also affects other keys on the keyboard. For example, you might notice that the numbers near the top of the keyboard have symbols above them. These symbols are entered when you hold the Shift key while typing the corresponding number. For example, Shift+1 enters an exclamation mark (!), while Shift+8 enters an asterisk (*). The same is true for the punctuation keys, such as period, comma, semicolon, etc. The lower symbols are entered when the Shift key is not being pressed, while the top symbols are entered when the Shift key is held down. Since Shift is a modifier key, it can also be used in conjunction with the mouse. For example, many programs will allow you to select more than one item by holding down the Shift key and clicking multiple items on the screen. It can also be used to select a section of text by clicking in one spot, holding Shift, then clicking in another spot. Finally, Shift is sometimes used for keyboard shortcuts that perform 195

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common commands. For example, Control+S is the standard "Save" shortcut, while "Control+Shift+S" is typically used for "Save As..."

SIM Card Stands for "Subscriber Identification Module Card." A SIM card is a small removable chipthat identifies a mobile device on a cellular network. It contains an integrated circuit that stores a unique identifier called an "international mobile subscriber identity" (IMSI) number and other information specific to the mobile carrier. A SIM card or an embedded SIM is required in order for any cell phone, smartphone, ortablet to be used on a cellular network. When you activate a cell phone, the cellular provider links your phone number to your SIM card, which allows you to make receive calls and access cellular data. If you replace your SIM card or a get a new phone with a new SIM card, the new SIM identifier must be linked to your account in order for your mobile device to be recognized on the network. SIM cards have been standardized in increasingly smaller sizes since the first SIM card was used in 1991. Below are several SIM card formats. 1. Full size (1991) - 85.6 x 53.98 mm x 0.76 mm 2. Mini-SIM (1996) - 25 x 15 mm x 0.76 mm 3. Micro-SIM (2003) - 15 x 12 mm x 0.76 mm 4. Nano-SIM (2012) - 12.3 x 8.8 mm x 0.67 mm 196

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Cellular devices are designed to work with a specific SIM card format so if you need to replace your SIM card, it is important to verify the correct size with your cellular provider. Removing a SIM card is usually pretty simple. Some devices, like the iPhone, have a SIM card tray that pops out from the side of the device. You can open the tray by pressing the access hole with a paperclip. Other devices, such as the Samsung Galaxy, require you to remove the back cover and battery to access the SIM card. You can remove and replace the SIM card without powering down your device.

SIMM Stands for "Single In-Line Memory Module." This is an older type of computer memory. A SIMM is a small circuit board with a bunch of memory chips on it. SIMMs use a 32-bit bus, which is not as wide as the 64-bit bus dual in-line memory modules (DIMMs) use. Newer processors require a 64-bit memory bus, so it is best to use DIMMs. Sometimes you can get away with installing SIMMS, but they have to be installed in pairs.

SLI Stands for "Scalable Link Interface." SLI is a technology developed by NVIDIA that allows multiple graphics cards to work together in a single 197

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computer system. This enables faster graphics performance than what is possible with a single card. For example, using SLI to link two cards together may offer up to twice the performance of a single video card. If each card has two GPUs, the result may be up to four times the performance of a typical video card! For video cards to be linked using NVIDIA's SLI system, the computer must have multiple PCI Express slots. PCI Express is the first video card interface that allows the linking of multiple graphics cards because the slots share the same bus. Previous technologies, such as PCI and AGP, used separate buses, which did not allow graphics cards to be bridged together. The PCI Express slots must also support enough bandwidth for the cards, which typically means they must be x8 or x16 slots. Of course, the cards themselves must also support SLI bridging in order to work together.

SMART Stands for "Self-Monitoring Analysis And Reporting Technology." It is used to protect and prevent errors in hard drives. The SMART technology basically monitors and analyzes hard drives (hence the name), then checks the health of your hard drive and lets you know if there are any problems. The main purpose of SMART is to keep your hard drive running smoothly and prevent it from crashing.

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Smartphone A smartphone is a mobile phone that includes advanced functionality beyond making phone calls and sending text messages. Most smartphones have the capability to display photos, play videos, check and send e-mail, and surf the Web. Modern smartphones, such as the iPhone and Android based phones can run third-party applications, which provides limitless functionality. While smartphones were initially used mostly by business users, they have become a common choice for consumers as well. Thanks to advancements in technology, modern smartphones are smaller and cheaper than earlier devices. Users also have a much wider range of smartphones to choose from than before. While the RIM Blackberry dominated

the

smartphone

market

for

many

years,

other

manufacturers like Apple, HTC, and Samsung now offer a wide variety of smartphone options as well. This increase in smartphone availability has led to a corresponding decline in the usage of standard PDAs, which do not include phone capabilities. Since smartphones have a wide range of functionality, they require advanced software, similar to a computer operating system. The smartphone software handles phone calls, runs applications, and provides configuration options for the user. Most smartphones include a USB connection, which allows users to sync data with their computers and update their smartphone software.

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SO-DIMM Stands for "Small Outline Dual In-Line Memory Module." Most desktop computers have plenty of space for RAM chips, so the size of the memory modules is not a concern. However, with laptops, the size of the memory modules matters significantly. Because laptops are designed to be as small and as light as possible, the size of each component matters. In fact, laptop parts are so crammed together, large RAM chips often do not fit into the overall laptop design. This is why SO-DIMMs were created. A SO-DIMM is about half the length of a regular size DIMM. This allows greater flexibility in designing the memory slots for laptops. Many laptops have a user-accessible section that houses the SO-DIMMs, which make it easy to upgrade the computer's RAM. If the RAM chips were full size DIMMs, this type of design would be harder to incorporate and would likely increase the size of the laptop. The first SO-DIMMs used 72 pins (or connectors) and supported 32-bit data transfers. Modern SO-DIMMs, however, typically use 144 pins, which allows for the same 64-bit transfers that a regular size DIMM does. While SO-DIMMs are used primarily in laptops, some desktop computers with small form factors also use SO-DIMMs to reduce the overall size of the case. However, when size is not an issue, regular DIMMs are typically used because they are a more cost-effective solution.

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SoC Stands for "System On a Chip." An SoC (pronounced "S-O-C") is an integrated circuitthat contains all the required circuitry and components of an electronic system on a single chip. It can be contrasted with a traditional computer system, which is comprised of many distinct components. Adesktop computer, for example, may have

aCPU, video

different buses on

card,

and sound

themotherboard.

card that An

SoC

are

connected

combines

these

components into a single chip. The primary advantage of a system on a chip is the reduction of physical

space required for the system.

By merging

multiple

components together, SoCs can be used to create fully functional systems that are a fraction of the the size of their traditional counterparts. Examples include smartphones, tablets, and wearable devices, such as smartwatches. A smartwatch SoC, for example, may include a primary CPU, graphics processor, DAC, ADC, flash memory, and voltage regulator. All of these components fit on a single chip roughly the size of a quarter. The size of an SoC is also its greatest disadvantage. Since all the components are compressed into a single integrated circuit, they are limited in their storage capacity and processing power. For example, a high-end

desktop

and SSD will

easily

computer outperform

with a

dedicated

smartphone

graphics

from

the

card same

generation. However, advances in mobile processing technology enable modern smartphones to provide similar performance to highend computers from only a few years ago. 201

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Solid State Solid state, at its most basic level, means "no moving parts." Therefore, solid state electronic devices are made up of solid components that do not

move.

Some

examples

include

computer motherboardsand integrated circuits. Devices that use only solid state parts, such as television sets, speakers, and digital watches, are often referred to as solid state products. Flash memory devices are solid state products, while hard drives are not. This is because hard drives use a spinning disk and moving drive head to read and write data, while flash memory uses electric charges to perform the same functions. For this reason, flash memory devices are seen as more durable than hard drives. This is why flash memory is often used in products such as portable MP3 players and digital cameras. Because solid state devices have no moving parts, they are less likely to break down than devices that have mobile mechanisms. For this reason, it is often more worthwhile to buy an extended warranty on electronics that have moving parts than those that do not. That is something you may want to think about next time you are shopping.

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Sound Card The sound card is a component inside the computer that provides audio input andoutput capabilities. Most sound cards have at least one analog line input and one stereo lineoutput connection. The connectors are typically 3.5 mm minijacks, which are the size most headphones use. Some sound cards also support digital audio input and output, either through a standard TRS (tip-ring-sleeve) connection or via an optical audio port, such as Toslink connector. While there are many types of sound cards, any type that produces an analog output must include a digital-to-analog converter (DAC). This converts the outgoing signal from digital to analog, which can be played through most speaker systems. Sounds cards that support analog input also require an analog-to-digital converter (ADC). This digitizes the incoming analog signal, so the computer can process it. In some computers, the sound card is part of the motherboard, while other machines may have an actual card that reside in a PCI slot. If you want to more audio capabilities to your computer, such as additional input or output channels, you can install a new sound card. Professional sound cards often support higher sampling rates (such as 192 kHz instead of 44.1 kHz) and may have more inputs and outputs. Some cards may also have 1/4 in. connectors instead of 3.5 mm, which accommodates most instrument outputs. While professional sound cards can add more audio capabilities to your computer, another popular option for multi-channel recording is a breakout box. This is an external box that typically includes a built-in 203

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

sound card and multiple audio connections. For example, a breakout box may support 16 channels of audio, which would be impossible to fit

single

a Firewireor USB port,

card.

Most

though

breakout

some

boxes

connect

connect sound

to card

specifically designed to communicate with the box.

Southbridge The southbridge is a chip that connects thenorthbridge to other components inside the computer, including hard drives, network connections, USB and Firewire devices,

the

system

clock,

and

standard PCI cards. The southbridge sends and receives data from the CPU through the northbridge chip, which is connected directly to the computer'sprocessor. Since the southbridge is not connected directly to the CPU, it does not have to run as fast as the northbridge chip. However, it processes data from more components, so it must be able to multitask well. On Intel systems, the southbridge is also referred to as the I/O Controller Hub, since it controls the input and output devices.

Speakers Speakers are one of the most common output devices used with computer systems. Some speakers are designed to work specifically with computers, while others can be hooked up to any type of sound 204 COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

system. Regardless of their design, the purpose of speakers is to produce audio output that can be heard by the listener. Speakers are transducers that convert electromagnetic waves into sound waves. The speakers receive audio input from a device such as a computer

audio

receiver.

This

input

may

either

in analog or digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Since sound waves are produced in analog form, digital speakers must first convert the digital input to an analog signal, then generate the sound waves. The sound produced by speakers is defined by frequency and amplitude. The frequency determines how high or low the pitch of the sound is. For example, a soprano singer's voice produces high frequency sound waves, while a bass guitar or kick drum generates sounds in the low frequency range. A speaker system's ability to accurately reproduce sound frequencies is a good indicator of how clear the audio will be. Many speakers include multiple speaker cones for different frequency ranges, which helps produce more accurate sounds for each range. Two-way speakers typically have a tweeter and a mid-range speaker, while three-way speakers have a tweeter, midrange speaker, and subwoofer. Amplitude, or loudness, is determined by the change in air pressure created by the speakers' sound waves. Therefore, when you crank up your speakers, you are actually increasing the air pressure of the sound waves they produce. Since the signal produced by some audio sources is not very high (like a computer's sound card), it may need to be amplified by the speakers. Therefore, most external computer speakers are amplified, meaning they use electricity to amplify the signal. Speakers that can amplify the sound input are often called 205

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active speakers. You can usually tell if a speaker is active if it has a volume control or can be plugged into an electrical outlet. Speakers that don't have any internal amplification are called passive speakers. Since these speakers don't amplify the audio signal, they require a high level of audio input, which may be produced by an audio amplifier. Speakers typically come in pairs, which allows them to produce stereo sound. This means the left and right speakers transmit audio on two completely separate channels. By using two speakers, music sounds much more natural since our ears are used to hearing sounds from the left and right at the same time. Surround systems may include four to seven speakers (plus a subwoofer), which creates an even more realistic experience.

SRAM Stands for "Static Random Access Memory." I know it is tempting to pronounce this term as "Sram," but it is correctly pronounced "S-ram." SRAM is a type of RAM that stores data using a static method, in which the data remains constant as long as electric power is supplied to the memory chip. This is different than DRAM (dynamic RAM), which stores data dynamically and constantly needs to refresh the data stored in the memory. Because SRAM stores data statically, it is faster and requires less power than DRAM. However, SRAM is more expensive to manufacture than DRAM because it is built using a more complex structure. This complexity also limits 206

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the amount of data a single chip can store, meaning SRAM chips cannot hold as much data as DRAM chips. For this reason, DRAM is most often used as the main memory for personal computers. However, SRAM is commonly used in smaller applications, such as CPU cache memory and hard drive buffers. It is also used in other consumer electronics, from large appliances to small children's toys. It is important to not confuse SRAM with SDRAM, which is a type of DRAM.

SSD Stands for "Solid State Drive." An SSD is a type of mass storage device similar to a hard disk drive (HDD). It supports reading and writing data and maintains stored data in a permanent state even without power. Internal SSDs connect to a computer like a hard drive, using standard IDE or SATA connections. While SSDs serve the same function as hard drives, their internal components are much different. Unlike hard drives, SSDs do not have any moving parts (which is why they are called solid state drives). Instead of storing data on magnetic platters, SSDs store data using flash memory. Since SSDs have no moving parts, they don't have to "spin up" while in a sleep state and they don't need to move a drive head to different parts of the drive to access data. Therefore, SSDs can access data faster than HDDs. SSDs have several other advantages over hard drives as well. For example, the read performance of a hard drive declines when data gets fragmented, or split up into multiple locations on the disk. The read 207

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performance of an SSD does not diminish based on where data is stored on the drive. Therefore defragmenting an SSD is not necessary. Since SSDs do not store data magnetically, they are not susceptible to data loss due to strong magnetic fields in close proximity to the drive. Additionally, since SSDs have no moving parts, there is far less chance of a mechanical breakdown. SSDs are also lighter, quieter, and use less power than hard drives. This is why SSDs have become a popular choice for laptop computers. While SSDs have many advantages over HDDs, they also have some drawbacks. Since the SSD technology is much newer than traditional hard drive technology, the price of SSDs is substantially higher. As of early 2011, SSDs cost about 10 times as much pergigabyte as a hard drive. Therefore, most SSD drives sold today have much smaller capacities than comparable hard drives. They also have a limited number or write cycles, which may cause their performance to degrade over time. Fortunately, newer SSDs have improved reliability and should last several years before any reduction in performance is noticeable. As the SSD technology improves and the prices continue to fall, it is likely that solid state drives will begin to replace hard disk drives for most purposes.

Storage Device A computer storage device is any type of hardware that stores data. The most common type of storage device, which nearly all computers have, is a hard drive. The computer's primary hard drive stores the 208

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operating system, applications, and files and folders for users of the computer. While the hard drive is the most ubiquitous of all storage devices, several other types are common as well. Flash memory devices, such as USB keychain drives and iPod nanos are popular ways to store data in a small, mobile format. Other types of flash memory, such as compact flash and SD cards are popular ways to store images taken by digital cameras. External

hard

drives

that

connect

via Firewire and USB are

also

common. These types of drives are often used for backing up internal hard drives, storing video or photo libraries, or for simply adding extra storage. Finally, tape drives, which use reels of tape to store data, are another type of storage device and are typically used for backing up data.

Supercomputer As the name implies, a supercomputer is no ordinary computer. It is a high performance computing machine designed to have extremely fast processing speeds. Supercomputers have various applications, such

performing

complex

scientific

calculations,

modeling

simulations, and rendering large amounts of 3D graphics. They may also be built to simply showcase the leading edge of computing technology. If you are hoping to have a supercomputer on your desk, you may be out of luck. Supercomputers are typically several times the size of a typical 209

desktop

computer

and

require

far

power.

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

supercomputer may also consist of a series of computers, which may fill an entire room. Examples of single machine supercomputers include the early Cray-1 and Cray X-MP systems developed by Cray Research

well

the

recent Blue

Gene and Roadrunner systems developed by IBM. System X is an example of a multi-system supercomputer, which was developed by Virginia Tech and is comprised of 1,100 Apple Xserve G5s. Supercomputers cost a fortune to build and are expensive to maintain, which is why only a few exist in the entire world. Furthermore, computing power continues to advance each year, meaning it isn't too long before a ground-breaking supercomputer isn't so super. The good news is that the supercomputers of the past eventually become the personal computers of today. Therefore, your home PC most likely has more computing power than many supercomputers from previous decades. Now that's super cool.

Superscalar A superscalar CPU can execute more than one instruction per clock cycle. Because processing speeds are measured in clock cycles per second (megahertz), a superscalar processor will be faster than a scalar processor rated at the same megahertz. A superscalar architecture includes parallel execution units, which can execute instructions simultaneously. This parallel architecture was first implemented

in RISCprocessors,

which

use

short

and

simple

instructions to perform calculations. Because of their superscalar 210

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capabilities,

RISC

processors

have

typically

performed

better

than CISCprocessors running at the same megahertz. However, most CISC-based processors (such as the Intel Pentium) now include some RISC architecture as well, which enables them to execute instructions in parallel. Nearly all processors developed after 1998 are superscalar.

Surface Surface is a tablet PC developed by Microsoft. The first Surface model was released on October 26, 2012, the same day as Windows 8and Windows RT. The Surface is a hybrid device that combines the features of a tablet and a laptop. It does not require any external input devices and can be used as a standalone touchscreentablet. However, the Surface easily connects to Microsoft's custom keyboard, which includes a trackpad that can be used to control a cursor on the screen. The built-in "kickstand" allows the tablet to stand upright, and when combined with the keyboard, makes the Surface look and feel like a laptop. The Surface runs both Windows RT and Windows 8 Pro, though the device initially shipped exclusively with Windows RT. Both operating systems support

touchscreen and keyboard/mouse

input,

which

means you can use the Surface however you prefer. For example, if you are on-the-go, you can use the on-screen keyboard to enter text input. If you are at a desk, you can flip out the kickstand and use the physical keyboard. You can also use the keyboard's built-in trackpad or a connected mouse to click on items rather than tapping the screen. 211

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The Surface is designed to be a highly portable device and therefore includes

built-inwireless communication,

such

as Wi-

Fi (802.11a/b/g/n) and Bluetooth 4.0. It also has aUSB port for wired peripherals, a micro SDXC card slot for extra storage, an audio input/output jack, and a micro HDMI video out port. The Surface's magnesium case includes built-in front and rear-facing 720p HD cameras and a 16x9 screen with a resolution of 1366x768 pixels. NOTE: The Surface can be purchased with or without a keyboard. You can choose between either the "touch keyboard," which has a flat, spillproof surface, or the "type keyboard," which has raised keys and feels more like a traditional keyboard. Both keyboards double as protective covers for the Surface and can be folded to the back of the tablet when not in use.

Surge Protector The surge protector is an important, yet often overlooked part of a computer setup. It allows multiple devices to plugged in to it at one time and protects each connected device from power surges. For example, a home office may have a computer, monitor, printer, cable modem, and powered speakers all plugged into one surge protector, which is plugged into a single outlet in the wall. The surge protector allows many devices to use one outlet, while protecting each of them from electrical surges. Surge protectors, sometimes called power strips, prevent surges in electrical current by sending the excess current to the grounding wire 212

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(which is the round part of the plug below the two flat metal pieces on U.S. outlet plugs). If the surge is extra high, such as from a lightning strike, a fuse in the surge protector will blow and the current will prevented from reaching any of the devices plugged into the surge protector. This means the noble surge protector will have given its life for the rest of the equipment, since the fuse is destroyed in the process. While surge protectors all perform the same basic function, they come in many shapes and sizes with different levels of protection. Some may look like basic power strips, while others may be rack mounted or fit directly against the wall. Most surge protectors offer six to ten different outlets. Cheaper surge protectors offer limited protection for surges (under 1000 joules), while more expensive ones offer protection for several thousand joules and include a monetary guarantee on connected devices if a power surge happens. Typically, you get what you pay for, so if you have an expensive computer system, it is wise to buy a quality surge protector that offers at least 1000 joules of protection. Some surge protectors also include line conditioning, which uses an electromagnet to maintain a consistent level of electricity when there are slight variations in current. For example, you might notice your computer monitor or television fade for a moment when you turn on a high-powered device, like a vacuum or air conditioner. A surge protector with line conditioning should prevent connected devices from being affected by these slight variances in current. While you may be able to hook up your computer system without a surge protector, it is important to protect your equipment by using one. You may not need a large, expensive surge protector with line 213

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conditioning, but using a quality surge protector for all your electronic devices is a smart choice.

Switch A switch is used to network multiple computers together. Switches made for the consumer market are typically small, flat boxes with 4 to 8 Ethernet ports. These ports can connect to computers, cable or DSL modems, and other switches. High-end switches can have more than 50 ports and often are rack mounted. Switches are more advanced than hubs and less capable than routers. Unlike hubs, switches can limit the traffic to and from each port so that each device connected to the switch has a sufficient amount of bandwidth. For this reason, you can think of a switch as a "smart hub." However, switches don't provide the firewall and logging capabilities that routers do. Routers can often be configured by software (typically via a Web interface), while switches only work the way the hardware was designed. The term "switch" can also be used to refer to a small lever or button on computer hardware. And while it has nothing to do with computers, "riding

switch"

means

riding

backwards

skateboarding

and

snowboarding.

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System Requirements Whenever you purchase software or hardware for your computer, you should

first

make

sure

your

computer

supports

the

system

requirements. These are the necessary specifications your computer must have in order to use the software or hardware. For example, a computer game may require you computer to have Windows XP or later, a 2.0 GHz processor, 512 MB or RAM, a 64 MB graphics card, and 500 MB or hard drive space. If your computer does not meet all of these requirements, the game will not run very well or might not run at all. It is just as important to check system requirements for hardware devices. For example, if you buy a printer, it may require either Windows XP or Mac OS X 10.3 or later. It may also require a USB port and 80 MB of available hard drive space. If your computer does not have any USB ports, you will not be able to physically connect the printer. If your machine does not have Windows XP or Mac OS X 10.3 or later, the printer drivers may be incompatible with your operating system. This means you computer will be unable to recognize the printer. Most hardware and software products have the system requirements printed on the side or bottom of the product packaging. When you are 215

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shopping for computer software or hardware, it is a good idea to first find out exactly what your system's specifications are and write them down on a piece of paper. The important information to record includes: 1. Operating System (i.e. Windows XP, SP 2 or Mac OS X 10.3.8) 2. Processor Speed (i.e. Pentium 4, 3.2 GHz or Power PC G5, 2.0 GHz) 3. Memory, a.k.a. RAM (i.e. 512 MB) 4. Graphics Card (i.e. ATI Radeon 9800 w/ 256 MB video memory) 5. Hard Disk Space (i.e. 80 GB available) 6. I/O Ports (i.e. USB, Firewire, Serial, Parallel, SCSI, VGA, DVI ports) By recording these specifications from your computer, you will be able to make sure your computer supports the products you are buying

System Unit The system unit, also known as a "tower" or "chassis," is the main part of a desktop computer. It includes the motherboard, CPU,RAM, and other components. The system unit also includes the case that houses the internal components of the computer. The term "system unit" is often used to differentiate between the computer

andperipheral devices,

such

the monitor,keyboard,

and mouse. For example, if a repair shop asks you to bring in your computer, it may be unclear whether you need to bring your monitor 216

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and peripheral devices as well. If you are told to just bring your system unit, it is clear you only need to bring the computer itself. Some modern computers, such as the iMac, combine the system unit and monitor into a single device. In this case, the monitor is part of the system unit. While laptops also have built-in displays, they are not called system units, since the term only refers to desktop computers.

Tablet A

tablet,

tablet

PC,

portable

computer

that

uses

a touchscreen as its primary input device. Most tablets are slightly smaller and weigh less than the average laptop. While some tablets include fold out keyboards, others, such as the Apple iPad and Motorola Xoom, only offer touchscreen input. Early tablet touchscreens were designed to work with light pens, but most modern tablets support human touch input. Many tablets now support multitouch input, which allows you to perform gestures with multiple fingers, such as pinching an image to zoom out, or spreading your fingers apart to zoom in. Tablets without physical keyboards allow you to enter text using a pop-up keyboard that appears on the screen. Since tablets do not use a traditional keyboard and mouse as their primary forms ofinput, the user interface of a tablet is different than a typical laptop. For example, instead of double-clicking to open a program, most applications open with a single tap. Instead of clicking on a scroll bar to scroll through a window, most tablet applications 217

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

allow you to swipe up and down anywhere within a window to scroll through the content. Since tablet PCs provide a different interface than traditional computers, they offer unique possibilities for graphics applications, games, and other programs. Because of their small form factor, they are extremely portable and can be easily stowed in a backpack or a briefcase. Still, because tablets lack a keyboard and mouse, some tasks such as typing documents and writing email messages, are more difficult on tablets than traditional computers. Therefore, tablets are generally seen as accessories to laptops and desktop computers rather than replacements.

Tape Drive This is a removable storage device mainly used for backing up data. It is similar to a Zip Drive, but instead of Zip disks, it uses small tapes. The drive acts like a tape recorder, reading data from the computer and writing it onto the tape. Since tape drives have to scan through lots of tape to read small amounts of scattered data, they are not practical for most storage purposes. That is why they are used almost exclusively for data backup. The benefit of tape drives is that they typically have large capacities for storing data, for a lower cost than hard drives similar in size. Also, multiple tapes can be used to make incremental backups (daily, weekly, monthly, etc.), which is much cheaper than using multiple hard drives.

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TFT Stands for "Thin Film Transistor." These transistors are used in highquality flat panel liquid-crystal displays (LCDs). TFT-based displays have a transistor for each pixel on the screen. This allows the electrical current that illuminates the display to be turned on and off at a faster rate, which makes the display brighter and shows motion smoother. LCDs that use TFT technology are called "active-matrix" displays, which are higher-quality than older "passive-matrix" displays. So if you ever see a TFTAMLCD monitor at your local computer store, it is a "thin-film transistor active-matrix liquid crystal display." Basically, it is a highquality flat screen monitor.

Thermistor A thermistor (short for "thermal resistor") is a type of resistor that is used to measure temperature. While typical resistors are designed to maintain

consistent

resistance

regardless

temperature,

thermistor's resistance varies significantly as the temperature changes. Once a thermistor is calibrated, changes in electrical resistance can be accurately translated into changes in temperature. Thermistors are commonly used in computers to monitor the ambient temperature of internal components. For example, thermistors may be used 219

record

the

temperature

near

the CPU, RAM slots,

and

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

the power supply. These thermistors are usually integrated into the computer's motherboard. The actual temperature of components such as the processor and memory modules is typically measured by a diode that is integrated into the chip. Computers use the information recorded by thermistors to prevent overheating. For example, if a processor is running near capacity for an extended period of time, the temperature may gradually increase. When this happens, the computer might speed up the internal fans to increase airflow and cool the computer. In extreme circumstances, such as when a laptop is used outside on a hot day, the fans may not be able to keep the computer at a safe temperature. If the thermistors record a dangerously high temperature, the computer may shut down to avoid overheating and damaging thehardware.

Thick Client Thick clients, also called heavy clients, are full-featured computers that are connected to a network. Unlike thin clients, which lack hard drives and other features, thick clients are functional whether they are connected to a network or not. While a thick client is fully functional without a network connection, it is only a "client" when it is connected to a server. The server may provide the thick client with programs and files that are not stored on the local machine's hard drive. It is not uncommon for workplaces to provide thick clients to their employees. This enables them to access files on a local server or use the computers offline. When a thick client 220

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is disconnected from the network, it is often referred to as a workstation.

Thin Client In the 1950s, minimalism emerged as an popular art movement. In the 1990s, minimalism emerged again as a popular computer trend. As computer

networking

became

commonplace,

minimalist

computers became more common as well. In fact, these trimmed-down machines, often referred to as thin clients, are still popular today. Thin clients function as regular PCs, but lackhard drives and typically do not have extra I/O ports or other unnecessary features. Since they do not have hard drives, thin clients do not have any software installed on them. Instead, they run programs and access data from a server. For this reason, thin clients must have a network connection and are sometimes referred to as "network computers" or "NCs." Thin clients can be a cost-effective solution for businesses or organizations that need several computers that all do the same thing. For example, students in a classroom could all run the same program from a server, each using his own thin client machine. Because the server provides the software to each computer on the network, it is not necessary for each NC to have a hard drive. Thin clients also make it easier to manage computer networks since software issues need to be managed only on the server instead of on each machine.

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Thunderbolt Thunderbolt is a high-speed I/O interface that was developed by Intel and was introduced by Apple in 2011. It is based on the PCI Expressand DisplayPort technologies and supports both data devices and displays. Since Thunderbolt is based on the PCI Express architecture, external devices connected via Thunderbolt can achieve performance that was previously only possible from internalcomponents. Additionally, the Thunderbolt interface offers 10 Gpbs of throughput in both directions. That is more than 12 times as fast as Firewire 800 and over 20 times faster than USB 2.0. While a FireWire 800 interface can only support one stream of 720p video, a Thunderbolt interface can support 8 simultaneous 720p video streams. Like

USB

and

FireWire,

Thunderbolt

can

provide

power

connected peripheral devices. That means external devices that require 10 watts of power or less can be powered directly from the Thunderbolt port. Additionally, simple adapters can be used to connect USB, FireWire, and Ethernet devices to a Thunderbolt port. While Thunderbolt is primarily used as a high-speed data interface, it can also be used to connect high-resolution displays. The Thunderbolt interface is physically identical to the Mini-DisplayPort interface and therefore can be used to connect a DisplayPortmonitor. Like HDMI, DisplayPort supports both audio and video, eliminating the need for a separate audio cable. 222

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Thunderbolt devices can be daisy-chained, meaning multiple devices can be connected in sequence to a single Thunderbolt port. For example, you can connect a Thunderbolt display to a computer and a Thunderbolt external hard drive to the display. You could also connect a second Thunderbolt monitor to the first display. This means you can connect two external displays to a laptop, as long as the laptop supports the resolutionrequired for two screens.

Thyristor A thyristor is a four-layer semiconductor that is often used for handling large amounts of power. While a thyristor can be turned on or off, it can also regulate power using something called phase angle control. This allows the amount of power output to be controlled by adjusting the angle of the current input. An example of this is the a dimmer switch for a light. While thyristors have the advantage of using phase angle control and handling large amounts of power, they are not as suitable for low power applications. This is because they can only be turned off by switching the direction of the current. For this reason, a thyristor may take longer to turn on or off that other semiconductors. Also, thyristors can only conduct in one direction, making them impractical for applications that require current to be conducted to and from each device.

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oggle Key A

toggle

key

toggles

the input from

group

keys

a keyboard between two different input modes. The most common toggle key isCaps Lock, which toggles the letter keys between lowercase and uppercase mode. Some keyboards also have other toggle keys, such as Num Lock, Scroll Lock, and Insert. Below is a list of toggle keys and their functions. 

Caps Lock - capitalizes the input of all letter keys when turned on; may allow lowercase letters to be entered using theShift key on some keyboards; does not affect the number keys.



Num Lock - ensures numbers are input from the numeric keypad rather than arrows or other commands; typically turned on by default; may also be used to change letter keys to numbers on laptop keyboards.



Scroll Lock - causes the arrow keys to scroll through the contents of a window when turned on; allows users to scroll using the arrow keys rather then clicking on the scroll bar at the right side or bottom of a window; not supported by most modern operating systems.



Insert - toggles between "insert mode" and "overtype mode" when entering text; insert mode is the default mode, which inserts characters wherever the cursor is located, while overtype

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mode overwrites characters as the user types; also not supported by most modern operating systems. Unlike modifer keys, toggle keys are switched on or off each time they are pressed. Therefore, toggle keys do not need to be held down when pressing other keys. Some keyboards have lights on or near the toggle keys to let the user know if they are turned on or off. Some modern operating systems also display the status of toggle keys on the user's screen. For example, the software installed with Logitech keyboards on Macintosh computers displays a Caps Lock icon in the menu bar whenever Caps Lock is turned on.

Toslink Toslink is a type of digital audio connection developed by Toshiba Corporation. It uses afiber optic cable to transmit an audio signal in the form of pulses of light. A single Toslink cable can be used to carry a mono, stereo, or even a surround audio signal. Toslink is similar to the Sony/Philips Digital Interfance, known as S/PDIF. It provides the same digital audio data as S/PDIF, but uses a light beam instead of an electrical current to send the data. Because the Toslink cable does not use electrical currents, the connection is immune to electrical or magnetic interference. Toslink connections are most commonly found on high-end home theater receivers, MiniDisc players, and professional audio equipment, as well as Power Mac G5 computers

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Touchscreen A touchscreen is a display that also serves as an input device. Some touchscreens require a proprietary pen for input, though most modern touchscreens detect human touch. Since touchscreen devices accept input directly through the screen, they do not require external input devices, such as miceand keyboards. This makes touchscreens ideal for

computer

kiosks,

well

portable

devices,

such

as tablets and smartphones. While a touchscreen may look like an ordinary display, the screen includes several extra layers that detect input. The first layer is a hard protective layer that protects the actual display and the touchscreen components. Beneath the protective layer is an electronic grid that detects input. Most modern touchscreens use capacitive material for this grid, in which the electrical charge changes wherever the screen is touched. Beneath the touchscreen layer is the LCD layer, which is used for the actual display. While early touchscreens could only detect a single point of input at a time,

modern

touchscreens

support

"multi-touch"

input.

This

technology, which was made popular by the original iPhone, enables the screen to detect multiple finger motions at once. For example, on some touchscreen devices, you can rotate an image by twisting three fingers in a clockwise or counterclockwise motion. Many touchscreen applications also allow you zoom in and out by spreading two fingers apart or pinching them together. Thanks to multi-touch and other improvements in touchscreen technology, today's touchscreens are easier and more natural to use 226

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

than they used to be. In fact, improved touchscreen technology has greatly contributed to the popularity of the iPad and other tablet PCs.

Trackball A trackball is an input device used to enter motion data into computers or other electronic devices. It serves the same purpose as a mouse, but is designed with a moveable ball on the top, which can be rolled in any direction. Instead of moving the whole device, you simply roll the moveable ball on top of the trackball unit with your hand to generate motion input. Trackballs

designed

for

computers

generally

serve

mouse

replacements and are primarily used to move the cursor on the screen. Like mice, computer trackball devices also include buttons, which can serve as left-click and right-click buttons, and may also be used to enter other commands. While trackballs are most commonly used with computers, they may also be found in other electronics, such as arcade games, mixing boards, and self-serve kiosks. These devices often have trackballs that are larger than the ones used in computer input devices. Besides the capability to be built into various devices, trackballs have a number of other advantages over mice. Some advantages include the small footprint (since they don't require a mousepad or large area to move the mouse), fingertip control (which may offer more accuracy), and improved ergonomics (since there is less strain on the wrist). Still, many people find trackballs harder to use than mice, since they feel less natural and may require practice to get used to. For this reason, 227

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

the vast majority of computers include a mouse, rather than a trackball, as the default input device.

Transistor A transistor is a basic electrical component that alters the flow of electrical current. Transistors are the building blocks ofintegrated circuits, such as computer processors, or CPUs. Modern CPUs contain millions of individual transistors that are microscopic in size. Most transistors include three connection points, or terminals, which can connect to other transistors or electrical components. By modifying the current between the first and second terminals, the current between the second and third terminals is changed. This allows a transistor to act as a switch, which can turn a signal on or off. Since computers operate in binary, and a transistor's "on" or "off" state can represent a 1 or 0, transistors are suitable for performing mathematical calculations. A series of transistors may also be used as a logic gate when performing logical operations. Transistors in computer processors often turn signals on or off. However, transistors can also change the amount of current being sent. For example, an audio amplifier may contain a series of transistors that are used to increase the signal flow. The increased signal generates an amplified sound output. Because of their low cost and high reliability, transistors have mostly replaced vacuum tubes for sound amplification purposes.

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While early transistors were large enough to hold in your hand, modern transistors are so small they cannot be seen with the naked eye. In fact, CPU transistors, such as those used in Intel's Ivy Bridge processor, are separated by a distance of 22 nanometers. Considering one nanometer is one millionth of a millimeter, that is pretty small. This microscopic size allows chip manufacturers to fit hundreds of millions of transistors into a single processor.

Trinitron Trinitron is arguably the best consumer CRT (Cathode Ray Tube) technology

available.

The

technology

was

developed

Sony

Corporation, who owns complete rights to it. The Trinitron design has helped the company lead the market in the manufacturing of TVs and monitors for many years. The difference between a Trinitron tube and most other tubes is that the Trinitron uses an aperture grille instead of a shadow mask for creating the image on the screen. An aperature grille consists of wires stretched vertically down the screen (allowing for a vertically flat screen). A shadow mask is basically a metal plate with holes in it, where light can pass through. Because Trinitron monitors are vertically flat, they have less image distortion and less glare than most other monitors. If you look very closey at a Trinitron screen, you should see one or two very thin dark horizontal lines that span the width of the screen. These lines are small wires that support the aperture grille.

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Ultra DMA This technology for transferring data between a computer's hard disk and memory was developed by Quantum and Intel. The maximum burst rate of an Ultra DMA hard drive is 33.3 MBps. The original DMA (Direct Memory Access) protocol could only transfer data at half that speed. Thanks to Ultra DMA, programs can open faster and run more smoothly. This is because Utlra DMA can send more data to the memory in less time than the original DMA. Ultra DMA also has a builtin utility called Cyclical Redundancy Checking (CRC) that helps protect data integrity. So if you want a nice, fast hard drive, look for one that supports Ultra DMA.

UML Stands for "Unified Modeling Language." This is a programming language that is used for object-oriented software development. To organize program code more efficiently, programmers often create "objects" that are sets of structured data within programs. UML, which has been standardized by the Object Management Group (OMG), was designed for this purpose. The language has gained enough support that it has become a standard language for visualizing and constructing software programs. 230

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UPnP Stands for "Universal Plug and Play." Plug and Play describes devices that work with a computer system as soon as they are connected. UPnP is an extension of this idea that expands the range of Plug and Play devices to networking equipment. Universal Plug and Play uses network

protocols

allow

wide

range

devices

interconnected and work seamlessly with each other. UPnP devices can be connected via wired (i.e.Ethernet and Firewire) or wireless (i.e. Wi-Fi and Bluetooth) connections. As long as a product supports UPnP, it can communicate with other UPnP devices within a network.

The

connections

are

typically

created

using

the DHCP networking protocol, which assigns each connected device a unique IP address. While UPnP is helpful for setting up networks, it also can be used to set up compatible audio and video (AV) devices. UPnP AV is a group of standards based on UPnP that allows audio and video components to be connected via network connections. This enables media files and streaming data to be sent between devices. For example, a movie stored on a hard drive in a bedroom could be played back on the TV screen in the living room. The central controller of a UPnP AV network is called a MediaServer and can be run from a Macintosh, Windows, or Linux computer or from a hardware device specifically designed to manage the network. Since most UPnP devices support zero-configuration setup (like ordinary Plug and Play devices), it is simple to add devices to a 231

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network and use them immediately. While the networking terms associated with UPnP can be a bit intimidating, setting up a UPnP network is meant to be hassle-free ? and that is a term we can all appreciate.

UPS Stands for "Uninterruptible Power Supply." In the technology world, UPS is more than just a brown shipping company. It is also a type of power supply that uses battery backup to maintain power during unexpected power outages. A typical consumer UPS is a surge protectorthat contains a highcapacity rechargeable battery. Smaller UPS devices look like bulky power strips, while larger ones may stand upright and look almost like small computers. Many businesses use uninterruptible power supplies to keep their equipment running in case of a power failure. While a UPS may only keep a computer running for 15 minutes after the power is lost, it is usually sufficient time to save all necessary documents and properly shut down the computer. That extra time can be invaluable to someone who is working on an important document or project that has not been recently saved. Because UPS devices run the power through a battery, they have a limit on the wattage load they can support. The maximum power load limit is often included in the name of the UPS, followed by the letters "VA." For example, the APC (American Power Conversion) Battery Backup 750VA has a load limit of 750VA. However, the maximum wattage a 232

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UPS supports is typically 60% of the VA number. So the 750VA UPS supports a maximum of 450 watts for connected devices. It is important to check how many total watts your computer setup uses before buying a UPS to make sure you get one with enough wattage so you don't overload it.

USB Stands for "Universal Serial Bus." USB is the most common type of computer port used in today's computers. It can be used to connect keyboards, mice, game controllers, printers, scanners, digital cameras, and removable media drives, just to name a few. With the help of a few USB hubs, you can connect up to 127 peripherals to a single USB port and use them all at once (though that would require quite a bit of dexterity). USB is also faster than older ports, such as serial and parallel ports. The USB 1.1 specification supports data transfer rates of up to 12Mb/sec and USB 2.0 has a maximum transfer rate of 480 Mbps. Though USB was introduced in 1997, the technology didn't really take off until the introduction of the Apple iMac (in late 1998) which used USB ports exclusively. It is somewhat ironic, considering USB was created and designed by Intel, Compaq, Digital, and IBM. Over the past few years, USB has become a widely-used cross-platform interface for both Macs and PCs.

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USB-C Stands

for

"Universal

Serial

Bus

Type-C."

USB-C

type

of USB connector that was introduced in 2015. It supports USB 3.1, which means a USB-C connection can transfer data up to 10 Gbps and send or receive up to 20 volts or 100 watts of power. Unlike the previous USB Type-A and USB Type-B ports, the USB-C port is symmetrical, which means you never have to worry about plugging in the cable the wrong way. The USB-C connector is the most significant change to the USB connector since the USB interface was standardized in 1996. USB 1.1, 2.0, and 3.0 all used the same flat, rectangular USB-A connector. While there have been several variations of USB-B, such as Mini-USB and Micro-USB, they are all designed for peripheral devices, which connect to a Type-A port on the other end. The Type-C connector introduced with USB 3.1 is designed to be the same on both ends. There is no mini or micro version of USB-C, since the standard USB-C connector is about the same size of a Micro-USB connector. This means it can be used in small devices likesmartphones and tablets. Since USBC supports up to 100 watts of power, it can also be used as the power connector for laptops. In fact, the first laptops to include USB-C ports â&#x20AC;&#x201C; the 2015 Apple MacBook and Google Chromebook Pixel â&#x20AC;&#x201C; do not include power connectors. Instead, the power cable connects directly to the USB-C port. A USB-C connector will only fit in a USB-C port, but USB-C cables are backwards-compatible with other USB standards. Therefore, a USB-C to USB-A or USB-C to USB-Badapter can be used to connect older USB 234

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devices to a USB-C port. However, the data transfer rate and wattage will be limited to the lower standard.

VDU Stands for "Visual Display Unit." A VDU displays images generated by a computer or other electronic device. The term VDU is often used synonymously with "monitor," but it can also refer to another type of display, such as a digital projector. Visual display units may beperipheral devices or may be integrated with the other components. For example, the Apple iMac uses an all-in-one design, in which the screen and computer are built into a single unit. Early VDUs were primarily cathode ray tube (CRT) displays and typically had a diagonal size of 13 inches or less. During the 1990s, 15" and 17" displays became standard, and some manufacturers began producing displays over 20" in size. At the turn of the century, flat panel displays became more common, and by 2006, CRT displays were hard to find. Today, it is common for computers to come with VDUs that are 20" to 30"

size.

Thanks

the

recent

growth

in LCD,

plasma,

and LED technology, manufacturing large screens is much more cost effective than before.

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Stands for "Video Graphics Array." It is the standard monitor or display interface used in most PCs. Therefore, if a montior is VGA-compatible, it should work with most new computers. The VGA standard was originally developed by IBM in 1987 and allowed for a display resolution of 640x480 pixels. Since then, many revisions of the standard have been introduced. The most common is Super VGA (SVGA), which allows for resolutions greater than 640x480, such as 800x600 or 1024x768. A standard VGA connection has 15 pins and is shaped like a trapezoid.

Video Card Most of the processing done on a computer is done via the computer's central processing unit, or CPU. So in order to give the CPU a break and help it run more efficiently, a video card can be used to process the graphics portion of the processing load. Because most of today's programs are graphically oriented, the video card can help almost any program run more efficiently. However, the difference in performance is especially noticeable in image editing applications and 3D games. Video cards, also called graphics accelerators, can speed up both 2D and 3D graphics rendering. Programs such as photo editors and Web browsers

may

benefit

from

acceleration,

while CAD design

programs and video games will most likely benefit from the card's 3D acceleration. Some programs rely so heavily on the video card, that they will not run if a supported video card is not installed. Most video cards support the OpenGL and DirectX libraries. These libraries 236

include

commands

for

manipulating

graphics

that

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

programmers can include in their code. Some of these commands may include moving or rotating an object, morphing polygons, or casting light and creating shadows. By using standard OpenGL or DirectX functions, it makes it easier for developers to create graphicallyoriented programs. Of course, it also makes it necessary for the computer to include a supported video card in order for the program to run. Video cards are typically installed in either the PCI or AGP slots in the back of a computer. Most computers come with a video card installed in one of these slots, which means it can be upgraded at a later time.

VLB Stands for "VESA Local Bus." (VESA stands for "Video Electronics Standards Association"). The VLB, or VL-bus is a hardware interface on the computer's motherboard that is attached to an expansion slot. By connecting a video expansion card to the VLB, you can add extra graphics capabilities to your computer. The interface supports 32-bit data flow at up to 50 MHz. Though the VLB architecture was popular in the early 1990s, it has since been replaced by the newer and faster, but still three-lettered, ISA, PCI, and AGP slots.

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Volume The word "volume" has several different meanings. The most common definition is the magnitude or intensity of a certain sound. Volume may also refer to how much space a three-dimensional object takes up. However, in the always ambiguous realm of computers, the word volume can also refer to a specific data storage device. Some examples of volumes include hard disks, DVD drives, and flash memory drives,

such

USB

keychain

drives.

Your

computer

recognizes all these data storage devices as volumes. The only requirement is that each volume has a file system that the computer can recognize. The file system tells the computer how the folders and files are organized on the volume. On a Macintosh, all volumes connected to the computer (either directly or by a network connection) will show up on the desktop. For example, a hard drive will have a hard drive icon and a CD will have a CD icon. In Windows, you will find a list of all available volumes when you open "My Computer." If a volume is connected, but is not showing up on the screen, you can often use a disk utility program to "mount" the volume so that the computer can communicate with it.

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VRAM Stands for "Video Random Access Memory" and is pronounced "VRAM." System RAM is great for loading and running programs, but when you need graphics power, VRAM is where it's at. This is the memory used to store image data that the computer displays; it acts as a buffer between the CPU and the video card. When a picture is to be displayed on the screen, the image is first read by the processor and then written to the VRAM. The data is then converted by a RAM digitalto-analog converter (RAMDAC) into analog signals that are sent to the display. Of course, the whole process happens so quickly, you don't notice it. Unlike most system RAM, VRAM chips are dual-ported, which means that while the display is reading from VRAM to refresh the currently displayed image, the processor is writing a new image to the VRAM. This prevents the display from flickering between the redrawing of images. There are many different types of VRAM. One popular kind is called Synchronous Graphics RAM (SGRAM). It is an inexpensive type of RAM that is clock-synchronized. This means data can be modified in a single operation rather than as a sequence of read, write, and update operations. This allows background, foreground, and image fills to be handled more efficiently. Another type of VRAM is Rambus Dynamic RAM (RDRAM). It is designed by Rambus and includes a proprietary Rambus bus that speeds up the transfer of data through it. Video editing pros like this chip since it is optimized for video streaming. A third type of VRAM is Window RAM (WRAM). This high-performance 239

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

VRAM is dual-ported, has about 25% more bandwidth than standard VRAM, and typically costs less. Finally, there is Multibank Dynamic RAM (MDRAM). This is also high-performance VRAM, developed by MoSys, which divides the memory into divisions of 32 KB that can be accessed individually. This makes memory transfers more efficient and increases overall performance. Another advantage of MDRAM is that it can be manufactured with just the right amount of memory for a given resolution, so it is cheaper to manufacture than most other types of VRAM.

Webcam The term webcam is a combination of "Web" and "video camera." The purpose of a webcam is, not surprisingly, to broadcast video on the Web. Webcams are typically small cameras that either attach to a user'smonitor or sit on a desk. Most webcams connect to the computer via USB, though some use a Firewire connection. Webcams typically come with software that allows the user to record video or stream the video on the Web. If the user has a website that supports streaming video, other users can watch the video stream from their Web browsers. Webcams can also be used for video chat sessions with other people. Instead of broadcasting the video on the Web, users can set up a video chat session with one or more friends and have a conversation with live audio and video. For example, Apple's iSight camera, which is built into Apple laptops and iMacs, allows users to video chat using the 240

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iChat instant messaging program. Several other chat programs also work with webcams, allowing users to set up video chat sessions with friends. Since streaming video over the Internet requires a lot of bandwidth, the video stream is typically compressed to reduce the "choppiness" of the video. The maximum resolutionof a webcam is also lower than most handheld video cameras, since higher resolutions would be reduced anyway. For this reason, webcams are relatively inexpensive compared to most video cameras. And while they may not be ideal for filming a movie, webcams are great for video chat sessions with friends.

Workstation It has been said that a bus stops at a bus station and a train stops at a train station, so what happens at a workstation? Hm... Actually, a workstation is a place where work gets done. It refers to a computer (and often the surrounding area) that has been configured to perform a certain set of tasks, such as photo editing, audio recording, or video production. An office may have several workstations for different purposes, which may be assigned to certain employees. For example, one workstation may be used for scanning and importing images, while another is used for editing images. Because workstations often work together like in the example above, they are commonly networked together. This allows them to send files 241

COMPUTER HARD WARE TERMS | SRIKANTHKAJUBOJU

back and forth over the network, which is important for various types of media production. To use another example, a user at a photoediting workstation may prepare images to be used in a video clip. Once the images are ready, he may send them to another user at a video-editing workstation, where they are incorporated into the video. Once the video has been put together, the video file may be sent to another user at an audio production workstation where the soundtrack and other sound effects are added. While

workstations

are

often

part

network,

they

can

be standalone machines as well. Even a home computer can be a workstation if it is used for certain kinds of work. So if you want to sound professional, the next time you send an e-mail to a friend from your home PC, you can let him know you are sending it from your home workstation.

X86 x86 is the generic name for Intel processorsreleased after the original 8086 processor. These include the 286, 386, 486, and 586 processors. As you can see, the "x" in x86 stands for a range of possible numbers. Technically, x86 is short for 80x86 since the full names of the processors are actually 80286, 80386, 80486, and 80586. The "80" is typically truncated to avoid redundancy. If a computer's technical specifications state that is based on the x86 architecture, that means it uses an Intel processor (not AMD or PowerPC). Since Intel's x86 processors are backwards compatible, 242

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newer x86 processors can run all the programs that older processors could run. However, older processors may not be able to run software that has been optimized for newer x86 processors. While numbers provide a simple way to distinguish between processor types, they cannot be trademarked. For this reason, Intel's 586 processor is formally known as the Pentium processor. However, software developers still often refer to processors by their number. Of course, what else would you expect from computer nerds?

ZIF Stands for "Zero Insertion Force." ZIF is a type of CPU socket on a computer motherboard that allows for the simple replacement or upgrade of the processor. Processors that use a ZIF socket can easily be removed by pulling a small release lever next to the processor and lifting it out. The replacement processor is then placed in the socket and secured by pushing the lever in the opposite direction -- hence the phrase, "zero insertion force." I suppose there is some force required to push the lever, but it is significantly less than non-ZIF sockets, which require special tools to force the processor out.

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