OFFICE AUTOMATION – I COMPUTERS AND APPLICATIONS 13. INTERACTING WITH COMPUTERS: INPUT/OUTPUT DEVICES, PRINTERS AND SCANNERS This topic reveals information on how the computers graduated from a room size calculation machine to the size of a palm top computer. The advancement in technology has not only led to reduction in size of the computer but has also led to infinite speed in processing of the information. The computer remembers every action and information processed, and uses that information along with the help of artificial intelligence. This is the most compelling reason for its extensive use by big companies as well as individuals. Today you can not expect an office establishment without a computer. Hence it becomes essential for you to know, understand and learn as much as you can about the computer.
13.0 Objectives On completion of this lesson, you will be able to understand about: Different generations of computers Classification of computers Various hardware components that make a computer system
13.1 Introduction This lesson is designed to give you a better understanding on the evolution of a computer - its commencement as well as its growth, parts that make up a computer system and a basic idea about how each component works in isolation.
13.2 Classification of Computers • • •
Computers can be basically classified into the following categories: Super Computers Mainframes and Minicomputer Servers
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• Personal computers (Microcomputer) • Notebook computers / Laptops and Palmtops 13.2.1 Super Computers A computer that lead the world in terms of processing capacity, particularly speed of calculation, at the time of its introduction. The term Super Computing was first used in 1920. India's “Param Padma” is one of the world’s fastest supercomputer today. Supercomputers are used for applications like weather maps, construction of atom bombs, finding oil, earthquake prediction, and sciences where there is a need for a whole lot of calculations. Historically, a supercomputer is associated with the fastest or largest computer available in size. Supercomputing means "mass computing at ultra high speed. “ In general, a supercomputer performs “above normal computing” The picture shows Cray-2, world's fastest computer. 13.2.2 Mainframes Another giant in computers after the super computer are the Mainframes. Modern mainframe computers are known for their high-quality internal engineering and result proving reliability. These are expensive but have high-quality technical support, top-notch security, and strict backward compatibility for older software. These machines run successfully for years without interruption, with repairs taking place whilst they run. Mainframes often support thousands of simultaneous users. This computer is commonly used in large hospitals, airline reservation companies, and many other huge companies which prefer mainframe because of its capability in retrieving huge data. A 1990 Honeywell-Bull DPS 7 mainframe is shown in the picture. 13.2.3 Minicomputer The term "minicomputer" evolved in the 1960s to describe the "small" third generation computers that became possible with the use of transistor and core memory technologies. Minicomputer is a largely an obsolete term for a class of multi-user computers.
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These are between the large multi-user systems (traditionally, mainframe computers) and the small single-user systems (microcomputers or personal computers). 13.2.4 Servers A server is a computer system that provides services to other connected computers. The typical server is a computer system that operates continuously on a network and awaits the requests for services from other computers on the network. Servers today are physically similar to most other general-purpose computers, although their hardware configurations may be particularly optimized to fit their server roles, if and when they are dedicated to that role. 13.2.5 Personal Computers (Microcomputer) Although there is no rigid definition, a microcomputer, is most often taken to mean a computer with a microprocessor (ÂľP). These computers are lesser in cost than the computers given above and also smaller in size. This is the computer mostly preferred by the home users and they are also called as PC (Personal Computer). 13.2.6 Notebooks / Laptops A laptop computer (also known as notebook computer) is a small mobile personal computer, usually weighing from 1 to 3 kilograms (2 to 7 pounds). Although Laptops are capable of many similar tasks that desktop computers perform, they are typically less powerful for the same price. Laptops contain components that are similar to those in their desktop counterparts and perform the same functions but are miniaturized and optimized for mobile users. 13.2.7 Palmtops A laptop (a knee top) is an extremely small and lightweight portable computer, which can be held in palm during its operation/working. It has all the features of a standard laptop computer and runs all applications.
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Self-Check Questions 1. What is the smallest class of computers? 2. What is the fastest class of computers? 3. What is another name of a Micro Computer?
13.3 Classification of Hardware The diagram shows the basic parts of a personal computer. Basic Components: Computer System •
Input Devices o Keyboard o Mouse o Scanners
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Output Devices o Monitor o Printer
13.3.1 Input Devices Input Devices are used for sending information to the computer. The Primary Input Device is the Keyboard. Mouse is another device used for input. Floppy Disk, Modem, CDs, DVDs and Scanner are other devices used to hold or send information. Information can be sent by Voice also.
Keyboard The most common input device is the keyboard, which is used to enter letters, numbers and special characters. The layout of
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the keys was borrowed from the typewriter with a number of new keys added. Function keys are special purpose keys whose function depends on the software being used. Cursor keys are used to move the cursor up, down, left, or right. Keyboard generally has 104 keys.
Mouse A mouse is a small Plastic box with two buttons on top and a ball underneath. When the mouse is moved the ball rolls and a marker appears on the monitor. This marker is referred to as the Cursor. By pointing the Cursor to selected items on the monitor and on clicking on any of the buttons, users can give instructions to the computer. Left mouse button is used to select the command/option (works as “Enter�) and right mouse button is used for having options menu appear on the screen. Scanners In computing, a scanner is a device that analyzes a physical image (such as a photograph, printed text, or handwritten document) or an object (such as an ornament) and converts it to a digital image. Most scanners today are variations of the desktop (or flatbed) scanners. The flatbed scanner is the most commonly used scanner and is preferred due to its simple and effective handling. Hand-held scanners were hand held versions, which were briefly popular but are now not used due to the difficulty in obtaining a high-quality image.
Microphone Microphone is a device which is used to give Voice commands to the computer. With the help of this device you can record any voice. It may be your voice or a recorded voice.
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Web Camera Web Camera is an input device used to input live picture to the computer. This is mainly used at the time of video conferencing. These pictures are sent by computer from one user to another user using Internet as a medium of communication. That is why this camera is named as Web Camera and the storage capacity of the pictures is lesser than normal cameras, which makes it more preferable during video conferencing sessions. 13.3.2 Output Devices Output Devices are devices through which a computer sends us Information. The Primary Output Device is the Monitor. Printer is an output device used for hard copies. Floppy Disk, Modem, CDs, DVDs and Scanner are other devices used to save or retrieve information. Computers can also send information through Voice. Monitor A monitor or video display unit (VDU) displays characters, graphics, photographic images, animation and video. Video Adapter connects the monitor to the computer. VRAM or video memory is a special portion of RAM to hold video images (more the video memory, more is the details of picture displayed). Types of Monitor The commonly used monitors are CRT (Cathode Ray Tube) and LCD (Liquid Crystal Display).
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Classification of Monitors Monochrome (MGA): Monochrome monitors display only two colors, one for the background and one for the foreground. The colors can be black and white, green and black, or amber and black. This can show 80 characters per line and only 25 lines on the screen with a resolution of 720x350 pixels. Enhanced Graphics Adapter (EGA): EGA allows up to 16 different colors with a resolution of 640x350 pixels, thus improving the appearance of the display and making it easier to read the text. Video Graphics Array (VGA)/Extended Graphics Array (XGA): These color monitors display up to 1 million different colors. These monitors have pixel resolution from 800x600 to 1024x768.
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Super VGA (SVGA): These color monitors display up to 16.7 million different colors. These monitors have pixel resolution from 800x600 to 1600x1200 and are available in the market. Specifications Monitor Size: Monitor size is measured as a diagonal line across the screen. Specified in inches/cms like a TV Screen. Pixels (or picture element): Pixels are tiny dots that compose a picture. Resolution: Resolution is the number of pixels displayed on the screen (higher the resolution, closer are all the dots resulting in higher quality image(s)). Bandwidth: Bandwidth is the range of signal frequencies the monitor can handle. This determines how much data it can process and therefore how fast it can refresh at higher resolutions. Refresh Rate: Refresh Rate is how many times per second the screen is refreshed (re-displayed). The minimum refresh rate should be at least 72 Hz, to avoid flickering. Interlaced or De-interlaced: Interlacing is a technique that enables a monitor to have better resolution by reducing the monitor's reaction speed and at lesser bandwidths. Most CRT Monitors and TVs work on the Interlace concept for display. The latest High Definition TVs come with the de-Interlace technology also known as Progressive Scan. Dot pitch: Dot pitch is the amount of space between each pixel. Smaller the dot pitch, sharper the image. Convergence: Convergence is the clarity and sharpness of each pixel. Printer Printers produce paper output or hard copy. Types of printers: Printers can be classified, on basis of their working, as Impact Printers and Non Impact Printers.
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Impact Printers: In this type of printer, the printer head strikes the paper as in the case of a type writer. Line Printer and Dot Matrix Printer are examples of Impact Printers.
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Non-impact Printers: In this type of printer, ink is sprinkled/ sprayed on the paper to print the image. Laser Printer, Inkjet Printer and Plotter are examples of Non-impact Printers. Printers can be classified, on basis of output, as Character Output, Line Output and Page Output.
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Character Output: Character Output is the printing of pixel or character, one at a time on the paper. For example: As in the case of Dot Matrix and Inkjet Printers.
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Line Output: Line Output is the printing of complete line at a time on the paper. For example: As in the case of Line Printer.
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Page Output: Page Output is the printing of complete page at a time on the paper. For example as in the case of Laser Printer and Plotter. Dot Matrix Printers Dot matrix printers involve small pins in the printer head that physically stamp the ink onto the page. These printers are available in 80 columns (8.5”x11”Letter and 8.27”x11.69”-A4) and 132 columns width (11.69”x16.53” –A3) sizes. Inkjet Printers Inkjet printers can be considered as financially viable solution to the home users. The nozzle in the printer head is fed ink from the cartridge and it sprays a fine mist. There are two types of color inkjet printers; one using the Red Green Blue combination and another using the Cyan Magenta Yellow combination, using black as the Key color. These are also referred to as DeskJet Printers. LaserJet Printer LaserJet printers are the most expensive type of printers, in terms of running costs, as the cost of the toner rolls are very high. Powder toner is statically stuck to the paper when it passes over the rollers, and is then very quickly heated to fuse it into the paper. These printers come with an ability to print pages of A4 and A3 sizes. Plotter The fourth type, a plotter, cannot be called a printer in the true sense. Plotters are employed solely by graphic designers and architects. Plotters use a custom-designed colored pen attached to an arm that can move side to side, which in turn is attached to a holder that can rotate smoothly through 360 degrees, to draw a line art onto a page. The actual plotter device has to be mounted on a tall stand, and physically needs a wider area to hold the lengthy bar for the drawing head to move up and down. This makes them quite expensive.
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Speakers Speakers are used as output devices, because you listen to voice when they are attached to the sound card available in the computer. Floppy/Compact Disk (CD - An Input and Output device) Floppies or Compact Disks are used to store the data. When you try to copy data into your computer then it is considered as Input Device, else when you try to copy data from your computer to this disk then it is considered as Output Device.
Self-Check Questions True or False 4. 5. 6. 7.
A plotter is used to print an A3 size page also. (T/F) Laser Printers are available for A4 and A3 size papers. (T/F) Speakers are used as input devices. (T/F) Floppies are used as both Input and Output device. (T/F)
Fill in the following blanks 8. The two types of scanners are ____________ and _______________ 9. Plotter holder can rotate ____________ degrees. 10. The commonly used monitors are ____________ and ____________ 11. The clarity and sharpness of each pixel is known as ______________ Match the following 12. Mouse 13. Scanner 14. Monitor 15. Keyboard
a. b. c. d.
Flatbed 104 Keys Left and Right Buttons CRT and LCD
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Select the right answer 16. Keyboard is a. Input Device b. Output Device c. All the above d. None 17. Laser Printer can print on paper size of a. A4 Size b. A2 Size c. A3 Size d. Both a. and c. 18. Size of A4 Size paper is a. 8.27”x11.68” b. 8.28”x11.68” c. 8.27”x11.69” d. None of the above
13.4 Summing Up In this lesson you have familiarized yourself with the following concepts in computers: Classification of Computers Input Devices Output Devices
13.5 Answers to Self-Check Questions 1. Palm Top 2. Super Computer 3. Personal Computer (PC) 4. T 5. T 6. F 7. T 8. Hand held and Flat Bed 9. 3600 10. CRT and LCD 11. Convergence 12. c 13. a 14. d
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15. b 16. a 17. d 18. c
13.6 Terminal Questions What are the classifications of computers? What type of computers are most preferred by home users and why? What is an Input Device? What is an Output Device?
13.7 Glossary •
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Vacuum tube: A vacuum tube (also called an electron tube or a valve) is a device sometimes used to amplify electronic signals. In most applications, the vacuum tube is obsolete Transistors: Transistors are solid state semiconductor devices that are used for voltage regulations, amplification and more. Microchips: A microchip (sometimes just called a "chip") is a unit of packaged computer circuitry (usually called an integrated circuit) that is manufactured from a material such as silicon.
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