Computer organization bca

a

Explain

functional units of computer?

Explain albout muli processors and multi computcrs

2.

7.

3Write

short notes on accessing 1/0

Write

about standard 1/O interfaces

What

is logic gate? Explain AND,OR,NOT gates

Explain about bus structures

6.

construct logic circuit for following expressions:

AB+A'BC+A'B'C+ABC

a)

b) (AB)+(AC)+(BC) 8.

Perform addition for following binary numbers

a) 1101+1011 b) 110011+101101

c)10101010+1110000 9.

Explain about înputdevics

10. Explain about ROM and its types

Section-B Answer any FIVE of the following Questions (5

1050

Marks)

11. Explain various types.of computers 12. Explain about CIsc&RISC instruction sets 13. What is interrupt? Explain its types

14. What is DMA? Explain 15. Explain multiplication of positive numbers with an

example 16. Explain non-restoring division with an example 17. Explain video displays in detail 18. Explain various flat panel display systems 19. What is cache memory? Explain its mapping functions

20. Explain about virtual memory

Instruc

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TYPES OF COMPI'TERS

instructious from the device tuut uccepts eluta und Definition: A computer is un electronic umonnt of duta very high speed. It cun also store lurge ser, processes data und givs output ut und instructions in its mennory pernnanenily.

Computers are classified in to five According to the size, memory and processing speed. types. They are

.

I.

11.

IV. V. VI.

VIl.

Micro Computers Mini Computers Super Compute3 Main Frame Computers Work Stations Note Book Computer or Laptop Computers lland held computers

I. Micro Computers A Micro Computer is the smallest and least cxpensive general purpose processing system. Functionality, it is similar to any other large systems. Microcomputers are selfcontained units and usually designed to be used by one person at a time. So, these computers are also called as "Personal Computers".

II. Mini Computers: A Mini Computer is a Small size computers i.e., more costly and more powerful than microcomputers and also more expensive inicomputer can handle much more input and output than PCs. Mini computers area caleas #Midrange ComputerS"

V. Super ComputerS:

These are the most powerfülecompatepand physically they are some of the largest.

These systems are built to procss hugeramointrofdata and the fastest super computer can perform more than one trillion alculationsgee-secondi Scientists and engineers frequently buit models of complex processes.

m. Main Frame Computers: A lkrge multi user computer system designed to handle huge amount input, output and storage. We can connect multiple computers or PCs to a mainframe computer for sharing data. Mainframe computers are used by rare and large organizations like Indian Airlines, Indian Railways, Banking Systems ete., V. Work Stations

Workstations are also desktop computers. They are however more powerful by providing processor speed about 10 times that of desktop PCs. Most workstations have a large colour video display unit. Normally they have main memory around 120 MB to 1GB. The standard operating system of work station is UNIX. Most of the workstations have built in hardware to connect to LAN

Note Book computers or Laptop computers: These computers are used by people who need portable computing power outside of the office or away from home. These computers approximately the shape of an 8.5/11 inches can fit inside the briefcase easily and looks like a notebook. So, these computers are also called as "Noteb0ok computers

Hand Held Computers:

In 1990s many new types of personal computers(PCs) have been introduced and all they as

fall into the category

of Hand held computers. These tiny computers are also called Palm-Top" computers. It is almost fit in user hands so, they can also know as Min

notebook computers. These computers do not provide disk but memory can be added through PC-Cards. We can connect these computers to full size computers to exchange the data. The Hand held PCs classified into three types. They are

SRIBALAJI XEROXopp LEELAMAD

1.

2.

Personal Digital Assistant (P'DA) Cellu lar

3. 1/PC Pro-devices

FUNCTIONAL. UNITS OF A COMPUTER(BLOCK DIAGRAM

ne ineral another. However

architectural design ofa conmputer system differs lrom one system basic organization remains tlhe same for all computer system.

model

to

tlhe

The block diagranm of any computer system is as shown below: C.P.U

Arithmetic

Data8 Inctrurtinne

&

Logic Unit

Input Unit

Output Unit

Result

Control Unit

Memory Unit

In the above diagram, the solid lines indicate the flow of data and instructions. The dotted lines indicate the flow of clectronic signals cptrolunit.

ote

Components or Parts of computer svgièm

.

The above diagram shows 5 umctiona niisofacomiputer system. They are

Input unit 2. Output Unit 3. C.P.U. a. Arithmetic & Logic Unit b. Memory Unit C. Control Unit

Alu

Input Unit

into the computer system are The devices that are used for entering data and instructions the computer system. with environment called input units. The input unit links the external Eg: Keyboard, Mouse etc.

2. Output Unit reverse of input unit. It means, the devices that are used to The job of output unit is just system called output units. Thus it also links the computer display or print the information are with external environment.

Eg: Monitor, Printer etc.

Unit (CPU) 3. Central Processing data and instructions is is used for processing and storing The centralized system that computer system. The C.P.U. contains is treated as heart of the It Unit.

Processing called Central components. They are three major

i.

Arithmetic & Logie Unit (ALU) Memory Unit ii.

Unit ii. Control Unit (ALU) Logic Arithmetic &

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processine ofdata is done inside and logical operaiions.

The

Arithmctic operalioi1s:

T.

1he

AL.l

The A

I..U

can perlorn both

aril hneie

X,

Logical operations: ii. Memory Unit

he storage area in the computer system is called memory unit. The data and instructions can be stored in the memory units either temporarily or permanently. Wc can use primary

memory to store information temporarily and the secondary memory for permanent storage.

Eg: RAM, Hard disk, CD ctc.

ii. Control Unit The control unit controls the operations of al the devices. It activates the devices the devices by giving the electronic signals. The control unit acts as central nervous system of a computer system.

BASIC OPERATINAL CONCEPTS The basic function of computer is to execute a sequence of instruction as a program.

The

instructions are executed to process data which already loaded into the computer memory through input unit. Ater performing the data, the result is either stored back into the computer's memory for further reference or it is sent to the outside world through the output. Therefore all functional units of the computer contribute to execute a program.

To perform execution of instruction, in addition to the ALU, control unit, the processor contains a number of registers used for temporary storage of data and some special function registers. They are:

Program Counter (PC)

Instruction Register (IR)

Memory Address Register (MAR) Memory Data Register

(DR)

Program Counter (PC- The PC is one gfthemostimgortant register in the CPU. PC helps the CPU, to exocute program instructions sequentiallt keçps track instructions of which is being executed and what the next instructions

wilbek

Instruction Repister (IR):- IR is used to hold the instructíon that is currently being executed.

The content of IR are available to the control unit, which generate the timing signals that control the various process elements involved in executing the instruction.

Memory Address Register (MAR):- MAR holds the address of the memory to or from which data is to be transferred.

Memory Data Register (MDR):- MDR contains the data to be written into or from the addressed word of the main memory.

Bus

Syslem

= LMAR

Processor

LMDR

PO

Contro

R ALU

BUS STRUCTURE

ne central

processing unit, memory unit and 1/0 units are the hardvware

Components/modules of the computer. They work together and have paths

tor connection the modules

with communicating

each

olner

together. The collection of paths tonnection the various modules is called the interconnection structure. The design of this interConnettio structure will depending on the cxecution that must be made betwcen modules. A Broup or wires, caled Bus is used to provide necossary signals for communication between modules. bus that connects

major computer components is called system bus. The system bus 15 a set or conductors that connects the CPU, memory modules. and 1/0 The system bus is separated into the following 3 groups.

Data Bus Address Bus Control Bus

Data Bus:-The data bus consists of 8, 16, 32 or more a parallel signal lines. The data bus are bi directional. This means that CPU can read data on these lines from memory or from a port, as well as send data out on these lines to a memory location or to a port. The data bus is connected in parallel to all peripherals.

Address Bus:-It is an unidirectional bus. The address bus consists of 16, 20, 24 or more parallel signal lines. On these lines the CPU sends out the address of the memory location or I/O portt that is to be written to or read from.

Control Bus:- The CPU sends signals on the control bus to enable the outputs of addressed memory devices or port devices. There are several signals, some of them are: Memory Read (MEMR) Memory Write (MEMw) /O Read (1OR) etc.

**

ECOntrlbusi

AddresSBUsKEnS REAEAN2DEata bus 2 .. o. ...-...

----...--

*************************************

COMPUTER SOFTWARE computer to solve user problems and to control different set of instructions given to the as computer software. (or) The set of computer programs and operations of the computer is known effective operation of a computer is called as software. The associated documentation related to the Is languages. The Computer software classified into two main software is developed in programming A

categories: 1.

Application software.

2.

System software.

APplicationSoftware

to perform speciliC of programs written banking system etc. bill, results, printing electricity It is a set

application such as processing examination 1t Is also known as application package. The

SRIBALAJI XEROX OPpLEELAMAHAL

users sove iheir problems

by using

quicKIy. SUe ready packages more casily and

oi

appiication

packages are: 1.

Word

processing

software.

2.

Spreadsheet software.

Database Management System software.

4. Presentation software.

5. Communication software.

3.

2. System Software

software is a set of programs that control the operations of a computer and devices attached with the computer. It creates links between user and computer as well as controls the execution of application programs. System software are essential for a computer to do work, without this software no link can be created between user and computer.

The examples of system software are: Operating systems.

Utility programs.

System

.Device Drivers.

Language Processors.

CISC and RISC Instruction Sets CiSC stands for Complex

Instruction Set Gomputer. It is a processor where each instruction can performed several low-level operations such as memoryoperations, arithmetic operations or address calculations. It uses microprogrammed conroaterethecontolmemory is needed to execute the operations. This may significantly slow to perform theoperation.

Whereas RISC (Reduced InstructionSebcomputër)ihaye simple instruction set to operate an instruction. The instructions are predominantyregister-basedThe limited (3 to 5) address modes are used by these processors. In RISC, the memonNaccescyce is broken into pipelined access operations.

This involves the use of caches and working registers. This benefits internal data forwarding and eliminates unnecessary storage of intermediate results. Using hardwired per instruction(CPI) are reduced to /for most RISC instruction. This is control, the clock cycle cycle the advantage of having all instruction of equal size.

Note:-the modern ClISC processors my also use hardwired control.

Difference between CISC and RISC

CISC Emphasis onhardware Muitiple

RISC Emphasls on šoftware

instruction stzes and fomats Instructions of same setwilth few

ormats

Less registers:

Uses more.registers

More addressing modes

Fewer addressing modes

EXxfensive.use of microprogramming Complexity in comple

nstruotionslake.a várvina amountof lnstructions take one cyle time Cycle time

ipeining

isdifficult

Pipeliningis easy MULTIPROCESSORS AND MULTICPOMPUTERS

Mu'" orocessor systems are used for gh perfor marce n systems exeCute a number of dfferent application tasks parale, in

age computer systems or they execute subtasks

or

ds

"5e

large task in parallel n munprocessor

system many times the memory is shared between all processors, e. di proces501s have the access to cntire memory in the system. Such multiprocessor systen is known

shared-memorynmultiprocessor system. In shared memory multiprocessor systems, multiple proces50fs and memory unit are interconnected with complex interconnected networks. This increases the cost ot the system. Hence we get higher performance at higher cost of the systems.

It is possible to

use multiple computers to use multiple computers to achieve high pertormance.

Such systems are called multicomputer systems. In these systems, group of complete computers dE

interconnected to achieve high total computational power. In contract to multiprocessor systems, the multicomputer systems can access only to their own memory units and perform various tasks in it. It need to communicate data or to access data from other computers. They used message passing mechanism to exchange the information.

UNIT-I1 BASIC LOGIC FUNCIONS Logic function is a

fundamental concept flogGgates. The binary logic is examined a practical problemthat arises in all homes. Considegalightbülbyhoseron/off status controlled two is switches, by X1 and xz. Each switch can be in one of twoPOSSIE itions 0or 1, are re0presented by a binary variable. The following diagram shows he proces

nary logical functions.

Lamp-ON= 1

Lamp-OFF 0 "0. Closed- "1 Switch B-Open = "0'. Closed- "1.

Switch A-Open

=

the above diagram, an electrical power supply and a light bulb. Here, the switch terminals are inter connected determines how the switches control the light. The light will be on only if a closed path exists from the power supply though the switch network to the light bulb.

In

binary variable f represent the condition of the light, if the light is on, f=1, and if the light is off, f-0. Then,f=1 means that there is at least one closed path through the network, and f-0 means that there is no closed path. Clearly, fis a function of two variables x1 and x2.

Let a

Let us

consider some possibilities for controlling tht light.

is in the 1 position, i.e. ff1.

If

If

x1=1 and x2=0

x1-0 and x2=1

If

the light

is

to be on,

if

either switch

X1 and x2e1 Simply a sipn

or

V

te

logic OR of he

The

iepreiented aeora-cAly

0peration

by

sign, so that

fex1

x2 xlvx?

We say that x1

In

two vanables x! and x

and

x2

are the inpul variables and ( s the output function

addition to the albove example, some of the A

O-

loglic

function are given below.

Inputo Loglo gato Control OFR

Loo-

Output

-0 Applied vollaga

(a)

(b)

Parallel connection (OR control)

X1

(x1, x2) xl x2

2 0

Serial Connection (AND control)

x1,

X2

x2) = xl. x2

1

Exclusive OR connection (XOR)

x1

x1,

x2

x2) xl

(+)

2

0

LOGICGATES A loglc gate Is an elementary bulding block of a digltal circult. Most loglc gates have two inputs one output. At any tiven movement, every terminal s In one of the two bnary condittons law (0) or and high (1), represented by different voltage levels. The loglc state of a termnal can, and

change often, as the cireuit processes data. In most loglc gates, the low state (0v), whlle the high state is approximately five volts (5v).

is

generally does, approxlmately zero volts

There are several kinds of loglc gates, the impor tant gates are glven bellow, They are:

SRIBALAJI XEROX opp LEELAMA=

NotC

S

0t

S utd

foy

aultpicahoD or3ani2at0(O AND

X

OR NOT

NAND

NOR XOR

XNOR

AND:A circuit which pertorms an AND operation is known as AND gate. It takes two or more inputs one output.

dnd

2 Input ANO Gale

INPUT

AND Ge

MTPUT

ZXY

OR:-A circuit which performs an OR operation output

A B

is

known as OR gate. It takes two or more inputs and one

Output

10

11

NOT:-A circuit which performs one input and one output.

gate. It is also known as Invertor, It has NOT operation ls known as NOT

aSRIBALAJI XEROX opp LEELAMAHAL

NotE

ec

he NAND A not AND operation

is

Calue d

Ngn

6

known as NAND operation. It takes two or more input and

give

one

output.

Ioputs

output Y

B

1

NOR:-A not OR operation is known as NOR operation. It takes two or more input and give one output.

NOR gate

InputA Inputg

Output

AB Output O 10 XOR: The XOR stands for exclusive OR. It is special type of gate. It can used in half

subtracter

NOC

extcusve

of

adder, full adder and

yubo Y=A®B

XNOR:-XNOR

stands for exclusive NOR operation. It is also special type of gate. It also used in half adder full adder and subtracter.

X-NOR G@

SRI BALAJI XEROX opp LEELAMAS

ACCESSINGI/O DEVICES A single bus (Simple) arrangenment is used to connoct 1/0 devices to a computer. he bus enabies devices which are connected to the the computer for exchange the informatlon. Generally, thhe bus consists of three sets of lines which used to carry address, data and control slgnals. Here, each yo device is assigned a unique set of address. When the processor places a partlcular address on tihe address line, the device that recognizes this address responds to the commands of Issued on the lines. controi

The processor requests either a read or write operatlon, and the requested data are over the data lines. When transterred devices /O and the memory share the same address space, thc arrangement is called Memory Mapped

/0

When memory-mapped i/0, any machine instruction that can access memory can be used transfer data to or data from an to 1/0 device. For example, if DATAIN Is the address of the input buffer associate with the keyboard, the instruction.

Move DATAIN,

Here, reads the datafrom DATAIN Move

RO,

RO

and stores themiptÒprocessor register

RO,slmilarly,

theinstruction

DATOU

Here, sends the contents of register ROtolocationDATAOUIwhlgh may be the output butter display unit or a printer. The of a diagrammatic representation.ofsingte bus is as follows.

MAB

CB

DB

Single-Bus Organizatlon "******"******

Most comoputer system use memory mapped /0, some processors have special In and Out instructions to perform 1/0 transfers. Using this I/0 transfer, the 1/0 address lines are physically separate from the memory address lines. Here, the address decoder enables the device to recognize its address when this address appears on the address linnes. The data register holds the data being tranferred to or from the processor. The status reglster contains Information relevent to the operation of the 1/0 devices. Both the data and status registers are connected to the data bus and assigned unique addresses. The address decoder, the data and status reglsters, and the control clrcutary required to coordinate l/0 tranfer constitute the device's interface circuite. The diagrammatic representatlon of l/0 interface is as follows.

SRI BALAJI XEROX opp LEELAMAHALL

1/O BUS and Interlace Module

L

Cemextenr in

utaepatmtt.kks

INTERRUPTS

Interrups are used to stop the execution of a process in order to execute other processes on priority basis. When an interrupt occurs, the current status of a program execution gets stored in the

program register and the program execution stops. The CPU control is immediately tranferrers to the operating system for executing the interrupt. After the compleation of the execution of an interrrupt, the CPU restarts the execution of the previous process by retrieving its last status. There are several type of interrupts that holds the execution of a process, some of them are given bellow. They are: Interrupt Hardware Enabling andiditablihg interrupts Handling multpeieices

CoptrolingendehequesE xfeptions Use of interrupinoperatingsystem

nteupHardware: The /O device requestan inteiupt by aétivating a bus line is called interrupt requet. In the hardware implements the speciargatës known as open-collector or open-drain are used to drive the INPT line. The output of an open-collector, gate is open its input is 0 and closed its state is 1.

Based on these states, the hardware interrupt device done by there system.

Enabling.and Dsabfinglntermupts: The arrival of an interrupt request from an external devices causes the processor to suspend the execution of one program and stats the execution of another. Hence, the interruption of progrm execution must be carefully controlled. A fundamental facility fource in all computer is the ability is enable and disable such interruption. For exam|le, the interrupt is enable for a proess. When a printer interrupt is enable to print n lines of printing. After print the last line of a a set of n lines, interrupts should be disabled until another set because avallable for print.

Handling Mutiple Devices-We may connect multiple devices to a computer system. While interrupting, ditferent devices requesting the interupts for different interrupts-servies (routines). In this situatiion. the processor will handle thru the following techniques Vectored interrupts

Interrupt nesting Interrupt priority (sirnultaneous requests) Controlling Device Requests: To controll the devices, the device's interface circuit pravids interrupteneble bit, which requests the processor is to ready to tranfer. For example, the keyboar interrupt

enable,

KEN,

and display interrupt-enable, DEN, flags are used to interrupt the request to the processor.

SRI

BALAJI XEROX opp LEELAM=

ExCCptionS

e term

example of exception Whie

interrupt

the

extCptton

is

often

usec to e'e

are 1/O interrups

to any event t^at

causes

a

^terJDiiOn.

itE

occurng the errors in a progam causes an exception. in this program. the best example of this

situatioin, the process0r kind of exception are division by 2er error.

de

dio

Use of Interruption in Operating System: The OS responsible for coordinating all activation of all device within a computer. Is Uses various schedules to interrupts different devices for control and co-ordinate the system.

DMA DMA stands for Direct Memrory Access. Is allows data transfer between the memeory unit andd the peripherals without allowing the CPU to interface.

When we want to enable the data transfer bwtween the fast speed storage devices such as registers, disk and the memory unit. The limited speed of the CPU degrades the speed of data transfer. To speed up the data transfer process, the DMA controller takes the control of memory buses from the CPU to eneble direct transfer between the magnetic disk and the memory unit. The DMA controller is an interface that enables communication between the peripheral and the CPU. The DMA controller allows the data trasfeer using memory busses.

During the data transfer between the memory unit and the peripherals, the CPU is idle and has no control over memroy buses. The DMA controller takes the controll of memory buses by directing them using control signals.

The DMA contol has three registersSoneis count and thrid is for status and controllatshe

diagrammetic representation

of DMA contorleris

tarting address, and second is for word

AWR for read W for write. The

Arrange different divices, top priority is given to high speed peripherals such as diska highspeed network interface, or a graphies display diveces. Since the procesor originates most memory access cycles. The DMA controller can be said to steal memory cycles from the processor. Hence, this kind of techinic is called cycle stealing.

Bus Arbitration:- The device which allowed to Initlate data transfer on the bus at a minimum given time by whlch the next device to become the bus is called the bus master. The Bius arbitration Is the process master is selected and bus mastership

is

transferred to it. There are two kind of approaches. They are:

Centralized arbitration Distributed arbltration Indicate to become the true master by activationg centralied arbitration, the DMA controller is activated, the processor activates the bus grant signals the bus-request line BR. When bust-request may use the bus when it bcomes free. In this situatllon, the BG, indicating to the DMA controller that BBSY. by generates signals l.e. Bus-Busy current bus master indicates to all devices In

SRI BALAJIXEROX OPp LEELAMAHAL

distributed arbitration, the devices waiting to use the bus have equal responsibility in carrying out the arbitration process. In this situatiionn, it used 4-bit identification number that are ARBS to control the devices. in

STANDARD 1/O INTERFACE

Standard 1/0 interface is an interface whichisused to support and connect various devices to computer system. There are several kindofJOmteface, Some of them are given the bellow. They are:

PC(Peeripheracopponent hterconnect) BUS SCSI (Small Computer Systemnterface) USB(URiversalserial Bus

PC:

The PCI was a low-cost bus that is truely processorihdependent.

It was a high-speed interface which supports disks and graphics and video devices. The PCI is still

any devices.

papular industry sandard to connect

An important features that the PCI is plug-and-play capability for connecting 1/0 devices. To connect a new device, that user simply connects the device interface broad to the bus.

SCSI:It is a special port, which links many devices with single SCSI port. It is an extenssion card for the data bus. It extends bus outside the computer by way of cabling.

For plugging one extension card into other to lengthen a circuit, we plug one SCSI device into another to form a chain. When devices are connected in this way an pluggued into a single port, that is

called a daisy chain.

USB: The USB allows 127 devices to be connected to the bus viaa single port.

Today most new computer feateures at least one or two USB prot.

SRIBALAJIXEROX opp LEELA

UNIT-11 ADDITIOIN AND SUBTRACTION OF POSSITIVE NUMBERS Computer circuits do not process decimal numbers.

They process binary numbers. The binaryy addition, subtraction, multiplication, and division are the arithmetic operation in computer. The binary addition is the key to binary subtraction, multiplication and division.

Addition: The number addition is used to perform addition operation.

The following table shows the process of addition.

A

(1010)

Add

101

001 1

10

Sum

and

{oO11)

Deciyna

0

DEcimal

1

Carry

1

10

3 13

Subtraction: The number subtraction is used to perform subtraction operation

on binary values. The

following table shows the process of subtraction.

Diff

0

0

Subtract

(0101)2

Borrow

From

(1011)2

-Borrow

SRIBALAJI XEROX opp LEELAMAHAL

11

Dec ma

011

0101

Decima 6

1 10

's ComplementSubtraction:: 1's complement method

is

also used to subtract a nurmber from another

binary number, In the following two cases, we use subtraction.

Subtraction of smaller number from large number and Subtraction of large number from small numbcr

Subtraction of smaller number from large number: To do this, we follow the following points Determine the 1's complement of smaller number Add the 1's complement to the large number

Remove the carry and add it to the result Ex:

Subtract (101011)

from (111001)

111001

1's complement 101011

010100 001101

addend-around carry

Swer

001110

Subtract a large number from smaller nmberTOdOthiSwefollow the following points.

Determine the 1's complement of the large number Add the 1's complement to the smaller number Change the 1's complement of the addition and assign negative sign Ex:

Subtract (111001)2

from

(101011)

101011

1'scomplement

0001100

answer

110001

in 1's

101011

complement

Final answer

001110

DESIGN OF FAST ADDER

the addition / subtraction may have too much delay in delay incurred is acceptable can be developing its outputs; so through Sn1 and cq. Whether or not the data transfer times of decided only in the context of the speed of other process or components and If

an n bit ripple-carry adder

is

used

in

registers and cache memories etc.

Carry-look ahead Addition:- A fast adder circuit must speedup the generation of the carry signals. The C (carry-out) of stage l is as follows. logic expression for si (sum) and

SRI BALAJI XEROX opp

LEELAMA

X, (+)y ()c

S

and

Ci this equation Ci1

X Yi t X, C +y

Ci

may wite XY

+ (X1 + Yi )C

we can write CG

Gi+

PC

Were G Here

G

X

yi and P= x +y

is called Generate and

Pi is

called Propagate.

The logic gates which are used to construct Bit Stage cell is as follows.

Bcell

samé

as

Unless

Bit-staga.cell

X*y1

and then

G1and it doesn't matter

whaPls

The adder which Is constructed as 4-blt adder using carry lookahead

Is

as follows.

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A

Bo

A

B

A

Full

Full

Full

Full

Adder

Adder

Adder

Adder

S

So

S

Carry Lookahead Logic (Generate,Propagate, Car B3

B

A

A

B1

Ao

Bo

MULTIPLICATION OF POSSITIVE NUMBERS

Multiplication is the process of multiplying a number with another. The multiplication process invoves the generation of partial products, one foreach digit in the multiplier. The partial products are then summed to produce the final product.

Inthe binary system, the partialpodud dredened when the multiplier bit is 0, then partial product is 0, or when the multiplier is the 4 paaprodutt isthemultiplicand. The binary multiplication of positive operands can be implemented in a combinati9nal twodimensional logic array like the following.

(12) multiplicandi (8) multiplier

1100 x

1000 0000

0000 0000

1100

1100000

X3

X2

(96) product

X1

X0

ADDER P7

P6

Ps

SRI BALAJI XEROX opp LEELAN P4

P3

P2

P1

Po

The simplest way to perform multiplication is to use the adder circuit in the AL1U for a number of sequential steps. The circuitry contains binay adder, shift add/noadd control and four registers A,, M, and a. A and C register contains initially zeros. Whereas register M hold multiplicand and Q holds multiplier. The product is computed in n cycles.

The partial product grows in length by one bit per cycle from initial vector. The carry-out from the adder is stored in flip-flop C. At the end of each cycle C,A and Qare shifted right one bit position. The final product is find out for n cycles. This process shown in the following process.

Initial Values

0

1

1

1

1

First

Add Shift

Cycle

Add

1Second

ShiftCycle No Add 1Third Shift

Add Shift

Cycde Eourth Cycle

Final Produ The hardware registers which are used to perform multiplication is as follows.

Register A (initially 0)

Shit right Muliplier Q

Add/Noadd.

Control

n-bit adder

Control Sequencer

MUX .

to Multiplicand M

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CARRY:SAVEADDITION.OFSUMMANDS

Multiplication requlres the adlitlon of several sunands. A teclnlque callecd corry 3UVe ddhtion (CSA) speeds up to addition process. Gienerally, the Ripple cariy array or carry sved affay lask time to save and introduced into the next row at the correct welglitecd positlons,

Through this carny-save adeditlon, we can group thhe summands In threas and perlorm Carry savs addition on each of these groups In parallel to generate a set of S (suum) and C (carry) vectors in one full adder delay. Next, we group all of the S and Cvectors Into threes, and perform carry-save additions on them. They generating a further set of S and C vectors ln one more full-adder delay, We continua this process until there are only two vectors remalnlpgythey can then be acldecd In rlpple carry or Cafry lookahead adder to produce the deslred produtR llowng example sliows thhe process of carryV

a

a

save addition summands

o

******

0

SRIBALAJI XEROX opp LEELA Hruve 6.18 The mulilieatlon exnmplé from Iizwe G.17 perforined tisiog

caIy savd alditlon.2

This

process ca^

oeror

with

ditterent eve

e:ne

s

toiow

n8

INTEGERDIVISION The division operation is used to perform a divisional operation on two binary numbers: one is dividend and another is divisor. In the binary division process the bits of dividend are examined from left to right until the set of bits examined represents a number greater than or equal to the divisor. This is referred to as the divisor being able to divide the number. When the condition is satisfied a 1 is placed in the quotient and the divisor is subtracted from the partial dividend.

Then the result is referred to as a partial remainder. The additional bits from dividend are brought down to the partial remainder until the result is greater than or equal to the divisor. This process continues until all the bits of the dividend are brought down and result is still less than the divisor. The following example shows the process of division.

00001101-Quotient Divisor

1011|

10010011

Dividend

1011 Partial remaindes

0011 10

10111 001111 1011 100

Remainder

Restoring Division:-Restoring division is one of the technique, which is used to perform division operation on binary digits. In this technique, an n-bit positive divisor is loaded into register M and an n bit positive dividend is loaded into Q at the start of the operation. The register A is initially 0. After one success division, the quotient is in Q and remainder is in A. the steps which are used to perform positive division is as follows.

Shift A and Q left one binary position Subtract M from A and place-the answer back in A If the sign of A is 1 set qo to 0 and add M back to A (i.e. restore A};

otherwise set

qo

to

1

Ex:

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Q

Restoring Division Example

M

0011

0000

0111

Initial Value

0000

1110

Shift

1101 0000

713

0001

TTO 1100

(101-10

0001

1100

Subtract Restore Shift

Subtract Restore Shift

0011 CL000 0000

TOUT Set Q =j

0001

0010

1000

1110 Quotlent Remainder 000D O O O

Subtract Shift

Subtract Restore

Tirst cyc

Secom

cycl

Third Cycle

Fourt cycl

Non-restoring division:- Non-restoring division is a division which is used to perform integer division.

This technique is improved by avoiding the need for restoring A after an unsuccessful subtraction. The following steps are used to perform the non-strong division.

If

the sign ofA50}shift A and Q left one bit position and subtract M form Aotherwiseshift Aand Q left an add M to A

Nowith

etgo to 1 otherwise qo to

0

EX:

e

AM SRI BALAJI XEROXopp LEELA

The circuit which is used to perform binary division is as follows

Shift left_ Dividenda A

N+1

bit

Quotent Seting

Add/Subtract

adder

Control Sequencer

m Divisor

M

UNTE INPULDENICES Input devices are used to enter differentoms.of datajinto the computer system. The data can be either text, graphical, audio

oryTdeo.

The following are the different inputdevicesised wití computer system.

. ii. iv.

.

vi. vii.

Keyboard Mouse Joystick Scanner Light pen Audio input system (Microphone) Video input system (Camera)

Keyboard: It is the most commonly used input device to enter data and instructions into the computer system. The keyboard is similar to a typewriter. A standard computer keyboard has

104 keys to manipulate various operations of the software.

All the keys of keyboard are classified into three parts. They are Normal or main keypad, functional keypad and numerical keypad.

Mouse: it is called pointing device.

It is used locate a particular position on the monitor. Hence mouse. A mouse has two or the in The mouse is palm size device with a ball built the bottom of The mouse devices may on the monitor. three buttons to point and open a particular position optical. or mechanical available in many shapes and can be

Scanner: papers and to store them in the Scanner is used to scan the information present on the graphical data. OMR (Optical or written computer system. The information can be either hand etc. are the examples of scanners.

Kecognition) Mark Reader), MICR (Magnetic Ink Character

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1Lighi

Pen: ight P'en

pen by louchimg

it

used to inpt hand written data tnto the computer systenm We opernte the on the screcn to wiite tevt

is

also used to draw mages on the sereen. It is very useful for graphic developers to draw various images or maps directly on the monitor.

Light pen

is

engineers

ad

Audio Input System: Audio input system devices are uscd to input audio data into the computer system. The microphone is the cxample for audio input system. These devices are also used to sencl voice hased instnictions to the computcr systcm to perform various tasks.

Video Input System: V1dco input system devices are uscd to input video data into the computer system. These device can copy or record vidco information in a computer system. Digital Camera, Web camera, Vidco camera are the examples.

OUTPUT DEVICEST (What are the various types of outputdevices1plain) The output devices are used t.displaor prnttheinformation. The following are the different output devices used with computersystem ii.

ii. iv.

L

Monitor Printer Plotter Audio Output System (Speakers)*

Monitor

The monitor is the most commonly used output device to display information. It is similar to a television. However, computer monitors provide more quality and clarity to display the information. The monitor is also called Visual Display Unit (VDU).

Computer monitors are available in many sizes and shapes. A standard monitor size is 15 inches. The output displayed on the monitor is called soft copy. ii. Printer

It is used to print the information on the paper. A printer is an optional devices used with computer system.

Based on the method of printing, printers are classified into two types. They are impact and non-impact printers. The output produced by any type of printer is called hard

copy.

Impact Printers The impact printers touch the paper 1or printing the output. These printers produce much noise when compared to non-impact printers.

The dot matrix printer is an example for impact type of printers. It prints the information in the form of dots. The dot matrix printers are also called character printers.

The speed of character printer is measured in tems of CPS (Characters Per Second).

Non-Impact Printers These printers do not touch the paper while printing. They spray the ink onto the paper in the form of character shape. They will not produce any no ise while printing.

The non-impact printer's output has more quality and clarity than impact printers.

SRI BALAJI XEROX opp

EELA

The nast popular non-impact printer is Iaser printer It is just like a \enn m.

Laser printer takes The informat te. ion from measured m terms of PPA1 (P'ages Per the computer sy stem The spced ot the priters Minute) ii. Plotter

N is

It is also a type of printer that produces hard copy output. However they are cngineering drawings, maps and urd to print large si7c images 0n charts.

They are nore printers expensine than

iv. Audio Output System

The audio output system deviccs bring the voicc based output The speakcr is an example for from the conmputer system. this type of devices. The output produced by these devices is called soft copy. Nccessary also hardware and software must be installcd in the computer system to use audio sy'stem devices.

(Detailed notes on INPUT and OUTPUT devices) INPUTDEVICES:

The input devices are uscd to communicate to the machine. The instructions or data is send into the computer to the input devices. The most common input devices are Keyboard, Mouse, Track ball, Scanner and etc.

KEYBOARD Keyboard is one of the most commonly used input devices in a computer. The keyboard is still the primary input device for entengtex and numbers.

The keyboard sends different signals to the CPU for processing, The Standard keyboard lay out sor pesonGonpitersin many styles, different sizes and shapes. This keyboard contains belowejhlndred keys The IBM(International Business Machine) enhance key board Contains T0AEIREys and above. The enhanced keyboard are arranged in the following five

groups

i.

Alpha Numeric Keys Modifier keys Numeric Key Pad Function Keys v.

Cursor movement keys Special purpose keys Alpha Numeric Keys:

The alphanumeric keys are the part of a keyboard that looks like a typewriter. These are collection of alphabets (A to Z), numeric (0 to 9) and a special key. In addition to letters and special symbol, this includes combinat ional keys (Alt, Cirl, Shift, Tab, etc.,) to perform special operations. ii. Modifier Keys: The modifier keys are so named because they are used to modify the input of other keys. We press another key while holding down one of the modifier keys Shift, Ctrl and Alt. ii. Numeric Keypad:

These are usually locate at the right side of the key board and appears like a nonscientific calculator, with the digits (0 to 9) and arithmetic operatíons+,, ',,%, etc., iv. Function Keys: The fourth part of the function keys. These function keys numbered from Fl to F12 are usually arranged in first row at the top of the keyboard. Fach function key perforis different functions based on the application. They allow us to enter input commands with out typing long string of characters or navigating menus or dialogue boxes.

v. Cursor Movement Keys;

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are

our arrow

hey is the set oft cursor mmoi Cment keys The tifth part of the keyboard used to change the position of the are These keyboard. on the right hand side o! the some keys (i-) In additron the keyboard also contain These nre also called edit ine keys. screcn. on the Cursor are other key in addit ion 1o the above groups they Insert) a) The editing keys (Back space, Delete, /End keys b) Home c) Page Up /Page Down d) Enter key or Return key

vi. Special Purpose keys: availablc in enhanced keyboard.

In addition to five goups the special purpose keys arc ctc., They' arc Print screen, Caps lock, Num lock, Esc, Pause/Break and

Advantages of the keyboard: can enter any type of data like alphabets, nunmbers, and special charactcrs ctC., one of the primary input devicc Easy to enter numeric values using numeric keypad We can cxecute a task by using function keys without typing any string of characters as a command 5. We can transfer the cursor from one place to another place by using cursor movement keys.

6. Issuing shortcuts for a task by using modifier keys.

Disadvantages of the keyboard: 1. lt is heavy device to enter input compared to other input devices (Mouse,

.We

2.

3.

It is

Trackball etc.,) 2. We can not draw graphics easily

Cursor movement is somewhatdiiicultcompared to other devices (Mouse, track ball) 4. It occupies more spaçe than otierampur devices 5. Typing and issuing isdifficuf than choosing commands 3.

i

VOUSE*

In 1980's PCs was used onlyaone inpu devicecalled keyboard. Today all new PCs a device is called a mouše-jthe mOnsis a graphical input device and is used to include pointing cursor on the screen. It allows controling our computer system without having to type position the instruction or commands at the keyboard.

Using the Mouse: We can use the mouse to point a location on the screen. For moving the mouse pointer on the By using the screen, we have to move the mouse forward, backward, left and right on the desk. mouse we can perform the following operations

Clicking Double clicking Dragging Right clicking Clicking: Clicking means moving the mouse on to the item in the screen. Pressing and releasing the mouse button once. in the sereen Double Clieking: Double Clicking means moving the mouse on to the item twice. mouse button pressing and releasing the Dragging: Dragging an item means to position the mouse pointer over the item. Press the mouse. As we nove the mouse pointer the mous button and hold it down as we move the a the screen. This it item is dragged along with we can then drop the item in new position on technique is called. Drag and drop editing It is generally üght Clieking: Clicking the right mouse button is known as right clicking. item. an properties of viewing used for

Advantages Of the Mouse

SRI BALAJI XEROX opp LEE

The circuit which is used to perform binary division

is

as follows

Shiftleft Dividend

A

a

Quotlent

Seting N+1

bit

Add/Subtract

adder

Control Sequencer

| mo Divisor

M

UNITEV INPUHNDEAICES Input devices are used to enter differentaoims.ofdatainto the computer system. The data

can be either text, graphical, audio oryideo

gto

The following are the different inputidevicesised wití computer system. ii.

ii. iv.

.

vi. vii.

Keyboard Mouse Joystick Scanner Light pen Audio input system (Microphone) Video input system (Camera)

Keyboard: Jt is the most commonly used input device to enter data and instructions into the computer system. The keyboard is similar to a typewriter. A standard computer keyboard has

manipulate various operations of the software.

All the keys of keyboard are classified into three parts. They are Nornmal or main keypad, functional keypad and numerical keypad.

04 keys to

Mouse: FHence it is called pointing device.

It is used locate a particular position on the monitor. mouse is palm size device with a ball built in the bottom of the mouse. A mouse has two or nree buttons to point and open a particular position on the montor. The mouse devices may

e

adDle

in

many shapes and can be mechanical or optical.

Scanner: on the papers and to store them in the Scanner is used to scan the information present or graphical data. OMR (Optical written be either hand puter system. The information canCharacter Recognition) ctc. are the examples of scanners. ark Reader), MICR (Magnetic Ink

Light Pen: Light Pen is used 1o inpit hand wTitten data into the computer system. We operate the pen by touching it on the screcn 1o wrile text.

Light pen is also used to draw images on the screen. It is very useful graphic developers to draw various images or maps directly on the monitor.

for engineers

and

Audio Input System: Audio input system devices are used to input audio data into the computer system. T he microphone is the cxample for audio input system. These devices are also used to send voiCe bascd instructions to the computer system to perform various tasks.

Video Input System: Video input system devices are used to input video data into the computer system. These device can copy or record video information in a computer system. Digital Camera, Web camera, Video camera are the examples.

OUTPUT DEVICESE (What are the various types of outputdevicesEplain) The output devices are used tö.displa or pinttheaniformation. The following are the different output devices used with computer systtem. ii. iii.

i.

v.

Monitor

Monitor Printer Plotter Audio Output System (Speakers)

The monitor is the most commonly used output device to display information.

It is similar to a television. However, computer monitors provide more quality and clarity to display the information. The monitor is also called Visual Display Unit (VDU).

Computer monitors are available in many sizes and shapes. A standard monitor size is 15 inches. The output displayed on the monitor is called soft copy. ii. Printer It is used to print the information on the paper. A printer is an optional devices used with

computer system.

Based on the method of printing, printers are classified into two types. They are impact and non-impact printers. The output produced by any type of printer is called hard copy.

Impact Printers The impact printers touch the p aper for printing the output. These printers produce much noise when compared to non-impact printers.

The dot matrix printer is an example for impact type of printers. It prints the information in the form of dots. The dot matrix printers are also called character printers. The speed of character printer is measured in terms of CPS (Characters Per Second).

Non-Impact Printers These printers do not touch the paper while printing. They spray the ink onto the paper in the form of character shape. They will not produce any noise while printing. The non-impact printer's output has more quality and clarity than impact printers.

SRI BALAJI XEROX opp LEELAMAHA

Theost popiular non-impact printer is laser printer It is just like a Xc7t 1*AP1V aser tases Ihe ntormaon trom printer i the sy stem The specd af thes conmputer measured in terms ot PPNI (Pages Per priers Minute) ii. Plotter It is also a type ot printer that produces hard copy oulput. 1lowever they arc ued ta engineering drawngs, maps and large prir si7e images on charts. They are more cxpensve than printers

iv. Audio

Output System

The audio output system devices bring the voicc bascd output from the computer system speaker is an example for this type of devices. The The output produccd by these devices is aln called soft copy. Necessary hardware and software must be installed in the cornputcr systen to use audio sy'stem devices.

(Detailed notes on INPUT and OUTPUT devices) INPUT DEVICES: The input devices are used to communicate to the machine. The instructions or data is send into the computer to the input devices. The most common input devices are Kcyboard, Mouse, Track ball, Scanner and etc.

KEY BOARD Keyboard is one of the most commonly used input devices in a computer. The keyboard is still the primary input device for enterinie and numbers. The keyboard sends different signals to the CPU for processing many styles, different sizes and The Standard keyboard lay out or peonalcompiters in Business shapes. This keyboard contains belowndred keys The IBM(International keyboard are Machine) enhance key board contäins T0Keys and ibove. The enhanced groupss arranged in the following five

Alpha Numeric Keys Modifier keys Numeric Key Pad rv.

Function Keys Cursor movement keys v.

Special purpose keys i Alpha Numeric Keys: like a typewriter. These are the part of a keyboard that looks are keys alphanumeric addition to letters and The (0'to 9) and a special key. In collection of alphabets (A to Z), numeric to perform special keys (At, Crl, Shit, Tab, etc.,) combinational includes this Special symbol,

i ii.

operations.

input of because they are used to modify the keys are so named modifier and Alt. Ctrl The keys Shit, Keys: Modifier modifier 1. holding down one of the while key another other keys. We press

ii. Numeric Keypad: SCientific

and appears liko a nonside of the key board right the at %, ctc., operations t,,,, These are usually locate to 9) and arithmetic (0 digits the calculator, with

keys numbered from FI to F12 are keys. These function performs different function 1:ach function key The fourth part of the keyboard. the with out lyping long row at the top of to enter input commands us Sually arranged in firstapplication. allow They unctions based on the or dialogue boxes. menus navigating Slring of characters or

iv. Function Keys:

V.

Cursor Movement Keys:

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opp LEELAMAHAL L

The ifth part of the keyboard is the set of cursor movemenn keys. They are fur arrow on the right had side o1 the keyboard. These are used to change the posit ion of the keys (1-) cursor on the screen. These are also callcd editing keys. In addition the keyboard also contain some other key in addition to the above groups they are The editing keys (Back space, Delete, Insert) Home /End keys c) P'age Up/ Page Down d) Enter key or Return key a)

b)

vi. Special Purpose keys: In addition to five goups the special purpose kcys are available in enhanced keyboard.

They are Print screen, Caps lock, Num lock, Esc, Pause/Break and etc.,

Advantages of the keyboard: We can entcr any type of data like alphabets, numbers, and special characters etc., It is onc of the primary input device

1.

Easy to enter numeric values using numeric keypad We can execute a task by using function keys without typing any string of characters as a command 5. We can transfer the cursor from one place to another place by using cursor movement keys.

6. Issuing shortcuts for a task by using modifier keys.

Disadvantages of the keyboard: 3.

4.

1.

2.

3.

4.

5.

It is heavy device to enter input compared to other input devices (Mouse, Trackball etc.,) We can not draw graphics easiy Cursor movement is sotmewhatdifcultcompared to other devices (Mouse, track ball) It occupies more spaçe than otieranput devices Typing and issuing isdifficut than choosing commands

MOUSE***

In 1980's PCs was used onlyaone npu

devicealled keyboard. Today all new PCs includea pointing device is called a mouše>The mouseais a graphical input device and is used to position the cursor on the screen. It allows instruction or commands at the keyboard.

controlling our computer system without having to type

Using the Mouse: We can use the mouse to point a location on the screen.

For moving the mouse pointer on screen, we have to move the mouse forward, backward, the left and right on the desk.

By using mouse we can perform the following operations the

Clicking

Double

clicking

Dragging

.

Right clicking Clicking: Clicking means moving the mouse on to the item in the screen.

Pressing and releasing the mouse button once.

Double Clicking: Double Clicking means moving the mouse on to the item in the screen pressing and releasing the mouse button twice.

Dragging: Dragging an item means to position the mouse pointer over the item. Press mouse button and hold it down as we move the mouse. the As we move the mouse pointer the item is dragged along with it we can then drop the item a in new position on the screen. This technique is called. Drag and drop editing Right Clicking: Clicking the right mouse button is known as right clicking. It is generally used for viewing properties of an item.

Advantages Of the Mouse

1.

2J

By using moise

we can issue the commands quickly and easily versatile tool to draw graphics. then key hoard Ii occupies less space than keyhOard 3. We can iransier the cursor from one place to anotlher keyboard. quickly and easily comparcd 4. 1 is also a primary input device used today with PCs. Disadvantages of the mouse is a

to

requires more space than trackball Mouse operations can also apply using key board 3. We can not periorm Ms-Dos operations properly using mouse 4. GUI operating systems are only support the mouse operations 5. There is no facility to enter alphabcts, numbers, special characters 6. To operate the mouse we must have the flat surface It

1.

2.

TRACK BALL:

track ball is a pointing device that uses a ball to position the cursor and works like an "upside down mouse. We rest our thumb on the exposed ball and our fingers on the buttons.

To move the pointer around the Screen, we roll the ball with our thumb, because we do not move the whole device. A Track ball requires less space than mouse. When space is limited a trackball can be an advantage. Track ball gained popularity with the invention of laptop computers. Like a mouse, track ball come in different models. Some track balls are large and heavy others are much smaller.

In portable computers track ball may be built directly into the keyboard. It has two or three keys.

They are available in right side and left side models. Some trackballs are not attached to computer and acts like a remote controller.

A

Advantages of Trackball

.

It occupies less space

2.

1t is

than mouse

also used as a versatile tool for graphic dIgnS We can issue the commands easily and quicki We can transfer the cursor from onephceto aothereasily and quickly

3.

4.

5.

6.

7.

as Some track balls built directly ontohe kepeard tienswe can operate trackball operations well as keyboard operations usingonly onedeuce Some trackballs are designed as afemote contioller Trackballs gained popularity at theinvention olap tops

Joystick:

used for playing games. The joystick The joystick is also a pointing device particularly screen. pointer on the has a gear shaft that is used to move the

photocopy Scanner images, documents etc. It acts like a Scanner is used to scan photograph, into directly image the it transfers the image on to paper, is machine, except that instead of copying slide paper a or on is copy images such as the image is an input tne computer. Using scanner the hard scanner computers.

The that can be stored on scanned image ranslated into electronic (digital) format cable and controlled by software. The result of' device attached to the computer by a

is a bitmap file" Advantages of Scanner

.

2.

.

It is a photocopy machine system i.e., hard copy to the data existing the can transfer styles It may come in different models and

Output Devices

Outnut

douices

of screen. There are several types output results on the the produce below. are used to douiros are given t

V Geo

at

ideo displayCRI)

disolay

0ane

display

un, ide o hetg

The Cathede Ray Tube monito1s are display the imapes thru the electrone Here, the clectronic gun shoots an electronic beam of fays on the tback phosphors coting. screen When clectronic beam hit the phosphor- coated screen, they plow, thereby enatbi'ng the ued

output The electronic gun shoots the beam of rays in a systematic way from left to right and top to bottom like human eyes tead a text on a page. The diagrammatic representation ot CRT SCreen 15 as follows.

SCe the

HORNZONTAL.

FOCUSSING ANODE

DEFLECTION PLATES

sCFIEEN

ACCELERATING ANODE

GRID

ELECTRON

m

L

DEAM

CATHODE

ELECTRON GUN

VERTICAL DEFLECTION PLATES

AQUADAG

Generally, the video displays are avail like the following.

Monochrome (Black and white) Monitors 2. Gray Scale Monitors 3. Color Monitors 1.

Monochrome Monitors Monochrome monitor displays onlyond colouSVhite". The background colour of this type monitor is usually "Black"Thesemd displays text only. Where the user doesn't see colour graphics.

sare

2. Sray Scale Monitors:E are These monitors

display "Graücolouratxmlf-white background", They are used in low and portable systems (Especiallhang,had.cqppüters)

3.

Color Monitors:

These monitors can display from 16 colors to 16 million colors. Today most monitors are color monitors.

Flat panel Display:- Flat panel display is another kind of monitors. These kind of monitors are used to display the images thru a special kind of crystal. In this technology two kinds of monitors one is passive matrix and another is active matrix.

Passive matrix has a single transistor to light-up the grid of dots whereas in active matrix monitor has more transistor to light-up the grid of dots

Now a day the LED monitors are also avail in the market with less cost and most portable to the uses.

CRT MONITORS

FLAT PANEL MONITORS

monitors are large size and OCcupy more area 2. They are heavy welght 3. They are less cost than flat panel monitors 4. It operates with the help of power 1.

CRT

1.

5.

supply It consists of an electronlc gun CRT monitors creates an Images with

or power It consists of an transistors 6. Flat panel monltors creates an image with the help of LCD technology.

7. Flat panel monltors also vlewable area

6.

the

help

of

chemlcals

and|

Flat panel monitors do not require a lot of desktop They are light weight 3. They are high cost than CRT monitors.

4. It operates with the help of batterles 5.

MAHAL

SRI BALAJIXEROX OPP LEELAN

phosonrous

The viewable are O CRT ranges from 14 inches ronitors to 21 inches

7

CRT

8.

9. It

monitors emits consumes a

electricity

refreshed 10.

to

8.

low level

radiation Breat amount keep the screen

Because the structure of these monitors, there will be distortion the picture, reducing the clarity.

9.

from 14 inches to 18 inches These type of monitors co not any radiation

em

These monitors do not consume a enerEY because they

of

have

transistors

10. Because the flat screen,

lot

tiny

do not cause

any distortion in the picture.

PRINTERS Printers are most important output devices, which They are divided into two is usced to print information categories on papers.

7.

Impaet Printerss Non Impact Printers IMPACT PRINTERS: 8.

An impact Printers creates an image by using pins or hammers ribbon against the paper. A Simple by pressing an inked example of an impact printer is a typewriter, which uses small hammers to strike the ribbon.

Each hammer is embossed with shape of a letter, number or symbol. That shape is transferred through the inked ribbon on to the paper. Many modern electric typewriters can be connected to PCs and used as a Letter Quality Printer.

Ex: Dot Matrix Printer, Typewriter, electronic typewriter etc.,

NON-IMPACT PRINTERS:

Non-Impact printers use chemicls

Example, Ink jet Printer used tiny Printer works like a photocopy

ozl

deat

to form the images on the paper.

oray droplets of ink on to the page. For Laser

Printers, Laser Printer ctc.

DOT MATRIX PRINTERS: (Describe dot matrix printers createsean imageason, thë page? or Have a dot matrix printer Ex: Ink-Jet

a

creates an image on the page?)

A Dot Matrix Printers is common type of impact printer. These Printers are used to print on to the page or to print carbon copy. These printers can produce sheets of plain text very quickly. images

A Dot Matrix Printers creates an image by using a print head. The print head contains a number of tiny pins. It prints the character or digits by putting group of dots on to the paper. Dot matrix name implies that a single pin strikes the ribbon and single dot ink is printed on to the page. haracters get printed as the head travel from left to right and in some cases it travels from reverse direction as well.

The resolutions of the lowest Dot Matrix Printers have only 9 pins. The highest resolution printers have 24 pins. The speed of this printer is measured in Character Per Second (CPS

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We can take sheet of plain text easily and quickly Maintenance cost is low compared to other printers 7 In

e

small organizations the dot matrix printer is commonly used can take carbon copies, tractor Seed papers (continuous) can used to take the printing using

dot matrix printer.

INK JET PRINTERS: printer. The difference Ink Jet or bubble jet Printers works in the same way as dot matrix a print head, Ink Jet called a machine by using an image nat, A dot matrix printer creates paper by spraying ink through tiny nozzles.

No ribbon is the Pnters creates an image directly on is very low when cost uired. This printer can print from 2 to4 pages per minute. The operating

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compared to laser printer. Expensine maintenance replacement is 1he Ink Cartridge

is

rare. and only part that

ne eds routin

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Operating cost

is low

compared

1o

laser

We

can take colour graphics

We

can maintain various caitridges lor printing various images tines inkjet printer is called as four colourcd printer(RED, BLUE,BLACK,YELLOw) is used for printing color inmages can take 20-30 copies/minute using inkjet printer

Some it

and

We

LASER PRINTERS: Laser printers are uscd to produce high quality images. These printers produce the image like as a photocopicr. As their name implies, a laser is at the heart of these printers. A separate CPU and memory is built into the printer to print the data i.e., receives from the computer and to control the laser. These printers are more expensive than inkjet printers, their print quality Is higher and printing is very fast. The quality and speed of laser printers that are used office environments, where several users can easily share the same printers through a LAN.

MERITS

We

It

can take good quality images using laser printer has special CPU and memory for printing various images

> Laser is the heart of these printers Laser printers can produce 416 papers/minutes The resolution of laser printer is 1200

UNIT-V MEMORY DEVICES The memory unit is an essential component in any computer system because it is needed store data and programs. The memory units are used to store information to either temporarily or permanently. The information is stored in the memory units in the form of a sequence of bits.

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I1emory units ot a compilei sy sder are classitied hierarchically as taliow s PRIMIR)1OR) MAIN MEMOR) The main

memory ot a tomputer system

is

classified hierarchically

as follows

Poiman

ROM ROM

EPROM

RAM EEPROM

SRAM

Caehe

Memon'slA

HDRAM

Read Only Memory 1ROM) The infornmation stored in this memory is used only for reading purpose. We cannot store, delete the contents in this memory.

modify and

The Read Only Memory chips contain the information for Power On Self Test (POST) and to specify /0 devices for Basic Input Output System (BIOs). Whenever we switch on the computer, this memory checks all the parts of the computer system at once. This process is called Power On Self Test (POST). This process

has to be performed each and every time when we switch on the compute

When power goes off or switched off the computer, it doesn't lose any information. Hence this memory is non-volatile and permanent type of primYmemory.

Programmable ROM (PROM) The PROM chips are empty ananufactuhineshePROM chips can be programmed by using ROM program devices. Howeve ongetheiformationstored in these chips, they cannot be modified later. They will become ROM chips.

Erasable PROM (EPROM) The EPROM chip also another type of ROM chip and can be erased and stored necessary intormation many number of times. It is read/write type of ROM.

Electrically Erasable PROM (EPROM) The EEPROM chip also another type of ROM chip and can be erased and stored necessary information many number of times. It is read/write type of ROM. It is similar to EPROM but using high

voltage current can erase its information.

Cache Memory memory is sometimes used to increase the special very high speed memory called cache to the CPU ata rapid rate. avallable programs and data of processing by making current A

peed

maln memory as shown in the diagram.

The cache memory is found between CPU and the

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Cache Memory

Main Memory

C.P.U

Secondaryy Memory

The cache memory is the fastest component in the memory hierarchy. Its size is also small when compared to other main memory units. It is more expensive. The cache memory access is less than the access time of the main memory by a factor of 5 to 10 times. By utilising cache memory, the total execution time of a program is reduced.

Working of cache memory

When the CPU (processor) needs to access some information, first the cache memory is examined. If the information is found in the cache memory then it is read from that memory. If the information is not found in the cache memory then the main memory is accessed. If the information is not present in the main memory then the secondary memory is accessed to read the information.

Normally the cache memory

holdsa partoaprogram and data than are most frequently used easured in terms of hit ratio. When the CPU

by the CPU. The performance of the cache me refers to the cache memory and findsitheinfog

ten

it i called a hit. foundin the cache memory then is it calledmis5ienumberofhitsdivided

If

the information is not

bythe total CPU references

(hit+miss) to the cache memory is called hitratio

hits+miss

Hit Ratio

=

hit

MAPPING FUNCTIONS

Memory mapping functions are used to map the main memory blocks memory. Usually, the cache memory can store a with cahe reasonable number given time, but this number of blocks at any is small compared to the total main memory. There are three kind of mapping functions. m=number of blocks in the They are: Direct mapping Associative mapping

Set-associative mapping Direct mapping:-Direct

mapping function is one of the simplest cache locations in which function to to store memory blocks. determine In this function, memory maps onto block block j of j modulo 128 of the main the cache. Thus, whenever memory block 0, 128, one 256,.....is of loaded in the cache, the main 129, 257 and so on. The it is stored in cache block diagrammatic representation 0, 1, of direct mapping is as follows.

Block 0 Line 0

Block

tay

Line

1

1

Blockj Line j mod n)

tag

Block j+1 Block j+2

Cache

Main Memory

Direct Mapping Associative mapping:- In this mappiog maimemory block can be placed into any catch block positions. uses 12bit It taied which hlps to identify a memory block when it is stored in code. The tag bit öran address received from the processor are compared to the tag bits of cathe«5löck of the Cache to see if the desired block is present. This is called the associative"mapping. ises the space of cache memory efficiently. The diagrammatic representarronusasFolows.

Block 0

Block Block 127 Block 128-

Block 0 Block 1 CPU

Block 126 Block 127

3lock 4094

Block 4095 Set-Assoclatlve The set Mapping functions.

Here, the assoclative and direct associative mapping use the combinatlon of allows a block of the main DlOck of the cache are grouped into sets, and the mapping two block memory to reside in any block of specific set. Generally, the set contains determines which set of the cache positions and more. While search ing the address representation of set-associative might contain the desired block. The dlagrammatic mapping is as follows.

Primary Memory

Cache Memory

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Ser

A

C

ne

cha St

0

Asrt

AS

Crbeüne l Caxho line

TAs6O

och

2

o

Elock 65 Cache ine

3

Block 255 Block 256

(

Tagi6-0) Cache Une 62

Set 31

Tagi6.0)

Cacbe Une 63 Block 4095

Lndex

OHset

VIRTUAL MEMORY

Virtual memory is a space that can be úsed on the hard drive of a computer to store information temporarily. Generallygthe physicamain memory of a computer is smaller than hard disk. Sometimes, thegprocesor ssuas32 bit address has an addressable spacethan the size of main memory.

Situation, the secondary memory is act as an actual main memory usually called asIntis virtualmemory.

The technique that automaticaly more programs and data blocks into physical main memory when they are requied ëxecution are called Virtual memory ifor technique. The processor which uses the address usually called as virtual or logical address. A hardware unit, called memory management unit (MMU) translate the logical address into physical address. The diagrammatic representation of virtual memory is as follows.

Processor Virtual address

MMU

DATA

Physical address

Cache DATA

Physical address

Main memory DMA transfer

Disk storage

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Address translation- Translating a virtual address into physical address is address translation. These are known as translated into pages. Generally, a page contains block of words. Usually, the virtual address is generated by the processor, weather is instruction fetch or an operand it for an fetch / store operation, is interpreted as a virtual page number followed by an offset (word) with in a page. Information about the main memory location of each page is kept in a page table. An area in the main memory can hold one page is called a page table. The starting address of the page table is keptthatin page a table base register. The following diagram shows the process of address mapping

Virtual Address

Page number

Offset

Page table pointer

Page Table

frame address

Frame address

Offset

Physical Address

page fault is page that is not in main memory, a a program generates an access request to a lsk Into the main memory and returns control to Occurred. Then OS copies the requested page from the

wen

the processor for further process.

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