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
SRI BALAJI XEROX opp LEELAMAHAL
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 &
SRI BALAJI XEROX opp LEELAMAHAL
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.
SRI BALAJI XEROX opp LEELAMAHAL
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.
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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.
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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
MERITS
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
MERITS
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.
AH
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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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