Transcript itc-lec-03-1

Components of Computer
Introduction
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Physical parts of the computer
Touch, see and feel the hardware
Consists of electronic circuits and mechanical
components to perform various functions in the
computer
The hardware components are:
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Input Devices
Output Devices
Central Processing Unit
Memory Unit
Storage Devices
System Unit
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It is a box that contains different electronic
components of computer used to process data
The electronic components in the system unit are
connected to motherboard
All computer systems have a system unit
System unit is made of plastic or metal to protect
the components in it
Most storage devices, memory processors, cards,
ports and connectors reside inside the system unit
Other devices like keyboard, mouse, speakers and
printer reside outside the system unit
https://www.pinterest.com/pin/522628731727026013/
Types of System Unit
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Tower Model
All-in-one Computer
Computer System
Motherboard
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Also called system board or main board
Most important circuit board in system unit
A communication medium for the entire computer
system
All components or devices of the computer are
connected to motherboard
Contain different chips
A chip is a small semi conductor that contains
integrated circuits on it
An integrated circuit is a microscopic path that
carries electrical current
Motherboard
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An IC may contain million of transistors
A transistor works as an electronic gate that opens
or closes the circuit for electronic signals
Motherboard
http://patkay.hubpages.com/hub/the-motherboard-components
Central Processing Unit
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Main component of the computer
Also called processor
Brain of the computer
Performs all the operations on the data according to
program’s instruction
It executes the program instructions and tells other
parts of the computer what to do
CPU fetches instructions of program from main
memory and executes them one by one
CPU also has the ability to decide which instruction
will be executed next
Central Processing Unit
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Speed of the CPU is measured in Mega Hertz or
Giga Hertz
CPU is divided into two parts or sub-units
◦ Control Unit (CU)
◦ Arithmetic Logic Unit (ALU)
Central Processing Unit
http://www.easy-computer-tech.com/cpu.html
Control Unit
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Most important component of the CPU
Controls and coordinates all the activities of all other
units of the computer
Considered as logical hub of the computer
Acts as central nervous system for other components
of the computer
◦ For example, the control unit receives the data and
instructions from the input device and stores them in main
memory
◦ It perform all these functions by issuing commands to the
relevant unit of the computer
Control Unit
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Also controls the execution of the instructions given
to the computer
Fetches the instruction and data from main memory
Decodes and executes the instruction one by one
Arithmetic Logic Unit
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Another important component of CPU
Performs the arithmetic and logical operations on the
data
When the control unit encounters an instruction
related to perform arithmetic or logical operation on
data, it passes that instruction to the ALU
ALU consists of a number of registers and adder
circuits
A register is a temporary storage device, which holds
data and instruction as long as it is being interpreted
and executed
Arithmetic Logic Unit
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When the data and instruction are fetched from the
main memory for processing, these have to be stored
in one of the registers of the CPU
Multi-Core Processor
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Dual Core Processor
Quad Core Processor
http://www.cse.wustl.edu/~jain/cse567-11/ftp/multcore/
Types of Processors
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Two designs of CPU are as follows:
◦ CISC
◦ RISC
CISC
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Complex Instruction Set Computing
Supports a large number of instructions
Executes complex instruction more quickly
Mostly used in PC and conventional mainframe
computers
RISC
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Reduced Instruction Set Computing
Reduces the instructions to only those used more
frequently
Executes simple instruction more quickly than CISC
CPU
Mostly used in workstations
Workstations can work up to 10 times faster than
most PCs due to RISC
Machine Cycle or Instruction Cycle
Instruction Set
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A set of instructions that can be performed by the
CPU is called instruction set
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Arithmetic Instructions
Logical Instructions
Data Transfer Instructions
Control Transfer Instructions
Pipelining
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In some computer, the control unit completes all four
stages of the machine cycle before beginning work on
the next instruction
Most of the modern PCs support a concept called
pipelining
Parallel work known as pipelining
Pipelining is a technique used to improve the
execution throughput of a CPU by using the
processor resources in a more efficient manner.
Pipelining
http://www.digitalinternals.com/hardware/how-pipelining-improves-cpu-performance/113/
Registers
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A processor contains high speed and small sized
locations, called registers
Temporarily hold data and instruction during
processing
Size of register is 2 to 4 bytes
May hold a program instruction while it is being
processed by CPU
May Hold the results of calculation
Part of processor, but not part of main memory or
storage devices
Types of Registers
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Memory Address Register (MAR)
Memory Buffer Register (MBR)
Instruction Pointer Register
Instruction Register
Accumulator Register
Input/Output Register (I/O)
Stack Control Register
Flag Register
Registers
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System Clock
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It is an electronic component
It generate the electric signals at a fast speed
Controls all functions of the computer using clock
ticks
The ticks of system are known as clock cycle
Set the speed of CPU
Computer clock can tick from millions to billions
times in one second
System Clock
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The power of CPU is determined by the speed with
which it processes data
A CPU that has higher clock speed can process more
instructions per second than a CPU with lower clock
speed
The speed at which the CPU executes instructions is
called clock speed or clock rate
Processor speed is measured in MHz and GHz
Hertz means “machine cycle per second”
Heat Sinks and Heat Pipes
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Heat sink is a small ceramic or metal component used
to absorb and ventilate the heat produced by electrical
components of computer
Part of processor chip
Can be installed on top or side of the chip
Size of heat sink is large
Occupies more space
Heat Pipes are used to absorb heat in note book
computers
Heat Sinks and Heat Pipes
http://slideplayer.com/slide/5990957/
Coprocessor
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Special Additional Processor Chip
Helps main processor to perform specific tasks
Increase the performance of a computer
A type of co-processor is known as floating-point co
processor or math coprocessor
Parallel Processing
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A method in which multiple processors are used to
speed up the processing is called parallel processing
Work simultaneously to complete a program
Divides the task into multiple smaller tasks
Each processor solves the smaller task independently
at the same time
Two types are parallel processing
◦ Single Instruction / Multiple Data (SIMD)
◦ Multiple Instruction / Multiple Data (MIMD)
Data Representation
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Computer is an electronic device that works with
digital signals
Computer works in binary system
This system consists of two digits 0 and 1 called bits
Bit stand for binary digit
Smallest unit of data that can be represented in
computer
A collection of 8 bits is called byte
1 byte can represent 256 different characters
Data Representation
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Data Representation
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Data is converted into binary form before it is stored
inside the computer
Process of converting data into binary form is known
as encoding
Data can be converted into binary form by using
different encoding techniques
Popular coding schemes are:
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BCD Code
EBCDIC Code
ASCII
Unicode
BCD Code
http://www.tutorialspoint.com/computer_logical_organization/binary_codes.htm
ASCII Code
http://www.jimprice.com/jim-asc.shtml
References
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Introduction to Information Technology by Riaz
Shahid, CM Aslam and Safia Iftikhar
The Concepts of Information Technology by Imran
Saeed, Ahsan Raza, Tariq Mehmood and Zafar
Hussain