1. Components of Computer

2. Introduction 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:
Input Devices
Output Devices
Central Processing Unit
Memory Unit
Storage Devices

3. System Unit
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

5. Types of System Unit
Tower Model
All-in-one Computer

6. Computer System

7. Motherboard 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

8. Motherboard An IC may contain million of transistors
A transistor works as an electronic gate that opens or closes the circuit for electronic signals

9. Motherboard

10. Central Processing Unit
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

11. Central Processing Unit
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)

12. Central Processing Unit

13. Control Unit 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

14. Control Unit
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

15. Arithmetic Logic Unit 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

16. Arithmetic Logic Unit
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

17. Multi-Core Processor Dual Core Processor Quad Core Processor

18. Types of Processors
Two designs of CPU are as follows:
CISC
RISC

19. CISC Complex Instruction Set Computing
Supports a large number of instructions
Executes complex instruction more quickly
Mostly used in PC and conventional mainframe computers

20. RISC 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

21. Machine Cycle or Instruction Cycle

22. Instruction Set
A set of instructions that can be performed by the CPU is called instruction set
Arithmetic Instructions
Logical Instructions
Data Transfer Instructions
Control Transfer Instructions

23. Pipelining
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.

24. Pipelining

25. Registers
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

26. Types of Registers 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

27. Registers

28. System Clock 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

29. System Clock
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”

30. Heat Sinks and Heat Pipes
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

31. Heat Sinks and Heat Pipes

32. Coprocessor 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

33. Parallel Processing
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)

34. Data Representation
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

35. Data Representation

36. Data Representation
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:
BCD Code
EBCDIC Code
ASCII
Unicode

37. BCD Code

38. ASCII Code

39. References
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