Components of Computer

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

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

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

Computer System

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

Motherboard 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 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 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 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 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 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 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 Dual Core Processor Quad Core Processor http://www.cse.wustl.edu/~jain/cse567-11/ftp/multcore/

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

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

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

Machine Cycle or Instruction Cycle

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

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.

Pipelining http://www.digitalinternals.com/hardware/how-pipelining-improves-cpu-performance/113/

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

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

Registers http://slideplayer.com/slide/5990957/

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

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”

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

Heat Sinks and Heat Pipes http://slideplayer.com/slide/5990957/

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

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)

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

Data Representation http://pathfinder.utsc.utoronto.ca/~dyer/csca57/book_P/node8.html

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

BCD Code http://www.tutorialspoint.com/computer_logical_organization/binary_codes.htm

ASCII Code http://www.jimprice.com/jim-asc.shtml

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