Chapter 1 Computer Hardware1 Computer Hardware A level Computing Book (Reference) By P.M.Heathcore.

Chapter 1 Computer Hardware

1

Computer Hardware

A level Computing Book (Reference)By P.M .Heathcore


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Computer System

Hardware Software


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DifferencesHardware Physical Component of a

Computer We can touch these parts Allow user to enter data

and information into computer and retrieve

Can not perform any task without Software

If problem occur in hardware then it will repaired.

Software Logical Component of a

Computer We can not touch These are in form of

instructions that tell the computer that what to do

It can not executed without hardware.

If any problem in software then it will reinstall.


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Computer Components

Logical units of a computer Input unit Output unit Memory unit ( Main Memory ) Central processing unit (CPU) Secondary storage unit


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Computer Component

Input Unit

CPUUnit

Ram / Rom

ALU & LogicalUnit

Control Unit

Output Unit

Storage Devices


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Types of computers by Size

Micro computers Mainframe Computers Super Computers Mini Computers Embedded Computers


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Micro Computers

Are the computers that you are most likely to

encounter at home or in school and colleges. It consist of one or more input device ,output

device, memory and processor.Examples PCs Apples


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Types of Micro Computers Desktop Computers Laptop and notebook

Computers Personal Digital Assistants

(PDA) Palmtop Computers


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Mainframe computers Thousands of terminals attached to it. Larger mainframe computers carry out 250

million instructions per second. It Consist of multiple processors. Used large organizations such as banks,

insurance companies, airlines and government department.

Disadvantage: Due to immense power they produce large

amount of heat so its require air conditioned.


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Examples

IBM43810 NEC610 DEC 10 etc


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Supercomputers

Largest category of computer, costing millions of pounds.

It is complex ,large storage and advanced computers.

They are mostly used by scientific and industrial research departments.


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Uses

NASA Weather centre Stock Exchange Weapon design Mapping the surface of planets. Studying the neural network of brain Preparing models of chemical

systems.


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Examples

CRAY-XP ETA-10 Blue sky ASCI White


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Mini computers

Have a size , power and cost somewhere between those of microcomputers and mainframes.

It is much powerful then some of the mainframes still in use.

It is used by business institutes and departments.


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Examples

Vax-8800 MV-1500


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Embedded Computers or Microprocessors

Is a single chip that perform the functions of a central processing unit

Many microprocessors makes are Microcontrollers also called embedded.

Embedded computers serve as the brain of a larger piece of machine.

Their software is stored in the computer’s own.

They serve as a personal computer but not have a monitor, keyboard and mouse


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Uses Microwaves programmable ovens Blood pressure monitors Air bag sensors Washing machines Video recorders Alarms Digital cameras MP3 players Car engine Controllers


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Processors Most computer use Ics. It hold millions of electronic

components such as transistors


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Functions

It controls the transmission of data from input device to memory

It processes the data held in main memory

It controls the transmission of information from main memory to output device.


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Main Memory

Instructions and data are held in main memory which is divided into millions of addressable storage units called bytes.

One byte can hold one character Total bytes in main memory

referred to as the computer’s memory size.


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Memory Sizes measurement

I nibble = 4 bits I byte = 8 bits I kilobytes (kb) = 1024 bytes 1 Megabytes (Mb) = 1024kilobytes 1 gigabytes (Gb) = 1024Megabytes 1 terabytes (TB) = 1024Gigabytes


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Types of Main Memory

Ram (Random Access Memory) Rom (Read Only Memory)


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RAM & ROM

Ram Its temporary memory Read and Write data Data can be changed

or deleted It is a Volatile memory The instructions

written in Ram at the time of execution

Rom Its Permanent memory It can only be read Data can not change or

deleted It is non Volatile The instructions are

written into Rom at manufacturing time. (BIOS)


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Cache Memory A Cache is a small and very fast memory To speed up the transfer of data and

instructions. It is located inside or close to the CPU

Chip. It is faster than Ram The data and instructions that are most

recently or most frequently used by CPU are stored in cache.

The amount of cache memory is generally between 1kb and 512kb


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How Cache memory Works

Processor

Cache Memory

Main Memory

Single Word of data Transferred

Block of data transferred


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CPUMemory

(main store)

Cachecontroller

Cachememory

Typically4MB

Typically64 KB

HitMiss


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Disk Storage The most common form of

auxiliary storage ( External or secondary or backing store) is disk

Magnetic media Hard disk Tape Floppy disk

Optical storage device CD DVD CD-R CD-RW CD-ROM USB Drive

Chapter 1 Computer Hardware1 Computer Hardware A level Computing Book (Reference) By P.M.Heathcore.

Documents

computer hardware examplesvax

personal computer

advanced computers

heathcore chapter

examplespcsapples chapter

larger mainframe computers

large storage

large organizations