Computer Hardware docx
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Computer HardwareHardware and Software
•
Hardware refers to all the parts of the
Computer System that we can touch.
Examples of hardware are monitors,
joysticks, printers, processors etc.
•
Software refers to all the programs and
data that we use with the computer.
•
A computer is an information processing
machine.
•
A computer only follows the instructions it
is given.
•
Data is Input, Processed and then Output.
What is a Computer?
I’m ONLY a
machine!
Sizes of Computers
•
Microprocessor
»
A small chip programmed with instructions.
•
Microcomputer
»
The most common type of computer. The IBM
PC is a microcomputer
•
Mini Computer
»
Medium to Large computers - mainly used to
process business information.
•
Mainframe Computer
»
Very powerful computers able to process 1000’s
of times more information a second than PCs
Smallest
Biggest
IPO - Input, Process, Output
INPUT PROCESS OUTPUT
Data is INPUT into the computer
system
It is then PROCESSED to produce
useful Information as OUTPUT.
Data and Information
Data has no meaning
•
Data is made up of symbols e.g.
871652; H789 IOS; £76.91
Information has a meaning
•
We understand what a piece of information
is about e.g
Telephone Number: 871652
Car License Plate: H789 IOS
More Input, Process, Output
•
Data is the RAW MATERIAL.
• This raw material is processed.
•
When the processing is completed a useful thing is
produced…INFORMATION
Computer - Block Diagram
•
The Computer System consists of four
parts.
Input, Processor [CPU], Output, Backing
Storage
Backing Storage
Devices
Input
Devices
Central Processing
Unit (CPU)
Output
Devices
The central processing
unit (CPU)
This is the part of the computer where the
searching and sorting of data, calculating
and decision-making goes on.
The CPU contains the processor [Control
Unit and the Arithmetic and Logic Unit
(ALU)] and the Main Memory
The Processor
•
The CONTROL UNIT fetches program
instructions from the memory storage
locations, decodes and then executes them.
•
The ALU (Arithmetic/Logic Unit) carries
out all the calculations as instructed by the
control unit.
MAIN MEMORY - ROM and RAM
•
ROM is Read Only Memory
•
Data stored in ROM can only be read, it can never be
written over or deleted. We normally store important
programs in ROM to do with the computers Operating
System (see later). NON VOLATILE MEMORY
•
RAM is Random Access Memory
•
It can be written to and read from. It is where most
programs and data are stored while the
computer is being used. RAM loses its contents when
the computer is switched off. VOLATILE
MEMORY
RAM
ROM
PROCESSOR
Data Flow
Memory
•
Computers store blocks of data called
‘words’ in memory (A 32 bit computer has
words that are 32 bits long).
•
Each place that can store a word is called a
storage location.
•
Each storage location has a unique address
that identifies it from all the other locations.
Machine Code
•
Computers only understand binary!!!
•
All programs have to end up in binary language in
order work.
•
The binary language that the computer
understands is called MACHINE CODE
•
Machine code looks like this…
00100111,01110100,10010001
Bits and Bytes [BINARY]
•
Each 1 or 0 is called a BIT (short for Binary Digit).
•
Eight bits are called a BYTE.
•
1024 bytes is a KILOBYTE (Kb for short)
•
1024 kilobytes is a MEGABYTE (Mb for short)
•
1024 megabytes is a GIGABYTE (Gb for short)
These units are used to measure
the size of storage or storage
requirements e.g. the available
memory, hard disk space,
program size.
Bits and Bytes [BINARY]
Name Abbr Size No of Bytes
Kilo Kb 2
10
1,024
Mega Mb 2
20
1,048,576
Giga Gb 2
30
1,073,741,824
Tera Tb 2
40
1,099,511,627,776
Peta Pb 2
50
1,125,899,906,842,624
Exa Eb 2
60
1,152,921,504,606,846,976
Zetta Zb 2
70
1,180,591,620,717,411,303,424
Yotta Yb 2
80
1,208,925,819,614,629,174,706,176
Binary Everywhere!
•
Binary is used to store all the data and
programs in a computer system.
•
We use binary to store:
Graphics, Text, Numbers, Video, Sound
and Programs.
•
Binary is just the code used to store the
data.
Storing Numbers
•
Numbers are stored in binary.
1
Bin
is 1
Dec
10
Bin
is
2
Dec
1000
Bin
is 8
Dec
1001
Bin
is 9
Dec
1111
Bin
is 15
Dec
11111111
Bin
is 255
Dec
•
You don’t need to understand binary (that’s
Maths) but you do need to know that it is how
most numbers are stored in the computer.
Storing Text
•
Text is stored using a special set of codes
called ASCII.
•
Each symbol (letter, number etc) has its own
unique code e.g.
•
a is 97, A is 65, ? is 63, 3 is 51
•
ASCII (American Standard Code for
Information Interchange)
•
One ASCII code is one byte long (eight bits).
Storing Graphics
•
Black and White graphics are stored using pixels
(Picture Elements).
•
The image to be stored is broken up into dots,
each dot is a pixel.
•
The pixels are ON for black and OFF for white
e.g.
1 0 0 0 0 0 0 1
1 0 1 0 0 1 0 1
1 0 1 0 0 1 0 1
0 0 0 0 0 0 0 0
0 0 0 1 1 0 0 0
0 1 0 0 0 0 1 0
0 1 1 1 1 1 1 0
0 1 1 1 1 1 1 0
•
Devices are either INPUT, OUTPUT or
BACKING STORAGE.
•
Input devices allow us to enter data into the
computer system (mouse, microphone etc).
•
Output devices allow us to receive information from
the computer system (monitor, speakers, robot).
•
Backing storage devices allow us to store programs
and data so that we can use them later (floppy
disc, magnetic tape, CD-ROM).
