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Exam technique

Lots of 3 mark questions

2 marks ­ A

1 mark - E


UNIT 1: Components of computer system

Hardware

Physical parts of a system

You can actually touch it and smash it

Printer, monitor, mouse

Electrical/electronic components

Devices/circuits

Electromechanical components

Disk drives

Mechanical components

Cabinet

Peripheral devices…

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Keep a computer running

Allow human beings to communicate with the computer

Control movement of data around the computer

Allows software and hardware to communicate

Operating system (OS)

Applications packages

Designed for a particular task

Word processor, presentation software

Input

Sends data to the computer

Output

Converts electrical signals representing…

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Fail to fully understand business opportunities

Difficulties arising

Organisational factors ignored

Jobs of individual users may be ignored/have to be changed

Aims of systems life cycle

Thoroughly understand goals

Formal procedures and methods

On time delivery to required specification

Methodology



UNIT 3: Binary, Hex

Binary

Base 2

1s and 0s…

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1+0=1

1 + 1 = 0 (carry the 1)

Subtracting binary

Like long subtraction

Use two's complement then add the minus so it's like taking the number away



UNIT 4: CPU Architecture

Control unit

Organises everything

Fast but slowed down by memory

Memory unit

Stores information

ALU does calculation and…

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And makes use of two separate statements only when both apply

Both inputs have to be true

Or makes use of two statements when only one needs to apply

Only one input has to be true

Boolean logic ­ only two states

Operator ­ thing that makes it do stuff…

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Quick to write data to

FASTER

Save before turning computer off saves to hard disk and makes it none volatile so you won't lose it if the
computer goes off

Volatile

Store numbers whilst doing a calculation

-R discs

Writeable, not rewriteable

+R discs

Rewritable

ROM read only memory

Put…

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Doesn't take long to give you your stuff

Can't change or update it

Backing store/secondary store

Hard disk

Slow but cheap

Closer memory > secondary storage

Secondary storage is cheaper

Closer memory is more expensive

Volatility

Reactive

Do spontaneous things

RAM is volatile

If you cut the power you lose…

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Cache

Local store of memory

More expensive than other memory

An store less than other memory (depending on cache size)

Quicker access

Memory bus takes time

For things you know will be used regularly

L1 cache

If needed quickly

Notepad right in front of you

L2 cache

If needed not…

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There are better ways of doing it

Still being used today

Hard drive disk

Needle reads disk

More precise

Multiple disks increase capacity

Very common

Flash storage

Do not call USB sticks

Can call memory sticks

USB

The whole things fit into

Flash storage

Bluetooth dongles

Printer is miles slower…

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Computers RUN or EXECUTE programs

In order to execute a program it must be stored in the computer memory

It must occupy a set of consecutive bytes

Be written in the computer's specific internal machine language

Each CPU has its own internal machine language

Program has to be rewritten to…

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