Unit 1 Hardware REVISION

Vonn Neumann Machine

Von Neumann Arcitecture

Fetch Decode Execute Cycle

ALU

Control Unit

Arithmatic Logic Unit

Buses

Carries out the mathematical and logical operations

Registers

Controls and directs the flow of instructions and controls the different parts of the CPU. (Central Processing Unit.

Input and output devices

input: keyboards, mice, microphones, keypads

A small amount of fast access storage only used for specific purposes

  1. The processor checks the program counter to see which instruction to run next
  1. The processor fetches the instruction value from this memory location.
  1. One the instruction has been fetched, it is decoded and executed
  1. Once this is complete, the processor increments to the program counter, then finds the next instruction.

The cycle is then repeated until the program ends

connects internal components of a computer system.

Address Bus

contains location of memory in ram

Data Bus

carries data between memory addresses

output: monitors, speakers, projectors

Control Bus

carries control signals internally and to peripherals

PC Components

GPU - graphics processing unit.

Motherboard - the main circuit board that connects components like, the CPU and hard disks.

a microprocessor that performs calculations needed to display graphics on screen.

Integrated GPUs use the computer's RAM. They're cheaper than dedicated GPUs but can't handle high-demanding programmes like GO 4 Schools

the dedicated GPU comes separate and is usually more expensive, but it doesn't use the computer's RAM and is better for high-demanding programmes. However, it may require cooling.

Hard Disk Drive

good compromise between price, storage, speed and performance

data is read and saved using an arm that has a special read/write head at the end

fragmentation can slow access speeds

Sound cards - specialised electronic circuits that generate analogue waveforms. They also provide input/output of audio signals.

Optical Disks

work by using lasers to burn data into a dvd, cd or blue ray

SSD

receive and write data almost instantly

Memory

ROM

used for permanent storage of data

Cache Memory

smaller and faster than ram and stores frequently used data or instructions

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