CPU Components: Systems Architecture: Computer Science: GCSE (9:1)

Central Processing Unit.

The component of a computer that processes data, by repeatedly fetching, decoding and executing instructions, it consists of the ALU, CU and Registers. Often abbreviated to CPU.

Registers

The collection of tiny areas of extremely fast memory located in the CPU, each with a specific purpose, where data or control information is stored temporarily. Examples are the MAR, MDR, PC and Accumulator

Cache

A small amount of fast memory in the CPU. It stores the data and instructions most likely to be needed again and it is faster to access than RAM

Arithmetic Logic Unit

Performs calculations like "ADD 3 to Accumulator", binary shifts like "Shift left 2 bits" and logical comparisons such as "Compare Accumulator with location 30". A component within the CPU abbreviated to ALU

Bus

Any of three communication pathways between the CPU and RAM in the Von Neumann architecture. There is one for addresses, one for data and one for control signals

Control Unit

Component of the CPU which controls the flow of data around the CPU, communication between the CPU and input and output devices, and decodes and executes instructions

Clock

Component of the CPU which synchronises all activity in the computer. It regulates the speed at which instructions are completed

Calculation

The ALU performs this type of instruction, an example would be "add 5 to accumulator"

Comparison

The logical operation of checking one number against another to see if they are the same or one is bigger. This is performed by the ALU when executing an instruction such as "compare with x".

Shift

An operation performed on the accumulator by the ALU, it moves the binary digits to the left or right when executing an instruction to do so

RAM

The Control Unit manages movement of data between the CPU and this component, also called main memory

Small

The size of the cache memory, compared to RAM

Fast

The speed of the cache memory, compared to RAM