CPU Registers

Program Counter

Copies the address of the next instruction it contains into the Memory Address Register

The address in the program counter is then incremented - increased - by one. The program counter now holds the address of the next instruction to be fetched.

MAR

Holds memory addresses before they are sent down the address bus.

MDR

Stores either an instruction or data once it is fetched from memory

CIR

Contains the information specifying the instruction that is being (or is about to be) performed

ALU

The ALU carries out calculations and makes decisions on the data sent to the processor.

Accumulator

Stores a running total of the calculation that is currently happening.

Clock Speed

A clock speed of 2 Hertz being the fetch-execute cycle happens twice every second

It is how fast the CPU runs

A 2 GHz CPU performs two billion cycles a second.

CU

The control unit manages instructions.

Bus

The wires through which data travels from one part of a computer to another on the motherboard.