Components of the CPU (Cambridge International AS Computer Science)

Exam board Cambridge International · ASUpdated 2025-04-04

Diagram showing a computer's architecture with CPU, ALU, control unit, main memory, data, address, and control buses labelled for data processing.

Component	Full name	Purpose / function
ALU	Arithmetic Logic Unit	Performs calculations (e.g. add, subtract) and logic operations (e.g. AND, OR)
CU	Control Unit	Manages and controls the execution of instructions and directs data flow
System Clock	–	Sends out regular pulses to synchronise all CPU operations
IAS	Immediate Access Store	Main memory where instructions and data needed by the CPU are temporarily stored

Components within the CPU and wider computer system are connected by buses
A bus is a set of parallel wires through which data/signals are transmitted from one component to another
There are 3 types of bus:
- Address- unidirectional, carries location data (addresses), data is written to/read from
- Data - bidirectional, carries data or instructions
- Control- bidirectional, carries commands and control signals to tell components when they should be receiving reads or writes etc..

3-1-computer-architecture--von-neumann-architecture-1

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Component

Full name

Purpose / function

ALU

Arithmetic Logic Unit

Performs calculations (e.g. add, subtract) and logic operations (e.g. AND, OR)

Control Unit

Manages and controls the execution of instructions and directs data flow

System Clock

–

Sends out regular pulses to synchronise all CPU operations

IAS

Immediate Access Store

Main memory where instructions and data needed by the CPU are temporarily stored