IGCSE Computer Science Topic 3: Hardware

CPU

Processes instructions and data that are output into the computer so that the result can be output

Microprocessor

A type of integrated circuit on a single chip

Arithmetic Logic Unit (ALU)

Performs arithmetic operations and logical decisions

Control Unit (CU)

Coordinates how data moves around the CPU by sending a signal to control the movement of the data; decodes the instructions fetched from memory

Program Counter (PC)

Holds the memory address of the next instructions to be executed

Memory Address Register (MAR)

Holds the memory address of where data or instructions are to be fetched from memory

Memory Data Register (MDR)

Stores the data or instruction which has been fetched from memory

Current Instruction Register (CIR)

Stores the instruction the CPU is currently decoding or executing

Accumulator (ACC)

Stores the results of any calculations that have taken place in the ALU

Address Bus

Carries location data (addresses); data is written to/read from

Data Bus

Carries data or instructions

Control Bus

Carries commands and control signals to tell components when they should be receiving reads or writes

Fetch-Decode Execute Cycle

The cycle that the CPU runs through billions of times per second to make a computer work

Embedded system

Instruction set