The System Unit of a Computer System

Periphearls

Input

Output

Storage

Communication

System Unit

Power Supply

Motherboard

Storage Device

CPU

Control Unit (CU)

Arithmetic and Logical Unit (ALU)

Registers

General Purpose Registers (GPRs)

Accumulator (AX)

Base register (BX)

Counter (CX)

Data register (DX)

Control Registers

Instruction Register (IR)

Program Counter (PC)

Memory Access Register (MAR)

Memory Data Register (MDR)

Status Registers

System bus (bus line)

Data bus

Address bus

Control bus

Machine cycle

Fetch

Decode

Execute

Interrupt

Clock rate

Word length

Main Memory

Random Access Memory (RAM)

Read-only Memory (ROM)

Erasable programmable ROM (EPROM)

Electrically erasable programmable ROM (EEPROM)