only data

only programs

data & programs

neither data nor programs

Accumulator

ALU

Program Counter

Memory Address Register

Control Bus Register

PC is incremented

The Instruction at the MAR address is read from RAM

The PC value is copied to the MAR

The instruction in the MAR is decoded

The value in the MDR is written to the address in the MAR.

PC is incremented

The Instruction at the MAR address is read from RAM

The PC value is copied to the MAR

The instruction in the MAR is decoded by the CU

The value in the MDR is written to the address in the MAR.

PC is incremented

The data at the MAR address is read from RAM

The ALU performs any calculations required on the ACC

The instruction in the MAR is decoded by the CU

The value in the MDR is written to the address in the MAR.

Main Address Register

Memory Address Register

Massive Address Register

Minimal Age Readable

Stored Program Concept

Memory Program System

Stored Memory Concept

Stored Memory Program

Registers

Addresses

Cache

Buses

CU

MAR

MDR

PC

Stores the address of the next instruction in memory

Stores the address of where the next item will be fetched from

Stores data fetched from memory, or waiting to be stored in memory

Stores the result of arithmetic calculations