Fetch, decode and execute cycle.

Can anyone explain the fetch, decode and execute cycle in simple terms using keywords such as the components and registers? Thanks

It's been a few years but I'll try to help from what I remember.

It essentially is the process cycle of a computer's central processing unit in retrieving instructions from programs during the computer's operation.

Fetch:
- Instructions pulled from memory and stored in main memory.
- Program Counter (a register) stores the address location of the instruction
- Program Counter and instructions are placed in the Instruction Register (IR)
- Program Counter is incremented by 1

Decode:
- Decoder interprets the opcode/function of the instruction within the IR
- Here the data from main memory are placed into registers (MDR and MAR)

Execute:
- CPU will execute the instructions that are placed inside the registers

Store:
- Store the result in memory (if required)

Rinse and repeat...

As a basic diagram (ALU refers to the arithmetic logic unit)


You can also use this site to help you
http://www.c-jump.com/CIS77/CPU/InstrCycle/lecture.html