How would you describe the fetch execute cycle?

Fetch Execute Cycle

A more complete form of the Instruction Fetch Execute Cycle can be broken

down into the following steps:

1. Fetch Cycle

2. Decode Cycle

3. Execute Cycle

4. Interrupt Cycle

1. Fetch Cycle

The fetch cycle begins with retrieving the address stored in the Program

Counter (PC). The address stored in the PC is some valid address in the

memory holding the instruction to be executed. (In case this address does

not exist we would end up causing an interrupt or exception).The Central

Processing Unit completes this step by fetching the instruction stored at

this address from the memory and transferring this instruction to a special

register - Instruction Register (IR) to hold the instruction to be executed.

The program counter is incremented to point to the next address from

which the new instruction is to be fetched.

2. Decode Cycle

The decode cycle is used for interpreting the instruction that was fetched in the Fetch Cycle. The operands are retrieved from the addresses if the need be.

3. Execute Cycle

This cycle as the name suggests, simply executes the instruction that was fetched and decoded