Question

What is a fetch-execute-cycle?

Answer 1

This is what the slides have to say:

initialize the program counter
repeat forever
	fetch the instruction pointed by the counter
	increment the counter
	decode the instruction
	execute the instruction
end repeat

Comments

Made by Von Neumann also know for his creation of the big bomb that rocked the world!

Answer 2

1. FETCH
   The first step the CPU carries out is to fetch some data and instructions (program) from main memory then store them in its own internal temporary memory areas. These memory areas are called 'registers'. fetch decode execute cycle
   This is called the 'fetch' part of the cycle.
   For this to happen, the CPU makes use of a vital hardware path called the 'address bus'.
   The CPU places the address of the next item to be fetched on to the address bus.
   Data from this address then moves from main memory into the CPU by travelling along another hardware path called the 'data bus'.
   You could imagine that it is a bit like a boat attendant at a lake calling in customers when their time is up -- "Boat number 3, time to come in!" The 'address' of the boat is 3 and the 'data' is its content. The boat is parked at a pier, which is like the internal register of the CPU.

2. DECODE

The next step is for the CPU to make sense of the instruction it has just fetched.
This process is called 'decode'.
The CPU is designed to understand a specific set of commands. These are called the 'instruction set' of the CPU. Each make of CPU has a different instruction set.
The CPU decodes the instruction and prepares various areas within the chip in readiness of the next step.

1. EXECUTE

This is the part of the cycle when data processing actually takes place. The instruction is carried out upon the data (executed). The result of this processing is stored in yet another register.
Once the execute stage is complete, the CPU sets itself up to begin another cycle once more.