The Fetch Execute Cycle

Question 1

Fetch-execute cycle

Answer 1

A continual sequence of tasks that results in instructions being fetched from main memory, decoded so that the CPU knows what do with them, and then executes them
Cycle happens many millions of times per second in a modern PC

Question 2

Fetch section

Answer 2

Clock pulses. Processor can only begin a task as the clock pulses
The of the registers contains the location where the next instruction is to be found, register usually called the program counter
The location (or an address) is transmitted along the address of the memory
Memory responds by sending the content of that address along the data bus, back to processor. An instruction being transmitted is called the instruction register

Question 3

Decode section

Answer 3

The instruction is read by CU, which prepares the registers for whatever data theywill be stroing
Nature of preparation depends on what the instruction was

Question 4

Execute section

Answer 4

Instruction is carried out
Can be to retrieve piece of data, perform some operation that is already in a register, store something currently in register
The program counter is updated because the current instruction has been executed
Cycle starts again