Fetch Decode Execute Cycle

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Fetch Decode Execute Cycle

The main job of the CPU is to execute programs using the fetch decode execute cycle. This cycle begins as soon as you turn your computer on. To execute a program the program code is copied from secondary storage into main memory. The CPU's program counter is set to the memory location where the first instruction in the program has been stored end execution begins so, the program is now running. The processor then fetches the instruction value from this memory location. Once it has been fetched, it needs to be decoded and executed for example, this could involve taking one value, putting it into the ALU then taking a different value form a register and adding the 2 together. Once this is complete the processor goes back to the program counter to find the next instruction and this cycle is repeated until the program ends or the computer is turned off.

Main job of cpu = execute programs

execute program --> program code copied from secondary storage to main memory.

main memory = where 1st instruction of program = stored + execution begins

Once fetched it needs to be decoded + executed

when complete processor goes back to program counter to get next instructions