Multiple Cycle Processor
The root of the single cycle processor’s problems:
- The cycle time has to be long enough for the slowest instruction
Solution:
- Break the instruction into smaller steps
- Execute each step (instead of the entire instruction) in 1 clock cycle
- Cycle time: time it takes to execute the longest step
- Try to make all the steps have similar length
- This is the essence of the multiple cycle processor
The advantages of the multiple cycle processor:
- Cycle time is much shorter
- Different instructions take different number of cycles to complete
- Load takes five cycles
- Jump only takes three cycles
- Allows a functional unit to be used more than once per instruction