Fetch, Decode & Execute Cycle

The Fetch Step
1. 1. Retrieve instruction from MAR and store in CIR
2. 2. Address of instruction is stored in PC (a register)
3. 3. Instructions are then passed to MAR
4. 4. Instruction is fetched and PC is updated
The Decode Step
1. 1. CPU identifies the op-code
  1. - This tells it what operation to preform
2. 2. CPU decodes the instruction in order to carry it out
The Execute Step
1. 1. CU links parts of CPU that are needed to execute the instruction
  1. - The CPU is designed to understand a set of instructions
Abbreviations
1. CPU - Central Processing Unit
2. CU - Control Unit
3. CIR - Current Instruction Register
4. MAR - Memory Address Register
5. MDR - Memory Data Register
6. PC - Program Counter
7. ALU - Arithmetic Logic Unit

Resource summary

	Created by M O over 5 years ago