The CPU is carries out a set of instructions determined by a program. A program consists of many CPU instructions. Instructions consists of instruction code operands, data that the instruction manipulates. Instruction code specifies to the CPU what to do, where the data is located etc. Instructions are held in RAM. RAM is used to store data and application programs awaiting execution. The instructions are then transferred into the CPU to be decoded and executed. This is called the instruction cycle or fetch decode execute cycle. The key components of the CPU are used to complete the instruction cycle. The steps in this process are initiating the cycle, fetch the instruction, decoding the instruction and execute the instruction. In simpler CPUs the instruction cycle is executed sequentially, each…show more content… The processor generates the necessary timing signals to fetch the next instruction from the memory system. The program counter holds the address of next instruction to fetch. The processor then fetches instruction from memory location. The memory address register stores the memory location which data will be fetched to the CPU or the location which data will be sent and stored. The memory places a “copy” of the instruction on the data Bus, processor copies instruction to the instruction register. The data bus is used to transfer data between processor and memory system/peripheral devices. The instruction register stores the fetched instruction. The processor interprets instruction and performs required actions. The memory buffer register holds the data being transferred to and from the immediate access storage. The CPU copies the data from the data bus into its MBR. The CPU copies the data from the MBR to the instruction register; this is where the fetch instructions are held. Finally, the processor interprets these instructions and performs necessary actions, ready for the next stage of the cycle to
