Exploring Computer Hardware

Fetch Execute Cycle

The fetch-execute cycle is the logical sequence of steps that a CPU follows to execute instructions of a program stored in memory (RAM). To demonstrate this cycle, we’ll use a very simplified CPU and memory. Many modern CPUs are far more complex, and have extra features such as caches, hyper-threading and so on. Our little system will look something like this...

The CPU is made up of a control unit that controls the program counter (PC). This counter increments in sequence to indicate the address of the next instruction to be called from memory.

We also have a current instruction register (CIR) to hold the instruction currently ...