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). It starts with step one: Copy PC to MAR.

Fetch execute cycle steps

The cycle continues millions of times a second to execute the instructions stored in memory.

Let’s take a look at executing an instruction in our program. Here, the first instruction is LDA 1000, which means load the accumulator with the value stored at address 1000.

Let’s look at the steps below.


Read page 159 of the textbook “Exploring Computer Hardware”.