How does the computer’s brain know what to do next?
It uses a simple process over and over:
-
Fetch the instruction
-
Decode what it means
-
Run the action
-
Move on to the next one
This is called the fetch-decode-run cycle.
Let’s break it down like a story.
📖 Step 1: “Go Get the Next Step”
Imagine your brain is standing in front of a recipe book.
First, it reads the first line:
“Mix sugar and flour”
That’s the fetch step.
🧾 Step 2: “What Does This Mean?”
Now it looks at the words:
“Mix sugar and flour”
Okay — I understand what to do.
That’s decode.
The computer’s brain looks at the 1s and 0s and decides what that instruction wants.
🛠️ Step 3: “Let’s Do It!”
Now the brain carries out the job:
-
Mixes
-
Adds
-
Shows
-
Saves
Whatever it says.
That’s the run step.
Then… it moves to the next instruction, and starts over.
♻️ It Does This Over and Over — Really Fast
Most programs have millions of steps.
But the brain doesn’t care.
It keeps going:
Fetch → Decode → Run → Repeat