🧩 Imagine You’re the Boss
Let’s pretend you’re the boss of a tiny robot. This robot doesn’t think for itself. It only does exactly what you say.
You tell it:
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“Pick up the red block.”
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“Put it on the table.”
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“Say hello.”
Each sentence you give the robot is a command.
In computer land, we call that an instruction.
An instruction is a tiny order you give to a computer’s brain — the CPU.
🤖 What Kind of Instructions Do CPUs Follow?
CPUs don’t understand human words like “hello” or “pick up.” They understand only tiny bits of code made of 0s and 1s.
Each instruction is like a super tiny sentence, such as:
1010 0001
Even though that looks like nonsense to us, to the CPU it might mean:
“Take the number from this spot and put it over there.”
These little 0s and 1s are like a secret language.
And guess what?
The CPU only knows a very small number of instructions — maybe 100 to 500 total.
💻 Types of Instructions
Let’s look at the kinds of instructions a CPU can follow:
| Type of Instruction | What It Means (Kid Style) |
|---|---|
| Move | “Pick this number up and carry it to a new place.” |
| Add/Subtract | “Do some math with these numbers.” |
| Compare | “Check if two numbers are the same or different.” |
| Jump/Branch | “If something is true, skip ahead to a new step.” |
| Store/Load | “Get something from memory or save something there.” |
| Do Nothing (NOP) | “Wait. Don’t do anything right now.” |
Each one of these is like a LEGO brick — small on its own, but powerful when stacked.
🛠️ How Are Instructions Built?
An instruction has two main parts:
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The Action (Opcode) – What to do
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The Details (Operands) – What to do it to
Let’s take a simple example:
Add Register A and Register B
That would break into:
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Opcode: Add
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Operands: A and B
In machine code (the CPU’s language), that could be:
0001 1010
This tells the CPU:
“Hey, add the numbers inside Register A and B!”
🧱 Why Are Instructions So Small?
Because CPUs love to work fast, instructions must be short and simple.
Big complicated ideas — like playing a video or saving a file — are broken into thousands or even millions of tiny instructions.
Just like how a long LEGO castle is built one block at a time.
🧠 Wait, Who Gives the Instructions?
Great question!
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You might click a button
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That tells your software (like a game or app)
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The software gives instructions to the CPU
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The CPU carries them out — step by step, tick by tick
The instructions are stored in a place called memory, and the CPU goes there to fetch them, one at a time.
We’ll learn more about this “fetching” in the next lesson.
🧪 What Happens If an Instruction Is Broken?
If an instruction is wrong or not understandable, the CPU usually:
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Stops
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Or shows an error message
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Or crashes the app
📚 Real-World Analogy: Cooking a Cake
Think of baking a cake.
You don’t just throw eggs, flour, and sugar in the oven and hope.
You follow steps:
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Crack eggs
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Mix with flour
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Pour in pan
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Bake for 30 mins
Each step is like an instruction.
The CPU does the same — but with numbers and data.
🔄 Recap
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An instruction is a tiny command for the CPU
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The CPU understands only special instructions made of 0s and 1s
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Each instruction has an action and some details (called operands)
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Instructions are simple, but many work together to do big jobs
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A CPU runs millions to billions of instructions every second
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Instructions must be perfect — one tiny mistake can break everything!