How Does a Modern Microprocessor Work?

A look at a made up RISC microprocessor called Calcutron-33, to learn how a microprocessor works.

Erik Engheim
The Startup

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A microprocessor being slotted into its socket on a PC motherboard.
A microprocessor being slotted into its socket on a PC motherboard.

Are you interested in better understanding articles written about new microprocessors such as Apple’s M1, AMD Ryzen, or even RISC-V?

To be able to read articles answering such questions it helps understanding what a microprocessor does. What an instruction is, a decoder, a register, an instruction-set architecture and so on.

And no, this is not nearly as hard as it may sound. I am going to teach you the assembly language of a very simple but modern microprocessor called Calcutron-33. What is assembly language? Microprocessors (CPU) cannot be instructed in plain English. They need to be told what to do using what is called machine language. Assembly code is how humans write machine code.

Before you go: “I have never even heard about Calcutron-33! Why don’t you teach me something useful like Intel x86 or ARM?”

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