Welcome to Computer Internals

Most explanations of how a computer works stop at one level: a programming tutorial never shows the assembly, an architecture course rarely runs your own code. Computer Internals follows one program all the way down.

Organized in levels

A computer is a stack of abstraction levels, each implemented by the one below:

1. Programming languages — the C you write
2. Assembly — one line per instruction
3. Operating system — processes, virtual memory, system calls
4. Instruction set — the bytes the CPU actually decodes
5. Microarchitecture — fetch, decode, execute, buses and caches
6. Digital logic — gates, adders, flip-flops
7. Devices — transistors and CMOS

Learn by stepping

The simulator compiles C to x86 in your browser and lets you execute it one instruction — or one micro-operation — at a time, with every register, flag, stack slot and bus cycle visible.