Overview
BIT4 is a 4-bit computer built entirely in software, from the lowest level up. It includes its own CPU, ALU, RAM, video unit, instruction set and an assembler for writing programs.
The challenge
Modern frameworks hide how a computer actually works. I wanted to understand it properly by designing every part myself: how instructions are fetched and decoded, how the ALU calculates and how memory and video output are connected.
How I built it
- Custom instruction set designed for a 4-bit architecture.
- CPU and ALU that fetch, decode and execute instructions step by step.
- RAM and a video unit (VPU) for storing data and drawing output.
- Assembler that turns readable assembly code into machine code for BIT4.
- No frameworks: everything is written from scratch.
Tech
- C#, WinForms