[Carsten] spent over a year developing a small CPU system, implementing his own minimalist instruction set entirely in TTL logic. The system uses a serial terminal interface for all I/O, hence the term UART in the title. [Carsten] began building this computer on multiple breadboards, which quickly got out of hand.

Tetris on the UART Computer

In addition to designing this CPU project, [Carsten] built an assembler and wrote a substantial operating system and various demo programs and games. He not only learned KiCAD to make this board, but also taught himself to use an auto-router. The KiCAD design, Gerbers, and BOM are all provided in his repository above. ROM images and source code are provided, as well as a Windows cross-assembler. But wait – there’s more. He also wrote a cycle exact emulator of the CPU, which, as he rightfully brags, comes in at under 250 lines of C++ code. This whole project is an amazing undertaking and represents a lot of good work. We hope he will eventually release the assembler project as well, in case others want to take on the challenge of building it to run under Linux or MacOS. Despite this, the documentation of the Minimal UART Computer is excellent.

[Carsten] claims the project has finally passed the finish line of his design requirements, but we wonder, will he really stop here? Do check out his YouTube channel for further informative videos. And thanks to [Bruce] for sending in the tip.