Fets and Crosses: Tic-Tac-Toe built from 2458 discrete transistors
3 days ago
- #Tic-Tac-Toe
- #Transistor-Logic
- #KiCad
- Implementation of a Tic-Tac-Toe game using 2458 discrete transistors.
- Features both player-vs-player and player-vs-computer modes.
- Capable of detecting all possible win/draw states and validating moves.
- Initial implementation used a ROM lookup table, later replaced with combinatorial logic.
- Final circuit uses 19 Flip-Flops and basic gates, estimated around 2000 transistors.
- Designed in KiCad with hierarchical schematic sheets for basic and complex gates.
- Split into two PCBs: main board with UI and logic, and a separate PCB for the engine.
- Manual assembly with a vacuum pick and place pen, requiring three revisions.
- Engine uses 64 decision gates for perfect play, implemented with 1074 transistors.
- Tested with an STM32-based bench and Python script to confirm the engine never loses.