Why build a computer from logic gates?

The goal was to gain a deep understanding of computer architecture and learn the fundamentals of logic gates, binary arithmetic, and memory circuits by building a working computer entirely out of 74-series TTL chips on breadboards, with no pre-built CPU anywhere in the design.

Key modules

  • Clock module to step the computer manually or run it continuously
  • Registers for holding and transferring data
  • Arithmetic Logic Unit (ALU) for binary addition and subtraction
  • Memory with read and write control on a shared data bus
  • Control logic that sequences each step of an instruction

Challenges along the way

The build was carried out in stages, with each module wired and tested individually before integration. The hardest problems were the quiet ones.

  • Resolving timing issues with the clock module
  • Debugging ALU operations
  • Ensuring stable memory read and write processes

The computer performs binary addition, subtraction, and register-to-register data transfer. Video documentation of the build is in progress.

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Curious about the build?

Happy to talk through the design, the build process, or the debugging.