Breadboard color computer from TTL

This is an 8-bits computer built out of 1970s TTL chips (74LS series)

  • 34 chips are used for the CPU
  • Only simple SSI and MSI chips, such as AND/OR, 4-bit adders, multiplexers and registers. Typically no more than 10-20 gates per IC.
  • So no microcontroller and no relatively complex ALU chips (such as 74181) are used
  • 32 kB static RAM (70ns)
  • Harvard architecture with program and data stored in EEPROM
  • System runs at 6.3 MHz. It can probably be pushed to 8 MHz.
  • RISC-like instruction set with pipelining: 1 instruction per clock cycle
  • Instruction decoding partly done with diodes
  • Comfortable instruction set: add, sub, and, or, xor, conditional jumps, several useful addressing modes, etc
  • Capable of generating VGA signals from software. Typically 160x120 pixels with 64 colors
  • Designed and built on a solderless breadboard in roughly 6 weeks

    Project pages

  • Project blog
  • Photo gallery and project details

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