GoKawiilNew open-source tool simulates Commodore 64 motherboard down to individual pins
A developer has released c64-hw-sim, a program that models the Commodore 64's ASSY 250407 motherboard at the level of individual chip pins and the board's netlist. Users can simulate faults such as lifting a chip leg or shorting it to ground or power, then observe the resulting effect on screen output, keyboard behavior, and board signals. The simulator derives these outcomes from circuit behavior rather than pre-programmed fault scenarios, and runs at 31-48% of real C64 speed depending on the host processor.
GoKawiil's interpretation of the reporting above, not reported fact.
The tool could give retrocomputing hobbyists and repair technicians a way to test failure hypotheses on a vintage, often fragile machine without risking damage to irreplaceable original hardware, many of whose chips are soldered rather than socketed. Because matching a simulated symptom to a real one is only a clue rather than proof, the creator cautions that it should guide troubleshooting order rather than replace physical diagnosis entirely.
- c64-hw-sim models the Commodore 64 motherboard pin-by-pin using its netlist and chip behavior.
- Users can simulate faults like lifted legs, shorts, or removed chips and observe realistic resulting glitches.
- The simulator runs below real-time speed (31-48% depending on hardware) but is intended for fault analysis, not real-time emulation.
Commodore 64 Reloaded MK2 motherboard — For anyone inspired by this pin-level simulator to get hands-on with real C64 hardware, a modern reproduction motherboard like the Reloaded MK2 lets you probe, test, and tinker without risking an irreplaceable vintage board. It's built with socketed chips, making it ideal for experimenting with the same kinds of faults the simulator models, but on actual silicon. A perfect bridge between the virtual exploration and real-world retrocomputing hardware hacking.
See Commodore 64 Reloaded MK2 motherboard on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: github.com, 2026-10-15
Published there as: “The Commodore 64 hardware simulator: break chips and pins, see the results”
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