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.