A pin-level Commodore 64 simulator lets you break chips and watch the results
The Commodore 64 hardware simulator: break chips and pins, see the results
antirez's c64-hw-sim simulates every pin on the Commodore 64 motherboard, so you can lift a chip leg, short a pin to ground, or pull a ROM and see the screen react. It computes failures from the circuit netlist rather than preloaded symptoms, making it a tool for learning and for diagnosing real broken boards. It runs at only 31–48% of real speed, so it's not for playing games.
It knows nothing about what a broken Commodore 64 looks like: when you simulate a broken part and the screen fills with garbage, that garbage was computed from the circuit, not chosen by someone who knew what to expect.
- linker3000
This is really cool, and a fantastic piece of work. It may come in handy when diagnosing / fixing C64 boards.
Stretch goals:
* Allow the simulation to run diagnostics carts.
* On the 250407 board I have had timing edge cases with PLA replacements - the fix is often to fit a small (~100pF) capacitor on the /CASRAM line to slow it down a bit. The cap is fitted from the left leg of an existing 82 Ohm resistor and a nearby ground point close to 'RAM6'. Some boards actually have official space for the capacitor - designated C204. With some original PLA variants on real boards the capacitor may already be fitted. It would be good to be able to enable and disable this capacitor and set its value to see the effects.
- Lerc
Is the simulation accurate enough that if you had a simulated cartridge like the REU it would be able to do the memory transfer tricks that it does?
I have been designing a cartridge in the back of my brain, and if this could assist before I start letting magic smoke out of my c64 it would be awesome.
- dwheeler
Amazing. Sadly, it can't run in real time even on strong real hardware. I wonder if its code could be optimized to run in real time?