It would be an interesting project though. One day if I have nothing but time on my hands.
Probably easier just to continue with an actual 6560 replacement, which is what I started as another side project.
TRON was a security program gone amok, wasn't it?
Something like that seems to happen inside my modern PC once a week!
No wonder I am so devoted to bringing my VIC back as my main computer.
Brad
Mike wrote: I just stated the minimal requirements to pull off the trick as seen in the video.
If you snoop more on what the 6502 produces as data traffic, you can surely improve on the model of the VIC-20 inside the FPGA, up to the point that the FPGA faithfully reproduces writes into the VIC registers: you'd need to emulate the instruction stream inside the FPGA to infer the missing address bits CA14 and CA15. Next you'd have to mirror the VIA chips, to account for any interrupts and I/O. People here are doing nice things by running VIC, CPU and VIAs in lock-step.
At one point you have a complete model of the VIC-20 inside the FPGA, and then you'd have something like the current emulators like VICE achieve without a VIC-20 being there 'in person'.
Good luck!
Michael
P.S. you actually remember the original purpose of the TRON program in the movie?