This looks nice, and might help someone somewhere understand about the 6502 and its instruction set. It purports to show internal operation of the 6502, but it's from 1982, and we now know rather more about how things work internally. It's nicely animated in Apple II high resolution graphics. I don't suppose it's cycle-accurate but it shows memory traffic byte by byte as well as internal register transfers and operations.



See the video A 6502 Simulator Mystery - Solved! (by Tea Leaves, aka @tleaves11, 13min)

The Internet Archive version (a bad rip, probably not useful or usable) is here.

The original (upstream) disk image is called
MECC-T691 Apple Assembly Language v1.0.dsk
and can be downloaded from this collection of MECC disk images. (MECC is the Minnesota Educational Computing Consortium.)

There's also a version of the program here.

(via)