[r3jjs]

By definition, all Atari 2600/VCS emulators are cycle accurate.

That machine required very precise timing of the CPU to drive the video output.

There are a number of other cycle-accurate emulators, including some you woudln't expect, like a cycle-accurate emulator for the C64 floppy disk (needed for anti-piracy and some high-end demos that use the floppy like a co-processor).

[tadfisher]

For the uninitiated, the Commodore 1541 (and later 1570) are external floppy drives that contain their own 6502 CPU and work RAM. In fact, you could daisy-chain two of them with a C64, tell one to copy a whole disk from the other, and disconnect the C64; the drives would continue to work as they do not rely on the C64 at all.

[thristian]

The "C64" demo "Freespin" wires the drive's data cable directly into the monitor's data cable to play a demo (including audio!) without an actual C64 involved at all:

https://www.youtube.com/watch?v=zprSxCMlECA

[shon]

That’s bananas. Thanks for the link!