AAE was the emulator. I'm not sure it was ever finished.
http://pages.suddenlink.net/aae/
That's the one -- the author (
aae) gave up on it about 3 years ago.

Biobern edited the source to tweak it for Asteroids and posted the custom build
here.
AAE does need some work:
- Keyboard-style encoder inputs are good AFAIK
- Mouse inputs are fairly functional, but still need tweaking
- Gamepad inputs not done
- Analog inputs not done -- SW looks great but no joy on using a yoke with AAE

Scott