racketboy.com

i had long been searching for an older version of rockNES (emulator enhancer) by richard bannister for mac os x. since upgrading, i couldn't get super mario bros. to run (my version was "a known corrupt version" but had worked fine in previous versions of rockNES) also, my games began getting choppy in the newer version and at times not comfortably playable (metroid for example). if you have had a similar problem and would like to downgrade your emulator, you can find the old versions of bannister's emulator ports here:
http://www.mac-emu.net/~bannister/filemirror/
note that these versions are no longer supported by richard bannister, but can be helpful

RockNES has had issues, especially with save states, but regardless, Nestopia is superior.

http://www.bannister.org/software/nestopia.htm

If you needed an older emulator because you have an older Mac, there are plenty of alternatives. http://www.emuscene.com/ has the best listings of Mac emulators.