An urban legend, because:
a. It's not emulation. The PS1 wasn't powerful enough for that. It only loads a few things from that ROM, or so I hear.
b. Its load times were bad over in Japan too.
Thanks a lot for your reply
That said the bit about Twinbee Collection PSP having a SNES emulator was from this youtube video
(recorded with a toaster). It's not perfect either..
TwinBee Portable actually uses a standard SMC format ROM image of the SNES game Pop 'n TwinBee, split into four parts. The Buster Busts Loose ROM is the same size as Pop 'n TwinBee, so I simply split in into four parts using a hex editor, then replaced the files in the UMD ISO image. The altered ISO image was then loaded using DA's custom firmware. This seems to work for *some* games, but not others. I have not tried any ROMs of a different size.