the bios is a file needed to run the emulator, you must add the file neocd.bin into the directory with the other files for the neo cd emulator. to find the file search on google for "neo geo bios" most dont work, good luck finding a working one!!! then after that, you must find working games (very elusive) in fact today is the first day i actually got a game to load
and not an error with ipl.txt or something like that. so i am here to contest that it works great, i have about 15 games that run from zip, and only 1 (last blade 2) runs slow as hell, but other than that Neo Cd is a good working emulator, however i dont think that it supports a fullscreen mode (does it??) 2 months to find, metal slug 2, and ninja commander was worth the wait!!