I found this info...
Flexible sampling with .WAV import
The MC-909 comes with 16MB of sample memory, expandable up to 272MB using optional DIMMs. Audio can be recorded via the stereo analog inputs or digitally using the S/PDIF input. You can even import .WAV/AIFF files from a computer via USB—making it possible to tap into the many free samples on the Internet. And when your track is complete, simply resample the output and export it back to a PC for CD burning or distribution on the World Wide Web.
Im sure that if you can do it with a pc, you can also do it with a zip drive.
-dac-