Unless it was one of the Net HD minidisks (which could be used like a MO drive directly by the OS - no scumware necessary), B00tdisk is right.
--edit--
To quote Karlos on the Minidisk - Minidisk was the Alpha Romeo of music players - it was frustrating as hell to get the software to play ball, to set the thing up.
But on those occasions where it all came together, it was sublime.
True, Minidisc is/was awesome hardware. Sony's software and DRM policy made it frustrating to use. If what you got was a recording model (i.e. with a microphone-in jack) then I don't think you got ripped off. That's an awesome price for a high quality portable digital recorder. I've picked up several for less than $10 myself at Thrift stores and use them to record sounds, song ideas and family history. I then dub them over to my computer. Sound quality is excellent. If you don't want it you could sell it to me!
The Minidisc is sort of like the Amiga as I see it. Amazing hardware that was way ahead of its time (small, portable, digital recording and playback in 1991 with great quality hardware). Like the Amiga, it could have become a mainstream platform but was not promoted properly by the parent company. Like the Amiga, it still has a small die-hard following even today.
The one good thing about the Minidisc is that today no one wants 'em, so if you want a cheap portable high quality recorder and are willing to live with the restrictions then you can get one for peanuts (less than $10).
If anyone is going to chuck their Minidisc hardware - get in touch with me first! I'll pay for shipping. I'm also looking for a full-sized Minidisc deck (home stereo component) - I've never had one of those.