Sony had weird ideas in those days.
I remember their first digital music player: it wouldn't play mp3 files and it used an obscene check-out/check-in DRM that *moved* ripped files back and forth from the PC to the player and back:
http://www.mp3newswire.net/stories/sonyclip.html
Mind you, a few since gone and forgotten ebook vendors did the same thing. Which is why they are gone and forgotten.