The obvious answer which come to mind is: have you tried to mount an A:\ save directory while playing the game?
Some very old games (or programs) never took into consideration that computers could have more than one drive in the future. That's why they are bent on asking for very specific drives like C:\ which was (and still is) default for a hard drive, A:\ which is default for a floppy and B:\ which became later on the default for a second floppy.
That's why C:\ is the standard for a HD, BTW: before HDs became the norm, very old computers had two floppies: one to boot from and the second to work with.
