Short Version: A: & B: are reserved by floppy disk drives, so C: is used by hard drives for backwards compatibility reasons. Once upon a time, the early CP/M and IBM PC style computers had no hard drive. You had one floppy drive, and that was it. Unless you spent another $1k or so on a second floppy drive, then your system was smokin'! If you only had one drive it was common to boot from one disk,
