ProDOS

ProDOS was a name used by multiple DOS, disk operating systems, in the 1980s and 1990s. The most famous and remembered ProDOS (and Pro DOS) releases were:
 * Apple ProDOS
 * Norton
 * Princeton (PPD)
 * MIT (MDS)
 * IBM (PC DOS Pro Dos 5+)
 * Atari Pro DOS
 * Commodore (Cdos/ProDOS)
 * Apple (SOS)

Apple ProDOS existed in 2 incompatible but similar forms, for the Apple II computers. Apple SOS was also maintained internally as pro dos during development.

With the exclusion of Apple, the ProDOS platform was universally compatible with minor exceptions in command function calls. The computer history museum and old software web sites contain extensive information and releases. As does way-back software and Old Software.

All non-Apple pro dos releases derive from Microsoft DOS 2.x