A DOS upgrade introduced in 1993 that included built-in real-time compression and new utilities for memory management, backup, file transfer, disk optimization, antivirus and for managing multiple startup configurations.
IBM's DOS 6
Prior to DOS 6, Microsoft's MS-DOS and IBM's PC-DOS were identical for all practical purposes. In PC-DOS 6, introduced as PC-DOS 6.1, all fundamental commands were the same, but PC-DOS 6.1 included support for pen-based computing and the PC Card. It also included a variety of enhanced utilities including a text editor, program scheduler, antivirus monitor and a full-screen Undelete for both DOS and Windows. For the first time, PC-DOS became available from IBM as a retail product, not just for IBM PCs. See DOS 7