MS-DOS 6

MS-DOS 6 is a family of versions of MS-DOS, initially released in March 1993, with updates being released until June 1994.

MS-DOS 6.00
MS-DOS 6.00 was released in 1993. This version included many new utilities and features:
 * Disk defragmenter
 * Disk compression
 * Anti-virus (MSAV and MWAV)
 * A new backup system
 * PC-PC file transfer tools

It was heavily criticized as buggy by the press, primarily due to file corruption issues with DoubleSpace (disk compression utility based on Vertisoft's DoubleDisk) and the lack of tools to repair such issues.

MS-DOS 6.20
MS-DOS 6.20 was released in November 1993. Microsoft skipped the 6.10 version number as a marketing response to IBM PC-DOS 6.10, which was released at the same timeframe. After complaints from users about data loss, DoubleSpace was finalized. The  program has been added, and   and SmartDrive have been improved.

MS-DOS 6.21
MS-DOS 6.21 was released in March 1994 specifically to remove DoubleSpace due to legal injunction by Stac Electronics over the use of Stacker code in DoubleSpace; during the interim period, the replacement software, DriveSpace was not yet ready.

MS-DOS 6.22
MS-DOS 6.22 was generally available in June 1994, three months after 6.21. MS-DOS 6.22 shipped with "Enhanced Tools", including a disk compression tool known as DriveSpace, which was free from Stacker code. An included supplemental disk also ships with copies of tools dropped from the previous version of MS-DOS. This version shifted the DOS Shell to another disk, called the "Supplemental" disk. This disk also includes.