MS-DOS is an acronym for Microsoft Disk Operating System.

Version 3.00 was first version of MS-DOS 3 and was released in August of 1984, it added support for FAT16 partitions up to 32 MB, 1.2 MB 5.25 inch floppy disk drives and the IBM AT internal clock. The successor to this was 3.10 which was released in April of 1985, it added support for Local Area Networks (LAN). The next release was version 3.20 which was released in January 1986 and added support for 720 KB 3.5 inch double-density (DD) floppy disk drives. The next release was version 3.21 which was released in May 1987 and added support for the IBM Enhanced and Convertible keyboads. The next MS-DOS 3.x version is 3.30 which was released in April 1987, it added support for 1.44 MB 3.5 inch floppy disk drives and extended hard disk partitions. The next version was 3.30 A and was released in July 1987 to OEM’s only. The final version was 3.31 which was released in November 1987 by a number of OEM’s and added support for FAT16 partitions larger than 32 MB. The next edition of MS-DOS was 4.x which was released in July of 1988.