MS-DOS 3.31

Originally 86-DOS, written by Tim Paterson of Seattle Computer Products, DOS was a rough clone of CP/M for 8086 based hardware. Microsoft purchased it and licensed it to IBM for use with Microsoft's IBM PC language products. In 1982, Microsoft began licensing DOS to other OEMs that ported it to their custom x86 hardware and IBM PC clones.

For IBM-specific releases, please see the IBM PC-DOS product page.

MS-DOS 3.31 was only sold through a few OEMs, mainly Compaq.

This version adds support for hard drives up to 512MB.

It also does not use as much conventional memory as DOS 4.x or later, making it a good choice for 8088/8086 based computers.

Product type
Release date
Minimum CPU
User interface


Download Name Version Language CPU File type File size
Microsoft MS-DOS 3.31 (3.5-1.44mb) 3.31 English x86 3½ Floppy 302.39KB
Microsoft MS-DOS 3.31 [Compaq OEM Rev G] (3.5-720k) 3.31 [Compaq OEM Rev G] English x86 3½ Floppy 438.86KB
Microsoft MS-DOS 3.31 [Compaq OEM] (3.5-720k) 3.31 [Compaq OEM] English x86 3½ Floppy 749.01KB
Microsoft MS-DOS 3.31 [Emerson OEM] (5.25-1.2mb) 3.31 [Emerson OEM] English x86 5¼ Floppy 739.87KB
Microsoft MS-DOS 3.31 [German] [Compaq OEM] (5.25-360k) 3.31 [Compaq OEM] German x86 5¼ Floppy 466.51KB


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