DOS Versions

MS-DOS

The most widespread DOS. Here are a few notable versions:

• 3.3 (1987): Allows multiple partitions, each still limited to 32MB (FAT12).
• 4.0 (1988): Allows partitions up to 2GB (FAT16). The numerous bugs were soon fixed in 4.01.
• 6.22 (1994): The last standalone MS-DOS version.
• 7.1 (1996): The DOS on which Windows 95 OSR2.0 and Windows 98 ran. Supports FAT32 (and thus, theoretically, partitions up to 8TB).

IBM PC DOS

Until IBM and Microsoft parted ways in, PC DOS and MS-DOS were identical. IBM supported and sold it until they sold their personal computer division to Lenovo in 2005.

• 3.3 (1987): Pre-installed on the early PS/2 machines.
• 7.0 (1994): Incorporated some OS/2 features, like the REXX scripting language and the XDF floppy format.
• 2000 (1998): A year 2k fixed version of 7.0.
• 7.1 (2003): Supports FAT32, only for embedded systems, never sold separately.

DR-DOS

DR-DOS is my favorite DOS version and my favorite operating system in general. It has its own page.

PTS DOS

PhysTechSoft sells two versions of this operating system, last time I looked both to the same price:

• PTS-DOS 32: Supports FAT32 and up to 4GB RAM, but seems to have no network. It can be configured to boot up to 10 operating systems.
• PTS-DOS 2000: Network support and numerous utilities, but seems to be FAT16 only.

There is a free evaluation version with a 60 second boot delay. I once tried to install this version on a 286, but it did not go well; though I clearly stated the processor at install, some 386-only memory manager threw a fatal error when I tried to boot it.

FreeDOS

A GPL project going back to 1994. I have no personal experiences with it.