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.
Microsoft DOS 6.22 was the last standalone version from Microsoft. It was also the last from Microsoft to run on an 8088, 8086, or 286.
6.22 adds DriveSpace, a replacement for DOS 6.20's DoubleSpace drive compression that was removed in 6.21.
There's a really detailed tutorial located at http://legroom.net/howto/msdos that gives tips on how to customize DOS. We suggest you follow this tutorials suggestions for setting up and customizing DOS. However, if you're installing to a virtual machine, writing the disk images to actual floppies isn't really necessary.