IBM PC DOS

IBM PC DOS, the IBM Personal Computer Disk Operating System, was a disk operating system for IBM's Personal Computers and compatible machines, released by IBM in August 1981. Microsoft developed the software, based on 86-DOS which it had purchased from Seattle Computer Products, and sold the same underlying program on the open market as MS-DOS; IBM wanted Microsoft to keep ownership of the code to avoid the legal complications of developing it in house, and the two products were identical or nearly identical until IBM began adding its own features starting with PC DOS 6.1 in 1993. IBM continued releasing new versions from 1.0 in 1981 through PC DOS 7.1 in 2003, adding hard disk support in version 2.0, networking in 3.1, and Y2K compliant features in the 1998 release PC DOS 2000, which found a niche in embedded software. One contemporary survey found 96.3 percent of PCs were ordered with the $40 PC DOS against 3.4 percent with the $240 CP/M-86. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/