CP 4 M
| Field | Early microcomputer operations |
| Went Obsolete | Mid 1980s |
| Made Obsolete By | MS-DOS and the IBM PC |
| Knowledge Assumed | What was a computer? WHY did you need one? WHAT would you do with it?l |
| When useful | If you wanted to use a computer |
CP/M, or Control Program for Microprocessors was an early operating system from Digital Research. It was popular in the early 1980s. It was a text based OS that ran primarily on Z80 and 8080 microcomputers, but was available for other architectures such as the 8086 and Motorola 68000. It entered decline after the increasing popularity of IBM PCs? that began to displace CP/M Z80 computers. CP/M was supposed to be the operating system for the PC instead of Microsoft's OS, but Gary Killdall, leader of Digital Research, brushed off IBM to take a vacation. Microsoft had nothing ready to sell, however; they adapted Gazelle Computer's QDOS in short order to run on the IBM PC and the functions people would expect. CPM/86 was eventually available as an option from IBM, but most people preferred to save their $300 as PC-DOS had better software and driver support.
Some people claim DOS used unlicensed CP/M code. This may have been initially true, but the old Gazelle code was discarded for DOS 2.x.