CP/M

CP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. Initially confined to single tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations, and were migrated to 16-bit processors.

CP/M stood for either Control Program/Monitor or Control Program for Microcomputers (the latter possibly being a backronym).[citation needed] The name shows a prevailing naming scheme of the time, as in Kildall's/Intel's PL/M (Programming Language for Microcomputers) and Prime Computer's PL/P (Programming Language for Prime), both suggesting IBM's PL/I; and IBM's CP/CMS operating system, which Kildall used when working at the Naval Postgraduate School, and which, like TOPS-10, has clear similarities to the CP/M user interface and file system.[1] Gary Kildall himself renamed CP/M in word form as part of the maturation of CP/M from personal project in 1974 to commercial enterprise in 1976.

The combination of CP/M and S-100 bus computers patterned on the MITS Altair was an early "industry standard" for microcomputers, and was widely used through the late 1970s and into the mid-'80s. By greatly reducing the amount of programming required to install an application on a new manufacturer's computer, CP/M increased the market size for both hardware and software.