Editing CP/M (section)

=== 16-bit versions ===
[[File:PRO CPM-80.jpg|thumb|DEC PRO-CP/M-80 floppy-disk distribution for the Z80-A co-processor in a DEC Professional 3xx series]]

There were versions of CP/M for some [[16-bit computing|16-bit]] CPUs as well.

The first version in the 16-bit family was [[CP/M-86]] for the [[Intel 8086]] in November 1981.<ref name="Digital_Research_1981_News"/> Kathryn Strutynski was the project manager for the evolving CP/M-86 line of operating systems.<ref name="Brown-Strutynski-Wharton_1983"/><ref name="Strutynski_2010"/> At this point, the original [[8-bit computing|8-bit]] CP/M became known by the [[retronym]] ''CP/M-80'' to avoid confusion.<ref name="Digital_Research_1981_News"/>

CP/M-86 was expected to be the standard operating system of the new [[IBM Personal Computer|IBM PC]]s, but DRI and [[IBM]] were unable to negotiate development and licensing terms. IBM turned to Microsoft instead, and Microsoft delivered [[PC&nbsp;DOS]] based on [[86-DOS]]. Although CP/M-86 became an option for the IBM PC after DRI threatened legal action, it never overtook Microsoft's system. Most customers were repelled by the significantly greater price IBM charged for CP/M-86 over PC DOS ({{currency|amount=240|code=USD|linked=yes}} and {{currency|amount=40|code=USD|linked=no}}, respectively).<ref name="Maher_2017"/>

When [[Digital Equipment Corporation]] (DEC) put out the [[Rainbow 100]] to compete with IBM, it came with CP/M-80 using a Z80 chip, CP/M-86 or MS-DOS using an 8088 microprocessor, or [[CP/M-86/80]] using both. The Z80 and 8088 CPUs ran concurrently.<ref name="Kildall_1982_8-bit"/><ref name="snyder198306"/> A benefit of the Rainbow was that it could continue to run 8-bit CP/M software, preserving a user's possibly sizable investment as they moved into the 16-bit world of MS-DOS.<ref name="Kildall_1982_8-bit"/> A similar [[multiprocessing|dual-processor]] adaption for the {{ill|CompuPro System 816|sr|Compupro System 816}} was named [[CP/M 8-16]]. The CP/M-86 adaptation for the 8085/8088-based [[Zenith Z-100]] also supported running programs for both of its CPUs.

Soon following CP/M-86, another 16-bit version of CP/M was ''CP/M-68K'' for the [[Motorola 68000]]. The original version of CP/M-68K in 1982 was written in [[Pascal/MT+68k]], but it was ported to C later on. CP/M-68K, already running on the Motorola [[EXORmacs]] systems, was initially to be used in the [[Atari ST]] computer, but Atari decided to go with a newer disk operating system called [[GEMDOS]]. CP/M-68K was also used on the SORD M68 and M68MX computers.<ref name="M68"/>

In 1982, there was also a port from CP/M-68K to the 16-bit [[Zilog Z8000]] for the [[Olivetti M20]], written in [[C (language)|C]], named ''CP/M-8000''.<ref name="Thomas_1981_CPM"/><ref name="Olmstead"/>

These 16-bit versions of CP/M required application programs to be re-compiled for the new CPUs. Some programs written in [[assembly language]] could be [[assembly language translator|automatically translated]] for a new processor. One tool for this was Digital Research's [[XLT86]], which translated .ASM source code for the Intel 8080 processor into .A86 source code for the Intel 8086. The translator would also optimize the output for code size and take care of calling conventions, so that [[CP/M-80]] and [[MP/M-80]] programs could be ported to the CP/M-86 and [[MP/M-86]] platforms automatically. XLT86 itself was written in [[PL/I-80]] and was available for CP/M-80 platforms as well as for [[VAX/VMS]].<ref name="DR_1981_XLT"/>