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CP/M-86 was a version of the CP/M operating system for the Intel 8086. The commands are those of CP/M-80. It was later reworked to become MS-DOS compatible and renamed to DR-DOS and is discussed at more length in that article.

CP/M was IBM's first choice as OS for the not-yet-released IBM PC. There are two alternative versions of what happened:

  • Gary Kildall, owner of Digital Research who developed CP/M, was not present when IBM visited in late 1980 on short notice, and when contacted he indicated he was not interested in developing a 16-bit compiler at the time and IBM was then forced to look elsewhere.
  • IBM considered Gary's licencing price too steep and looked elsewhere for a better deal.
IBM then went to Microsoft, who provided them with PC-DOS 1.0. PC-DOS was based on QDOS (Quick and Dirty Operating System) which Microsoft had just bought and hurriedly polished up.

IBM immediately found a large number of bugs in it and had to extensively rewrite it. Compared to CP/M, PC-DOS was primitive:

  • No support for fixed disks.
  • Filesystem did not support subdirectories.
These were not critical limitations since the original PC had no hard disk anyway, and there was not much need for subdirectories when a floppy disk only held 160 kilobytes. The original IBM PC was not sold bundled with an operating system, and a purchaser was free to buy a copy of CP/M-86 when it became available a few months after the PC's release in August, 1981. However, PC-DOS sold for $60 while CP/M-86 was priced at $240. The large range of CP/M programs were easy to port to CP/M-86 by software companies, but the price difference meant that there was little demand for them.

As a result, CP/M-86 never really got off the ground, appearing on only a relatively few systems in the early 1980s.

Versions

A given version of CP/M-86 will have two version numbers. One applies to the whole system and is usually displayed at startup; the other applies to the BDOS kernel. Versions known to exist include:

  • CP/M-86 for the IBM Personal Computer Version 1.0 (BDOS 2.2) - January 1982 - Initial release for the IBM PC.
  • CP/M-86 for the IBM Personal Computer Version 1.1 (BDOS 2.2) - March 1983 - Hard drive support was added.
  • Personal CP/M-86 Version 1.0 (BDOS 3.1) - November 1983 - Released for the Siemens PG685. Based on the multitasking Concurrent CP/M kernel, it could run up to four tasks at once.
  • Personal CP/M-86 Version 3.1 (BDOS 3.3) - January 1985 - A version for the Apricot F-Series computers. This version gained the ability to use MS-DOS formatted disks.
  • Personal CP/M-86 Version 2.0 (BDOS 4.1) - 1986 or later - Released for the Siemens PC16-20. This is the same BDOS used in DOS Plus.
  • Personal CP/M-86 Version 2.11 (BDOS 4.1) - 1986 or later - Released for the Siemens PG685.

It is believed that the various Personal CP/M-86 versions were based on an unreleased product known as CP/M-86 Plus; all known Personal CP/M-86 versions contain this string.

External links

Operating systems | CP/M

CP/M-86

 

This article is licensed under the GNU Free Documentation License. It uses material from the "CP/M-86".

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