CP/M-86 was a version of the
CP/MCP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
operating systemAn operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
that
Digital ResearchDigital Research, Inc. was the company created by Dr. Gary Kildall to market and develop his CP/M operating system and related products. It was the first large software company in the microcomputer world...
(DR) made for the
Intel 8086The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The 8086 gave rise to the x86 architecture of Intel's future processors...
and
Intel 8088The Intel 8088 microprocessor was a variant of the Intel 8086 and was introduced on July 1, 1979. It had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however...
. The commands are those of CP/M-80. Executable files used the relocatable
.CMD file formatIn CP/M-86, CMD is the filename extension used by executable programs. It corresponds to COM in CP/M-80 and EXE in DOS. The same extension is used by Microsoft Windows for unrelated batch files.-Binary format:...
(the same
filename extensionA filename extension is a suffix to the name of a computer file applied to indicate the encoding of its contents or usage....
.CMD is used by
Microsoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
for unrelated
batch fileIn DOS, OS/2, and Microsoft Windows, batch file is the name given to a type of script file, a text file containing a series of commands to be executed by the command interpreter....
s). Digital Research also produced a multi-user multitasking operating system compatible with CP/M-86, MP/M-86, which later evolved into Concurrent CP/M-86. When an emulator was added to provide PC DOS compatibility, the system was renamed to Concurrent DOS, which later became
Multiuser DOSMultiuser DOS is a soft real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers.An evolution of the older Concurrent CP/M-86 and Concurrent DOS operating systems, it was originally developed by Digital Research and later further developed by Novell...
. The
DOS PlusDOS Plus is an operating system written by Digital Research, first released in 1985. It can be seen as an intermediate step between CP/M-86 and DR-DOS....
,
FlexOSFlexOS was a modular real-time multi-user multi-tasking operating system designed for computer-integrated manufacturing, laboratory, retail and financial markets...
and DR DOS families of operating systems started as derivations of Concurrent DOS.
CP/M-86 and the IBM PC
When
IBMInternational Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
contacted other companies to obtain components for the
IBM PCThe IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
, the as-yet unreleased CP/M-86 was its first choice for an operating system because CP/M had the most applications at the time. Negotiations between Digital Research and IBM quickly deteriorated over IBM's
non-disclosure agreementA non-disclosure agreement , also known as a confidentiality agreement , confidential disclosure agreement , proprietary information agreement , or secrecy agreement, is a legal contract between at least two parties that outlines confidential material, knowledge, or information that the parties...
and its insistence on a one-time fee rather than DRI's usual
royaltyRoyalties are usage-based payments made by one party to another for the right to ongoing use of an asset, sometimes an intellectual property...
licensing plan.
After discussions with the small company
MicrosoftMicrosoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
, IBM decided to use 86-DOS (QDOS), a CP/M-like operating system that a Seattle area computer company had made for its own hardware. Microsoft bought 86-DOS, adapted it for computers using the Intel 8086 and 8088 processors, and called it MS-DOS; IBM sold it for the IBM PC as PC DOS.
After learning about the deal, Digital Research founder
Gary KildallGary Arlen Kildall was an American computer scientist and microcomputer entrepreneur who created the CP/M operating system and founded Digital Research, Inc....
threatened to sue IBM for infringing DRI's
intellectual propertyIntellectual property is a term referring to a number of distinct types of creations of the mind for which a set of exclusive rights are recognized—and the corresponding fields of law...
, and IBM agreed to offer CP/M-86 as an alternative operating system on the PC to settle the claim. CP/M-86 was released a few months after the PC and was one of three operating systems available for purchase from IBM, PC DOS, CP/M-86 and
UCSD PascalUCSD Pascal was a Pascal programming language system that ran on the UCSD p-System, a portable, highly machine-independent operating system. UCSD Pascal was first released in 1978...
. At US$240 per copy it sold poorly compared to the $40 PC DOS. Kildall later accused IBM of setting the prices to marginalize DR, but according to Microsoft, IBM, and other DRI executives Kildall had demanded a substantial royalty for CP/M-86 while Microsoft had accepted a fixed sum. Customers rapidly adopted the PC platform with PC DOS as the new industry standard, and opportunities for DRI to license CP/M-86 to other customers dwindled.
CP/M-86 and MS-DOS had very similar functionality, but were not compatible as the system calls for the same function and program file formats were different, so two versions of the same software had to be produced and marketed to run under both operating systems. The command interface again had similar functionality but different syntax; where CP/M-86 (and CP/M) copied file
SOURCE to
TARGET with the command
PIPPeripheral Interchange Program was a utility to transfer files on and between devices on Digital Equipment Corporation's computers. It was first implemented on the PDP-6 architecture by Harrison "Dit" Morse early in the 1960s...
TARGET=SOURCE, MS-DOS used
COPY SOURCE TARGET.
Initially MS-DOS and CP/M-86 also ran on computers not necessarily hardware-compatible with the IBM PC such as the
ApricotApricot Computers is a British manufacturer of business personal computers, originally founded in 1965 as "Applied Computer Techniques" , changing its name to Apricot Computers, Ltd. in the 1980s...
and
SiriusSirius Systems Technology was a personal computer manufacturer in Scotts Valley, California. It was founded in 1980 by Chuck Peddle and Chris Fish, formerly of MOS Technology and capitalized by Walter Kidde Inc. In late 1982 Sirius acquired Victor Business Systems from Kidde and changed its name...
, the intention being that software would be independent of hardware by making standardised operating
system callIn computing, a system call is how a program requests a service from an operating system's kernel. This may include hardware related services , creating and executing new processes, and communicating with integral kernel services...
s to a version of the operating system custom tailored to the particular hardware. However, writers of software which required fast performance made direct calls to the IBM PC hardware instead of going through the operating system, resulting in PC-specific software which performed better than other MS-DOS and CP/M-86 versions; for example, games would display fast by writing to video memory directly instead of suffering the delay of making a call to the operating system, which would then write to a hardware-dependent memory location. Non-PC-compatible computers were soon replaced by models with hardware which behaved identically to the PC's. A consequence of the universal adoption of detailed PC architecture was that no more than 640 kilobytes of memory were supported; early machines running MS-DOS and CP/M-86 did not suffer from this restriction, and some could make use of nearly one megabyte of RAM.
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:
| OS |
BDOS |
Date |
Notes |
CP/M-86 for the IBM Personal ComputerThe IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
Version 1.0 |
2.2 |
January 1982 |
Initial release for the IBM PC. |
| CP/M-86 for the IBM Personal Computer Version 1.1 |
2.2 |
March 1983 |
Hard drive support was added. |
| CP/M-86 Plus Version 3.1 |
3.1 |
October 1983 |
Released for the Apricot PC The Apricot PC was Apricot Computers' first personal computer made for business use. The press received it well, especially for the high resolution of its time and its trackball cable . It is the first non-Japanese computer using 3.5" Sony floppy disc units.It uses a Intel 8086 processor running...
. Based on the multitasking Concurrent CP/M-86 kernel, it could run up to four tasks at once. |
| Personal CP/M-86 Version 1.0 |
3.1 |
November 1983 |
Released for the SiemensSiemens AG is a German multinational conglomerate company headquartered in Munich, Germany. It is the largest Europe-based electronics and electrical engineering company....
PG685. |
| Personal CP/M-86 Version 3.1 |
3.3 |
January 1985 |
A version for the Apricot Apricot Computers is a British manufacturer of business personal computers, originally founded in 1965 as "Applied Computer Techniques" , changing its name to Apricot Computers, Ltd. in the 1980s...
F-Series computers. This version gained the ability to use MS-DOS formatted disks. |
| Personal CP/M-86 Version 2.0 |
4.1 |
1986 or later |
Released for the Siemens PC16-20. This is the same BDOS used in DOS Plus DOS Plus is an operating system written by Digital Research, first released in 1985. It can be seen as an intermediate step between CP/M-86 and DR-DOS....
. |
| Personal CP/M-86 Version 2.11 |
4.1 |
1986 or later |
Released for the Siemens PG685. |
All known Personal CP/M-86 versions contain references to CP/M-86 Plus, suggesting that they are derived from the CP/M-86 Plus codebase.
External links