Kanji CP/M-86
| Industry | Software, Operating systems |
|---|---|
| Founder | Gary Kildall |
| Headquarters | United States |
| Products | CP/M-86, MP/M-86, Concurrent CP/M-86, Concurrent DOS, Multiuser DOS, FlexOS, DOS Plus, DR DOS |
CP/M-86 represents a discontinued iteration of the CP/M operating system, developed by Digital Research (DR) specifically for the Intel 8086 and Intel 8088 CPUs. It preserved the original CP/M-80 command set, utilizing relocatable .CMD files for executables. Digital Research also engineered a multi-user, multitasking variant compatible with CP/M-86 known as MP/M-86, which later advanced into Concurrent CP/M-86. Incorporating an emulator for PC DOS compatibility, this system was rebranded as Concurrent DOS, eventually evolving into Multiuser DOS, with its most recent release being REAL/32. The operating systems FlexOS, DOS Plus, and DR DOS all trace their origins back to Concurrent DOS.
History
Initially slated for release in November 1979, Digital Research's CP/M-86 experienced multiple postponements. When IBM sought an operating system for its forthcoming IBM PC, CP/M-86 was considered the primary candidate due to CP/M’s extensive software ecosystem. However, negotiations faltered because IBM insisted on a non-disclosure agreement and preferred a one-time payment instead of Digital Research’s royalty-based model. Following this breakdown, IBM engaged Microsoft, which licensed 86-DOS (also called QDOS)—an OS resembling CP/M that Microsoft had acquired from Seattle Computer Products—renaming it MS-DOS and marketing it as PC DOS. After Digital Research founder Gary Kildall threatened legal action, IBM agreed to offer CP/M-86 as an alternative OS on the PC platform. The majority of CP/M-86 BIOS drivers for the IBM PC were authored by Andy Johnson-Laird.
The IBM PC officially launched on August 12, 1981, with sales beginning in October; at launch, three operating systems were available: PC DOS, UCSD p-System, and CP/M-86. Digital Research introduced their CP/M-86 version approximately six months after PC DOS’s debut in spring 1982. Transitioning applications from CP/M-80 to either OS presented a similar level of difficulty. In November 1981, Digital Research also released a specialized edition tailored for the proprietary IBM Displaywriter.
Certain dual-processor systems combining 8-bit and 16-bit architectures supported unique CP/M-86 variants capable of running both CP/M-86 and CP/M-80 applications natively. Examples include the DEC Rainbow running CP/M-86/80, CompuPro System 816 utilizing CP/M 8-16, and the Zenith Z-100 supporting software designed for its 8085 and 8088 processors.
With the proliferation of IBM PC clones, Microsoft broadly licensed MS-DOS. Although CP/M-86 offered advantages such as enhanced memory management while DOS provided faster execution speed, CP/M-86 failed to gain significant market traction. BYTE magazine observed that Microsoft’s focus on multitasking through Xenix created an opportunity for Concurrent CP/M-86.
Retail pricing positioned CP/M-86 at approximately $240 per copy—six times the cost of PC DOS at $40—resulting in weak sales; surveys indicated that 96.3% of IBM PCs shipped with DOS compared to just 3.4% running CP/M-86 or Concurrent CP/M-86. By mid-1982, major software distributor Lifeboat Associates shifted its support exclusively toward DOS on the IBM PC platform. BYTE cautioned that this alliance threatened CP/M-86’s viability, with industry analysts attributing Digital Research’s struggles to ineffective marketing strategies.
By early 1983, Digital Research offered version 1.1 of CP/M-86 directly to end users at $60 per license, promoting it as an excellent value due to access to a broad software catalog and inclusion of the Graphics System Extension (GSX). Distribution expanded through retail outlets, and in May 1983 the company announced DOS-compatible versions of its programming languages and utilities—acknowledging DOS’s market dominance while denying it influenced their decision-making process. In early 1984, Digital Research bundled free copies of Concurrent CP/M-86 with purchases of two CP/M-86 applications, marketing these as self-booting disks that eliminated the need to load the OS separately.
In January 1984, Digital Research launched Kanji CP/M-86—a Japanese-language variant—in collaboration with nine Japanese corporations including Mitsubishi Electric and Sanyo Electric. Later that year Fujitsu introduced FM-16-based computers running Kanji CP/M-86.
While offering comparable features, CP/M-86 and DOS were incompatible due to differences in system calls and executable file formats; consequently, separate software versions were required for each OS. Although command-line interfaces shared similar functions, syntax differed—for instance, copying files used "PIP TARGET=SOURCE" in CP/M versus "COPY SOURCE TARGET" under DOS.
Initially, both MS-DOS and CP/M-86 operated on non-PC-compatible hardware such as Apricot and Sirius systems by adapting OS versions to specific platforms via standardized system calls. However, performance-sensitive programs frequently bypassed the OS layer to access IBM PC hardware directly, resulting in faster execution of PC-specific applications. This trend encouraged widespread adoption of IBM PC-compatible architectures that imposed a conventional memory limit of 640 KB—a constraint absent from earlier MS-DOS and CP/M-86 implementations capable of addressing nearly one megabyte of RAM.
Reception
According to PC Magazine, CP/M-86 appeared to be more suitably designed for the PC than DOS in several respects; nonetheless, its considerably higher cost—approximately six times that of DOS—deterred users who did not engage in assembly language programming. The review underscored areas where CP/M-86 outperformed DOS and vice versa, concluding that the extent of application compatibility would ultimately determine success. However, the absence of a run-time module for applications was identified as a limitation of CP/M-86.
Versions
CP/M-86 releases are characterized by two version numbers: one representing the complete operating system (displayed during startup) and another indicating the BDOS kernel version. Documented editions include:
| Operating System | BDOS Version | Release Date | Remarks |
|---|---|---|---|
| CP/M-86 1.0 for AST Research | 2.2? | Circa 1981? | |
| CP/M-86 1.0 for Altos Computer Systems ACS 16000/8600 | 2.2? | November 1981 | |
| CP/M-86 Version 1.1 for IBM Displaywriter | 2.2 | November 1981 | |
| CP/M-86 1.0 for Sirius 1/Victor 9000 | 2.2a | 1981/1982 | |
| CompuView CP/M-86 | Approximately 2.x | 1982 | Featured 196 KB disk capacity; compatible with IBM PC hardware |
| IBM CP/M-86 for IBM Personal Computer Version 1.0 | 2.2 | April 1982 | Initial launch; supported 141 KB disk capacity |
| IBM CP/M-86 for IBM PC Version 1.1 | 2.2 | March 1983 | Introduced hard drive compatibility |
| CP/M-86 Plus Version 3.1 | 3.1 | October 1983 | Designed for Apricot PC; multitasking kernel enabling up to four concurrent tasks |
| Personal CP/M-86 Version 1.0 | 3.1 | November 1983 | Released for Siemens PG685 model |
| Personal CP/M-86 Version 3.1 | 3.3 | January 1985 | Developed for Apricot Computers F-Series; incorporated FAT disk support compatible with DOS |
| Personal CP/M-86 Version 2.0 | 4.1 | From 1986 onward | Targeted Siemens PC16-20; shared BDOS with DOS Plus 1.2 |
| Personal CP/M-86 Version 2.11 | 4.1 | From 1986 onward | Intended for Siemens PG685 |
All iterations labeled as Personal CP/M-86 trace their origins to CP/M-86 Plus, reflecting their derivation from its source code.
In addition, several Eastern Bloc variants of CP/M-86 were developed under designations such as SCP1700, CP/K, and K8918-OS by East German manufacturers including VEB Robotron Dresden and Energiekombinat Berlin.
Legacy
Since 1997, Caldera has permitted the free redistribution and modification of all original Digital Research materials, including source code for the entire CP/M family, via Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead's passing in 2001, the license allowing free distribution was renewed and extended by Lineo, then the proprietor of these Digital Research assets, on October 19, 2001.
See also
Further reading
- The Byte Guide to CP/M-86 by Mark Dahmke, published in 1984 by McGraw-Hill, ISBN 978-0-07-015072-0
External links
- The Unofficial CP/M Website – authorized distributor of original Digital Research software
- The comp.os.cpm FAQ
- Intel iPDS-100 Using CP/M - Video