GENCMD.COM
| Industry | Software, Operating systems |
|---|---|
| Founded | 1974 |
| Founder | Gary Kildall |
| Products | CP/M, CP/M-86, MP/M-86, Concurrent DOS, Multiuser DOS, FlexOS, DOS Plus, DR DOS |
CP/M-86 represents a discontinued iteration of the CP/M operating system, engineered by Digital Research (DR) specifically for the Intel 8086 and Intel 8088 CPUs. It preserved the original CP/M-80 command structure and employed the relocatable .CMD file format for its executable files. Digital Research also developed a multitasking, multi-user system compatible with CP/M-86 known as MP/M-86, which later evolved into Concurrent CP/M-86. Incorporating a PC DOS compatibility emulator led to its rebranding as Concurrent DOS, which subsequently advanced into Multiuser DOS, with the latest version being REAL/32. Other operating systems such as FlexOS, DOS Plus, and DR DOS trace their origins back to Concurrent DOS.
History
Although Digital Research announced CP/M-86 in November 1979, its launch was postponed multiple times. When IBM was selecting an operating system for the IBM PC, CP/M-86 was initially favored due to its extensive software ecosystem. However, negotiations faltered because IBM insisted on a non-disclosure agreement and preferred a one-time payment rather than Digital Research’s royalty-based model. Consequently, IBM turned to Microsoft, which licensed 86-DOS (also called QDOS) from Seattle Computer Products, adapted it into MS-DOS, and marketed it as PC DOS.
Upon learning of IBM’s arrangement with Microsoft, Digital Research’s founder Gary Kildall threatened legal action over intellectual property rights. IBM then offered CP/M-86 as an alternative operating system option on the PC. The majority of CP/M-86 BIOS drivers for the IBM PC were created by Andy Johnson-Laird.
The IBM PC was officially introduced on August 12, 1981, with shipments commencing in October. Alongside PC DOS and UCSD p-System, CP/M-86 was one of three operating systems made available by IBM. Digital Research released CP/M-86 for the IBM PC approximately six months after PC DOS’s debut in spring 1982; migrating applications from CP/M-80 proved equally challenging for both platforms. Additionally, Digital Research launched a version for the proprietary IBM Displaywriter in November 1981.
Certain dual-processor systems combining 8-bit and 16-bit CPUs supported specialized CP/M-86 variants capable of running both CP/M-86 and CP/M-80 applications natively. For example, the DEC Rainbow’s edition was named CP/M-86/80, CompuPro System 816 used CP/M 8-16, and the Zenith Z-100 accommodated software designed for its 8085 and 8088 processors.
With the proliferation of PC clones, Microsoft expanded MS-DOS licensing extensively. Technical evaluations found CP/M-86 and DOS comparable; while CP/M-86 offered enhanced memory management capabilities, DOS demonstrated faster performance. BYTE magazine observed that Microsoft reserved multitasking functionality for Xenix, creating an opportunity for Concurrent CP/M-86.
Despite these strengths, CP/M-86's retail price of $240 per copy versus $40 for PC DOS resulted in significantly lower sales on the IBM PC platform; surveys indicated that 96.3% of IBM PCs were ordered with DOS compared to just 3.4% with either CP/M-86 or Concurrent CP/M-86. By mid-1982, Lifeboat Associates—a prominent vendor of CP/M software—shifted its focus toward DOS support. BYTE cautioned that combined backing from IBM, Microsoft, and Lifeboat posed a substantial threat to CP/M-86’s market position, with industry analysts attributing this to Digital Research’s inadequate marketing strategies.
By early 1983, Digital Research began selling version 1.1 of CP/M-86 directly to consumers at $60 per copy, promoting it as providing immediate access to the largest collection of business and educational software while including Graphics System Extension (GSX). The company also broadened retail distribution and announced DOS-compatible editions of its programming languages and utilities in May 1983, acknowledging PC DOS’s dominance but denying this influenced their product decisions.
In early 1984, Digital Research bundled free copies of Concurrent CP/M-86 with application purchases and introduced Kanji CP/M-86—a Japanese-language variant—through partnerships with nine Japanese corporations such as Mitsubishi Electric and Sanyo. Subsequently, Fujitsu revealed FM-16 machines running Kanji CP/M-86.
Though sharing similar functionalities, CP/M-86 and DOS were incompatible due to differences in system calls and executable file formats; this necessitated distinct software versions for each environment. Their command-line interfaces featured comparable functions but differed in syntax—for instance, copying files required PIP TARGET=SOURCE on CP/M-86 versus COPY SOURCE TARGET under DOS.
Initially, both MS-DOS and CP/M-86 operated on non-PC-compatible hardware like Apricot and Sirius machines by customizing OS versions tailored to specific hardware through standardized system calls. However, software demanding high performance often bypassed the operating system to directly access hardware—particularly games manipulating video memory—resulting in superior performance on PC-compatible systems. This shift toward hardware standardization established the prevailing PC architecture but restricted memory usage to 640 KB; earlier MS-DOS and CP/M-86 implementations without this limit could utilize nearly one megabyte of RAM.
Reception
PC Magazine observed that CP/M-86 appeared to be, in multiple respects, more suitably designed for the PC than DOS; nevertheless, its cost—being six times greater—deterred users who were not engaged in assembly language programming. The evaluation underscored areas where CP/M-86 excelled compared to DOS and vice versa, stressing that the extent of application support would ultimately determine user preference. A significant limitation identified was CP/M-86's absence of a run-time environment for applications.
Versions
Each CP/M-86 release carries two version identifiers: one representing the full operating system (visible during startup) and another for the BDOS kernel component. Important versions include:
| Operating System | BDOS Version | Release Date | Remarks |
|---|---|---|---|
| CP/M-86 1.0 tailored for AST Research | 2.2? | Circa 1981? | |
| CP/M-86 1.0 for Altos Computer Systems ACS 16000/ACS 8600 | 2.2? | November 1981 | |
| CP/M-86 Version 1.1 for IBM Displaywriter | 2.2 | November 1981 | |
| CP/M-86 1.0 built for Sirius 1/Victor 9000 | 2.2a | Between 1981 and 1982 | |
| CompuView CP/M-86 | Approximately 2.x | 1982 | Compatible with IBM PC hardware; supports 196 KB disk capacity |
| IBM CP/M-86 for IBM Personal Computer Version 1.0 | 2.2 | April 1982 | Initial launch; disk capacity of 141 KB |
| IBM CP/M-86 for IBM PC Version 1.1 | 2.2 | March 1983 | Introduced hard disk compatibility |
| CP/M-86 Plus Version 3.1 | 3.1 | October 1983 | Developed for Apricot PC; based on a multitasking Concurrent CP/M-86 kernel capable of handling up to four concurrent tasks |
| Personal CP/M-86 Version 1.0 | 3.1 | November 1983 | Released specifically for Siemens Siemens PG685 |
| Personal CP/M-86 Version 3.1 | 3.3 | January 1985 | Designed for Apricot Computers Apricot F-Series, added FAT filesystem support compatible with DOS disks |
| Personal CP/M-86 Version 2.0 | 4.1 | From 1986 onward | Available for Siemens PC16-20, sharing BDOS with DOS Plus 1.2 |
| Personal CP/M-86 Version 2.11 | 4.1 | From 1986 onward | Released for Siemens PG685 |
All Personal CP/M-86 editions trace their lineage back to CP/M-86 Plus, indicating they were derived from its source code.
In addition, several Eastern Bloc variants existed under designations such as SCP1700 (Single User Control Program), CP/K, and K8918-OS, developed by East German manufacturers VEB Robotron Dresden and Energiekombinat Berlin, showcasing localized adaptations of the CP/M-86 system.
Legacy
Starting in 1997, Caldera granted permission to distribute and modify all original Digital Research materials, including source code related to the CP/M family, via Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead's passing in September 2001, the license allowing free distribution was renewed and broadened by Lineo, then proprietor of these Digital Research assets, in October of the same year.
See also
Further reading
- The Byte Guide to CP/M-86 authored by Mark Dahmke (1984), McGraw-Hill, ISBN 978-0-07-015072-0
External links
- The Unofficial CP/M Website – licensed reseller of authentic Digital Research software
- The comp.os.cpm FAQ