GENCMD.CMD
| Industry | Software, Operating Systems |
|---|---|
| Founded | 1970 |
| Founder | Gary Kildall |
| Headquarters | United States |
| Products | CP/M-86, MP/M-86, Concurrent DOS, Multiuser DOS, REAL/32, FlexOS, DOS Plus, DR DOS |
CP/M-86 represents a now-obsolete variant of the CP/M operating system, crafted by Digital Research (DR) for the Intel 8086 and Intel 8088 CPU architectures. It preserved the command structure of CP/M-80, while its executable files utilized the relocatable .CMD file format. Digital Research also developed a multitasking, multi-user OS compatible with CP/M-86 named MP/M-86, which eventually evolved into Concurrent CP/M-86. Incorporating an emulator to support PC DOS compatibility led to its rebranding as Concurrent DOS, later known as Multiuser DOS, with the most recent iteration being REAL/32. The operating system families of FlexOS, DOS Plus, and DR DOS trace their origins back to Concurrent DOS.
History
Digital Research originally planned to release CP/M-86 in November 1979, but encountered several postponements. When IBM was searching for an operating system for its new IBM PC, CP/M-86 was favored because of its wide application ecosystem. However, negotiations broke down due to IBM’s insistence on a non-disclosure agreement and a preference for a one-time payment, conflicting with Digital Research’s royalty-based licensing. Consequently, IBM collaborated with Microsoft, adopting 86-DOS (also known as QDOS), which Microsoft had acquired from Seattle Computer Products, rebranding it as MS-DOS and licensing it to IBM as PC DOS. Digital Research’s founder Gary Kildall threatened legal action over intellectual property concerns, prompting IBM to offer CP/M-86 as an alternative OS option. Most BIOS drivers for CP/M-86 on the IBM PC were developed by Andy Johnson-Laird.
The IBM PC debuted on August 12, 1981, and by October it was available with three operating systems: PC DOS, CP/M-86, and UCSD p-System. Digital Research’s CP/M-86 version arrived approximately six months after PC DOS, in spring 1982. Porting software from CP/M-80 proved equally challenging for both operating systems. In November 1981, Digital Research launched a version tailored for the proprietary IBM Displaywriter.
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; for example, the DEC Rainbow used CP/M-86/80, while CompuPro System 816 employed CP/M 8-16. The Zenith Z-100’s implementation of CP/M-86 enabled running programs designed for both its 8085 and 8088 processors.
As PC clones gained prominence, Microsoft licensed MS-DOS extensively. Although CP/M-86 provided more advanced memory management capabilities, DOS outperformed it in speed. BYTE magazine observed that Microsoft’s decision to reserve multitasking features for Xenix created a niche opportunity for Concurrent CP/M-86.
CP/M-86 faced commercial difficulties on the IBM PC largely due to its $240 price tag compared to $40 for PC DOS; surveys indicated that over 96% of shipped PCs ran DOS. Lifeboat Associates, a leading distributor of CP/M software, transitioned support toward DOS by mid-1982. Industry commentators and BYTE highlighted shortcomings in Digital Research’s marketing approach.
By early 1983, Digital Research reduced CP/M-86’s price to $60 for end users while emphasizing its extensive software catalog and bundling Graphics System Extension (GSX). The company expanded retail availability through various partners. In May 1983, Digital Research announced versions of its programming languages and utilities compatible with DOS, recognizing DOS’s market dominance but denying that this influenced their strategy. Promotions in early 1984 included offering Concurrent CP/M-86 free with certain software purchases and providing self-booting disks that circumvented loading the OS first. In January 1984, Kanji CP/M-86 was introduced targeting Japanese corporations such as Mitsubishi Electric and Sanyo; Fujitsu later adopted it for their FM-16 series.
While CP/M-86 and DOS shared similar functionality, their system calls and file formats were incompatible, necessitating distinct software versions. Their command-line interfaces also differed syntactically despite offering comparable features.
Initially, MS-DOS and CP/M-86 operated on non-PC-compatible hardware like Apricot and Sirius machines by using standardized OS calls customized per platform. However, performance-critical applications often bypassed these OS calls to access PC hardware directly, favoring PC-compatible computers that soon dominated the market. This standardization restricted memory usage to 640 KB despite earlier systems supporting nearly 1 MB of RAM.
Reception
According to PC Magazine, CP/M-86 appeared in certain respects to be more suitably designed for the PC compared to DOS. Nevertheless, its price—approximately six times greater—deterred users who did not primarily engage in assembly language programming. The evaluation underscored CP/M-86's advantages in areas where DOS underperformed, and vice versa, stressing that the extent of application compatibility would be the decisive factor for widespread adoption. A significant limitation identified was the absence of a run-time version for application software within CP/M-86.
Versions
CP/M-86 releases are characterized by dual version identifiers: one representing the entire operating system (visible during startup) and another indicating the BDOS kernel version. Important editions include:
| Operating System | BDOS Version | Release Date | Remarks |
|---|---|---|---|
| CP/M-86 1.0 for AST | 2.2? | Circa 1981? | |
| CP/M-86 1.0 for Altos 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 | 2.x? | 1982 | Compatible with IBM PC hardware; disk capacity of 196 KB |
| IBM CP/M-86 for IBM PC 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 support for hard disk drives |
| CP/M-86 Plus Version 3.1 | 3.1 | October 1983 | Designed for Apricot PC; multitasking kernel capable of handling up to four simultaneous tasks |
| Personal CP/M-86 Version 1.0 | 3.1 | November 1983 | Distributed for Siemens PG685 |
| Personal CP/M-86 Version 3.1 | 3.3 | January 1985 | Targeted at Apricot Computers F-Series; incorporated support for FAT-formatted disks compatible with DOS |
| Personal CP/M-86 Version 2.0 | 4.1 | From 1986 onward | Released for Siemens PC16-20; shares BDOS with DOS Plus 1.2 |
| Personal CP/M-86 Version 2.11 | 4.1 | From 1986 onward | Available for Siemens PG685 |
All Personal CP/M-86 editions cite CP/M-86 Plus as their foundation, indicating they are derived from its codebase.
In addition, multiple Eastern Bloc adaptations of CP/M-86 existed under various names such as SCP1700 (Single User Control Program), CP/K, and K8918-OS, which were developed by East German companies VEB Robotron Dresden and Berlin.
Legacy
Starting in 1997, Caldera granted permission to redistribute and modify all original Digital Research files, including source code from the CP/M family, through Tim Olmstead's "The Unofficial CP/M Web site." Following Olmstead's passing in 2001, Lineo, the then-owner of these Digital Research assets, renewed and broadened the free distribution license later that year.
See also
Further reading
- The Byte Guide to CP/M-86 by Mark Dahmke, McGraw-Hill, 1984, 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