Jump to content

DRMK

From Alfawiki
Adapted from the English Wikipedia article DRMK, available under CC BY-SA 4.0Updated 9 August 2025
DR-DOS
Company typeProduct/Software
IndustryComputer software
PredecessorConcurrent PC DOS 6.0
FoundedMay 28, 1988; 38 years ago (1988-05-28)
FounderGary A. Kildall
FateDevelopment shifted to embedded applications under Caldera and DeviceLogics
SuccessorNovell DOS 7.0 (after Novell acquisition)
Headquarters
Pacific Grove / Monterey
,
United States
Area served
IBM PC-compatible computers
Key people
Gary A. Kildall, Kazuhiko "Kay" Nishi (partner)
ProductsDR-DOS operating system, ViewMAX GUI shell, PalmDOS
OwnerDigital Research, later Novell, then Caldera, then DeviceLogics
ParentDigital Research, Inc.

DR-DOS (styled as DR DOS through version 6.0) is a disk operating system designed for IBM PC-compatible computers. It was originally created by Digital Research, Inc., led by Gary A. Kildall, and evolved from Concurrent PC DOS 6.0, which itself was an advanced iteration of CP/M-86. Launched in 1988, DR-DOS was the first DOS variant to target compatibility with both IBM PC DOS and Microsoft's MS-DOS.

The debut version was 3.31, a number chosen to correspond with MS-DOS’s versioning scheme. The first retail edition, DR DOS 5.0, arrived in 1990 and garnered positive reviews, establishing itself as the primary rival to Microsoft’s MS-DOS. Microsoft responded by releasing MS-DOS 5.0 more than a year afterward. DR-DOS was notable for introducing the ViewMAX graphical user interface shell. The follow-up, DR DOS 6.0, appeared in 1991; after Novell acquired Digital Research, the software was renamed Novell DOS 7.0 in 1994. Later ownership by Caldera produced updated releases under the Caldera brand, some partially open-sourced and briefly marketed as OpenDOS. The last desktop edition, Caldera DR-DOS 7.03, was issued in 1999 before development shifted toward embedded applications under Caldera and subsequently DeviceLogics.

CP/M Foundations

Digital Research initially developed CP/M for 8-bit processors such as the Intel 8080 and Z80, later creating CP/M-86 for the Intel 8086/8088 CPUs. Although CP/M had been dominant since the mid-1970s and widely adopted on non-proprietary PCs, the introduction of the IBM PC in 1981 dramatically altered the market landscape.

In 1980, IBM approached Digital Research about producing an x86-compatible version of CP/M, but contractual disagreements led IBM to collaborate with Microsoft, which had acquired 86-DOS from Seattle Computer Products (SCP). This product evolved into Microsoft’s MS-DOS and IBM’s PC DOS. Digital Research asserted that PC DOS/MS-DOS bore significant similarities to CP/M and threatened legal action. IBM resolved this in early 1982 by agreeing to offer Digital Research’s CP/M-86 alongside PC DOS; however, CP/M-86 was priced at $240 compared to PC DOS’s $40, limiting its commercial success despite superior software support initially.

Digital Research encountered difficulties marketing CP/M-86 and its successors MP/M-86 and Concurrent CP/M-86. Eventually, they adapted Concurrent CP/M-86 to run MS-DOS/PC DOS programs natively—a capability demonstrated publicly in December 1983 and launched in March 1984 as Concurrent DOS 3.1 (CDOS with BDOS 3.1) targeted at hardware manufacturers. While Concurrent DOS evolved into products like Multiuser DOS and REAL/32, it remained expensive and unsuitable for typical desktop use, motivating Digital Research to develop more user-friendly alternatives.

In 1985, Digital Research released DOS Plus versions 1.0 through 2.1—a simplified single-user derivative of Concurrent DOS that supported multitasking with limited DOS compatibility. Pursuing deeper integration with the DOS environment, Digital Research introduced DR DOS in 1988 as a fully native DOS operating system.

Although headquartered in Pacific Grove and later Monterey, California, much of the early development work on DOS Plus took place at Digital Research Europe’s OEM Support Group located in Newbury, Berkshire starting in 1983. From 1986 onward, key operating system projects—including Concurrent DOS 386, Multiuser DOS, DR DOS, and PalmDOS—were primarily developed at the European Development Centre in Hungerford, Berkshire, with additional contributions from Digital Research GmbH based in Munich, Germany.

Initial DR DOS Release

In 1987, responding to demands from original equipment manufacturers, Digital Research introduced a new DOS operating system designed to overcome limitations found in MS-DOS. A significant partnership with Kazuhiko "Kay" Nishi of ASCII Corporation facilitated entry into the Japanese OEM market. The inaugural DR DOS version officially launched on May 28, 1988.

The version numbering system was aligned with MS-DOS releases; the first public iteration was DR DOS 3.31, corresponding to Compaq's MS-DOS 3.31 which supported large disks (FAT16B/"BIGDOS"). DR DOS 3.31 identified itself as "IBM PC DOS 3.31," while its BDOS kernel bore version 6.0, derived from Concurrent DOS 6.0 but stripped of multitasking, multiuser capabilities, and CP/M API support, replacing the XIOS component with an IBM-compatible DOS-BIOS. Core system files included DRBIOS.SYS (the DOS-BIOS) and DRBDOS.SYS (the BDOS kernel), bearing the OEM label "DIGITAL␠".

DR DOS offered enhanced command-line utilities featuring integrated help, detailed error messages, sophisticated command history and editing managed through the HISTORY directive, as well as native password protection for files and directories. It was more cost-effective to license than MS-DOS and was engineered for ROM integration from inception; its ROM-based variant was named ROS (ROM Operating System). The platform attracted attention from various PC manufacturers, prompting multiple system updates.

At that period, MS-DOS was exclusively provided bundled with hardware to OEMs, enabling DR DOS to achieve early market success by being available for retail purchase starting with the 3.4x series.

Documented releases include DR DOS 3.31 (BDOS 6.0, June 1988, OEM only), 3.32 (August 1988, OEM only), 3.33 (September 1988, OEM only), 3.34 (OEM only), 3.35 (October 1988, OEM only), 3.40 (January 1989), and 3.41 (BDOS 6.3, June 1989, available both OEM and retail). Many versions were customized for different hardware platforms. While most OEMs retained the DR DOS branding, the product was marketed as EZ-DOS 3.41 (also known as EZ-DOS 4.1) by 2001 Sales, Inc.

DR DOS Version 5.0

Released in May 1990 under the codename "Leopard," DR DOS 5.0 maintained backward compatibility by identifying itself as "PC DOS 3.31" while internally operating on a single-user BDOS kernel version 6.4 (skipping version 4 to distance itself from the unpopular MS-DOS 4.0). This release introduced ViewMAX, a GEM-based graphical file management shell promoted with the tagline "Digital Research - We make computers work."

Notable features included the patented BatteryMAX power management technology, bundled disk caching software named DRCACHE, a remote file transfer utility called FILELINK, a cursor customization tool labeled CURSOR, and an improved memory management system known as MemoryMAX. System files were renamed to IBMBIO.COM and IBMDOS.COM, complemented by an advanced boot loader that allowed flexible placement of disk storage components. The OEM label within boot sectors was updated to "IBM␠␠3.3".

DR DOS 5.0 pioneered load-high functionality in DOS environments by relocating its kernel and data structures into the High Memory Area (HMA), thereby freeing up valuable conventional memory—the first 640 KB of RAM used by DOS applications.

On systems powered by the Intel 80386, its EMS memory manager enabled device drivers to load into upper memory blocks, further conserving base memory resources beyond what third-party utilities like QEMM could achieve. This optimization allowed DR DOS to offer substantially more free conventional memory compared to competitors: while MS-DOS typically left between 300 and 400 KB free after loading drivers for peripherals such as mice, multimedia devices, and networking components, DR DOS 5.0 could preserve up to approximately 620 KB with minimal manual configuration. Utilizing MEMMAX +V extended this further by reclaiming unused graphics adapter RAM between an additional 64 and 96 KB.

Because this expansion of free memory changed program loading addresses, some legacy applications relying on address wrapping failed to operate correctly. To mitigate this issue, DR DOS provided the MEMMAX -L option which pre-allocates a low-memory block to maintain compatibility at the expense of reducing available conventional memory space. By default, MEMMAX was configured with +L enabled to maximize application-accessible memory capacity.

DR DOS 6.0 / Rivalry with Microsoft

Confronted with fierce competition, Microsoft unveiled MS-DOS 5.0 in May 1990, launching it in June 1991. This version incorporated enhanced capabilities comparable to those found in DR DOS, particularly in memory management.

Digital Research introduced DR DOS 6.0, codenamed "Buxton," in September 1991. Although internally identified as BDOS version 6.7, it reported itself as "IBM PC DOS 3.31" to ensure compatibility. This release featured bundled SuperStor disk compression technology to optimize hard drive utilization and incorporated file deletion tracking along with undelete functionality developed by Roger A. Gross.

A notable innovation in DR DOS 6.0 was TASKMAX, a task-switching utility conforming to industry-standard APIs that enabled multiple applications to run concurrently by suspending background processes until they were brought to the foreground. TASKMAX leveraged XMS memory on systems with 286 processors or higher and provided limited Copy & Paste capabilities between programs. Graphical user interfaces such as ViewMAX and PC/GEOS could integrate with TASKMAX, replacing its textual menu with a graphical front end.

Microsoft countered with MS-DOS 6.0, which incorporated many similar features.

In December 1991, the pre-release version of Windows 3.1 included the AARD code, a non-critical compatibility check designed to detect non-Microsoft DOS variants. Digital Research promptly issued a patch for DR DOS 6.0 to circumvent this check without impacting system functionality, releasing the so-called "business update" within six weeks of Windows 3.1's debut. This allowed Windows to operate smoothly on DR DOS and Novell DOS platforms; the detection mechanism was disabled in the final Windows release.

In July 1992, Digital Research Japan introduced DR DOS 6.0/V, a Japanese edition compatible with DOS/V, alongside a Korean-language version.

PalmDOS

In 1992, following Novell’s acquisition of Digital Research in July 1991, the company released "Merlin," later branded as NetWare PalmDOS 1—a streamlined variant of DR DOS 6.0 tailored for the emerging palmtop and PDA markets.

PalmDOS was the first DR DOS variant to utilize the BDOS 7.0 kernel featuring native DOS-compatible internal structures rather than emulation layers, enhancing application compatibility and reducing kernel size—critical for portable devices. However, it imposed a limitation of 66 characters for working directory depth, aligning with MS-DOS/PC DOS restrictions rather than earlier DR DOS versions. To maintain Windows compatibility and minimize kernel footprint, PalmDOS identified itself as "PC DOS 3.31."

Optimized for execution from ROM, PalmDOS supported palmtop-specific features such as PCMCIA card interfaces (including DPMS), power management technologies like BatteryMAX and patented dynamic idle detection, and MINIMAX task switching for PIM applications stored in ROM via execute-in-place (XIP). The PCMCIA stack development involved Ian H. S. Cullimore, a key contributor to the PCMCIA/PC Card standard.

Novell DOS 7 / Novell’s Enhancements

Novell DOS was the brand name Novell Corporation assigned to DR DOS after acquiring Digital Research in 1991. It typically introduced features and performance improvements ahead of MS-DOS releases. By 1993, Novell DOS 7 had outpaced PC DOS 6.1 as well as MS-DOS versions 6.2 and 6.3.

Under CEO Robert J. Frankenberg’s leadership, Novell streamlined its product portfolio by divesting Btrieve and discontinuing some offerings such as multimedia titles under Novell DOS branding. The company also licensed technology from Stac Electronics for integration into Novell DOS and NetWare products. On July 23, 1996, Novell sold the DR DOS line to Caldera, which intended to bundle it with its OpenLinux distribution.

Marc Perkel has asserted that he influenced Novell’s decision to acquire Digital Research in early 1991 with the vision of developing "NovOS." Novell aimed to challenge Microsoft's dominance through this acquisition alongside purchases of WordPerfect, Borland products, and investments in Unix technologies. Internal delays postponed the planned "DR DOS 7.0" ("Panther") release while Novell worked on a Unix-like multi-user security extension and two graphical user interfaces—ViewMAX 3 (based on GEM) and "Star Trek" (a port of Apple’s System 7.1)—intended to operate atop the multitasking "Vladivar" kernel.

When Novell DOS 7 (NWDOS) launched in December 1993, these planned components were absent, disappointing some users. Despite being larger and less refined than anticipated, industry analysts considered it the premier DOS available.

In Germany, Novell aggressively promoted Novell DOS 7 with the slogan "" ("Don’t trust any DOS below version 7"), achieving approximately 1.5 million units sold by February 1994 and attracting over three thousand dealers interested in distribution through OEMs, mail order, and authorized resellers.

A significant feature was Personal NetWare (PNW), Novell's enhanced peer-to-peer networking solution that improved upon NetWare Lite but faced limited adoption due to incompatibility with Microsoft's expanding networking standards.

Novell DOS 7 implemented the DOSMGR API along with updated internal structures allowing its BDOS version 7.2 kernel to report as DOS version 6.0 with an OEM ID string of "IBM," thereby preserving compatibility with Windows environments.

The operating system introduced advanced memory management supporting DPMI and DPMS standards along with flexible loadhigh options for memory optimization. It also offered genuine pre-emptive multitasking for multiple DOS applications within virtual DOS machines (VDMs) through MultiMAX technology. When combined with EMM386 /MULTI drivers, it provided a native protected-mode core operating at 32-bit level that supported multitasking, multithreading, hardware virtualization, and domain management compatible with Windows multitasking capabilities.

Novell DOS 7 and Personal NetWare included NetWars, a network-enabled arcade-style game.

Although several bug-fix updates were issued, Novell DOS 7 was not entirely stable by the time Microsoft released Windows 95 ("Chicago") beta versions. Development ceased in September 1994 with maintenance support ending in January 1996 after more than fifteen revisions had been released.

Post-Novell Era

In search of a DOS operating system to package with their OpenLinux distribution, Caldera acquired the product line from Novell on July 23, 1996, as Novell no longer considered it commercially valuable.

Amid competition from IBM's PC DOS 6.3 and Caldera's own DR-DOS, Microsoft limited Windows 95 compatibility solely to its proprietary DOS versions. This restriction triggered a prominent legal dispute, financially backed by the Canopy Group, which concluded with a $280 million settlement in 2000.

By August 1996, Roger A. Gross, one of the original DR-DOS engineers, proposed reviving DR-DOS development and ensuring Windows 95 compatibility to support the ongoing lawsuit. After discussions with Caldera leadership including Raymond John Noorda, Gross set up a UK branch in Andover, Hampshire, recruiting original and new developers to advance the system.

Caldera UK unveiled OpenDOS (COD) in September 1996 and intended to release its source code publicly. Over the subsequent two years, they integrated significant additions such as a TCP/IP stack derived from LAN WorkPlace for DOS, a 32-bit graphical browser named DR-WebSpyder (based on Arachne (web browser)), POSIX Pthreads support, long filename functionality, and FAT32 support (DRFAT32). Consultant Andrew Schulman contributed to "WinGlue," an initiative aimed at enabling DR-DOS compatibility with Windows 95/98 by substituting MS-DOS components. Demonstrated at CeBIT 1998, this project evolved into "WinBolt," which remained unreleased but played a crucial role in legal proceedings.

The February 1997 release of OpenDOS 7.01 by Caldera UK was essentially an update to Novell DOS 7 update 10 with minimal modifications and lacked later Novell patches due to missing source code. This version excluded previously bundled utilities such as Fifth Generation's Search&Destroy antivirus but incorporated updated tools like PNUNPACK and an enhanced NetWars edition.

Although portions of OpenDOS 7.01 were briefly made available as open source under restrictive licenses, they were subsequently closed again to protect commercial interests.

Following beta versions in late 1997, Caldera launched DR-OpenDOS 7.02, soon rebranded as Caldera DR-DOS 7.02, featuring BDOS version 7.3. This update delivered numerous BIOS and BDOS enhancements improving compatibility with Windows 9x and third-party drivers including Microsoft's DriveSpace. It introduced a diagnostics mode, integrated debugger support, enriched CONFIG.SYS scripting with new commands and hotkeys for flexible boot options, improved environment variable management, and advanced memory handling that increased available conventional memory.

Additionally, the release featured an enhanced National Language Support subsystem capable of managing multiple COUNTRY.SYS files simultaneously, ISO 8601 date format recognition, and Euro currency integration. Fully compliant with Year 2000 standards, it also included an updated FDISK utility supporting FAT32 partitioning (without LBA). Recovered Novell patches from Germany were incorporated, marking DR-DOS 7.02 as a substantial improvement over Novell DOS 7.

However, some legacy third-party software failed due to stricter BDOS version checks introduced in this update. To address this, the SETVER utility was upgraded to dynamically mask DOS and BDOS versions, preserving compatibility with applications expecting earlier Novell DOS or DR-DOS versions.

A compatibility conflict emerged between the new HIFILES feature and QEMM 8's DOS-UP memory manager because of differing assumptions about handle structures in conventional memory. This was resolved through a patch (IBMBIO85.SCR) that toggled behavior modes but involved trade-offs affecting compatibility between Windows versions.

In August 1998, Caldera established two subsidiaries: Caldera Systems, Inc., focusing on Linux-related ventures, and Caldera Thin Clients, Inc., targeting embedded systems and thin-client markets.

DR-DOS 7.03 was initially released as a pre-release during Christmas 1998 and officially launched on January 6, 1999 by Caldera UK. This version featured improved memory managers with better DPMI support along with additional utilities such as DEVLOAD and DRMOUSE. However, alterations in FAT OEM labels occasionally caused interoperability challenges with other operating systems.

Following internal restructuring and Roger Gross’s resignation in February 1999, Caldera closed its successful UK division; development efforts were relocated to the US but lacked sufficient expertise to continue effectively. The DR-DOS product line was transferred to Caldera Thin Clients, which was renamed Lineo, Inc. in July 1999. Lineo reissued DR-DOS 7.03 without changes but concentrated primarily on Linux-based embedded platforms via their Embedix offering.

Subsequent independently developed OEM variants included DR-DOS 7.04 (August 1999) and 7.05 (November 1999), featuring streamlined kernels with native FAT32 support utilized in products like Ontrack's Easy Recovery 5, Seagate's SeaTools suite, and Nero Burning ROM. These editions internally reported as "PC DOS 7.10" to signify FAT32 integration while maintaining backward compatibility through combined kernel components supporting LBA.

Development continued with DR-DOS version 7.06 released in December 1999 consolidating kernel files for boot sector compatibility similar to Windows 98’s IO.SYS method. Version 7.07 introduced updated bootstrap loaders capable of handling CHS/LBA disk access across FAT12/16/32 file systems and various boot methods (DR-DOS, PC DOS, MS-DOS, Windows dual-boot), streamlining multi-boot configurations.

These enhancements prolonged DR-DOS’s relevance primarily within embedded systems and specialized OEM applications rather than mainstream desktop usage following the late-1990s transition period.

Later releases

Following Lineo's acquisition in 2002, former Lineo executives purchased the DR-DOS trademark and established DRDOS, Inc., operating as DeviceLogics L.L.C., to continue distributing DR-DOS tailored for embedded applications. On March 30, 2004, DR-DOS 8.0 was launched, featuring support for FAT32 and large storage devices, booting from ROM/Flash memory, multitasking capabilities, and a DPMI memory manager, all built upon kernel version 7.03.

The subsequent release, DR-DOS 8.1, arrived in late 2005 with enhanced FAT32 compatibility and was based on OpenDOS 7.01.xx. However, it was retracted due to violations of the GNU General Public License (refer to Controversies). Apart from product sales, DRDOS, Inc. also provided an option to purchase the DR-DOS rights for $25,000.

The OpenDOS 7.01 source code served as the foundation for The DR-DOS/OpenDOS Enhancement Project initiated in July 2002, aimed at updating and expanding DR-DOS features. This project introduced native support for large disks using LBA and FAT32, improved memory handling, and the FAT32+ extension that allowed file sizes up to 256 GB on FAT partitions. A work-in-progress version, DR-DOS 7.01.08 WIP, was released on July 21, 2011.

Starting in 2023, the final Enhanced DR-DOS version (7.01.08 WIP) was adapted to an open-source build system enabling cross-compilation from non-DOS platforms. The kernel compiles into a single binary file named KERNEL.SYS, compatible with FreeDOS boot loaders. This version has been continuously updated with bug fixes and improvements and remains actively maintained as of October 2024.

Controversies

In October 2005, it was discovered that DR-DOS 8.1 incorporated FreeDOS utilities along with an outdated Enhanced DR-DOS kernel without adhering to the GNU General Public License (GPL) requirements—specifically failing to acknowledge FreeDOS contributors or provide source code access. In response to grievances raised by FreeDOS developers, DRDOS, Inc. removed versions 8.1 and 8.0 from their website.

Commands

Beginning with DR-DOS 3.31, internal commands included APPEND, ASSIGN, BATCH, DBG, DELQ, ERA, ERAQ, MORE, and SUBST. With the release of DR-DOS 5.0, BATCH was eliminated while HILOAD was introduced. DR-DOS 6.0 added internal commands such as GOSUB, IDLE, RETURN, and SWITCH; meanwhile ASSIGN and SUBST were converted into external commands. Although ECHOERR and PAUSEERR existed internally in version 6.0 and Multiuser DOS, they were generally disabled by default. The MORE command remained internal through PalmDOS but became external in Novell DOS 7; DBG was removed in Novell DOS 7; LOADHIGH (LH) and TRUENAME were integrated internally starting with update 8 and DR DOS 6.0 (1993). APPEND shifted from internal in DR-DOS 6.0 to external in Novell DOS 7.

Internal commands

The following internal commands are supported by DR DOS 6.0:


Batch processing subcommands

The batch processing subcommands available in DR DOS 6.0 consist of the following:

External commands

The external commands supported by DR  DOS 6.0 include:

See also

Further reading

  • DR DOS 5.0 Retail box with lid (1990) – Digital Research, Inc.
  • DR DOS 5.0 User Guide (May 1990, 501 pages) – Digital Research, Inc.
  • ViewMAX User Guide (May 1990, 88 pages) – Digital Research, Inc.
  • DR DOS 5.0 Release Notes (August 1990, 11 pages) – Digital Research, Inc.
  • DR DOS 6.0 Software performance report (August 1991) – Digital Research, Inc.
  • DR DOS 6.0 User Guide (August 1991, 698 pages) – Digital Research, Inc.
  • ViewMAX User Guide (August 1991, 106 pages) – Digital Research, Inc.
  • DRTIPS.ZIP (January 1993) – Novell Desktop Systems Group / Digital Research / Novell

External links

Related profiles

DDell Real Mode KernelPPalmDOSNNovell DOSEEZ-DOS
Retrieved from "https://www.alfawiki.org/index.php?title=DRMK&oldid=25210"