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DR- DOS
DOS
(DR DOS, without hyphen up to and including version 6.0) is an operating system of the DOS
DOS
family, written for IBM PC-compatible personal computers. It was originally developed by Gary Kildall's Digital Research and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86. As ownership changed, various later versions were produced with names including Novell
Novell
DOS
DOS
and Caldera OpenDOS.

Contents

1 History

1.1 Origins in CP/M 1.2 First DR DOS
DOS
version 1.3 Version 5.0 1.4 Competition from Microsoft 1.5 Patching to counter Microsoft 1.6 PalmDOS 1.7 Contribution by Novell 1.8 After Novell 1.9 Recent versions

2 Controversies 3 See also 4 References 5 Further reading 6 External links

History[edit] Origins in CP/M[edit] Digital Research's original CP/M
CP/M
for the 8-bit Intel 8080
Intel 8080
and Z-80 based systems spawned numerous spin-off versions, most notably CP/M-86
CP/M-86
for the Intel 8086/8088 family of processors. Although CP/M had dominated the market, and was shipped with the vast majority of non-proprietary-architecture personal computers, the IBM PC in 1981 brought the beginning of what was eventually to be a massive change. IBM
IBM
originally approached Digital Research, seeking an x86 version of CP/M. However, there were disagreements over the contract, and IBM
IBM
withdrew. Instead, a deal was struck with Microsoft, who purchased another operating system, 86-DOS, from Seattle Computer Products. This became Microsoft
Microsoft
MS- DOS
DOS
and IBM PC DOS. 86-DOS' command structure and application programming interface imitated that of CP/M. Digital Research threatened legal action, claiming PC DOS/MS- DOS
DOS
to be too similar to CP/M. IBM
IBM
settled by agreeing to sell their x86 version of CP/M, CP/M-86, alongside PC DOS. However, PC  DOS
DOS
sold for $40, while CP/M-86
CP/M-86
had a $240 price tag. The proportion of PC buyers prepared to spend six times as much to buy CP/M-86
CP/M-86
was very small, and the availability of compatible application software, at first decisively in Digital Research's favor, was only temporary.[2] Digital Research fought a long losing battle to promote CP/M-86 and its multi-tasking multi-user successors MP/M-86 and Concurrent CP/M-86, and eventually decided that they could not beat the Microsoft- IBM
IBM
lead in application software availability, so they modified Concurrent CP/M-86
CP/M-86
to allow it to run the same applications as MS- DOS
DOS
and PC DOS. This was shown publicly in December 1983[3] and shipped in March 1984 as Concurrent DOS
DOS
3.1 (a.k.a. C DOS
DOS
with B DOS
DOS
3.1) to hardware vendors.[4] While Concurrent DOS
DOS
continued to evolve in various flavours over the years to eventually become Multiuser DOS, it was not specifically tailored for the desktop market and too expensive for single-user applications. Therefore, over time two attempts were made to sideline the product. In 1985, Digital Research developed DOS Plus 1.1 to 2.1, a stripped-down and modified single-user derivative of Concurrent DOS 4.1 and 5.0, which ran applications for both platforms, and allowed switching between several tasks[5] as did the original CP/M-86. Its DOS
DOS
compatibility was limited, and Digital Research made another attempt, this time a native DOS
DOS
system. This new disk operating system was launched in 1988 as DR DOS. Although DRI was based in Pacific Grove and later in Monterey, California, USA, the work on DOS Plus started in Newbury, Berkshire, UK, where Digital Research Europe had its OEM Support Group (51°24′22″N 1°19′35″W / 51.40612°N 1.326374°W / 51.40612; -1.326374 ( Digital Research (UK) Ltd., Oxford House, 12-20 Oxford Street, Newbury, Berkshire, UK)) located since 1983. Since 1986, most of the operating system work on Concurrent DOS 386 and XM, Multiuser DOS, DR DOS and Palm DOS
DOS
was done in Digital Research's European Development Centre (EDC) (51°24′52″N 1°30′47″W / 51.414478°N 1.512946°W / 51.414478; -1.512946 ( Digital Research (UK) Ltd., Station Road, Hungerford, Berkshire, UK) and 51°25′13″N 1°30′55″W / 51.420339°N 1.515223°W / 51.420339; -1.515223 ( Digital Research (UK) Ltd., Charnham Park, Hungerford, Berkshire, UK)) in Hungerford, Berkshire, UK. First DR DOS
DOS
version[edit] As requested by several OEMs Digital Research started to plan develop a new DOS
DOS
operating system addressing the shortcomings left by MS- DOS
DOS
in 1987.[6] The first DR  DOS
DOS
version was released on 28 May 1988.[6] Version numbers were chosen to reflect features relative to MS-DOS; the first version promoted to the public was DR DOS 3.31,[6] which offered features comparable to Compaq MS- DOS
DOS
3.31 with large disk support ( FAT16B a.k.a. "BIGDOS"). DR DOS 3.31 reported itself as " IBM
IBM
PC  DOS
DOS
3.31", while the internal B DOS
DOS
(Basic Disk Operating System) kernel version was reported as 6.0, single-user nature, reflecting its origin as derivative of Concurrent DOS 6.0 with the multitasking and multiuser capabilities as well as CP/M
CP/M
API support stripped out and the XIOS replaced by an IBM-compatible DOS-BIOS. The system files were named DRBIOS.SYS (for the DOS-BIOS) and DRBDOS.SYS (for the BDOS kernel), the disk OEM label used was "DIGITAL␠". DR  DOS
DOS
offered some extended command line tools with command line help, verbose error messages, sophisticated command line history and editing (HISTORY directive) as well as support for file and directory passwords built right into the kernel. It was also cheaper to license than MS-DOS, and was ROMable right from the start. The ROMed version of DR  DOS
DOS
was also named ROS (ROM Operating System).[7] DRI was approached by a number of PC manufacturers who were interested in a third-party DOS, which prompted several updates to the system. At this time, MS- DOS
DOS
was only available to OEMs bundled with hardware. Consequently, DR DOS
DOS
achieved some immediate success when it became possible for consumers to buy it through normal retail channels since 3.4x. Known versions are DR DOS 3.31 (B DOS
DOS
6.0, 1988-06, OEM only), 3.32 (B DOS
DOS
6.0, 1988-08-17, OEM only), 3.33 (B DOS
DOS
6.0, 1988-09-01, OEM only), 3.34 (B DOS
DOS
6.0, OEM only), 3.35 (B DOS
DOS
6.0, 1988-10-21, OEM only), 3.40 (B DOS
DOS
6.0, 1989-01-25), 3.41 (B DOS
DOS
6.3, 1989-06, OEM and retail). Like MS-DOS, most of them were produced in several flavors for different hardware. While most OEMs kept the DR  DOS
DOS
name designation, one OEM version is known to be called EZ-DOS 3.41. Further information: Comparison of DOS
DOS
operating systems Version 5.0[edit] DR  DOS
DOS
version 5.0 (code-named "Leopard") was released in May 1990,[6] still reporting itself as "PC DOS
DOS
3.31" for compatibility purposes, but internally indicating a single-user BDOS 6.4 kernel. (Version 4 was skipped to avoid being associated with the relatively unpopular MS- DOS
DOS
4.0.) This introduced ViewMAX, a GEM-based GUI
GUI
file management shell, the patented BatteryMAX power management system, bundled disk-caching software, and also offers vastly improved memory management. For compatibility purposes, the DR DOS 5.0 system files were now named IBMBIO.COM (for the DOS-BIOS) and IBMDOS.COM (for the B DOS
DOS
kernel), and the OEM label in boot sectors was changed to "IBM␠␠3.3".

Front and rear views of the Carry-I
Carry-I
book-size diskless workstation, bundled with DR DOS
DOS
5.0, based on an Intel 80286
Intel 80286
processor and produced by Taiwan's Flytech Technology circa 1991.

First, the DR  DOS
DOS
kernel and structures such as disk buffers can be located in the High Memory Area
High Memory Area
(HMA), the first 64 KB of extended memory which are accessible in real mode due to an incomplete compatibility of the 80286 with earlier processors. This freed up the equivalent amount of critical "base" or conventional memory, the first 640 KB of the PC's RAM – the area in which all MS-DOS applications run. Additionally, on Intel 80386
Intel 80386
machines, DR DOS's EMS memory manager allowed the OS to load DOS
DOS
device drivers into upper memory blocks, further freeing base memory. For more information on this, see the article on the Upper Memory Area (UMA). DR DOS 5.0 was the first DOS
DOS
to integrate such functionality into the base OS (loading device drivers into upper memory blocks was possible using third-party software like QEMM). This allowed it, on a 386 system, to provide significantly more free conventional memory than any other DOS. Once drivers for a mouse, multimedia hardware and a network stack were loaded, an MS- DOS
DOS
machine typically might only have 300 to 400 KB of free conventional memory – too little to run much late-1980s software. DR DOS 5.0, with a little manual tweaking, could load all this and still keep all of its conventional memory free – allowing for some necessary DOS
DOS
data structures, as much as 620 KB out of the 640 KB. Because DR  DOS
DOS
left so much conventional memory available, some old programs utilizing certain address wrapping techniques failed to run properly as they were now loaded unexpectedly (or, under MS-DOS, "impossibly") low in memory – inside the first 64 KB segment (known as "low memory"). Therefore, DR DOS 5.0's new MEMMAX -L command worked around this by pre-allocating a chunk of memory at the start of the memory map in order for programs to load above this barrier (but with less usable conventional memory then). By default, MEMMAX was configured for +L, so that applications could take advantage of the extra memory. Competition from Microsoft[edit] Faced with substantial competition in the DOS
DOS
arena, Microsoft responded with an announcement of a yet-to-be released MS-DOS 5.0 in May 1990.[6] This would be released in June 1991[6] and include similar advanced features to those of DR DOS. It included matches of the DR's enhancements in memory management. Almost immediately in September 1991, Digital Research responded with DR  DOS
DOS
6.0,[6] code-named "Buxton". DR DOS 6.0, while already at B DOS
DOS
level 6.7 internally, would still report itself as " IBM
IBM
PC  DOS
DOS
3.31" to normal DOS applications for compatibility purposes. This bundled in SuperStor on-the-fly disk compression, to maximize available hard disk space, and file deletion tracking and undelete functionality by Roger Gross. DR DOS 6.0 also includes a task-switcher named TASKMAX, support for the industry-standard task-switching API[8] to run multiple applications at the same time. In contrast to Digital Research's Multiuser  DOS
DOS
(successor of Concurrent  DOS
DOS
in the multi-user products line), which would run DOS
DOS
applications in pre-emptively multitasked virtual DOS
DOS
machines, the DR DOS 6.0 task switcher would freeze background applications until brought back into the foreground. While it runs on x86-machines, it is able to swap to XMS memory on 286+ machines. TASKMAX did support some Copy & Paste facility between applications. Via the task-switcher API, graphical user interfaces such as ViewMAX
ViewMAX
or PC/GEOS
PC/GEOS
could register as the task manager menu and thereby replace the TASKMAX text mode menu, so that users could switch between tasks from within a GUI. Microsoft
Microsoft
responded with MS-DOS 6.0, which again matched some features of DR DOS 6.0. Since December 1991 a pre-release version of Windows 3.1 was designed to return a non-fatal error message if it detected a non- Microsoft
Microsoft
DOS.[6] This check came to be known as the AARD code.[9] With the detection code disabled, Windows ran perfectly under DR  DOS
DOS
and its successor Novell DOS. The code was present but disabled in the released version of Windows 3.1.[10] In July 1992, Digital Research Japan released DR DOS
DOS
6.0/V, a Japanese DOS/V
DOS/V
compatible version of DR DOS
DOS
6.0.[11][12] A Korean version appears to have been available as well. Patching to counter Microsoft[edit] It was a simple matter for Digital Research to patch DR DOS 6.0 to circumvent the AARD 'authenticity check' in Windows 3.1 beta by rearranging the order to two internal tables in memory (with no changes in functionality), and the patched version was on the streets within six weeks of the release of Windows 3.1. PalmDOS[edit] In 1992 Digital Research, still under its old name but already bought by Novell
Novell
in July 1991, also embarked on a spin-off product code-named "Merlin" and later released as NetWare Palm DOS
DOS
1, which, as its name implies, was a very resource light DR DOS
DOS
6.0 derivative aimed at the emerging Palmtop/PDA market.[13] Palm DOS
DOS
was the first operating system in the family to sport the new B DOS
DOS
7.0 kernel with native DOS
DOS
compatible internal data structures instead of emulations thereof. Replacing the DOS
DOS
emulation on top of a CP/M
CP/M
kernel by a true DOS
DOS
compatible kernel helped a lot in improving compatibility with some applications using some of DOS' internal data structures and also was the key in reducing the resident size of the kernel code even further - a particular requirement for the PDA market. On the other hand, introducing a genuine Current Directory Structure (CDS) imposed a limit on the depth of working directories down to 66 characters (as in MS-DOS/PC DOS), whereas previous issues of DR DOS
DOS
had no such limitation due to their internal organization of directories as relative links to parent directories instead of as absolute paths. Palm DOS
DOS
still reported itself as "PC DOS
DOS
3.31" to applications in order to keep the kernel small and not run into compatibility problems with Windows, which would expect the DOSMGR API to be implemented for any DOS
DOS
version since 5.0. As well as a ROM-executing kernel, Palm DOS
DOS
had palmtop-type support for features such as PCMCIA
PCMCIA
PC Cards (with DPMS support), Power Management ( BatteryMAX and the $IDLE$ device driver with its patented dynamic idle detection[14] by Roger Gross and John Constant), MINIMAX task switcher support for PIM (Personal Information Modules) applications stored and executed from ROM via XIP (Execute-In-Place), etc. The PCMCIA
PCMCIA
stack for Palm DOS
DOS
was partially written by Ian Cullimore. Contribution by Novell[edit]

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Novell
Novell
DOS
DOS
was Novell
Novell
Corporation's name for DR- DOS
DOS
during the period when Novell
Novell
sold DR-DOS, after the acquisition of Digital Research in 1991.[15][16][17][18] Regarding features and performance, it was typically at least one release ahead of MS-DOS.[19] In 1993, PC DOS 6.1, MS- DOS
DOS
6.2 and PC DOS
DOS
6.3 were trumped by Novell's DOS
DOS
7.[20] Novell
Novell
CEO Robert Frankenberg's strategy included "major trimming", selling off products like transactional database Btrieve
Btrieve
and killing others such as Novell
Novell
DOS
DOS
and WordPerfect's multimedia Main Street children's titles.[21] Novell
Novell
licensed technology from Stac Electronics for use in Novell
Novell
DOS
DOS
and its Network operating system, NetWare.[22] Novell
Novell
sold the product line off to Caldera on 23 July 1996, after it approached Novell
Novell
looking for a DOS
DOS
operating system to bundle with its OpenLinux
OpenLinux
distribution,[6] Novell
Novell
DOS
DOS
was described in TechRepublic by John Sheesley as a failure.[23] Novell
Novell
had bought Digital Research with a view to using DR's product line as a lever in their comprehensive strategy to break the Microsoft monopoly. (This was part of a massive and ultimately disastrous spending spree for Novell: they bought WordPerfect
WordPerfect
Corporation at about the same time, some of Borland's products, and invested heavily in Unix
Unix
as well.) The planned DR DOS
DOS
7.0, internally named "Panther", intended to trump Microsoft's troubled MS- DOS
DOS
6.0, was repeatedly delayed, while Novell
Novell
was working on a Unix-like multi-user security extension (compatible with its Multiuser DOS) and two new graphical user interfaces (ViewMAX/3, a derivative of GEM, and "Star Trek", a true port of Apple's System 7.1 to run under the new DR DOS multitasker named "Vladivar"). When DR DOS
DOS
eventually arrived in December 1993 (with localized versions released in March 1994), renamed Novell
Novell
DOS
DOS
7 (a.k.a. "NWDOS"), and without these three components, it was a disappointment to some.[who?] It was larger and introduced many new bugs, and the main functional addition was Novell's second attempt at a peer-to-peer networking system, Personal NetWare (PNW). This worked and was better than its predecessor, NetWare Lite (NWL), but it was incompatible with Microsoft's networking system, now growing popular with support in Windows for Workgroups, OS/2
OS/2
and Windows NT. A considerable amount of manual configuration was needed to get both to co-exist on the same PC, and Personal NetWare never achieved much success. Since Novell
Novell
DOS
DOS
7 implemented the DOSMGR API and internal data structures had been updated, its B DOS
DOS
7.2 kernel could report with a DOS
DOS
version of 6.0 and OEM ID "IBM" without risking compatibility problems with Windows. Most tools would report this as "PC DOS
DOS
6.1", because IBM PC
IBM PC
DOS
DOS
6.1 also reported as DOS
DOS
6.0 to applications. Novell
Novell
DOS
DOS
7 introduced much advanced memory management including new support for DPMI ( DOS
DOS
Protected Mode Interface) and DPMS (DOS Protected Mode Services) as well as more flexible loadhigh options. It also introduced support for "true" pre-emptive multitasking of multiple DOS
DOS
applications in virtual DOS
DOS
machines (VDM), similar to Multiuser DOS, but now on the basis of a natively DOS
DOS
compatible environment, similar to Windows 386 Enhanced Mode without GUI. By default, the bundled TASKMGR would behave similar to the former DR DOS 6.0 TASKMAX. However, if EMM386 was loaded with the option /MULTI, EMM386 would load a natively 32-bit 386 Protected Mode operating system core providing API support for pre-emptive multitasking, multi-threading, hardware virtualization and domain management of virtual DOS
DOS
machines. This API could be used by DR DOS-aware applications. If TASKMGR was run later on, it would use these APIs to instance the current 16-bit DOS
DOS
system environment, create virtual DOS machines and run applications in them instead of using its own Real Mode task-switcher support. The multitasker was compatible with Windows, so that tasks started before launching Windows could be seen as tasks under Windows as well. Novell
Novell
DOS
DOS
7 and Personal NetWare 1.0 also shipped with NetWars, a network-enabled 3D arcade game. Novell
Novell
DOS
DOS
7 and Personal NetWare required several bug-fix releases and were not completely stable when the next development occurred. With beta versions of Microsoft's "Chicago" (what would later become Windows 95) in sight, Novell
Novell
wound down further development on Novell DOS
DOS
7 in September 1994[6] and stopped maintenance in January 1996 after more than 15 updates. After Novell[edit] When Caldera approached Novell
Novell
looking for a DOS
DOS
operating system to bundle with their OpenLinux
OpenLinux
distribution, Novell
Novell
sold the product line off to Caldera on 23 July 1996,[6] by which time it was of little commercial value to them. Between the Caldera-owned DR- DOS
DOS
and competition from IBM's PC DOS 6.3, Microsoft
Microsoft
moved to make it impossible to use or buy the subsequent Windows version, Windows 95, with any DOS
DOS
product other than their own. Claimed by them to be a purely technical change, this was later to be the subject of a major lawsuit brought in Salt Lake City by Caldera with the help of the Canopy Group.[6][24] Microsoft lawyers tried repeatedly to have the case dismissed but without success. Immediately after the completion of the pre-trial deposition stage (where the parties list the evidence they intend to present), there was an out-of-court settlement on 7 January 2000 for an undisclosed sum.[25] This was revealed in November 2009 to be 280 million US dollars.[26] In August 1996, the US-based Caldera, Inc. was approached by Roger Gross, one of the original DR- DOS
DOS
engineers, with a proposal to restart DR- DOS
DOS
development and to make Windows 95
Windows 95
run on DR- DOS
DOS
which would help the court case. Following a meeting in September 1996 in Lindon, Utah, between Gross, Ransom Love, Bryan Sparks and Ray Noorda, Gross was hired and tasked to set up a new subsidiary in the UK. On 10 September 1996, Caldera announced the coming release of Open DOS
DOS
(COD) and their intent to also release the source code to the system, and Caldera UK Ltd. (51°12′19″N 1°28′44″W / 51.20531°N 1.478786°W / 51.20531; -1.478786 (Caldera UK Ltd., Aldwych House, Winchester Street, Andover, Hampshire, SP10 2EA, UK)) was incorporated on 20 September 1996.[27] Gross hired some of the original developers of the operating system from the Novell
Novell
EDC as well as some new talents to continue work on the operating system in a converted barn (51°11′18″N 1°29′15″W / 51.188306°N 1.487498°W / 51.188306; -1.487498 (Caldera UK Ltd., Norman Court Barns, Norman Court Lane, Upper Clatford, Andover, Hampshire, UK)) at the periphery of Andover, Hampshire, UK, nearby the former Digital Research and Novell
Novell
EDC. Besides other improvements and enhancements all over the system, a string of new key features were added subsequently over the course of the next two years, including a TCP/IP
TCP/IP
stack (derived from NetWare Mobile / LAN Workplace for DOS), a graphical 32-bit DOS
DOS
Protected Mode HTML 3.2 web-browser DR-WebSpyder (originally based on source code from the Arachne web browser by Michal Polák) with LAN and modem dialup, a POSIX Pthreads extension to the multi-tasker by Andy Wightman, long filename (LONGNAME) support by Edward Hill as well as LBA and FAT32 support (DRFAT32) by Matthias Paul. Gross also hired Andrew Schulman (who had been, with Geoff Chappell, instrumental in identifying the AARD code in 1992) to work as a consultant and, in Andover, join Paul in his work on "WinGlue", a secret project to create a version of DR-DOS compatible with Windows 95, 98 and 98 SE and replace its MS-DOS 7.xx component.[28] This was demonstrated at CeBIT
CeBIT
in March 1998,[28] and later, in a small team, developed into "WinBolt", both versions of DR-DOS, which remained unreleased as of 2014[update], but played an important role in the court case.[24][29] Caldera UK officially released Caldera Open DOS
DOS
7.01 in February 1997, but this version was just Novell
Novell
DOS
DOS
7 update 10 (as of December 1994) with a new name, missing a year's worth of patches which had been developed for the Novell
Novell
DOS
DOS
updates 11 (January 1995) to 15.2 (January 1996).[30] This was due to parts of the Novell
Novell
DOS
DOS
sources having been lost at Novell
Novell
meanwhile.[31] Consequently, this version still reported an internal B DOS
DOS
version of 7.2, identical to Novell DOS
DOS
7. The new suite also lacked the SETFIFO command, which had been added with one of the Novell
Novell
DOS
DOS
updates, as well as Fifth Generation's Search&Destroy virus scanner and FastBack Plus 2.0 utility, which previously came bundled with Novell
Novell
DOS. Instead it brought an advanced version of NetWars. Parts of Open DOS
DOS
7.01 were released as open source in form of the M.R.S. kit (for Machine Readable Sources) in May 1997, but with licence terms mostly incompatible with existing open source licences. The source was then closed again as Gross felt this would undermine the commercial aspirations of the system. After beta releases in September and November 1997, the next official release came in December 1997, with the name changed to Caldera DR-Open DOS
DOS
7.02, soon followed by a further release in March 1998, when the DR- DOS
DOS
name returned as Caldera DR- DOS
DOS
7.02, now for the first time written with a hyphen. Version 7.02 (now reporting itself as B DOS
DOS
7.3) incorporated improved BIOS and B DOS
DOS
issues, developed by Paul,[31][32] adding many new boot and configuration options, integrating many compatibility enhancements, bug-fixes and optimizations for size and speed, and re-implementing all fixes of the missing Novell
Novell
DOS
DOS
updates.[31][32] The BIOS improved the coexistence of DR- DOS
DOS
with Windows 9x and its support for third-party disk compression drivers such as Microsoft's DriveSpace. It introduced a diagnostics mode (activated by Scroll Lock), integrated debugger support (with DEBUG=ON and a debugger loaded before or from within CONFIG.SYS) and more flexible CONFIG.SYS tracing capabilities via the F5/F6/F7/F8 hotkeys and the TRACE and TIMEOUT commands, thereby also improving the integration of alternative command line shells such as 4DOS.[31][33] Together with LOADER, SYS /DR:ext and the CHAIN directive, it brought enhanced multi-configuration support for DR/D/CONFIG.ext files and came with enhancements to the BASIC-like CONFIG.SYS language for more powerful boot menus, convenient user interaction and programmatical acting upon conditions (CPU386), return codes and error levels (ERROR, ONERROR).[31] It also allowed to change the SCROLLOCK, CAPSLOCK, INSERT and VERIFY settings as well as the SWITCHAR, YESCHAR, NOCHAR and RESUMECHAR characters. Various behavioural details could be controlled with new parameters /Q, /L, /Y and /S for SWITCHES. Further, it provided optional support for a LPT4: device and allowed to configure the built-in COMx: and LPTx: devices as well as to change the PRN: and AUX: defaults. The handling of environment variables in CONFIG.SYS was improved and new load-high facilities included such as the HIFILES/FILESHIGH and HIFCBS/FCBSHIGH options to relocate file handles and FCB structures into UMBs, which typically gave between 1 and 4 KB (and up to 15 KB) more free conventional memory compared to previous versions, or the HISHELL/SHELLHIGH SIZE directive to control the pre-allocation of HMA memory for COMMAND.COM, which helped to avoid memory fragmentation and thereby typically gave between 5 and 8 KB more continuous HMA memory for HMA-capable third-party drivers to work with in conjunction with third-party command line shells, which could not load into the HMA as COMMAND.COM with its /MH option. At a reduced memory footprint version 7.02 also brought an enhanced NLS 4.xx sub-system by Paul to allow multiple, distributed and possibly user-configured COUNTRY.SYS files to be used by the system at the same time in a hierarchical model.[31][34] This also gave dynamic parser support for MS-DOS/PC DOS COUNTRY.SYS file formats in addition to DR-DOS' own COUNTRY.SYS formats,[31][34][35][36] and it introduced support for the ISO 8601 international date format[34] (including automatic detection) and the then-new Euro currency.[34] DR- DOS
DOS
7.02 was fully Year 2000 compliant and provided special support to work with buggy system BIOSes. It also came with an updated FDISK, which could partition and format FAT32 volumes (but not yet work with LBA). The sources of the Novell
Novell
patches for the external tools and drivers had meanwhile been found in Germany and could thus be retro-fitted into the system as well, so that DR-DOS 7.02 finally not only caught up with Novell
Novell
DOS
DOS
7, but was a true step forward. The release was followed by various updates in June, August and September 1998. The updated internal B DOS
DOS
version number introduced a new problem: some legacy third-party applications with special support for Novell DOS, which were no longer being updated, stopped working. SETVER already allowed Novell
Novell
DOS
DOS
to disguise itself as DOS
DOS
versions by file name and globally and, specifying a magic sub-version of 255, it would even disable its own internal B DOS
DOS
version check in order to cope with programs specifically probing for "DR-DOS". The modified kernel and SETVER driver by Paul would, in an hierarchical model, also support load paths in order to distinguish between multiple executables of the same file name, and it introduced an extended mode, in which SETVER could not only fake DOS
DOS
versions, but also B DOS
DOS
kernel versions. Sub-versions of 128 to 255 would be reported as DOS
DOS
sub-versions 0 to 127 to applications, but with the B DOS
DOS
version check disabled, while sub-versions 100 to 127 could be used to fake different B DOS
DOS
versions, whereas the DOS
DOS
revision number (typically set to 0 in a static, pre-boot patchable data structure) would be taken as the reported sub-version instead, so that SETVER /G /X 6.114 would allow versions of DR- DOS
DOS
since 7.02 to still report themselves as a " DOS
DOS
6.0" and with a faked B DOS
DOS
version 7.2 (114 decimal = 72 hexadecimal), thereby masquerading as Novell
Novell
DOS
DOS
7 / Open DOS
DOS
7.01. While otherwise beneficial, the new HIFILES triggered a compatibility problem in the DOS-UP feature of the third-party memory manager QEMM 8, which was hard-wired to expect a chunk of five handle structures in conventional memory under DR- DOS
DOS
(as with previous versions up to 7.01), whereas version 7.02 by design left eight handles in low memory when loading high files in order to maintain full compatibility with older versions of Windows 3.xx. Compatibility with Windows for Workgroups 3.11 had not been affected by this. A maintenance fix was devised to patch a single byte in IBMBIO.COM in order to switch the behaviour and optionally re-invoke the old chunking. This freed some 150 bytes of conventional memory and enabled full compatibility with DOS-UP, but at the same time broke compatibility with older versions of Windows 3.xx when using the HIFILES feature, and vice versa. The patch named IBMBIO85.SCR continued to work with newer versions of DR-DOS. In August 1998[37] the US-based Caldera, Inc. created two new subsidiaries, Caldera Systems, Inc. for the Linux
Linux
business, and Caldera Thin Clients, Inc. for the embedded and thin-client market.[38] Another version, DR- DOS
DOS
7.03 (still with B DOS
DOS
7.3 and reporting itself to applications as "PC DOS
DOS
6.0" for compatibility purposes), was pre-released at Christmas 1998 and then officially released on 6 January 1999 by Caldera UK. It came with significantly improved memory managers (in particular enhanced DPMI support in conjunction with the multitasker) and other enhancements, such as added DEVLOAD and DRMOUSE utilities, but a changed OEM label in the boot sector of volumes formatted under DR- DOS
DOS
could also cause problems under other operating systems (which can be circumvented by NOVOLTRK).[39][40] DR- DOS
DOS
7.03 would become the last version of DR- DOS
DOS
also tailored for desktop use. Caldera, Inc. wanted to relocate the DR- DOS
DOS
business into the US and closed the successful UK operation in February 1999 after Gross resigned and set up iCentrix to develop the MarioNet split web browser. Development was then moved into the US (which never worked out due to a total lack of expertise in this field at Caldera US), and the DR- DOS
DOS
line fell to its branch company, Caldera Thin Clients, which was renamed Lineo, Inc. on 20 July 1999.[41] DR-WebSpyder
DR-WebSpyder
was renamed EmBrowser and was said to be ported to Linux.[41] Lineo re-released DR- DOS
DOS
7.03 in June and September 1999, still branded as "Caldera DR-DOS"[42] and without any changes, but otherwise focussed on Linux
Linux
for embedded systems, based on a stripped-down version of OpenLinux
OpenLinux
named Embedix.[41] Among the latest and independently-developed versions of DR- DOS
DOS
were OEM DR- DOS
DOS
7.04 (as of 19 August 1999) and 7.05 (as of 30 November 1999), still branded as "Caldera DR-DOS".[43][44] These were variants of the system consisting only of the kernel and command shell. With a specialized native implementation of FAT32 and large hard disk support they could be found bundled with Ontrack's Easy Recovery 5 in 2000, replacing the dynamically-loadable DR FAT32 redirector driver, which still came with Easy Recovery 4. They were also used for Seagate Technology's SeaTools[45] and the CD imaging software Nero Burning ROM. While still reporting a B DOS
DOS
7.3 internally, these were the first versions to report themselves as "PC DOS
DOS
7.10" to applications in order to indicate integrated FAT32 support. Designed to be mostly backwards-compatible, the DR- DOS
DOS
7.04/7.05 IBMBIO.COM could be combined with the DR- DOS
DOS
7.03 IBMDOS.COM in order to give the desktop-approved DR- DOS
DOS
7.03 kernel LBA capabilities and work with drives larger than 8 GB. For specific OEM requirements, DR- DOS
DOS
7.06 by Wightman combined the kernel files into a single binary executable, so that, similar to IO.SYS of Windows 98, it could be booted by MS-DOS 7.10 boot sectors (but no longer by DR- DOS
DOS
boot sectors). DR- DOS
DOS
7.07 (with B DOS
DOS
7.4/7.7) by Paul introduced new bootstrap loaders and updated disk tools in order to combine support for CHS and LBA disk access, the FAT12, FAT16 and FAT32 file systems, and the differing bootstrapping conventions of DR-DOS, PC DOS, MS-DOS, Windows, REAL/32 and LOADER into a single MBR and boot sector, so that the code would continue to load any version of DR- DOS
DOS
down to 3.31 (and since DR-DOS 7.04 also with FAT32 support), but could also be used to launch the PC DOS
DOS
or MS- DOS
DOS
system files, including those of Windows 9x and PC DOS 7.10. At the same time the kernel could not only be booted by the new sectors, but also by any previously DR- DOS
DOS
formatted disks, as well as off disks with existing PC DOS
DOS
or MS- DOS
DOS
boot sectors and a variety of other boot-loaders, thereby easing the coexistence and setup of multi-boot scenarios in conjunction with other operating systems. Recent versions[edit] In 2002, Lineo
Lineo
was bought out, and some of Lineo's former managers purchased the name and formed a new company, DRDOS, Inc. dba DeviceLogics L.L.C. They have continued to sell DR- DOS
DOS
for use in embedded systems. DR- DOS
DOS
8.0 was released on March 30, 2004 featuring FAT32 and large disk support, the ability to boot from ROM or Flash, multitasking and a DPMI memory manager. This version was based on the kernel from version 7.03.[46] The company later released DR- DOS
DOS
8.1 (with better FAT32 support) in autumn 2005. This version was instead based on Open DOS
DOS
7.01.xx. Both 8.0 and 8.1 were withdrawn. Aside from selling copies of the operating system, the DRDOS, Inc. website lists a buyout option for DR-DOS; the asking price is $25,000.[47] The Open DOS
DOS
7.01 source code was a base for The DR-DOS/OpenDOS Enhancement Project, set up in July 2002 in an attempt to bring the functionality of DR- DOS
DOS
up to parity with modern PC non-Windows operating systems. The project's added native support for large disks (LBA) and the FAT32 file system, and several other enhancements, including improved memory management and support for the new FAT32+ file system extension which allows files of up to 256 GB in size on normal FAT partitions. DR- DOS
DOS
7.01.08 was released on July 21, 2011.[48] Controversies[edit] In October 2005, it was discovered that DR- DOS
DOS
8.1 included several utilities from Free DOS
DOS
as well as other sources, and that the kernel was an outdated version of the Enhanced DR- DOS
DOS
kernel. DR DOS, Inc. failed to comply with the GNU General Public License
GNU General Public License
(GPL) by not crediting the Free DOS
DOS
utilities to their authors and including the source code.[46] After complaints from Free DOS
DOS
developers (including the suggestion to provide the source code, and hence comply with the GPL), DR DOS, Inc. instead withdrew version 8.1, and also the unaffected 8.0, from its website. See also[edit]

CP/M MP/M DOS
DOS
Plus Multiuser DOS MarioNet split web browser Comparison of DOS
DOS
operating systems Timeline of DOS
DOS
operating systems AARD code

References[edit]

^ http://drdos.com/company/about-drdos/ ^ The rest of the story: How Bill Gates beat Gary Kildall in OS war, Part 1 ScobleShow: Videoblog about geeks, technology, and developers ^ Borreson, Nan, ed. (March 1984). "PC-Mode bridges CP/M
CP/M
and PC-DOS". Digital Dialogue - Employee Newsletter of Digital Research Inc. Digital Research. 3 (1): 3. Archived from the original on 2017-09-10. Retrieved 2017-09-10.  [1] ^ Borreson, Nan, ed. (May 1984). "Concurrent DOS
DOS
bridges PC-DOS, CP/M". Digital Research News - For Digital Research Users Everywhere. Digital Research. 4 (2): 3. Archived from the original on 2017-09-10. Retrieved 2017-09-10. Concurrent DOS
DOS
Release 3.1 is rapidly gaining momentum and support from a wide range of microcomputer manufacturers," Wandryk said. "Some 60 hardware companies have licensed the product since it was released in early March.  [2] ^ " DOS
DOS
Plus: A short history".  ^ a b c d e f g h i j k l Software Developer Caldera sues Microsoft for Antitrust practices alleges monopolistic acts shut its DR DOS operating system out of market Caldera News, 1996-07-24 ([3]). ^ Ponting, Bob (1988-08-15). "Award Software plans to implement Digital Research's OS on ROM chip". Infoworld. Retrieved 2014-09-06.  ^ Caldera, Inc. (1997). Open DOS
DOS
Developer's Reference Series — Open DOS
DOS
Multitasking API Guide — Programmer's Guide. Printed in the UK, August 1997. Caldera Part No. 200-DOMG-004 ([4]). ^ The AARD Code ^ Dr. Dobb's Journal investigation ^ "Timeline of DOS/V
DOS/V
versions" (in Japanese). 2014-11-28. Retrieved 2017-01-16.  ^ Tam, Roy; Elliott, John (2014-01-12). "DR DOS
DOS
6.0/V". Retrieved 2017-01-16.  (NB. Has screenshots of a DBCS-enabled version of ViewMAX/2
ViewMAX/2
running on DR DOS
DOS
6.0/V and a hex dump of the corresponding DRFONT database SCREENHZ.FNT for its $FONT.SYS. ^ CW (1992-09-11). "Markt für Desktop-Betriebssysteme im Visier - Novell
Novell
kündigt die ersten Low-end-Produkte mit dem Betiebssystem DR DOS
DOS
6.0 an". Computerwoche
Computerwoche
(in German). Munich, Germany: IDG Business Media GmbH. Archived from the original on 2017-07-04. Retrieved 2017-07-04.  ^ [https://web.archive.org/web/20120407072428/http://www.wikipatents.com/US-Patent-5355501/idle-detection-system ^ Hildebrand, J. D. (2011-12-19). " Novell
Novell
v. Microsoft
Microsoft
trial ends in hung jury". SD Times. Retrieved 2012-03-02.  ^ " Novell
Novell
DOS". PC Magazine. Retrieved 2012-03-02.  ^ Scott, Karyl (1991-07-29). "Novell/DRI merger to reap better client management". InfoWorld: 33. Retrieved 2017-01-21.  ^ Allchin, Jim (1992-05-27) [1991-07-17]. "Novell/Digital Research reach definitive agreement..." (PDF) (Court document). Plaintiff's exhibit 828, Comes v. Microsoft. Archived (PDF) from the original on 2016-11-19. Retrieved 2017-01-21.  ^ Fisher, Lawrence M. (1994-07-24). "The Executive Computer; Microsoft's Operating System Rivals Get a Boost, Sort Of". The New York Times. Retrieved 2012-03-02.  ^ Anthony, Sebastian (2011-07-27). "MS- DOS
DOS
is 30 years old today". ExtremeTech. Retrieved 2012-03-02.  ^ Fisher, Lawrence M. (1995-09-18). " Novell
Novell
Readies a Response to Windows". The New York Times. Retrieved 2012-03-02.  ^ Fisher, Lawrence M. (1994-03-06). "The Executive Computer; Will Users Be the Big Losers in Software Patent Battles?". The New York Times. Retrieved 2012-03-02.  ^ Sheesley, John (2008-04-09). "My DOS
DOS
version can beat up your DOS version". TechRepublic. Retrieved 2012-03-02.  ^ a b Susman, Stephen D.; Eskridge III, Charles R.; Susman, Harry P.; Southwick, James T.; Folse III, Parker C.; Borchers, Timothy K.; Palumbo, Ralph H.; Harris, Matthew R.; Engel, Lynn M.; McCune, Philip S.; Locker, Lawrence C.; Wheeler, Max D.; Hill, Stephen J.; Tibbitts, Ryan E. (May 1999). "In the United States District Court - District of Utah, Central Division - Caldera, Inc. vs. Microsoft
Microsoft
Corporation - Case No. 2:96CV 0645B - Caldera, Inc.'s Memorandum in opposition to defendant's motion for partial Summary Judgment on plaintiff's "Technological Tying" claim" (Court document). Caldera Inc. Archived from the original on 2013-10-03. Retrieved 2013-10-05.  ^ BBC News BUSINESS Caldera vs Microsoft
Microsoft
- the settlement ^ "Exhibits to Microsoft's Cross Motion for Summary Judgment in Novell WordPerfect
WordPerfect
Case". Groklaw. 2009-11-23. Retrieved 2011-10-22.  ^ Company Data Rex: Basic information about company Caldera (UK) Limited. Company Number 03252883, Record as of 2001-07-01 ([5]). ^ a b Lea, Graham (1998-03-23). "Cebit: Caldera shows Windows on DR-DOS, denying MS claims". Cebit news. Hanover, Germany. Retrieved 2009-06-01.  ^ Mike Romano. The mouse that roared. Forget the feds. It's up to an obscure Utah company to prove what we already know: that Microsoft
Microsoft
is a monopoly. Seattle Weekly, 16 September 1998, ([6]): "Furthermore, Caldera claims that Microsoft's flagship product, Windows 95, is nothing more than an "artificial tie" between its MS- DOS
DOS
operating system and Windows graphic interface with no business justification other than to keep competing underlying operating systems—like Caldera's DR-DOS—off the market. To prove its point, Caldera will soon release a piece of demonstration software called "Winbolt," which, it says, will allow users to install the Windows 95
Windows 95
interface atop DR-DOS. The demo will show, Caldera says, that there is no significant technological advancement, or justified business efficiency, to the combination of MS- DOS
DOS
with Windows in Windows 95." ^ Paul, Matthias (1997-07-30). NWDOS-TIPs — Tips & Tricks rund um Novell
Novell
DOS
DOS
7, mit Blick auf undokumentierte Details, Bugs und Workarounds (e-book). MPDOSTIP (in German) (3, release 157 ed.). Archived from the original on 2017-09-10. Retrieved 2014-08-06.  NWDOSTIP.TXT is a comprehensive work on Novell
Novell
DOS
DOS
7 and Open DOS
DOS
7.01, including the description of many undocumented features and internals. It is part of the author's yet larger MPDOSTIP.ZIP collection maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the NWDOSTIP.TXT file. ^ a b c d e f g Paul, Matthias (1997-10-02). "Caldera OpenDOS 7.01/7.02 Update Alpha 3 IBMBIO.COM README.TXT". Archived from the original on 2003-10-04. Retrieved 2009-03-29.  ^ a b Ralf D. Brown. Ralf Brown's Interrupt List, INTER61 as of 2000-07-16 ([7]), entry for DR- DOS
DOS
version check under INT 21h/AH=4452h. ^ Brothers, Hardin; Rawson, Tom; Conn, Rex C.; Paul, Matthias; Dye, Charles E.; Georgiev, Luchezar I. (2002-02-27). 4 DOS
DOS
8.00 online help.  ^ a b c d Paul, Matthias (2001-06-10) [1995]. " DOS
DOS
COUNTRY.SYS file format" (COUNTRY.LST file) (1.44 ed.). Archived from the original on 2016-04-20. Retrieved 2016-08-20.  ^ Paul, Matthias (2001-06-10) [1995]. "Format description of DOS, OS/2, and Windows NT
Windows NT
.CPI, and Linux
Linux
.CP files" (CPI.LST file) (1.30 ed.). Archived from the original on 2016-04-20. Retrieved 2016-08-20.  ^ Paul, Matthias (2001-06-10) [1995]. "Overview on DOS, OS/2, and Windows codepages" (CODEPAGE.LST file) (1.59 preliminary ed.). Archived from the original on 2016-04-20. Retrieved 2016-08-20.  ^ Pamela Jones: Caldera, Inc./Caldera Systems, Inc. 1998 Asset Purchase and Sale Agreement. Groklaw Blog, 2004-02-29 ([8]). ^ Caldera. Caldera creates two wholly-owned subsidiaries. Press-release, 1998-09-02, PR-Newswire ([9]). ^ Paul, Matthias (2002-02-20). "Need DOS
DOS
6.22 (Not OEM)". alt.msdos.programmer. Archived from the original on 2017-09-09. Retrieved 2006-10-14.  ^ Paul, Matthias (2004-08-25). "NOVOLTRK.REG". www.drdos.org. Archived from the original on 2016-03-04. Retrieved 2011-12-17.  ^ a b c Caldera. Embedded Linux
Linux
moved to top priority at Lineo, Inc., formerly known as Caldera Thin Clients, Inc.. Caldera, Inc. press-release as of 1999-07-20 ([10]). ^ http://www.freedos.org/freedos/news/press/2000-drdos-hist.txt ^ http://drdos.moriy.com/files/autoexec.gif ^ http://drdos.moriy.com/files/configsys.gif ^ FREE SOFTWARE FOR DOS
DOS
— Operating Systems ^ a b http://www.freedos.org/freedos/news/press/2005-drdos.txt ^ DR DOS
DOS
Buy Out DR DOS
DOS
Embedded DOS ^ Welcome to the DR-DOS/Open DOS
DOS
Enhancement Project!

Further reading[edit]

Digital Research, Inc. (1990). DR DOS
DOS
5.0 Retail box with lid. Digital Research, Inc. Part Number 1176-6114-001.  Digital Research, Inc. (May 1990). DR DOS
DOS
5.0 User Guide (1st ed.). Digital Research, Inc. Part Number 1176-2004-002.  (501 pages) Digital Research, Inc. (May 1990). ViewMAX
ViewMAX
User Guide (1st ed.). Digital Research, Inc. Part Number: 1174-2004-002.  (88 pages) Digital Research, Inc. (August 1990). DR DOS
DOS
5.0 Release Notes. Digital Research, Inc. Part Number: 1176-1001-002.  (11 pages) Digital Research, Inc. (August 1991). DR DOS
DOS
6.0 Software performance report. Digital Research, Inc. Part No. 000-1200-00.  (A5 – 1 fold) Digital Research, Inc. (August 1991). DR DOS
DOS
6.0 User Guide (2nd ed.). Digital Research, Inc. Part Number. 1182-2004-002.  (698 pages) Digital Research, Inc. (August 1991). ViewMAX
ViewMAX
User Guide (2nd ed.). Digital Research, Inc. Part Number. 1192-2054-002.  (106 pages)

External links[edit]

Official website Enhanced DR-DOS/Open DOS
DOS
Project DR- DOS
DOS
7 online

.