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(Enhanced) DR-DOS
Website	DRDOS, Inc. / The DR-DOS/OpenDOS Enhancement Project
Company/ developer	Originally by Digital Research, now developed by DRDOS, Inc. and The DR-DOS/OpenDOS Enhancement Project
OS family	DOS
Source model	Mixed - partly Closed source, partly Open Source
Latest stable release	DR-DOS 8.1, Enhanced DR-DOS 7.01.07 / Oct 2005, Mar 2005
Kernel type	Monolithic kernel
Default user interface	CLI, GUI available separately
License	Proprietary
Working state	Current

DR-DOS is a PC DOS-compatible operating system for IBM PC-compatible personal computers, originally developed by Gary Kildall's Digital Research and derived from CP/M-86.

Contents 1 History 1.1 Origins in CP/M 1.2 First DR-DOS version 1.3 Most significant update 1.4 Aggressive competition by Microsoft 1.5 PalmDOS 1.6 Hungerford/Monterey 1.7 Patching to counter Microsoft 1.8 Contribution by Novell 1.9 After Novell 1.10 The Microsoft Lawsuit 2 Recent Versions 3 Controversies 4 Curiosities 5 See also 6 References 7 External links

DR-DOS was a new name given to what was then the latest version of Digital Research's long line of computer operating systems. Their original CP/M for 8-bit 8080, Z-80, and 8085 based systems spawned numerous spin-off versions, most notably 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.

Rather than license CP/M-86 from Digital Research as some other 8088-based computer makers did, IBM chose to supply disk based IBM PCs with PC-DOS, and offered CP/M-86 as an option (as well as the UCSD p-System) when it arrived a few months later. PC-DOS, like MS-DOS, was based on Seattle Computer Products 86-DOS, which was in turn based on CP/M. Industry experts in 1982 held that CP/M-86 was a technically superior product that would eventually prevail in the marketplace.^{[citation needed]} However,? CP/M-86 was not yet ready at the August 1981 IBM PC introduction^{[citation needed]}, and Microsoft agreed with IBM to sell PC-DOS for $60, compared to the $240 asked for CP/M-86 by Digital Research. Later the price of PC-DOS would be included in new PCs. The proportion of PC buyers prepared to spend four times as much to buy CP/M-86 was very small, and the availability of compatible application software, at first decisively in Digital Research's favour, was only temporary.

Digital Research fought a long losing battle to promote CP/M-86, and eventually decided that they could not beat the Microsoft-IBM lead in application software availability, so they modified CP/M-86 to allow it to run the same applications as MS-DOS and PC-DOS. The new disk operating system was launched in 1988 as DR-DOS.

The first version was released in May, 1988. Version numbers were chosen to reflect features relative to MS-DOS; the first version promoted to the public was DR-DOS 3.41, which offered comparable but better features to the massively successful MS-DOS 3.3 - and Compaq's version, Compaq DOS 3.31. (Compaq's variant was the first to introduce the system for supporting hard disk partitions of over 32MB which was later to become the standard used in MS-DOS 4.0 and all subsequent releases.)

At this time, MS-DOS was only available bundled with hardware, so DR-DOS achieved some immediate success as it was possible for consumers to buy it through normal retail channels. Also, DR-DOS was cheaper to license than MS-DOS. As a result, DRI was approached by a number of PC manufacturers who were interested in a third-party DOS, and this prompted several updates to the system.

The most significant was DR-DOS 5.0 in May 1990. (The company skipped version 4, avoiding comparison with the relatively unpopular MS-DOS 4.0.) This introduced ViewMAX, a GEM based GUI file management shell, and bundled disk-caching software, but more significantly, it also offered vastly improved memory management over MS-DOS. Memory management in DR-DOS had two extra features, compared to earlier MS-DOS 4.01 which already bundled a 386-mode memory manager (EMM386.SYS), capable of converting extended memory (XMS) memory into expanded memory (EMS) memory which was more commonly used by DOS applications at that time.

First, on Intel 80286 or better microprocessors with 1MB or more RAM, the DR-DOS kernel and structures such as disk buffers could be located in the High Memory Area (HMA), the first 64KB of extended memory which were 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 640KB of the PC's RAM – which was the area in which all MS-DOS applications had to run. Using high memory was not a new idea, as this memory could previously be used by Windows applications starting with Windows/286 2.1 released in 1988, but offering more memory to old DOS applications was more interesting.

Additionally, on Intel 80386 machines, DR-DOS's EMS memory manager allowed the OS to load 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 was the first DOS to integrate such functionality into the base OS (loading device drivers into upper memory blocks was possible using QEMM and MS-DOS). As such, on a 386 system, it could offer vastly more free conventional memory than any other DOS. Once drivers for a mouse, multimedia hardware and a network stack were loaded, an MS-DOS machine typically might only have 300 to 400KB of free conventional memory – too little to run most late-1980s software. DR-DOS 5, with a small amount of manual tweaking, could load all this and still keep all of its conventional memory free – allowing for some necessary DOS data structures, as much as 620KB out of the 640KB.

So much, in fact, that some programs would fail to load as they started "impossibly" low in memory – inside the first 64KB. DR-DOS 5's new LOADFIX command worked around this by leaving a small empty space at the start of the memory map.

Faced with substantial competition in the DOS arena, Microsoft responded strongly. They announced the development of MS-DOS 5.0 in May 1990, to be released a few months later and include similar advanced features to those of DR-DOS. This has been seen as vaporware, as MS-DOS 5.0 was released June 1991. It included matches of the DR's enhancements in memory management, but did not offer all of the improvements to the syntax of DOS commands that DR did.

DR responded with DR-DOS 6.0 in 1991. This bundled in SuperStor on-the-fly disk compression, to maximise the space available on the tiny hard disks of the time - 40MB was still a common size, which with the growth of larger applications and especially Microsoft Windows was frequently not enough space. DR-DOS 6.0 also included an API for multitasking on CPUs capable of memory protection, namely the Intel 80386 and newer. The API was available only to DR-DOS aware applications, but well-behaved ordinary DOS applications could also be pre-emptively multitasked by the bundled task-switcher, TaskMax. On 286-based systems, DOS applications could be suspended to the background to allow others to run. However, DR's multitasking system was seen as technically inferior to third-party offerings such as DESQview, which could multitask applications which performed direct hardware access and graphical applications and even present them in scalable on-screen windows. Though far from being a true "multitasking" operating system, TaskMax nonetheless represented an important " tick on the box" - a feature on the list of specifications.

Microsoft responded with MS-DOS 6.0, which again matched the more important features of DR-DOS 6.0.

Though DR-DOS was apparently 100% binary compatible with applications written for MS-DOS, Microsoft nevertheless expended considerable effort in attempts to break compatibility. In one example, they inserted code into a beta version Windows 3.1 to return a non-fatal error message if it detected a non-Microsoft DOS. This check came to be known as the AARD code^[1]. With the detection code disabled (or if the user canceled the error message), Windows ran perfectly under DR-DOS and its successor Novell DOS. The code was present, but disabled in the released version of Windows 3.1, as documented in a Dr. Dobb's Journal investigation .

At about this time Digital Research also embarked on a spin-off Product called PalmDOS (and later released as Netware PalmDOS), which as its name implies was a DR-DOS derivative aimed at the emerging Palmtop/PDA market.

As well a ROM-executing kernel it had palmtop-type support for features such as PCMCIA PC Cards, Power Management, etc.

Although DRI was based in Monterey, California, most of the operating system work (especially DR-DOS, Multiuser DOS and PalmDOS) was done in Hungerford, UK.

It was a simple matter for Digital Research to patch DR-DOS to circumvent the 'authenticity check' in Windows 3.1 beta, and the patched version was on the streets within six weeks of the release of Windows 3.1. With improved marketing and packaging, very advanced memory management, disk compression and the Super PC-Kwik caching software, DR-DOS 6.0 was an outstanding value and easily the most successful version.

Around this time, networking giant Novell 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 Corporation at about the same time, some of Borland's products, and invested heavily in Unix as well.) The planned DR-DOS 7.0, intended to trump Microsoft's troubled MS-DOS 6.0, was repeatedly delayed. When it eventually arrived – renamed to Novell DOS 7.0 – it was a disappointment. It was bigger and introduced many new bugs and the main functional addition was Novell's second attempt at a peer-to-peer networking system, Personal Netware. This worked and was better than its predecessor Netware Lite but it was incompatible with Microsoft's networking system, now growing popular with support in Windows for Workgroups, 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.

Novell DOS 7 required several bug-fix releases and was not completely stable when the next development occurred. Realising eventually that their formidable networking skills did not translate into other areas, Novell sold the product line off to Caldera Systems in 1996, by which time it was of little commercial value.

Caldera released the operating system as open source, under the name "Caldera OpenDOS". OpenDOS was released as version 7.01 and 7.02, and the source was then closed. (Version 7.02 was called "Caldera OpenDOS 7.02" while in beta testing; by the time it was released in December of 1997, it was branded "Caldera DR-OpenDOS 7.02". The next release came in March of 1998; it was branded "Caldera DR DOS 7.02") Another version was released, 7.03, before Caldera transferred the DR DOS line to a branch company, Caldera Thin Clients, which would become Lineo. Lineo would later release revisions of 7.03, still branded as "Caldera DR DOS"^[2]

The last Lineo version was DR DOS 7.04/7.05, still branded as "Caldera DR DOS".^[3][4] This was an embedded system consisting only of the kernel and command shell. It was built for Seagate Technology's Seatools, with a buggy implementation of FAT32 and large hard disk support.^[5]

Although DR-DOS had ceased to be a significant present threat to their market share by 1995, Microsoft now faced growing competition from IBM's PC-DOS 6.3, and moved to make it impossible to use or buy the subsequent Windows version, Windows 95, with any 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 law suit brought in Salt Lake City by Caldera. Microsoft lawyers tried repeatedly to have the case thrown out 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 for an undisclosed sum.

The OpenDOS 7.01 source code is still actively being developed by The DR-DOS/OpenDOS Enhancement Project, founded in July 2002 in an attempt to bring the functionality of DR-DOS up to parity with modern PC operating systems. The project's efforts have resulted so far in adding native support for large disks (LBA) and the FAT32 filesystem. There were also several other enhancements, including improved memory management and support for the new FAT+ filesystem extension which allows files of almost 256 GB in size on normal FAT partitions.

In 2002, Lineo was bought out, and some of Lineo's former managers purchased the name and formed a new company, DeviceLogics. They have continued to sell DR-DOS for use in embedded systems. DR-DOS 8.0 was released on 30 March 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.^[6]The company then split into Devicelogics Inc. and DRDOS Inc, which released DR-DOS 8.1 (with better FAT32 support) in autumn 2005. This version was not based upon version 8.0, but was a complete rewrite. Both 8.0 and 8.1 have now been pulled (because of the discoveries outlined below), and replaced with Caldera DR DOS 7.03.

Aside from selling copies of the operating system, the DeviceLogics website lists a buyout option for DR DOS; the asking price is $25,000.^[7]

Current Versions:

• Enhanced DR-DOS 7.01.08 WIP (17.6.2007) (open source; under active development)
• DRDOS Inc.'s DR-DOS 7.03 (closed-source; no visible development occurring)

In October 2005, it was discovered that DR-DOS 8.1, included several utilities from FreeDOS and Enhanced DR-DOS, and the kernel was a patched form of the FreeDOS kernel. DR-DOS Inc. failed to comply with the GPL by not crediting these to their authors and including the source code.^[6] Following complaints from FreeDOS developers, DR DOS Inc. pulled all 8.x versions from their website.

This section may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can (November 2007).

There are some lessons about how to make a graphic bootable floppy disk with Dr-Dos 7.03 for children written at the beginning of the 2000 by the Italian author Claudio Colitti as "made especially to assist missionary and humanitarian educational projects against digital divide in underpriveledged areas globally." The project was also a reply to another Italian author who made Mulinux, a not graphic OS on a single floppy disk. The site do not include any kind of file but only the old addresses where to find them and how to assemble them in a way to obtain a quasi-QNX floppy disk (including the graphic browser Arachne and the graphic desktop Desktop2)^[8]. Because the actual asking price of 25,000 dollars for the use of Dr-Dos 7.03, today these lessons are became part of the Archaeological Informatics' lessons loosing the original educational projects against the digital divide typical of a non-commercial use only source code license.

• Comparison of x86 DOS operating systems
• CP/M
• MP/M
• DOS Plus
• OpenDOS
• Multiuser DOS
• FreeDOS

1. ^ http://members.ozemail.com.au/~geoffch@ozemail.com.au/editorial/aard/index.html
2. ^ http://www.cisnet.com/glennmcc/download/drdos-hist.txt
3. ^ http://drdos.moriy.com/files/autoexec.gif
4. ^ http://drdos.moriy.com/files/configsys.gif
5. ^ http://home.att.net/~short.stop/freesoft/os.htm#drdos45
6. ^ ^{a b} http://www.freedos.org/freedos/news/press/2005-drdos.html
7. ^ http://www.drdos.com/products/buyout.htm?rnd=1079633491511
8. ^ http://treasure.reset00.com

• Official DR-DOS site
• Enhanced DR-DOS/OpenDOS Project
• Enhanced DR-DOS Forum
• Dr-DOS Wiki
• Graphic Dr-DOS 7.03 Project (with Graphic Browser) on a single bootable floppy disk for children