DR-DOS

In the early 70’s, there was a company known as intergalactic Digital Research. The name was just a little too geeky for even them, and was later shortened to Digital Research. The founder, Gary Kildall, created the first Disk Operating System for Microcomputers called CP/M (Control Program for Microcomputers). This became THE operating system for hobbyist microcomputers. A few years later this changed a bit (or was supplemented) when Steve Jobs and Steve Wozniak designed a home computer that came prebuilt. It was a wild concept for the time, not having to build your computer — it was a wildly successful idea as well. The micro(home)-computer bloomed from a small little hobby toy, into something that many small businesses wanted and felt they needed. But there was still the other group of CP/M builders and users.

Digital Research’s original CP/M for the 8-bit Intel 8080 and Z-80 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.

IBM originally approached Digital Research, seeking an x86 version of CP/M. However, there were disagreements over the contract, and IBM withdrew. Instead, a deal was struck with Microsoft, who purchased another operating system, 86-DOS, fromSeattle Computer Products. This became Microsoft MS-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 to be too similar to CP/M. IBM settled by agreeing to sell their x86 version of CP/M, CP/M-86, alongside PC DOS. However, PC DOS sold for $40, while 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 was very small, and the availability of compatible application software, at first decisively in Digital Research’s favor, was only temporary.

Digital Research fought a long losing battle to promote CP/M-86 and its multi-tasking multi-user successor Concurrent CP/M-86, and eventually decided that they could not beat the Microsoft-IBM lead in application software availability, so they modified Concurrent CP/M-86 to allow it to run the same applications as MS-DOS and PC DOS.

First DR DOS version

As requested by several OEMs Digital Research started to plan develop a new DOS operating system addressing the shortcomings left by MS-DOS in 1987. The first DR DOS version was released on 28 May 1988. Version numbers were chosen to reflect features relative to MS-DOS; the first version promoted to the public was DR DOS 3.31, which offered features comparable to Compaq MS-DOS 3.31 with large disk support (FAT16B aka “BIGDOS”). DR DOS 3.31 reported itself as “IBM PC DOS 3.31”, while the internal BDOS (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 API support stripped out and the XIOSreplaced 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 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 was also named ROS (ROM Operating System). 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 was only available to OEMs bundled with hardware. Consequently, DR 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 (BDOS 6.0, 1988-06, OEM only), 3.32 (BDOS 6.0, 1988-08-17, OEM only), 3.33 (BDOS 6.0, 1988-09-01, OEM only), 3.34 (OEM only), 3.35 (BDOS 6.0, 1988-10-21, OEM only), 3.40, 3.41 (BDOS 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 name designation, one OEM version is known to be called EZ-DOS 3.41.

Novell DOS was Novell Corporation’s name for DR-DOS during the period when Novell sold DR-DOS, after the acquisition of Digital Research in 1991. Regarding features and performance, it was typically at least one release ahead of MS-DOS.[13] In 1993, PC DOS 6.1, MS-DOS 6.2 and PC DOS 6.3 were trumped by Novell’s DOS 7.0.

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