DR-DOS
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| Developer |
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|---|---|
| Written in | assembly language |
| OS family | DOS |
| Working state | Current |
| Source model | Mixed; primarily closed-source, some versions open-source |
| Latest release | 7.01.08 / July 2011 |
| Kernel type | Monolithic kernel |
| Default user interface | CLI |
| License | Proprietary |
| Official website | drdos |
DR-DOS (DR DOS, without hyphen up to and including version 6.0) is an operating system of the 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 DOS and Caldera OpenDOS.
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, from Seattle 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.
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