<P> MS - DOS resulted from a request in 1981 by IBM for an operating system to use in its IBM PC range of personal computers . Microsoft quickly bought the rights to 86 - DOS from Seattle Computer Products, and began work on modifying it to meet IBM's specification . IBM licensed and released it in August 1981 as PC DOS 1.0 for use in their PCs . Although MS - DOS and PC DOS were initially developed in parallel by Microsoft and IBM, the two products diverged after twelve years, in 1993, with recognizable differences in compatibility, syntax, and capabilities . </P> <P> During its lifetime, several competing products were released for the x86 platform, and MS - DOS went through eight versions, until development ceased in 2000 . Initially MS - DOS was targeted at Intel 8086 processors running on computer hardware using floppy disks to store and access not only the operating system, but application software and user data as well . Progressive version releases delivered support for other mass storage media in ever greater sizes and formats, along with added feature support for newer processors and rapidly evolving computer architectures . Ultimately it was the key product in Microsoft's growth from a programming languages company to a diverse software development firm, providing the company with essential revenue and marketing resources . It was also the underlying basic operating system on which early versions of Windows ran as a GUI . It is a flexible operating system, and consumes negligible installation space . </P> <P> MS - DOS was a renamed form of 86 - DOS--owned by Seattle Computer Products, written by Tim Paterson . Development of 86 - DOS took only six weeks, as it was basically a clone of Digital Research's CP / M (for 8080 / Z80 processors), ported to run on 8086 processors and with two notable differences compared to CP / M; an improved disk sector buffering logic and the introduction of FAT12 instead of the CP / M filesystem . This first version was shipped in August 1980 . Microsoft, which needed an operating system for the IBM Personal Computer hired Tim Paterson in May 1981 and bought 86 - DOS 1.10 for $75,000 in July of the same year . Microsoft kept the version number, but renamed it MS - DOS . They also licensed MS - DOS 1.10 / 1.14 to IBM, who, in August 1981, offered it as PC DOS 1.0 as one of three operating systems for the IBM 5150, or the IBM PC . </P> <P> Within a year Microsoft licensed MS - DOS to over 70 other companies . It was designed to be an OS that could run on any 8086 - family computer . Each computer would have its own distinct hardware and its own version of MS - DOS, similar to the situation that existed for CP / M, and with MS - DOS emulating the same solution as CP / M to adapt for different hardware platforms . To this end, MS - DOS was designed with a modular structure with internal device drivers, minimally for primary disk drives and the console, integrated with the kernel and loaded by the boot loader, and installable device drivers for other devices loaded and integrated at boot time . The OEM would use a development kit provided by Microsoft to build a version of MS - DOS with their basic I / O drivers and a standard Microsoft kernel, which they would typically supply on disk to end users along with the hardware . Thus, there were many different versions of "MS - DOS" for different hardware, and there is a major distinction between an IBM - compatible (or ISA) machine and an MS - DOS (compatible) machine . Some machines, like the Tandy 2000, were MS - DOS compatible but not IBM - compatible, so they could run software written exclusively for MS - DOS without dependence on the peripheral hardware of the IBM PC architecture . </P>

Who was the programmer of ms-dos operating system