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MS-DOS: The $50,000 Operating System That Built Microsoft

Zusammenfassung

Microsoft did not write MS-DOS. They bought it for $50,000 from Seattle Computer Products, where it had been written in six weeks by programmer Tim Paterson as a temporary placeholder. Microsoft then licensed it to IBM for a per-copy fee while retaining the right to sell it to other computer manufacturers. This licensing structure — not the $50,000 purchase — was the decision that made Microsoft the dominant software company of the personal computing era. IBM paid Microsoft for copies; Microsoft owned the operating system; the clone market ran Microsoft software on IBM-compatible hardware. By 1990, Microsoft had revenues of $1.18 billion.

The IBM Opportunity

In 1980, IBM was building a personal computer in secret under the codename “Project Chess.” The 12-person team in Boca Raton, Florida, led by Don Estridge, needed an operating system. IBM approached Digital Research, the company of Gary Kildall, to license CP/M — then the dominant microcomputer operating system. The meeting went poorly; Kildall was unavailable, and the negotiations broke down. IBM turned to Microsoft.

Bill Gates and Paul Allen at Microsoft did not have an operating system to offer. But Gates knew of Seattle Computer Products’ QDOS (Quick and Dirty Operating System), which Tim Paterson had written as a CP/M-compatible system for the 8086 processor. Microsoft purchased the rights to QDOS for $50,000 in July 1981 (having previously licensed it for a smaller amount), renamed it MS-DOS, and licensed it to IBM.

The Critical Clause

The IBM contract gave IBM the right to use MS-DOS in its PC, under the name PC-DOS. But Microsoft retained the right to license MS-DOS to other companies. This single clause determined the personal computing industry.

When the IBM PC launched in August 1981 and became commercially successful, a clone market quickly developed: Compaq, Tandy, NEC, and hundreds of others built IBM-compatible computers. IBM-compatible hardware required IBM-compatible software — which meant MS-DOS. Every clone PC maker was a Microsoft customer. IBM had inadvertently paid to build a market for its competitor’s most profitable product.

By 1984, MS-DOS was installed on nearly every IBM-compatible personal computer sold. Tim Paterson, who had written the original in six weeks, was hired by Microsoft. He received no share of the revenue from the product he had written.

The Trajectory to Windows

MS-DOS provided the revenue and market position that allowed Microsoft to develop and ship Windows. Windows 1.0 (1985) and Windows 2.0 (1987) were graphical shells on top of DOS; Windows 3.0 (1990) and Windows 3.1 (1992) were the first versions widely adopted by businesses. The transition from DOS to Windows maintained Microsoft’s operating system dominance through the shift from command-line to graphical interfaces.

The full story of how the IBM PC’s open architecture created the conditions for Microsoft’s dominance is one of the central narratives of personal computing history.

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