William H. Gates III (born 1955) entered computing history through the microcomputer revolution of the mid-1970s. In a Video History Interview conducted for the National Museum of American History by David Allison, Gates recounts the founding moment: he and Paul Allen saw the Altair 8800 on the cover of Popular Electronics, realized the new microprocessors needed software, and resolved to write a BASIC for the machine before anyone else did. They wrote it without ever touching an Altair, testing their code on a simulator of the Intel processor running on a DEC PDP-10 time-sharing system.
That gamble produced Altair BASIC and, with it, Microsoft. Gates laid out the design and wrote much of the BASIC code while Allen handled the interface to the actual hardware. The Computer History Museum dates the working interpreter to March 1975, and the surviving paper tape bears the inscription “Bill Gates Paul Allen MITS Altair 2 Mar 75.” The company the two founded that year was built on a single idea Gates pursued relentlessly: that software was a product to be written once and licensed, not given away with hardware.
Gates pressed that conviction publicly and bluntly. In February 1976, frustrated that hobbyists were copying Altair BASIC freely, he published “An Open Letter to Hobbyists” in the Homebrew Computer Club Newsletter, charging that “as the majority of hobbyists must be aware, most of you steal your software,” and asking “who can afford to do professional work for nothing?” The letter, covered in this library under the slug the-open-letter-to-hobbyists, is one of the earliest and clearest statements of the proprietary-software position.
In the years that followed, Gates extended the same licensing model from a language to an operating system. When IBM came looking for software for its 1981 personal computer, Microsoft supplied the operating system that became PC DOS and MS-DOS, retaining the right to license it to other manufacturers. That arrangement, more than any single piece of code, made Microsoft the dominant software company of the personal-computer era and Gates one of its central figures.