Paul Gardner Allen (1953-2018) was the co-founder of Microsoft and, with Bill Gates, the co-author of the company’s first product. The 1975 MITS Altair BASIC Reference Manual lists “Bill Gates, Paul Allen and Monte Davidoff” as the “joint authors of the ALTAIR BASIC Interpreter,” and the Computer History Museum’s catalog record for the original paper tape (X507.84) preserves Allen’s name alongside Gates on the artifact that began Microsoft, inscribed “Bill Gates Paul Allen MITS Altair 2 Mar 75.”
Allen’s role in the founding story was as much instigator as implementer. It was Allen who brought Gates the January 1975 issue of Popular Electronics announcing the Altair 8800, arguing that microprocessors were about to change everything and that they had to act before the moment passed. When they decided to write a BASIC for a machine neither had seen, Allen wrote the simulator of the Intel processor on a DEC PDP-10 that let them develop and debug the interpreter, and he flew to MITS in Albuquerque to demonstrate it.
The name of the company was Allen’s coinage. The partnership the two formed in 1975 to sell the interpreter was called Micro-Soft, a contraction of microcomputer and software, later written without the hyphen as Microsoft. While Gates concentrated on the BASIC language code, Allen focused on the systems and hardware side, the layer that connected the software to real machines.
Allen remained central through Microsoft’s rise in the personal-computer era before stepping back from day-to-day work later in the decade. His firsthand recollections, including talks given at the Computer History Museum, consistently describe the same arc: spotting the Altair, racing to write BASIC for it, and turning a paper-tape interpreter into the seed of one of the most influential software companies in history.