Like a not inconsiderable number of other people, Bill Gates was in the right place at the right time to write an operating system for the first generation of personal computers. That he did not write one of them isn’t surprising, since a lot of other people didn’t, either. What distinguishes Gates is that, unlike everyone else, he came to own the legal rights to PC-DOS. Why him, and how? The “Open Letter to Hobbyists” helps explain. It’s a landmark assertion of property rights within the community: It attempts to draw a thick line between the hobbyist era and the microcomputer industry, and it’s characteristic of the way Gates made his billions with Microsoft. The Homebrew pirates saw computer science as essentially a public domain, and in the 1970s, in a descriptive sense, they were right. Public dollars paid for almost all the computing power in the country, even when the computers were technically privately owned. The hackers could point to Gates’s use of the ARPA PDP at Harvard not only because they had experience pulling the same con, using official processors after hours for personal projects, but also because there were only so many computers he could have used to write the BASIC interpreter. They all learned to code on publicly financed Big Science machines, whether at universities, at commercial defense contractors, or in the military itself. With a draft on, where exactly individuals fit in this complex wasn’t usually up to them anyway. The knowledge products of that work, like BASIC, belonged to the people. It was acceptable to use the knowledge to make products and sell them—hobbyists were always first in line to buy, too—but to fence off an important set of instructions and start charging monopoly rents for them was an audacious move. [...]