Gates addresses early personal-computer hobbyists about the widespread copying of Altair BASIC, developed by Gates, Paul Allen and Monte Davidoff. He says that although many people report using the software, relatively few have bought it. He contrasts the expectation that computer hardware must be purchased with an emerging culture in which software is freely copied, arguing that this leaves programmers poorly compensated for their work.

Gates presents the issue as a threat to the development of professional software for the hobbyist market. He cites the time and computing costs involved in creating, improving, testing and documenting BASIC, and argues that developers have little incentive to make similar investments without adequate payment. He also criticises people who resell copied versions of the software. The letter closes by inviting payments, comments and suggestions, while expressing Gates’s aim of employing more programmers to produce software for the growing personal-computer market.