In April 2025, Microsoft co-founder Bill Gates celebrated the company's 50th anniversary by releasing the original source code for Altair BASIC, the first product developed by Microsoft (then known as Micro-Soft). This code, written in 1975, laid the foundation for Microsoft's future innovations. Gates described it as "the coolest code I’ve ever written to this day." (gatesnotes.com)

The Altair 8800, featured on the cover of the January 1975 issue of Popular Electronics, inspired Gates and his friend Paul Allen to create a BASIC interpreter for the machine. Despite not having written the code yet, they contacted MITS, the manufacturer of the Altair, and promised a compatible software solution. Over the next two months, they developed the interpreter, overcoming challenges like fitting it into the limited memory of the Altair 8800. (gatesnotes.com)

The release of the Altair BASIC source code is available as a 157-page PDF, providing a glimpse into the early days of personal computing and Microsoft's origins. (gatesnotes.com)

Bill Gates Reflects on Altair BASIC and Microsoft's Origins: