Still, the keyword was "easy." So, early developers kept using BASIC and porting it to one computer after another. Then, as the years rolled by, another paradigm for computing power emerged: The PC.

While remembering a Kodak moment of holding a foot-long piece of paper featuring the code, Gates indicated that Altair BASIC was inspired by the January 1975 copy of "Popular Electronics" magazine.

Gates and Paul Allen wrote it in BASIC using a PDP-10 mainframe at Harvard. Gates has now published a 157-page PDF of scanned, yellowed pages for all to see. "That code remains the coolest code I ...