Writing in his bog Gates said: “Before there was Office, Windows 95, Xbox, or AI, there was Altair BASIC,” Gates reminded readers as he reminisced about those long-ago days of nerding out on a PDP-10 at Harvard.

“I still get a kick out of seeing it, even all these years later,” he added, clearly chuffed.

Written in 1975 with Paul Allen, Altair BASIC was the first software Microsoft ever flogged. The pair knocked it out for the Altair 8800, a tinkertoy of a machine that looked like a microwave with knobs. But it worked, and it set the wheels in motion for what would become the beast of Redmond.

In a nod to that “Genesis story for the PC industry,” Gates has bundled the source code drop with his new autobiography Source Code: My Beginnings—the first of three memoirs, because one book isn’t enough for the man who helped wire up the planet.

The drop itself is pure retro gold: 150+ pages of raw assembly, more arcane than most modern developers would dare look at without goggles. It's a museum piece with bite.

Gates called the 50-year milestone “bittersweet,” giving a shout-out to Vole legends like the shy and retiring Steve [sounds of one hand clapping] Ballmer and current boss Satya Nadella for keeping the ship steady. And while Job’s Mob and Chipzilla have each had their rollercoasters over the decades, it’s hard to argue that anyone else owns the legacy Gates just dusted off and flung into the public eye.