To mark the occasion, Gates has released the source code he and Allen wrote for the Altair 8800 – dubbed Altair BASIC – which became the company's first product.

Microsoft is celebrating its 50th birthday these days, and it all started with the Altair Basic program. Bill Gates has now published its source code.

In the 1970s, Gates and his Microsoft co-founder, Paul Allen, used a computer in Harvard's lab to compose what he calls the 'coolest code I've written.' It's now public for the first time.