Here’s the original source code for Microsoft’s very first product

Bill Gates celebrated Microsoft’s 50th Anniversary by sharing the source code that created the company’s foundation. The 157-page PDF available to download on Gates’ blog contains the origins of Altair Basic — a programming language interpreter for the MITS Altair 8800 microcomputer — and “remains the coolest code I’ve ever written to this day,” according to the Microsoft co-founder.

Altair Basic was developed by Gates, fellow Microsoft co-founder Paul Allen, and programmer Monte Davidoff. The trio reportedly coded “day and night for two months” in 1975. Personal computers were extremely rare, but after seeing the Altair 8800 on the cover of a magazine, Gates and Allen believed that enabling its chip to run a version of the Basic programming language would revolutionize the industry.

“We considered creating a similar tool called a compiler that translates the entire program and then runs it all at once,” Gates said on his blog. “But we figured the line-by-line approach of an interpreter would be helpful to novice programmers since it would give instant feedback on their code, allowing them to fix any mistakes that crop up.”

MITS decided to license the software from Gates and Allen, and Altair Basic became the first product under their new company Micro-soft. You can check out the full code document below or on Gates’ blog. Not only does it have some other details about the early history of Microsoft, but the web page UI has been designed with some funky animations and graphics that pay homage to the retro coding project.