Bill Gates Reflects on 50-Year-Old Code That Helped Shape Modern Computing

Half a century ago, a young Bill Gates wrote a piece of code that would change the course of technology forever. Looking back, the Microsoft co-founder still considers it “the coolest code” he ever wrote—one that set the foundation for a tech empire and revolutionized personal computing.

In January 1975, a 19-year-old Gates, then a freshman at Harvard, came across an article in Popular Electronics magazine. The piece introduced the Altair 8800, a minicomputer powered by an Intel microprocessor, marking a pivotal moment in computing history.

Excited by the possibilities, Gates and his high school friend Paul Allen saw an opportunity. They contacted Ed Roberts, the CEO of Micro Instrumentation and Telemetry Systems (MITS), the company behind the Altair, and boldly claimed they had developed software to run on the new machine. There was just one problem—they hadn’t written it yet.

With no actual Altair 8800 to test on, Gates and Allen had to create their software in the dark, relying on their knowledge of the BASIC programming language developed at Dartmouth in 1964. For two months, they worked tirelessly, often sacrificing sleep, to craft a program that would make the Altair functional.

When the final code was ready, they tested it for the first time—miraculously, it worked. That moment not only marked the beginning of personal computing but also paved the way for the birth of Microsoft in April 1975.

“That was the revolution,” Gates recalled in a recent blog post celebrating the golden anniversary of Microsoft’s founding. “That was the thing that ushered in personal computing.”

The software that Gates and Allen developed became the first operating system for the Altair 8800, proving that personal computers could be accessible to everyday users. This breakthrough led to the creation of Microsoft, a company that would go on to dominate the software industry with products like Windows, Word, Excel, and PowerPoint—tools that remain essential today.

Microsoft’s impact has only grown over the decades. While Gates stepped down as CEO in 2000 to focus on philanthropy, the company has flourished under current CEO Satya Nadella, reaching a staggering market valuation of $2.8 trillion.

At 69, Gates has been in a reflective mood, revisiting his past as he prepares to turn 70 in October. His recent memoir explores his childhood, his early days in computing, and his complex relationship with fellow tech pioneer Steve Jobs, whose company, Apple, will mark its 50th anniversary in 2026.

Fifty years after writing that first game-changing code, Gates remains in awe of how his dream became a reality.

“It’s crazy that the dream came true,” he said.