In a significant move for tech enthusiasts and history buffs alike, Microsoft co-founder Bill Gates has made the original 1975 source code for Altair BASIC publicly available. This code is not just a piece of software; it represents the very foundation upon which Microsoft was built. Long before the introduction of Windows and Office, Gates and his team developed a meticulously crafted BASIC interpreter tailored for the limited resources of the Altair 8800 microcomputer.
Why did Gates and his team opt for an interpreter rather than a compiler? Gates explained that utilizing a line-by-line approach offered significant advantages for novice programmers. This method provided instant feedback on their code, enabling them to identify and rectify mistakes as they emerged. Such an approach was crucial in fostering a learning environment for beginners in the burgeoning field of computer programming.
The inception of Altair BASIC can be traced back to January 1975, when Gates and fellow co-founder Paul Allen noticed the Altair on the cover of Popular Mechanics. Recognizing the impending PC revolution, they were eager to capitalize on this opportunity. The duo quickly set to work, creating the software in just two months. Interestingly, they pitched their product to MITS founder Ed Roberts as if it were already completed, which added a layer of urgency and excitement to their endeavor.
One of the challenges they faced was the constraint of fitting the entire code into just four kilobytes. This limitation was essential for Altair owners who often could not afford additional memory, which could exceed the cost of the computer itself. Gates reminisced about the difficulties of this early stage, highlighting the innovative spirit that drove the project forward.
Another hurdle was the lack of access to the Intel 8080 chip, the processor on which the Altair ran. To address this, Allen developed a program to simulate the chip on a PDP-10 mainframe, enabling them to test the software without the actual hardware. Additionally, a friend named Monte Davidoff contributed by developing a math package that further enhanced their offering.
While the original version, known as 4K BASIC, may seem limited by today’s standards, it was sufficient for MITS to license the software. Gates reflected on this milestone, stating, “This was a pivotal moment for Paul and me. Altair BASIC became the first product of our new company, which we decided to call Micro-Soft.”
The recently released source code is available as a 157-page PDF of scanned fan-fold paper, rather than in a more modern code repository. Additionally, an annotated disassembly of Altair BASIC 3.2 can be found on GitHub, offering further insights into this historic software. Gates expressed his continued excitement over the project, stating, “I still get a kick out of seeing it, even all these years later.”
As we look back over the past fifty years, it’s evident that computer programming has evolved dramatically. However, Gates remains proud of the humble beginnings that shaped Microsoft and the software industry as a whole. The release of Altair BASIC not only marks a significant moment in tech history but also serves as an inspiration for future generations of programmers.
