Original 1975 Altair BASIC Source Code Released via GatesNotes

The original source code for the Altair BASIC interpreter, the software that served as the catalyst for the modern software industry, has been released as a PDF via GatesNotes. Developed in 1975, this document provides a rare look at the technical origins of Microsoft.

The code was written by Bill Gates and Paul Allen specifically for the MITS Altair 8800, which is widely regarded as the first commercially successful personal computer. The interpreter allowed users to program the machine using a high-level language rather than the cumbersome machine code typically required for early microcomputers. By providing a way to interact with the Intel 8080 processor more intuitively, the software transformed the Altair from a hobbyist's kit into a functional tool.

The Birth of Micro-Soft

This project was more than a technical exercise; it was the foundational event that led to the formal creation of "Micro-Soft." In 1975, the development of the BASIC interpreter established a critical precedent for the entire computing industry: the model of licensing software separately from the hardware it ran on. At the time, software was often bundled for free or treated as an afterthought to the physical machine. Gates and Allen's approach shifted the value proposition, treating software as a proprietary product with its own independent commercial worth.

Industry Implications

The release of this source code serves as a historical artifact documenting the birth of the PC market. It highlights the extreme technical constraints of early microcomputing, where every byte of memory was precious and efficiency was paramount. For the industry, this document represents the starting point of a company that would eventually dominate the global PC market, illustrating how a single interpreter for a niche machine could scale into a global empire.

Historical Legacy

While the code is now a relic of a bygone era of computing, its availability allows researchers and historians to analyze the logic and structure used by Gates and Allen during the microcomputer revolution. The document remains a primary source for understanding how the transition from mainframe computing to personal computing was executed at the software level. As the industry continues to evolve toward cloud and AI-driven architectures, the Altair BASIC source code stands as a reminder of the lean, hardware-constrained environment that defined the first era of personal computing.