Microsoft has quietly open-sourced the original 6502 BASIC programming language code, written by Bill Gates back in the early days of the company. This version of BASIC was built for some of the most iconic early 8-bit computers, including the Apple II and the Commodore PET. Now, the source code is freely available for developers, historians, and computing enthusiasts to study.
It is not just any code, it represents a cornerstone of personal computing history. Gates, along with his small team, developed this interpreter to work with the MOS Technology 6502 microprocessor, which was one of the most widely used chips of its era. The release came without much fanfare, tucked into a GitHub repository, but its importance is undeniable. What makes it even more fascinating is that the code is thoroughly commented, giving today’s readers a glimpse into the programming mindset of that time.
Key Takeaways
- Microsoft open-sourced the 6502 BASIC code written by Bill Gates.
- Originally created for 8-bit computers like the Apple II and Commodore PET.
- Public release allows open access for study, development, and preservation.
- Available on GitHub with original developer comments intact.
- The 6502 BASIC interpreter was a key building block of early personal computing.
The History of 6502 BASIC
The MOS Technology 6502 was an 8-bit microprocessor that shaped the computing landscape of the late 1970s and early 1980s. It powered machines that would go on to define the home computing revolution, including the Apple II, the Commodore PET, and the BBC Micro. These machines needed something approachable, a way for ordinary users to write programs, and BASIC interpreters filled that role.
At the time, Bill Gates and Paul Allen’s fledgling company, Micro-Soft (as it was spelled back then), had already proven itself with Altair BASIC, their very first commercial product for the MITS Altair 8800. Building on that success, they reworked BASIC for different processors, ensuring manufacturers could bundle it with their systems. The 6502 version was particularly important. Apple and Commodore both relied on it, and the inclusion of Microsoft BASIC helped legitimize their machines in the eyes of users. In a way, it also cemented Microsoft’s reputation as a serious software company.
The Code Itself
What Microsoft has released is the raw assembly language source code. Unlike modern programming languages such as Python or C++, assembly speaks directly to the hardware. Reading through it is like looking under the hood of computing’s early engine.
The files come packed with handwritten comments, where the developers explained what different pieces of the interpreter were doing. This is invaluable because it shows not only how things worked but also how programmers thought when working within extreme limitations. Every byte mattered, memory was scarce, and the software had to be small, efficient, and clever to run on those machines. The interpreter handled everything from reading user input to executing commands, and the code demonstrates how those seemingly simple tasks were managed in such a constrained environment.
This release is also part of a larger movement among tech companies to preserve historical code. Making it public ensures it does not just survive as a footnote but can be studied, modified, or even tinkered with in modern projects. For some, it is a nostalgic trip, and for others, it is an educational resource or a playground for retrocomputing experiments.
The GitHub repository now serves as a permanent archive, keeping the code accessible to anyone curious enough to explore it. It is a small but meaningful way to keep the roots of modern computing alive, showing just how far we have come and perhaps reminding us of the ingenuity that was required to get things started.
Frequently Asked Questions
Q. Why is these 6502 BASIC codes so important?
A. This code is important because it represents a key piece of early personal computing. It was one of the first widely used software products from Microsoft and a core component of many early home computers.
Q. What is a BASIC interpreter?
A. A BASIC interpreter is a program that reads and executes code written in the BASIC programming language line by line. It allows users to write and run their own simple programs.
Q. Where can I find this open-sourced code?
A. The code is available in a public repository on the official Microsoft GitHub account. You can access and download it from there.
Q. Did Bill Gates write the entire code by himself?
A. Bill Gates wrote a significant portion of the core code for this BASIC interpreter. His team at Micro-Soft also contributed to its development and porting to different machines.
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