Microsoft Unlocks Its 6502 Basic: Bringing a Classic to Open Source Life

Microsoft Open Sources Historic 6502 BASIC Code, Reviving Computing’s Past

September 5, 2025 – A pivotal moment in computer history unfolded today as Microsoft officially released the source code for its 6502 BASIC interpreter under an open-source license. This action makes available one of the company’s earliest products, now accessible on GitHub, promising a resurgence of interest in the roots of personal computing.

The Dawn of Microsoft and the 6502 BASIC

The story begins in 1975, when Bill Gates and Paul Allen embarked on their entrepreneurial journey, creating a BASIC interpreter for the altair 8800. Recognizing its potential, they adapted the code for a range of 8-bit processors, moast notably the MOS 6502. This processor powered iconic machines of the 1970s and 80s. By 1976,gates and Ric Weiland had finalized the 6502 version,securing a $25,000 investment that catapulted Microsoft into the heart of the burgeoning home computer market.

This foundational code quickly became integral to systems like the PET,VIC-20,and the wildly popular Commodore 64. The Commodore 64, in particular, became a gateway for a generation, fostering a love of programming through its accessible BASIC environment.

A Nostalgic Easter Egg and Enduring influence

The version now available – Basic M6502 8K Ver 1.1 – is the same code that powered those original Commodore machines starting in 1978. Interestingly, a hidden easter egg, signed by Bill Gates himself, was recently confirmed through documentation dating back to 2010, located in the ‘Stordo’ and ‘Stord0’ labels.

The impact of this code extended far beyond Commodore. It directly influenced the progress of Applesoft BASIC for the Apple II, providing a simple yet powerful entry point for millions learning to code. the now-iconic loop – “10 PRINT “HELLO” / 20 GOTO 10″ – became a rite of passage for budding programmers.

Processor	Key Computers	Impact
MOS 6502	Commodore 64, Apple II, Atari 2600, NES	Provided a foundation for early personal computing and gaming.
Altair 8800	Altair 8800	Microsoft’s first product; spurred early software development.

legacy Lives On

The 6502 processor maintains a dedicated following among retro-computing enthusiasts. Actually, a new Commodore 64, built using FPGA technology, was recently announced, demonstrating the lasting appeal of this classic platform. This open-source release builds on years of dedicated work by enthusiasts, like Michael Steil, who painstakingly reconstructed and documented the original source code.

This move follows Microsoft’s 2020 open-sourcing of GW-BASIC, used on early IBM PCs, and serves as a testament to the company’s growing commitment to open-source principles. This decision formalizes and expands the community’s ability to explore, modify, and share this pivotal piece of software history.

A living Archive for Future Generations

Microsoft’s release provides more than just a historical artifact. It offers a usable tool, supported by modern FPGA emulators and projects. From the familiar green screen of the Commodore 64 to contemporary development environments, BASIC continues to bridge generations of programmers. The 6502 BASIC is no longer simply a memory – it is indeed now officially available, modifiable, and shareable under an open-source license.

The Enduring Relevance of BASIC

While modern programming languages have evolved substantially, the core concepts taught through BASIC-variables, loops, conditional statements-remain essential to software development today. Understanding the simplicity of BASIC can provide valuable insights into the foundations of more complex languages.

Pro Tip: Explore online emulators to run the 6502 BASIC code within your web browser for a truly nostalgic experience.

Frequently Asked Questions About Microsoft 6502 BASIC

• What is 6502 BASIC? It is an early version of the BASIC programming language designed for computers using the MOS 6502 processor.
• Why did Microsoft open-source this code? To preserve computing history and encourage further exploration and development by enthusiasts.
• Where can I find the code? The source code is available on GitHub at https://github.com/microsoft/BASIC-M6502.
• What was the Commodore 64? A hugely popular home computer from the 1980s, known for its affordability and ease of use.
• Is BASIC still relevant today? While not widely used for professional development, BASIC’s core concepts remain fundamental to programming.
• What is an FPGA? A Field-Programmable Gate Array, a reconfigurable integrated circuit used to emulate older hardware.
• How did Bill Gates leave his mark on the code? He included an Easter egg within the code, confirmed as a signature of his work.

what are your fondest memories of early computing? do you think open-sourcing historical code is important for preserving tech history?

How does open-sourcing the 6502 BASIC interpreter contribute to the preservation of computing history?

A Deep Dive into the Microsoft 6502 BASIC Release

Microsoft’s recent decision to open-source its version of the 6502 BASIC interpreter is a notable moment for retrocomputing enthusiasts, software historians, and anyone interested in the roots of modern programming. This isn’t just about nostalgia; it’s about preserving a crucial piece of computing history and enabling a new wave of experimentation. the release, available on GitHub, includes the original source code, documentation, and even some example programs. This move unlocks a treasure trove for developers and hobbyists alike.

What is 6502 BASIC and Why Does It Matter?

The 6502 microprocessor, released in 1975, powered iconic machines like the Apple II, Commodore 64, Atari 8-bit family, and the Nintendo entertainment System. 6502 BASIC was the primary programming language for many of these systems, offering a relatively simple entry point into the world of coding.

Accessibility: BASIC (Beginner’s All-purpose Symbolic Instruction Code) was designed to be easy to learn, making it ideal for introducing people to programming.

Ancient Importance: It represents a foundational era of personal computing, shaping the skills of a generation of programmers.

Influence on Modern Languages: Concepts introduced in BASIC, like loops and conditional statements, are still fundamental to modern programming languages like Python and JavaScript.

The Microsoft Connection: Microsoft’s early success was largely built on licensing its 6502 BASIC to hardware manufacturers. This release acknowledges that pivotal role.

The Details of the Open-Source Release

Microsoft’s release isn’t just a code dump. It’s a carefully curated package that includes:

Source Code: The complete source code for the 6502 BASIC interpreter, written in assembly language. This allows for deep analysis and modification.

Documentation: Original documentation, including manuals and technical notes, providing insights into the interpreter’s design and functionality.

Example Programs: A collection of example programs demonstrating various BASIC features and techniques. These are invaluable for learning and experimentation.

Licence: Released under the MIT License, allowing for broad use, modification, and distribution. This permissive license encourages community contributions.

GitHub Repository: Hosted on GitHub (https://github.com/microsoft/6502-basic), facilitating collaboration and version control.

What Can You Do with Open-Source 6502 BASIC?

The possibilities are extensive. Here are a few ideas:

1. Emulation and Preservation: Improve existing 6502 emulators or create new ones, ensuring these classic systems remain accessible.
2. reverse Engineering: Study the interpreter’s code to understand how it works and gain insights into 6502 assembly programming.
3. Porting: Port the interpreter to new platforms, allowing you to run 6502 BASIC programs on modern hardware.
4. enhancements: Add new features to the interpreter, such as improved graphics capabilities or networking support.
5. educational Purposes: Use the code as a teaching tool to introduce students to the fundamentals of programming and computer architecture. Retro computing is gaining traction in education.
6. Game Growth: Create new games for classic 6502 systems, leveraging the power of modern development tools.

Benefits of Open Sourcing: A Community-Driven Future

Open-sourcing the 6502 BASIC interpreter offers several key benefits:

Community collaboration: A global community of developers can contribute to the project, improving its quality and functionality.

Preservation of History: Ensures that this significant piece of computing history is preserved for future generations.

Innovation: Encourages experimentation and innovation,leading to new and exciting applications of 6502 BASIC.

Educational Resource: Provides a valuable resource for students and educators interested in learning about the history of computing.

Increased Accessibility: Makes the interpreter more accessible to a wider audience, fostering a vibrant retrocomputing community.

Practical Tips for Getting Started

If you’re interested in diving into the 6502 BASIC source code,here are a few tips:

* Familiarize Yourself with 6502 Assembly Language: understanding 6502 assembly is crucial for comprehending the interpreter’s code. Resources like the 6502.org website ([https://www650[https://www650