Microsoft has revealed its GW-BASIC fork of the BASIC programming language is now open source. If you’re unfamiliar with the platform, it is worth noting it is not something you will be using for modern program building.

GW-BASIC was released by Microsoft way back in 1983 for the IBM PC XT. It is based on IBM’s Advanced BASIC/BASICA, which itself was ported from Microsoft’s own BASIC language.

Microsoft says GW-BASIC is now available on GitHub. Microsoft says the source code has been written on the assembly language:

“These sources, as clearly stated in the repo’s readme, are the 8088 assembly language sources from 10th Feb 1983, and are being open-sourced for historical reference and educational purposes. This means we will not be accepting PRs that modify the source in any way.”

Features of Microsoft GW-BASIC

Below are some of the core features that shipped with GW-BASIC back in the day:

  • “WHILE…WEND loops
  • Variable names of up to 40 characters
  • OPTION BASE statement to set the starting index of array variables as either 0 or 1
  • Dynamic string space allocation
  • LINE INPUT statement for reading in data from the keyboard
  • CALL statement for executing machine language routines
  • CHAIN and MERGE commands
  • Ability to save programs in either tokenized binary format or ASCII text”

In recent years, Microsoft has been open sourcing some of its old services and platforms. In 2014, the company open sourced MS-DOS and then did so again in 2018. It was a leading operating system for x86 during the 1980s and 1990s before Microsoft ceased development in 2000. The GitHub repository for the OS can be downloaded here.