Microsoft BASIC For The Dragon 64 Recovered

There are a great many pieces of software of yesteryear that are no longer readily accessible. It’s now possible to cross Microsoft BASIC for the Dragon 64 off that list, with the source code now posted for all to enjoy on GitHub.

The repository concerns the Microsoft 16K BASIC Interpreter as built for the Motorola 6809, as used in the Dragon 64 computer. This is also known as BASIC-69 or Extended Color Basic.

Hilariously, the source code was recovered from 340 pages of fan-fold tractor paper stored in four bundles. The output of a Motorola assembler was printed back in 1983 at Dragon Data’s R&D facility in Wales, and was recently recovered after being stored in an attic for much of the last four decades. The paper was carefully scanned at the 2022 Dragon Meetup, before passing the resulting images through OCR software. The output was then manually corrected and the source code was complete for both the 32K and 64K mode ROMs. There are some differences between the scanned source and what Microsoft shipped, which is outlined in the repository.

We’ve seen other heroic retrocomputer recovery efforts before, too, like the work to save the Polish CROOK OS. If you’ve been working on similar feats, be sure to let us know.

17 thoughts on “Microsoft BASIC For The Dragon 64 Recovered

  1. I’m impressed the ink was still readable – I know I’ve lost lineprinted documents in a lot less than 4 decades! Facetiously, though, the source could’ve been put to better use given it was on perforated sheets already. I had a D32, and the BASIC was almost as bad as the keyboard.

    1. Oops, I now see he was actually involved. Which is odd that it’s got a look-but-don’t-touch license. It seems they did get permission to release the Dragon Data code, so I wonder why it doesn’t have a proper open source license?

  2. I wish I still had my Dragon 64, but I swapped it with a mate for something – don’t remember what. It’s the only computer from back in the 80s that I had then but don’t have now.

  3. “The paper was carefully scanned”. If only I had this capability as a teenager in c.1980, it would have saved me from having to type in the entire assembler source of Sargon Chess from the book!

  4. In a sense, most of this was already available in the “Color Basic Unravelled” series of books, where hobbiest disassembled the 6809 rom on their own. (Just as the 8080/Z80 Basic code was explained in “Microsoft Basic Decoded & Other Mysteries”, and a ton of equivalent 6502 Basic dissembles.) But it’s good to have source comments

    Microsoft 6809 Basic was a translation of their 6502 version (with new graphics commands) which has also leaked. Michael Steil has been documented it and various releases in many entries at, like

  5. The ROMs of the TRS 80 model one were dumped decades ago and the assembler “source” made available in a book. As I recall, there was a page or two left out initially in an attempt to avoid legal issues. The missing pages were quickly filled in by others.

    1. Not just the ROM but the TRSDOS as well. Not just the assembly but comments, descriptions and callouts covering major functionality. There were several books that covered the ROMs but only one that I recall for TRSDOS.

      The most prevalent ones I remember:

      I have both of the Soft Sector Marketing published books and I remember swallowing hard buying them (they weren’t cheap if I recall) but the knowledge I gained from looking at that was huge.

      Both books disappeared after SSM went out of business in 1983 but I still have my copies after all these years.

      I ended up writing my first commercial software packages based on that knowledge: a print spooler and a cursor-oriented directory utility that showed you what was on the disk and executed files appropriately based on the extension.

      It was sold in via an 80 Micro ad from Lynn Computer Services and Joe paid me a royalty for each one sold. Didn’t get rich but it more than paid for the books – the knowledge is just a bonus that keeps on paying off.

  6. Pretty sure I’ve got a Dragon ROM disassembly printout in the attic along with various other interesting bits and pieces. Dragon times were very happy times indeed for me!

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