Learn Forth On The Commodore VIC-20

Although BASIC was most commonly used on home computers like the Commodore VIC-20, it was possible to write programs in other languages, such as Forth. Conveniently, all it took to set up a Forth development system was inserting the cartridge into the VIC-20 and powering it on, with the VIC-FORTH cartridge by [Tom Zimmer] being a popular choice for the Commodore VIC-20. In a recent video, the [My Developer Thoughts] YouTube channel covers Forth development using this cartridge.

In addition to the video tutorial, the original VIC-FORTH Instruction Manual is also available, together with the 1541 disk image. In an upcoming video, the Commodore 64 version of the cartridge will also be covered, which is called 64Forth, and which is also readily available to tinker with. For those interested in learning more about [Tom Zimmer] and his Forth-related work, a 2010 interview could be interesting. This covers the other platforms which he developed an implementation for.

As for why Forth might be interesting to developers and users, this comes mostly down to the much lower overhead of Forth compared to BASIC, while avoiding the pitfalls of ASM and resource-intensive nature of developing in C, as the entire Forth development system (compiler, editor, etc.) comfortably fits in the limited memory of the average 8-bit home computer.

(Thanks to [Stephen Walters] for the tip)

14 thoughts on “Learn Forth On The Commodore VIC-20

  1. Forth can run with increadible small memory footbrint. But people say, that often you do not know what a programm does after 2 weeks, even if you have written it yourself…

  2. I remember VIC FORTH by HES on a cartridge. Bought it at Children’s Palace Toy Store. It was the second language I learned followed by assembler for the 6502. Great memories.

  3. From Eckehard Fiedler, above:

    “…people say, that often you do not know what a programm[sic] does after 2 weeks, even if you have written it yourself…”

    The almost complete inability to read one’s own Forth program after two week, if it were not documented, is very true, and and results in the following extremely valuable characteristic of Forth–

    …with no documentation, it is almost impossible (some who have tried would say, “completely” impossible) to reverse-engineer a Forth program from object code.
    There are documented instances where Forth has been used as a very effective way to–almost automatically, and immediately–create trade secrets, via the simple expedient of writing the application in a language which most people cannot be bothered to learn because it is too old; not modern enough…
    “Simplicity and elegance are unpopular because they require hard work and discipline to achieve and education to be appreciated.”–Edsger Dijkstra

    “Object-oriented programming is an exceptionally bad idea which could only have originated in California.”–Edsger Dijkstra

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