Forth Computers

Most 8-bit era home computers had a built-in Basic both as the programming language and the command line interface (in the 16-bit era and later on programming languages weren’t built-in any more and either a command shell or a graphical desktop system took over the task to handle the basic command needs of the user).

Well, “most computers” is not all computers and there are a few that had (or have) a built-in Forth dialect. I want to list these in this posting (if you click on the names, you find more in-depth information on

Jupiter Ace 3000 and 4000

This is the Forth computer per se. Widely known in collectors’ circles, these UK-built machines exist in a 9000 devices series (Ace 3000) and in a 800 devices series (Ace 4000). The 3000 series was the UK model while the 4000 was (mainly) the US model. Being mainly ZX81-likes with Forth, the programming language provided the far better computing performance than the Basic of the ZX81 even if the machine had only 3k RAM…

Unfortunately, the company soon ceased operation because the machine was behind the then state of the art.

The Collectors Index of the 3000 model is 13, of the 4000 model is 3. The average price of the 3000 model is 214 Euro (7 sales), of the 4000 unknown (since there were no recorded sales).

Here is a link to the definitive Ace page,

Micronique Hector HRX

Far lesser known than the Aces, also a French company built a Forth-based machine, namely the Hector HRX from Micronique.  Nothing seems to be known on the number of produced machines, but it should be small. The Collector Index is only 5, and the sole recorded sale was the one to me 🙂 (it did not go via Ebay, but a french gentleman reacted on a small ad on a french board). Therefore, the average price is not very trustworthy… In general, french computers have a small collectors community, not only, but also because the french have all documentation and the texts stored in the computer in french :-).

Micronique Hector MX

The MX was the last model, featuring both Basic and Forth. It is a very rare machine with a Collectors Index of 0 and no recorded sales, but it seems some collectors have it.

<update 14.01.2009>

Canon Cat

Oops, now I forgot another interesting Forth computer, the Canon Cat. This was a very rare computer that “was targeted at low-level clerical workers such as secretaries.” “The Cat featured an innovative text based user interface that did not rely upon a mouse, icons, or graphics. The key person behind the Cat was Jef Raskin, an eclectic gadgeteer, who began the design of the Cat during his work on the first Macintosh project at Apple Computer in 1979.”

The Cat’s built-in software contains not only a Forth interpreter (see this link on how to activate Forth on this machine), but the entire built-in software was written in Forth.

The prototypes of the Cat called Swyft and the SwyftCard (an Apple II card) from Jef Raskin’s company Information Appliances therefore were also equipped with Forth, but the first is a prototype and the latter not a computer.


OpenFirmware (OpenBoot)

This is not a computer, but a booting or firmware architecture used by quite some computers based on Forth. This means that on these machines, you can reach a built-in Forth interpreter prompt. Unfortunately, you can do this only after switching on the computer, i.e. in the boot phase. The computers that use this architecture are:

  • Sun SPARC systems
  • post-NuBus PowerPC-based Apple Macintosh computers
  • Pegasos
  • IBM POWER systems
  • OLPC XO-1 (yes, the famous $100 Laptop)

These are all common (well, except the Pegasos) computers that are not rare, or still actual products.

I will not start listing printers, although 1) printers are computers, 2) Postscript is some-sort-of-Forth-dialect 🙂


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