Couplement Forth   README


Couplement Forth is a small and experimental STC (Subroutine-Threaded Code) Forth system under development for ZX Spectrum, with a BASIC file interface easy to adapt to any DOS.

Home page and repository:


Couplement Forth was forked on 2014-12-30 from ForthCoupe, an abandoned project based on John A. Avis' SamForth .


“Couplement” resembles first to the SAM Coupé origin of this Forth system, and the combination of the original source with the ZX Spectrum operating system; and second, it resembles to the file interface combination with BASIC.

Besides, I found the following quote in the “couplement” entry of The Collaborative International Dictionary of English v.0.48 [gcide], which was definitive for choosing the name:

And forth together rode, a goodly couplement.

— Spenser


Couplement Forth is usable, but many common words and are still missing, and there’s no disk support yet: the only input is the keyboard.

A Git repository was created on 2016-03-12 from the development backups, in order to make future development easier and preserve the evolution of the code. On 2020-12-06 the Git repository was converted to a Fossil repository, keeping GitHub as a mirror.

Most ideas noted for Couplement Forth have already been implemented in Solo Forth, a DTC (Direct-Threaded Code) Forth system under active development for ZX Spectrum 128 with G+DOS, +3DOS or TR-DOS, with a huge library.


Couplement Forth will evolve slowly, as a test system to try and benchmark a subroutine-threaded Forth in the Z80 processor.


A Makefile is provided. The only requirement is the Pasmo assembler. Do make and a TAP file will be created in the <bin> directory.