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16-bit SUBLEQ eForth

If you feel like supporting the project you can buy a book from Amazon, available here that describes how the project works and how to port a Forth to a new platform.

This project contains a working (self-hosting) Forth interpreter that runs on top of a SUBLEQ 16-bit machine. SUBLEQ machines belong to the class of One Instruction Set Computers, they only execute a single instruction but are still Turing Complete. The Forth system, specifically a variant of eForth, is provided as subleq.dec, passing this image to the tiny (~ 600 bytes) SUBLEQ C virtual machine allows you to run eForth on the machine. For a list of commands type "words" and hit enter, numbers are entered using Reverse Polish Notation, eg. "2 2 + . cr" prints "4", and new functions can be defined like so:

: hello cr ." Hello, World" ;

Be careful with the spaces, they matter, after typing that in, type "hello" and hit enter. A Forth tutorial will not be provided here. Many Forth words are defined including the bitwise words.

To build and run you will need a C compiler and Make, type "make run", failing that:

cc subleq.c -o subleq
./subleq subleq.dec

The system is self hosting, that is it can generate new eForth images using the current eForth image and the eForth source code. This is done like so:

./subleq subleq.dec < subleq.fth > new-image.dec

There is a website available that runs an interactive SUBLEQ interpreter in the browser in case you do not want to both compiling things, it is available at https://github.com/howerj/subleq-js. Or if you just want to try it out directly https://howerj.github.io/subleq.htm.

Happy hacking, and a shiny penny for anyone that manages to do something useful with this project!

Other SUBLEQ projects

References