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https://github.com/bartgo/forth-atari

Programs and code snippets for APX Extended Fig-Forth
https://github.com/bartgo/forth-atari

6502 8-bit apx atari atari800 atari800xl atari8bit atarixl fig-forth figforth forth

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Programs and code snippets for APX Extended Fig-Forth

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README 

          
# "Forth-Atari": source code snippets for Atari 8-bit computers



![fig-Forth booting banner](drafts/figboot.png)



## TL;DR



A collection of fig-Forth code snippets, tools, editors, experiments, and oddities for Atari 8‑bit systems—mostly targeting APX Extended Fig-Forth. Everything comes from old type‑in listings, so expect quirks, broken bits, and nostalgia. Use an emulator (Altirra recommended), not real hardware, unless you enjoy surprises.



## No, really, what is this?



This repository contains different snippets of code implemented in fig-Forth - useful words, data structures, utilities and "stuff" - mainly for Atari 8-bit and the "APX Extended Fig-Forth" by Patrick Mullarky. Despite being a faithful implementation of the FIG "model", APX Forth was nearly never used for commercial purposes, unlike its successor, valForth. Neither was immensely successfull but both deserve being remembered.



Fig-Forth was a "model", described in a standard-like document and sources for multiple microcomputers, popular in the beginning of the 1980s. 



Read about history of Forth [here](https://www.forth.com/resources/forth-programming-language).



## Why would I need it?



If you know, you know.

## How to use these source files?



Any information where the code came from and its possible issues, are mentioned in the comments. I give no guarantee that anything published here will work safely for you - and I especially recommend NOT TO RUN any of it on a real Atari hardware without heavy testing.



All the code comes from type-in listings, published mostly in "Forth Dimensions",  "Micro 6502" or "Tajemnice Atari" in the 1980s and 1990s - so typically are in the public domain or otherwise "free-like". The license was not explicitely stated but the intention was clearly similar to contemporary MIT and in the spirit of fig-Forth. 



The most unstable snippets are in the "drafts" folder and may be in a completely broken state.



Recommended method of using the code snippets:

- check the comments and understand the general concept of the code

- start Atari emulator (Altirra recommended), use atarixl.rom, disable Basic, potentially change the disk saving mode (perhaps to R/W - please check the emulator's manual)

- boot Forth (usually APX Forth)

- paste code into Altirra and test

- if you can't paste the code (i.e. not using Altirra), it has to be converted to an ATR file and connected as a floppy (could be the second one, with the first one being the Forth); scripts present in the "pc-tools" folder may help you



In some cases the code is prepared for storage on the "source screens" and it has to be put on the floppy / ATR by using the FIG editor commands. To see what I mean, check "editors/edit.4th". In any case, running some of the code snippets will not be straightforward.



When in doubt, raise a ticket!

## How to obtain APX Forth?



Er, I knew but forgot... perhaps, buy it on eBay?



## What EXACTLY are the sources?

### ["/asm"](/asm) - snippets of the Forth Assembler code



* LINER2 - shows a line on the screen and allows to move it down (with Help) or up (with Shift-Help); this is a slightly extended port from a machine code application written by Marek Omirski and published in "Bajtek"

* I put here my minor experiments with Forth Assemblers (typically with the Ragsdale Assembler)



### ["/debug"](/debug) - debugging tools



* BREAK&GO - adding breakpoints and starting an internal interpreter to better debug your fig-Forth code

* QMEG - call a machine language monitor, Self Test or QMEG

* STACK-PROMPT - enable or disable stack display



### ["/dictionary"](/dictionary) - manipulating the Forth dictionary



* NAMESPACES - a (failed) attempt to have vocabularies working more like real namespaces 

* RECOLON - redefining a colon word is a great method, allowing to reconnect a more recent definition to its previous version - and to avoid FORGETing and recompiling parts of the dictionary

* TRANSIENTS - temporary (disposable) areas of the dictionary; a typical usage would be to load there development tools (assembler, debugging words, editor) and remove them when no longer needed, without recompiling the rest

* VOCABULARIES - showing that vocabularies allow multi-level inheritance (kind of)

* WHERE-USED - identifying uses of a word, very useful when modifying the language



### ["/docs"](/docs) - miscelleneaus documentation



* ATARI-CONCEPTS - a mysterious description of Forth usage in Atari Coin-Op department as a means of game debugging; extracted from the file: "figasm, f69asm, computype master.atr" originally present at "http://annex.retroarchive.org/disks/Atari/Forth-Disks/"; the file is not converted correctly yet (missing inverse) and it is not clear whether it describes an unrealized concept or something which was actually used



### ["/drafts"](/drafts) - unstable but potentially interesting 



* work in progress, usually not working - failed attempts to run or port Forth code, broken data structures, crashing tools and procedures, unfinished type-in conversions...

* when stabilized, code is moved to other (relevant) folders



### ["/editors"](/editors) - source code editors



* EDIT - a very nice (even if slow, as it's written only in Forth) screen editor, written by M. Dougherty

* EDYTOR-FORTH - a very fast and modern (even if allowing editing of only one screen at once) screen editor by R. Pantola; includes (as a prerequisite) slightly tuned "Ragsdale Assembler" and Roland's "Edytor Wprowadzania" ("Entry Editor" - used to check control codes for type-in programs); contains a clipboard with a ring buffer; Esc-Space exits (without saving)

* EWK - "Edytor Wyswietlania Kodow" ("Code Display Editor") - control code generator by R. Pantola, supplementary to the above mentioned "Edytor Wprowadzania" and allowing to generate control codes for single lines of Forth code

* FIG-MINI - smallest useful subset of the FIG line editor (contains only Put and Erase)

* MTF - this is Micro Text Formatter by Robert La Quey, a small tool to store slightly formatted text on Forth screens



### ["/games"](/games) - very simple games and demos



* ESCAPE - a conversion (by John Mattes) of a small graphical demo, wirtten by an unknown author

* LIFE - a super-slow implementation of Life from the book "Forth" by Salman, Tisserand and Toulout

* MUGWUMP - a conversion (from the Basic language) of an ancient logical game, enhanced by me with some graphics

* Mugwump-240816.atr - above, bootable



### ["/io"](/io) - external device management (drives etc)



* DISKCOPY - a disk copy routine from Space Forth, not included later in APX Forth

* DISKSIMUL - ram disk simulation from the fig-Forth installation guide



### ["/mods"](/mods) - modifications of major words



* BLIST - a better (?) LIST, trying to show both screens with sources and blocks with binary data

* CASEINS - making the interpreter case-insensitive (ported from pns-Forth)

* COMPENT-XLIST - "compiled comments" as a wasteful way to document words in-memory; XLIST is a VLIST, showing extended word info (with immediate/smudge bits, with CFA references and these "compiled comments" as well); APX's DECOMP modification is also described here not to break it completely with the compiled comments

* MESSAGE - static error messages to avoid reading from the floppy

* PICK&ROLL - tricky stack operations PICK and ROLL



### ["/pc-tools"](/pc-tools) - file format conversion scripts



* FS2ATR - a script by Buki to potentially convert Forth source files from PC into ATR images, may work in some cases

* TXT2SCR - my attempts to solve the same problem (an in reverse), may work in some cases



### ["/spin-offs"](/spin-offs) - modifications of Forth environments



* APXFORTH-IDE - routines to transform APX Forth floppy image into a more contemporary environment, suitable for Forth studies and small development tasks; includes source editing and debugging tools; contains help

* *.ATR files - floppy files related to these environments, some ready to be booted and played with - see the dedicated [README.md](spin-offs/README.md) for details



![banner](drafts/s1boot.png)



## ["/variables"](/variables) - less usual ways to define variables



* ANON - anonymous variables by Leonard Morgenstern, published in Forth Dimensions

* ARGRES - simple but useful local variables by Marc Perkel, published in Forth Dimensions as "Turning the Stack into Local Variables"

* DEFER-IS - example of "deferred words" (vectored execution), based on Henry Laxen's code published in Forth Dimensions

* LOCALS-MINI - my attempt to implement local variables; too many limitations to be practical

* LOCALS-STACK - local variables as described by Baranov & Nozdrunov in "Language Forth and its Implementations"

* MAP - a simple map-like data structure (apply a function when fetching an element of an array)

* SEQUENCE - a simple Oracle sequence-like data structure (increase variable when fetching), also similar to ++ from C

* STRINGS - multiple (not always consistent) concepts how to handle text strings 

* TABLE-LOOKUP - table lookup example by Henry Laxen, as published in Forth Dimensions