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Afera stands for “Abersoft Forth Extensions, Resources and Addons”. It’s a library for Abersoft Forth, a fig-Forth system for ZX Spectrum from 1983. I wrote Afera in 2015, in order to make the development of Tron 0xF (an improved remake of an old game of mine) easier, but improving an old tape-based fig-Forth and making it more powerful was such a nice programming challenge that the library soon grew beyond the requirements of the game.

Some of the main features of Afera are the following:

  • Many common words and tools found in modern Forth systems.

  • Improved tape support.

  • 1 KiB of additional free memory on Spectrum 48K.

  • 11 KiB of additional free memory on Spectrum 128K.

  • Two 16-KiB RAM-disks on Spectrum 128K.

  • Improved blocks handling.

  • Full screen mode.

  • Faster color commands.

  • G+DOS support.

  • Fixes some bugs of the original system.

About this file

This file is not intended to teach about the Forth language, the fig-Forth model, the Abersoft Forth system, what a TAP file is, what a Makefile is…​ You are supposed to know all that and much more.

The build instructions are for a GNU/Linux system or similar, but the library is ready to be used on any ZX Spectrum emulator on any platform.

The sources in <src/> are the main documentation. They are fully commented. Also the <Makefile> is useful, as an example of building customized TAP files to use the library with your own Forth programs.



The credits.


The instructions for make to build the TAP files from the sources.


This file.


The to-do tasks (abandoned, kept only for reference).


Main changes in latest versions.


Some benchmarks used during the development.


The source of all modules.


Abersoft Forth binaries, BASIC loader, DOS and ROM used to build the library or during the development.


The TAP files of all modules.


TAP files and launchers for the Fuse emulator, with selected groups of modules, used to test the library during the development.

How to build the library files

If you modify the sources, you must create updated TAP files. If you just want to use the library, skip this section.

A <Makefile> contains the instructions required to convert the fsb-format sources (in the <scr/> directory) to TAP files (in the <tap/>) directory and an MGT file (a disk image for G+DOS).

Requirements: read the section "Requirements" of the file <Makefile> and install them.

Then simply use the make command.

How to run Abersoft Forth with Afera

Tape (manually)

Two bundled files are ready to be used:

  • sys/abersoft_forth_afera.tap

  • sys/abersoft_forth_afera_tools.tap

The first one contains only the main module of Afera. The second one contains also some tools usually required during development.

Open any of them with a ZX Spectrum emulator. Abersoft Forth will run. Then use the following Forth command: LOADT 1 LOAD. This will load and compile the first RAM-disk from tape (containing the loader module) and then all following modules in the TAP file.

In order to load another library module, open its TAP file from the <tap/> directory using the correspondent command of your ZX Spectrum emulator. Then use the Forth word RUNT (already defined by Afera) to load and compile the next RAM-disk from the tape.

Some modules need other modules. The word NEEDS (defined in <src/afera.fsb>) is used for that. When using tapes, NEEDS stops with an error. When using disks (see below) NEEDS loads the required module from disk.

A customized tape

In order to use Afera with your own program you must create a TAP file with first a copy of Abersoft Forth, then the required modules and finally you application. The first Afera module in the TAP file must be <loader.tap>, the second one <afera.tap>, then the rest, ordered by their own requirements.


  • See how the Afera’s <Makefile> creates the TAP files in the <tests/> directory.

  • See how Tron 0xF creates its TAP file.

After creating your TAP file, you can run your program as usual:

  1. Open the TAP file with a ZX Spectrum emulator.

  2. Load Abersoft Forth with LOAD "".

  3. Give the following Forth command: LOADT 1 LOAD. This will load all Afera modules and your program.


Afera provides support for G+DOS (the disk operating system of the Plus D interface), but the first time the library itself must be loaded from tape. Then a modified system, with compiled support for G+DOS, could be saved to disk. See <src/afera.fsb> and the G+DOS modules <scr/gplusdos_*.fsb> for reference on how to save a modified system).

The <tests/> directory contains two files ready to try the G+DOS support, for 48K and 128K:

  • tests/gplusdos_128k_test.tap

  • tests/gplusdos_test.tap

For convenience, launchers for the Fuse emulator are provided:

  • tests/

  • tests/

In <Makefile> you can see the modules used by each version. Both versions use <tests/afera.mgt>, a disk image that contains a selection of Afera modules.

Steps to run Abersoft Forth with Afera and disk support:

  1. If you have the Fuse emulator installed, you can execute the provided launchers. Otherwise you must run your ZX Spectrum emulator manually with Plus D interface, associate the correspondent TAP file (<tests/gplusdos_128k_test.tap> or <tests/gplusdos_test.tap>) as input tape and <tests/afera.mgt> as drive 1.

  2. Give the BASIC command RUN. This will load G+DOS and Abersoft Forth from disk.

  3. Load the main Afera modules from tape, with the following Forth command: LOADT 1 LOAD.

  4. When all modules have been loaded, you are ready to use the disk. Examples: S" *" CAT, S" modulename" LOADD…​

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