I'm sharing a bitmap painting program and a text editor/IDE which I wrote for my Atari-ST in MC-68000 assembly mainly between 1986-1988. The original purpose for writing these was for learning about the new platform (especially the GEMDOS CP/M clone, about graphical user-interface design in general and the rich AES/VDI libraries in particular) as well as for my own use.
I don't expect these programs to be useful for more than satisfying historical interest these days. I started the effort for creating this page mainly for rediscovering myself what I created 30 years ago, but also for brushing-up my assembly skills. The repository contains the original sources written in the 80s, but in case of TH-paint the latest version is partially reworked, which was unavoidable for getting to understand at all what the sparsely commented code was doing. (Please don't assume even the latest version reflects my current coding style though. I wrote these programs before I ever used a structured programming language.)
This is a basic bitmap-based painting program. It offers all the usual drawing tools, such as pencil, brush, straight lines & rectangles - some neat variants and extensions are available via the "Attributes" menu though. Naturally the program also offers selecting areas of the images, and then moving these, or performing transformations. (Currently only mirroring and zooming transformations are implemented.) The program contains a printer driver for the Gemini Star dot matrix printer.
The program is described in detail in the TH-Paint documentation
This is an editor based on the GEMDOS VT-52 emulation, which means it's a pure text-based application without GUI. The text editor is the central part, but I integrated almost everything that I needed for development, thus creating what's called today an "Integrated Development Environment" (IDE).
The screenshot above shows the starting message on top of the screen. Then the current directory is listed and a 3-line text file is loaded and listed. Then it demonstrates what "line based editing means" by showing how the first text line with number 10 is moved to 25 and what the result looks like. (Note the symbols visible at line ends are the line-feed and carriage-return characters.)
The program is described in detail in the Text Editor documentation
In case you wonder "Why in Assembly and not in C?": The short answer is I simply didn't have a C compiler yet, but coming from an 8-bit system (see my VIC-20 games repository) I knew assembly well and was interested in learning it for a 32-bit CPU. Some assembly would have been required anyway to get acceptable performance for graphics operations (after all the CPU still was clocked only at 8 MHz). I reused some of the code written here in later C projects.
For specifications I used the books "ATARI ST GEM" covering AES/VDI, "ATARI ST Intern" covering GEMDOS, BIOS and chipset, and "Das Prozessor Buch zum 68000" covering 68k instruction set and architecture. All of these were released by Data Becker.
The resource files fa_en.rsc and fa_de.rsc (containing definition of the
menu and dialog boxes) were originally created using the DRI Resource Editor.
For current updates I used the freely available tool "Interface" (by Gerd
Hoeller, version 2.33 released 03.10.1994). Unfortunately the tools do not
support multiple columns of menu entries as used in the "Shapes" menu, so I
additionally used a hex-editor to patch X/Y coordinates of those menu entries.
The assembly code was originally written for the "GST 68000 Macro Assembler
A246V040". I still found a mention in a
review of ST assemblers
but otherwise the company seems to have disappeared and no documentation is to
be found anywhere on the Internet. Fortunately the assembly syntax seems to be
the official Motorola syntax and thus supported by many other assemblers such as
vasm. Only the macros used for AES and VDI
system calls are not portable. Therefore I added a little Perl script asm_macro.pl
that generates assembly code for these specific macros.
To build the software simply type "make".
Pre-requisite for building is vasm configured for CPU=m68k SYNTAX=mot. Since vasm does not come with a linker, the assembly source modules are all concatenated to single files for assembling & immediately creating TOS binaries.
For running the generated executables I used HATARI. Pre-requisite is a TOS image
TH-Paint supports both English and German language in the GUI. Default is English.
For switching to German, copy resource file src_paint/fa_de.rcs to fa.rcs in
the same directory the executable is in.