Emulate the Atari ST home computer with Linux

Last Updated on April 22, 2022

Emulation is the practice of using a program (called an emulator) on a PC to mimic the behaviour of a home computer or a video game console, in order to play (usually retro) games on a computer.

Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single non-technical user.

Back in the 1980s, home computers came to the forefront of teenagers’ minds. Specifically, the Amiga, ZX Spectrum, and Atari ST were extremely popular. They were hugely popular home computers targeted heavily towards games, but they also ran other types of software.

The Atari ST is a line of home computers from Atari Corporation and the successor to the Atari 8-bit family. The initial model, the 520ST, saw limited release in April–June 1985. Heralded as Atari’s flagship graphics machine, it competed against the Commodore Amiga and Acorn Archimedes.

The Atari ST runs on the Motorola 68000 CPU. “ST” stands for sixteen/thirty-two, in reference to the 16-bit external bus and 32-bit internals of the 68000 chip. It ran Digital Research’s GEM (Graphical Environment Manager) on Atari’s proprietary TOS (The Operating System).

Atari ST ROM

TOS (The Operating System) is the operating system of the Atari ST range of computers. TOS combines Digital Research’s GEM GUI running on top of the DOS-like GEMDOS. Features include a flat memory model, DOS-compatible disk format (starting with TOS 1.04), support for MIDI, and a variant of SCSI called ACSI in later versions. Atari’s TOS is usually run from ROM chips contained in the computer.

TOS includes the following:

• Desktop – The main interface loaded after boot up;
• GEM – Graphics Environment Manager, licensed from Digital Research:
  • AES – Application Environment Services. It deals with all those parts of GEM that go above elementary graphic output and input functions.;
  • VDI – Virtual Device Interface – this forms the lower half of GEM; it is so to speak the basis of all AES functions. The VDI complies with the ANSI standard X3H3.6CG-VDI;
• GEMDOS – GEM Disk Operating System. GEM was based on CP/M-68K, essentially a direct port of CP/M to the 68000 processor;
• BIOS – Basic Input/Output System;
• XBIOS – Extended BIOS;
• Line-A – Low-level high-speed graphics calls.

TOS is proprietary software.

EmuTOS is a replacement for TOS, released as free and open source software. It is mainly intended to be used with Atari emulators and clones, such as Hatari.

Atari ST Emulators

Hatari tries to emulate the hardware of a ST as close as possible so that it is able to run most ST games and demos.

It supports more graphics modes than the ST and does not require an original TOS image (as it supports EmuTOS). Besides the ST, the emulator supports the Mega ST, STE, Mega STE, TT, and the Falcon.

Clock Signal is also a high quality emulator. It supports a wide number of home computers although the emulation of the Atari ST is rather basic. Only a 512K Atari ST is supported.. Through static and runtime analysis CLK seeks automatically to select and configure the appropriate machine to run any provided disk, tape or ROM; to issue any commands necessary to run the software contained on the disk, tape or ROM; and to provide accelerated loading where feasible. CLK doesn’t provide a ROM image given the uncertainty about its copyright status. It needs the file tos100.img, a 196kb image of the UK Atari ST TOS 1.00 ROM.

ARAnyM is a software virtual machine (similar to VirtualBox or Bochs) designed and developed for running 32-bit Atari ST/TT/Falcon operating systems (TOS, FreeMiNT, MagiC and Linux-m68k) and TOS/GEM applications

Atari ST Software

The Atari ST enjoyed success in gaming due to the low cost, fast performance, and colorful graphics.

The machine was the first major home computer to include MIDI in/out ports as standard equipment, which prompted the development of a wide variety of music composition programs. STs became very popular in the music industry,

In a few countries, including Germany, the machine was used as a small business machine for CAD and desktop publishing. Desktop publishing software included PageStream and Calamus.

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