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Atari ST

The Atari ST was a home computer system released by Atari in 1985. The "ST" allegedly stood for "Sixteen/Thirty-two" which referred to the Motorola 68000's 32-bit internals with 16-bit external busses. Other theories say that ST really stood for "Sam Tramiel", the son of Atari owner Jack Tramiel.

The Atari ST was a competitor to the Commodore Amiga systems. This platform rivalry was often reflected by the owners and was most prominent in the Demo Scene.

Where the Amiga had custom hardware which gave it the edge in the games market, the ST was generally cheaper, and thanks to its built-in MIDI ports enjoyed success as a sequencer and controller of musical instruments. In some markets, particularly Germany, the machine gained a strong foothold as a small business machine for CAD and Desktop publishing work.

Since Atari pulled out of the computer market there has been a market for powerful TOS based machines (clones). Like most retro computers the Atari enjoys support in the emulator scene.

Table of contents


Atari had created two released machines in the form of the Atari 2600 console (also known as VCS) and the various Atari 8-bit based home computers. Both of these lines were created around the 6502 CPU and included a number of additional chips to provide graphics and sound from this rather basic CPU. In fact the 8-bit machines had originally intended to be the replacement for the 2600, but they were later "re-purposed" as home computers to cash in on their much higher selling prices.

As Atari grew and the management was shuffled by Warner (their parent company), the original creators of the 2600 and 8-bit machines eventually got fed up and left. A group of them formed a small think-tank called Amiga and set about creating the third generation machine, this time based on the much more powerful 68000 CPU.

During this time, the home computer market started to slow down, and the video game market underwent a crash. Warner management decided to "get out" and started looking to sell Atari outright. Meanwhile the same effects were in the process of decimating Commodore International, and eventually their board got fed up and fired Jack Tramiel, the CEO. He quickly bought the remains of Atari from Warner for a very low price, and set about re-creating his empire.

In the process they laid off huge parts of the engineering staff, and cancelled almost all ongoing research. Among the plans that were killed off was the deal with Amiga, who then turned to Commodore for support. Atari would instead collect anyone remaining who had any 68000 experience and put them on a crash program to develop a machine, any machine, which could be brought to market as soon as possible.

The result was the 520 ST. The machine went from conception to store shelves in a little under a year. As one might expect it was built largely from "off the shelf" parts, and thus had little of the finese that was the hallmark of their earlier projects (or the Amiga). This was true of the operating system as well, which was a re-labelled version of Digital Research's CP/M 68K, and largely compatible with their 8-bit versions. Atari had originally intended to release versions with 128kB and 256kB as the 130 ST and 260 ST respectively, but the rapidly falling prices of RAM at the time led them to cancel these versions and it was released with 512k.

Atari machines under the Tramiel rule are marked by infamously "cheap" cases. The original 520 design was quite flimsy, and while the 1040-style case was much stronger, it was also becoming too large and rather unwieldy. Add to this that the majority of the machines had very poor quality keyboards (third-party spring kits were created to improve the keys). They got the design completely right with the Mega series, but this apparently cost too much to produce and the design was not used widely.

An annoying problem concerned the disk drives. Early models were shipped with an external single-sided drive that could store up to 360kB, with an optional double-sided version that stored 720kB for considerably more money. Due to the early sales of so many of the single-sided drives, almost all software would ship on two single-sided disks instead of a single double-sided one, in fear of cutting off all the other owners. This was true even years later, long after the single-sided drives had been off the market.

Additionally they had originally intended to include GEM's GDOS hardware abstraction layer, which allowed programs to draw (display, print, etc.) graphics to any supported device with no changes. This allowed developers to write a program for display to the screen, and get high quality printing "for free". However GDOS was not ready at the time the ST started shipping, and while Atari promised to include it as soon as possible, they never did. This left printing support up to the developers, who had to create their own engines for every possible printer. Similarly the custom "BLiTTER" was to be included to speed the performance of graphics operations on the screen, but this was isolated to their "upscale" machines when it was eventually released years later. As a result, the power of GEM was largely lost on the ST platform, even when GDOS and BLiTTER eventually shipped, it was ignored by developers because it was on so few machines.

On the plus side the ST was less expensive than most machines, including 8-bit machines like the Apple II, and tended to be faster than most. Largely as a result of the price/performance factor, the ST would go on to be a fairly big seller, notably in markets where the foreign exchange rates amplified prices. For this reason the ST was most popular in Europe, notably Germany. Also, the very crisp picture of its black&white monitor made it quite popular for small-office applications.

Technical specifications

As originally released in the 520 ST:

  • CPU: 8Mhz Motorola 68000
  • RAM: 512kB
  • Drive: single-sided 3.5" floppy drive
  • Ports: TV out (on FM models), MIDI In/Out, RS-232, Printer, Monitor (RGB and Mono), Extra Disk drive port, Joystick and Mouse ports
  • Operating System: TOS (Tramiel Operating System) with the GEM (Graphical Enviroment Manager) GUI
  • Display modes: 320x200 (16 colour), 640x200 (4 colour), 640x400 (mono), palette of 512 colours

Very early machines included the OS on a floppy disk, but this was quickly replaced with ROM versions instead. Another early addition (after about 6 months) was an RF Modulator that allowed the machine to be hooked to a colour TV when run in it low resolution mode. These models were known as the 520 STm, although the m did not appear on the label.


A number of machines were released in the ST family. Here they are, in rough chronological order:

  • 520 STfm - a 520 STm in a larger case and a built-in floppy disk
  • 1040 ST - a 520 with 1 MB of RAM and a built-in double-sided floppy disk
  • MEGA2 and MEGA4 - 1040 with either 2 or 4MB of RAM, in a much improved "pizza box" case with a detached keyboard. These models included the BLiTTER chip, but the OS was not upgraded and the extra GEM functionality needed to be booted from disk.
  • 520 STe and 1040 STe - enhanced sound, the BLiTTER chip, and a 4096 color palette, in the older 1040 style all-in-one case
  • TT 030 - new machine based on the Motorola 68030 processor running at 32 Mhz, in yet another new case design with a detached keyboard.
  • Mega STE - same hardware as 1040 STe except for a faster 16 MHz processor, in the TT case
  • Falcon 030 - another '030 based machine like the TT, but in the 1040 style case (yet again) with another upgrade to the graphics, sound, a Motorola 56000 DSP, and a LocalTalk port for networking
  • STacy - A portable (but definitely not laptop) version of the ST. Originally designed to operate on 12 standard C cell[?] flashlight batteries for portability, when Atari finally realized how quickly the machine would use up a set of batteries (the batteries were not rechargable), they simply glued the lid of the battery compartment shut.
  • ST Book (later version of portable atari)

There was also some unrelased prototypes: Falcon 040 (based on a Motorola 68040), and STylus (palmtop)

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