The Atari ST is a line of home computers from Atari Corporation and the successor to the Atari 8-bit family. The initial ST model, the 520ST, saw limited release in April–June 1985 and was widely available in July. The Atari ST is the first personal computer to come with a bitmapped color GUI, using a version of Digital Research’s GEM released in February 1985. The 1040ST, released in 1986, is the first personal computer to ship with a megabyte of RAM in the base configuration and also the first with a cost-per-kilobyte of less than US$1.

The Atari ST is part of a mid-1980s generation of home computers that have 16 or 32-bit processors, 256 KB or more of RAM, and mouse-controlled graphical user interfaces. This generation includes the Macintosh, Commodore Amiga, Apple IIGS, and, in certain markets, the Acorn Archimedes. “ST” officially stands for “Sixteen/Thirty-two”, which refers to the Motorola 68000’s 16-bit external bus and 32-bit internals.

The ST was sold with either Atari’s color monitor or the less expensive monochrome monitor. The system’s two color graphics modes are only available on the former while the highest-resolution mode needs the monochrome monitor.

In some markets, particularly Germany, the machine gained a strong foothold as a small business machine for CAD and desktop publishing work. Thanks to its built-in MIDI ports, the ST enjoyed success for running music-sequencer software and as a controller of musical instruments among amateurs and well-known musicians alike.

The ST was superseded by the Atari STE, Atari TT, Atari MEGA STE, and Falcon computers.

Jay Miner, one of the original designers for the custom chips found in the Atari 2600 and Atari 8-bit family, tried to convince Atari management to create a new chipset for a video game console and computer. When his idea was rejected, Miner left Atari to form a small think tank called Hi-Toro in 1982 and began designing the new “Lorraine” chipset. The company, which was later renamed Amiga Corporation, was pretending to sell video game controllers to deceive competition while it developed a Lorraine-based computer.

Amiga ran out of capital to complete Lorraine’s development, and Atari, owned by Warner Communications, paid Amiga to continue development work. In return Atari received exclusive use of the Lorraine design for one year as a video game console. After one year Atari would have the right to add a keyboard and market the complete computer, designated the 1850XLD. As Atari was heavily involved with Disney at the time, it was later code-named “Mickey”, and the 256K memory expansion board was codenamed “Minnie”.

After leaving Commodore International in January 1984, Jack Tramiel formed Tramel Technology with his sons and other ex-Commodore employees and, in April, began planning a new computer. The company initially considered the National Semiconductor NS320xx microprocessor but was disappointed with its performance. This started the move to the 68000. The lead designer of the Atari ST was ex-Commodore employee Shiraz Shivji, who had previously worked on the Commodore 64‘s development.

Atari in mid-1984 was losing about a million dollars per day. Interested in Atari’s overseas manufacturing and worldwide distribution network for his new computer, Tramiel negotiated with Warner in May and June 1984. He secured funding and bought Atari’s Consumer Division (which included the console and home computer departments) in July. As executives and engineers left Commodore to join Tramiel’s new Atari Corporation, Commodore responded by filing lawsuits against four former engineers for theft of trade secrets.

The Tramiels did not purchase the employee contracts when they bought the assets of Atari Inc., so one of their first acts was to interview Atari Inc. employees to decide whom to hire at what was essentially a brand new company. This company was originally called TTL (Tramiel Technologies Limited), later renamed to Atari Corp. At the time of the purchase of Atari Inc’s assets, there were roughly 900 employees remaining from a high point of 10,000. After the interviews, approximately 100 employees were hired to work at Atari Corp.

At one point a custom sound processor called AMY was a planned component for the new ST computer design, but the chip needed more time to complete, so AMY was dropped in favor of an off-the-shelf Yamaha sound chip.

It was during this time in late July/early August that Leonard Tramiel discovered the original Amiga contract, which required Amiga Corporation to deliver the Lorraine chipset to Atari on June 30, 1984. Amiga Corp. had sought more monetary support from investors in spring 1984 (among them Tramel Technology, which wished to replace nearly everyone at Amiga).

Having heard rumors that Tramiel was negotiating to buy Atari, Amiga Corp. entered into discussions with Commodore. The discussions led to Commodore wanting to purchase Amiga Corporation outright, which Commodore believed would cancel any outstanding contracts, including Atari’s. Instead of Amiga Corp. delivering Lorraine to Atari, Commodore delivered a check of $500,000 to Atari on Amiga’s behalf, in effect returning the funds Atari invested into Amiga for the chipset. Tramiel countersued Amiga Corp. on August 13, 1984. He sought damages and an injunction to bar Amiga (and effectively Commodore) from producing anything with its technology.

At Commodore, the Amiga team was in limbo during the summer of 1984 because of the lawsuit. No word on the status of the chipset, the Lorraine computer, or the team’s fate was known. In the fall of 1984, Commodore informed the team that the Lorraine project was active again, the chipset was to be improved, the operating system (OS) developed, and the hardware design completed. While Commodore announced the Amiga 1000 with the Lorraine chipset in July 1985, the delay gave Atari, with its many former Commodore engineers, time to deliver the first Atari ST units in June 1985. In March 1987, the two companies settled the dispute out of court in a closed decision.

Atari ST print advertisements stated “America, We Built It For You”, and quoted Atari president Sam Tramiel: “We promised. We delivered. With pride, determination, and good old ATARI know how”. Although Atari was out of cash, sales of its 8-bit computers were “very, very slow” according to Jack Tramiel, and employees feared that he would shut the company down, the 520ST shipped during spring 1985 to the press, developers, and user groups, and in early July 1985 for general retail sales, saving the company. By November the company stated that it had sold more than 50 thousand 520STs, “with U.S. sales alone well into five figures”. The machine had gone from concept to store shelves in a little under a year.

Atari had intended to release versions with 128 KB and 256 KB of RAM as the 130ST and 260ST respectively. However, the ST initially shipped with TOS on disk, requiring 206 KB RAM when loaded, leaving no or little room for applications. The 260ST did make its way into Europe on a limited basis. Early models were designed with six ROM sockets allow easy upgrading to the future ROM-based TOS. These became available only a few months later and were included in all new machines as well as being available as an upgrade for older machines. By late 1985 the machines were also upgraded with the addition of an RF modulator (for TV display), a version known as the 520ST^M. ST systems before the Mega ST range have no battery-backed clock.

Atari originally intended to include GEM’s GDOS (Graphical Device Operating System), which allowed programs to send GEM VDI (Virtual Device Interface) commands to drivers loaded by GDOS. This allowed developers to send VDI instructions to other devices simply by pointing to it. However, GDOS was not ready at the time the ST started shipping and was included in software packages and later ST machines. Later versions of GDOS supported vector fonts.

A limited set of GEM fonts were included in the ROMs, including the standard 8×8 pixel graphical character set for the ST. It contained four unusual characters which can be placed together in a square, forming a facsimile of the face of J. R. “Bob” Dobbs (the figurehead of the Church of the SubGenius).

The ST was less expensive than most machines, including the Macintosh Plus, 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 popular machine, notably in European markets where the foreign-exchange rates amplified prices. Indeed, the company’s English advertising strapline of the era was “power without the price.” In fact, an Atari ST and terminal emulation software was much cheaper than a Digital VT220 terminal, which was commonly needed by offices with central computers.

Atari later upgraded the basic design in 1986 with the 1040ST^F (also written STF). The machine is generally similar to the earlier 520ST, but moved the power supply and a double-sided floppy drive into the rear of the housing of the computer, as opposed to being external. This added to the size of the machine, but reduced cable clutter in the back. The joystick/mouse ports, formerly on the right side of the machine where the disk drive now sat, were moved to a niche underneath the keyboard.

The 1040ST was the first personal computer shipped with a base RAM configuration of 1 MB. When the list price was reduced to $999 in the U.S. it appeared on the cover of BYTE in March 1986 as the first computer to break the $1000/megabyte price barrier; Compute! noted that, in fact, the 1040ST was the first computer to break the $2500/megabyte price barrier. However, the ST remained generally the same internally over the majority of its several-year lifespan. The choice of model numbers was inherited from the model numbers of the XE series of the Atari 8-bit family of computers. A limited number of 1040STFs shipped with a single-sided floppy drive.

The same basic design was also used for a cut-down version, the 512 kB 520STFM, which replaced the earlier 520ST models in the market. The early ‘STF’ machines lack the ‘M’ modulator that allows a TV to be used and will only work with a monitor.

In late 1989, Atari released the 520ST^E and 1040ST^E (also written STE), enhanced version of the ST with improvements to the multimedia hardware and operating system. It features an increased color palette of 4,096 colors from the ST’s 512 (though the maximum displayable palette of these without programming tricks was still limited to 16 in the lowest 320×200 resolution, and even fewer in higher resolutions), Genlock support, and a blitter co-processor (stylized as “BLiTTER”) which can quickly move large blocks of data (most particularly, graphics data) around in RAM. The STE was the first Atari with PCM audio; using a new chip, it added the ability to play back 8-bit (signed) samples at 6258 Hz, 12517 Hz, 25033 Hz and even 50066 Hz, via DMA (Direct Memory Addressing). The channels are arranged as either a mono track or a track of LRLRLRLR… bytes. RAM was now much more simply upgradable via SIMMs.

Also popular on the ST was professional desktop publishing software, such as PageStream and Calamus; office tools such as word processors (WordPerfect, Microsoft Write, AtariWorks, WordWriter ST, First Word [shipped with the machine] and its Plus continuation, and others); spreadsheets (3D-Calc, LDW Power, LDW Power 2, LOGiSTiX Senior, PowerLedger ST, SwiftCalc ST, VIP Professional, and others); turnkey programs (Mail-Pro, Sales-Pro 6, Video-Pro, and others); database programs (A-Calc Prime, Data Manager, Data Manager Professional, DBMan V, Base Two, H&DBase, Informer II, DB Master One, SBT Database Accounting Library (dLedger, dInvoice, dOrder, dPurchases, and dPayables), Superbase Personal, Superbase Professional, Tracker ST, Zoomracks and others); and various CAD and CAM tools from amateur hobbyist to professional grade (Campus CAD, DynaCADD, Leonard ST, Technobox CAD/2…): all being largely targeted at, or even limited to owners of high-resolution monochrome monitors.

Graphics programs such as NEOchrome, Degas & Degas Elite, Canvas, Deluxe Paint, and Cyber Paint (which author Jim Kent would later evolve into Autodesk Animator) featured advanced features such as 3D design and animation. One paint program, Spectrum 512, uses the ST’s rapid palette switching ability to expand the maximum number of colors to be displayed on-screen at once to 512 (up to 46 in each scan line).

The ST enjoyed success in gaming due to the low cost, fast performance, and colorful graphics. Notable individuals who developed games on the ST include Peter Molyneux, Doug Bell, Jeff Minter, Éric Chahi, Jez San, and David Braben.

The realtime pseudo-3D role-playing video game Dungeon Master, was developed and released first on the ST, and was the best-selling software ever produced for the platform. Simulation games like Falcon and Flight Simulator II made use of the ST’s graphics, as did many arcade ports. Proto first person shooter MIDI Maze, uses the MIDI ports to connect up to 16 machines for networked deathmatch play. The critically acclaimed Another World was originally released for ST and Amiga in 1991 with the engine developed on the ST and the rotoscoped animations created on the Amiga. Games simultaneously released on the Amiga that didn’t use the Amiga’s superior graphics and sound capabilities were often accused by video game magazines of simply being ST ports.

Garry Kasparov became the first player to register the commercial ChessBase, a popular commercial database program produced for storing and searching records of games of chess. The first version was built for Atari ST with his collaboration in January 1987. In his autobiography Child of Change, he regards this facility as “the most important development in chess research since printing.”

Technical specifications

All STs are made up of both custom and commercial chips:

• Custom chips:
  • ST Shifter “Video shift register chip” – Enables bitmap graphics using 32 KB of contiguous memory for all resolutions. Screen address has to be a multiple of 256.
  • ST GLU “Generalized Logic Unit” – Control logic for the system used to connect the ST’s chips. Not part of the data path, but needed to bridge chips with each other.
  • ST MMU “Memory Management Unit” – Provides signals needed for CPU/blitter/DMA and Shifter to access dynamic RAM. Even memory accesses are given to CPU/blitter/DMA while odd cycles are reserved for DRAM refresh or used by Shifter for displaying contents of the frame buffer.
  • ST DMA “Direct Memory Access” – Used for floppy and hard drive data transfers. Can directly access main memory in the ST.
• Support chips:
  • MC6850P ACIA “Asynchronous Common Interface Adapter” – Enables the ST to directly communicate with MIDI devices and keyboard (two chips used). 31.250 kbit/s for MIDI, 7812.5 bit/s for keyboard.
  • MC68901 MFP “Multi Function Peripheral” – Used for interrupt generation/control, serial and misc. control input signals. Atari TT030 has two MFP chips.
  • WD-1772-PH “Western Digital Floppy Disk Controller” – Floppy controller chip.
  • YM2149F PSG “Programmable Sound Generator” – Provides three—voice sound synthesis, also used for floppy signalling, serial control output and printer parallel port.
  • HD6301V1 “Hitachi keyboard processor” – Used for keyboard scanning and mouse/joystick ports.