The Atari ST is a home/personal computer that was commercially popular from 1985 to the early 1990s. It was released by Atari in 1985. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals.

Retrobrad has been created and maintained by me - Brad!
This page has been visited times since June 2007

  The Atari ST was a notable home computer, based on the Motorola 68000 CPU, with 512 KB of RAM or more, and 3½" floppy disks as storage. It was similar to other contemporary machines which used the Motorola 68000, the Apple Macintosh and the Commodore Amiga. Although the Macintosh was the first widely available computer with a graphical user interface (GUI), it was limited to a monochromatic display on a smaller built-in monitor. The Atari ST was the first computer with a fully bit-mapped color GUI. It had an innovative single-chip graphics subsystem (designed by Shiraz Shivji) which shared the full amount of system memory, in alternating clock cycles, with the processor, similar to the earlier BBC Micro and the Unified Memory systems that have become common today. It was also the first home computer with integral MIDI support.

The ST was primarily a competitor to the Apple Macintosh and 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 processors which gave it the edge in the games and video market, the ST was generally cheaper, had a slightly faster CPU, and had a high-resolution monochrome display, ideal for business and CAD. Thanks to its built-in MIDI ports it enjoyed success as a music sequencer and controller of musical instruments among amateurs and professionals alike, being used in concert by bands such as Tangerine Dream and 90s UK dance act 808 State. In some markets, particularly Germany, the machine gained a strong foothold as a small business machine for CAD and Desktop publishing work.

The ST was later superseded by the Atari TT and Falcon computers.

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.

  All ST's were made up of both custom and commercial chips:
  Custom chips  
  ST Shifter "Video shift register chip" — Enabled bitmap graphics using 32 KB of contiguous memory for all resolutions. Screen address had 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" — Enabled physical memory access up to 4 MB. Maps out the memory space in the ST.  
  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" — Enabled the ST to directly communicate with MIDI devices and keyboard (2 chips used). 31.25 kBaud for MIDI, 7812.5 bps for keyboard.  
  MC68901 MFP "Multi Function Peripheral" — Used for interrupt generation/control, serial and parallel port. Atari TT030 had 2 MFP chips.  
  WD-1772-PH "Western Digital Floppy Disk Controller" — Floppy controller chip.  
  YM2149F PSG "Programmable Sound Generator" — Provided 3-voice sound synthesis, also used for floppy signalling and printer port control.  
  HD6301V1 "Hitachi keyboard processor" — Used for keyboard scanning and mouse/joystick ports.  
  As originally released in the 520ST:  
  CPU: Motorola 68000 @ 8 MHz. 16-bit data/24-bit address bus.  
  RAM: 512 KB or 1 Megabyte  
  Display modes (60 Hz NTSC, 50 Hz PAL, 71.2 Hz monochrome): Low resolution - 320×200 (16 color), palette of 512 colors: Medium resolution - 640×200 (4 color), palette of 512 colors: High resolution - 640×400 (mono), monochrome  
  Sound: Yamaha YM2149 3-voice squarewave plus 1-voice white noise mono soundchip  
  Drive: Single-sided 3½" floppy disk drive, 360 KB capacity when formatted to standard 9 sector, 80 track layout.  
  Ports: TV out (on ST-M and ST-FM models, NTSC or PAL standard RF modulated), MIDI in/out (with 'out-thru'), RS-232 serial, Centronics parallel (printer), monitor (RGB or Composite Video colour and mono, 13-pin DIN), extra disk drive port (15-pin DIN), DMA port (ACSI port, Atari Computer System Interface) for hard disks and Atari Laser Printer (sharing RAM with computer system), joystick and mouse ports (9-pin MSX standard)  
  Operating System: TOS v1.00 (The Operating System) with the Graphical Environment Manager (GEM) WiMP (Windows, Mouse, Pointer) GUI  
  Very early machines included the OS on a floppy disk due to it not being ready to be burned to ROM (Like the Amiga 1000 had) This early version of TOS was bootstrapped from a very small core boot ROM, but this was quickly replaced with (expanded capacity) ROM versions of TOS 1.0 when it was ready. (This change was also greatly welcomed as older ST machines with memory below 512 KB suffered, as GEM loaded its entire 192 KB code into RAM when booting the desktop). Having the OS loaded from disk was due to Atari (and Commodore) trying to rush the machines to market without ironing out all the bugs in the OS. Soon after this change, most production models became STFs, with an integrated single- (520STF/512 KB RAM) or double-sided (1040STF/1024 KB RAM) double density drive built-in, but no other changes. The next later models used an upgraded version of TOS - 1.02 (also known as TOS 1.2). 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 its low or medium resolution (525/625 line 60/50 Hz interlace, even on RGB monitors) modes, greatly enhancing the machine's saleability and perceived value (no need to buy a prohibitively expensive, even if exceptionally crisp and clear, monitor). These models were known as the 520STM (or 520STM). Later F and FM models of the 520 had a built in double-sided disk drive instead of a single-sided one.  
  As originally released in the 520STE/1040STE:  
  All of the features of the 520STFM/1040STFM  
  Extended palette of 4,096 available colours to choose from  
  BLiTTER chip for fast movement of large data blocks around memory  
  Hardware-support for horizontal and vertical fine scrolling and split screen (using the Shifter video chip)  
  DMA sound chip with 2-channels stereo 8-bit PCM sound at 6.25/12.5/25/50kHz and stereo RCA audio-out jacks (using enhancements to the Shifter video chip to support audio shifting)  
  National LMC 1992 audio controller chip, allowing adjustable left/right/master volume and bass and treble EQ via a "Microwire" (3-bit serial) interface  
  Memory: 30-pin SIMM memory slots allowing upgrades up to 4 MB Allowable memory sizes including only 0.5, 1.0, 2.0, 2.5, 3.0, and 4.0 MB due to configuration restraints (however, 2.5 and 3.0 MB are unsupported and have compatibilty problems). Later 3rd-party upgrade kits allow a maximum of 14MB, bypassing the stock MMU  
  Ability to synchronise the video-timings with an external device so that a video Genlock device can be used without having to make any modifications to computer's hardware  
  Analogue joypad ports (2), with support for devices such as paddles and light pens in addition to joysticks/joypads. The Atari Jaguar joypads and Power Pad joypads (grey version of Jaguar joypads marketed for the STE and Falcon) can be used without an adaptor. Two standard Atari-style digital joysticks could be plugged into each analogue port with an adaptor.  
  TOS 1.06 (also known as TOS 1.6) or TOS 1.62 (which fixed some major backwards-compatibility bugs in TOS 1.6) in two socketed 128 KB ROM chips.  
  Socketed PLCC 68000 CPU  
  With the hardware design nearing completion, the team started looking at solutions for the operating system. Soon after the buyout Microsoft approached Tramiel with the suggestion that they port Windows to the platform, but the delivery date was out by about two years, far too long for their needs. Another possibility was Digital Research, who were working on a new GUI-based system then known as Crystal, soon to become GEM. Another option was to write a new operating system in-house, but this was eventually rejected due to the risk.

Digital Research was fully committed to the Intel platform, so a team from Atari was sent to the Digital Research headquarters to work with the "Monterey Team" which comprised a mixture of Atari and Digital Research engineers. Atari's Jim Tittsler was Atari key OS engineer overseeing "Project Jason" (aka - The Operating System) for the Atari ST line of computers.
TOS 1.0 with the GEM user interface

CP/M-68K was essentially a direct port of CP/M's original, mature operating system. By 1985, it was becoming increasingly outdated in comparison to MS-DOS 2.0; for instance, CP/M did not support sub-directories and did not have a hierarchical file system. Digital Research was also in the process of building a new DOS-like operating system specifically for GEM, GEMDOS, and there was some discussion of whether or not a port of GEMDOS could be completed in time for product delivery in June. The decision was eventually taken to port it, resulting in a GEMDOS file system which became part of TOS (The Operating System). This was beneficial as it gave the ST a fast, hierarchical file system, essential for hard drive storage disks, plus programmers had function calls similar to the IBM PC DOS.

  The 520ST was an all-in-one unit, similar to earlier home computers like the Commodore 64. By the time the 520ST reached the market, however, consumers demanded a keyboard with cursor keys and a numeric keypad. For this reason, the 520ST was a fairly large and awkward computer console.

Adding to this problem was the number of large cables needed to connect to the peripherals. This problem was addressed to some degree in the follow-on models which included a built-in floppy disk, though this addition resulted in the awkward placement of the mouse and joystick ports to a cramped niche underneath the keyboard.

Early 520ST owners became accustomed to the "Atari Twist" and the "Atari Drop" service procedures. "Atari Twist" seemed to help discharge built-up static electricity (Atari soldered-down the metal shielding to fix the problem) while the "Atari Drop" appeared to help re-seat chips which may have become partially unseated over time.

The case design was created by Ira Valenski - Atari's chief Industrial Designer.[3] The ST was basically wedge shaped, with a series of grilles cut into the rear for airflow. The majority of the machines had keyboards with soft tactile feedback resulting in a "cheap" feel, with rhomboid function keys across the top edge. The original 520ST design used an external floppy drive; the 1040ST-style case featured a built-in floppy drive. The power supply for the early 520ST was a large external brick while the 1040ST's was inside the machine.

  Atari later upgraded the basic design in 1986 with the 1040STF (also written STF). The machine was 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 1040 shipped with 1 MB of RAM, and the same design was also used for the new 512 KB 520STFM, which replaced the earlier models in the market.

The 1040ST was the first personal computer shipped with a base RAM configuration of 1 MB, and when the list price was reduced to $999 in the U.S. it became the first computer to break the $1000/megabyte price barrier, and was featured on the cover of Byte Magazine. 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.

  Initial sales were strong, especially in Europe where Atari sold 75% of its computers. Germany became Atari's strongest market, with small business users using them for desktop publishing and CAD.

To address this growing market segment, Atari came up with the ST1. First debuted at Comdex, 1986, it was received favorably. Renamed the Mega, this new machine included a detached high-quality keyboard, stronger case (to support the weight of a monitor), and internal bus expansion connector. The upcoming SLM804 laser printer would not come with a processor or memory, reducing costs. It would attach to the Mega through the ST DMA port and have the Mega computer render the pages. Initially equipped with 2 or 4 MB (a 1 MB version, the Mega 1 would later follow), the Mega machines would complement the Atari laser printer for a low-cost desktop publishing package.

A custom blitter co-processor was to be included to speed the performance of some graphics operations on the screen, but due to delays it was eventually released on the Mega 2 and Mega 4 machines. Developers wanting to use it had to detect for it in their programs because it was not present on all machines. However, properly-written programs using the screen VDI commands could use the blitter seamlessly since GEM API was a higher-level interface to TOS.

  In late 1989, Atari released the STE (also written STE), a version of the ST with improvements to the multimedia hardware and operating system. The STE featured an increased colour palette of 4096 colours from the ST's 512 (though the maximum displayable palette of these without programming tricks was still limited to 16 in the lowest 320x200 resolution and even fewer in higher resolutions), Genlock support, and a graphics co-processor chip called Blitter which could quickly move large blocks of data (most particularly, graphics sprites) around in RAM. It also included a new 2-channels digital sound chip that could play 8-bit stereo samples in hardware at up to 50 kHz. Two enhanced joystick ports (EJP) were added (two normal joysticks could be plugged into each port with an adaptor), with the new connectors placed in more easily-accessed locations on the side of the case. The enhanced joystick ports were compatible with joypads from Atari's Jaguar console. RAM was now much more simply upgradable via SIMMs. Despite all of this, it still ran at 8 MHz, and the enhanced hardware was clearly designed to catch up with the Amiga.

The STE models initially had software and hardware conflicts resulting in some applications and games written for the ST line being unstable or even completely unusable (sometimes, this could be solved by expanding the RAM). To make matters worse, the built-in floppy disk drives could not read as many tracks on a floppy disk as the built-in floppy disk drives on older models. While this was not a problem for most users, some games used the extra tracks as a crude form of copy protection and as a means of cramming more data onto the disk, and formatting as many as 86 tracks on an "80-track" disk was a common space-expanding option in custom formatting utilities. Furthermore, even having a joystick plugged in would sometimes cause strange behaviour with a few applications (such as First Word Plus).

Very little use was made of the extra features of the STE: STE-enhanced and STE-only software was rare, generally being limited to serious art, CAD or music applications, with very few games taking advantage of the hardware as it was found on so few machines. Quality did, however, seem to substitute for quantity, as the coders who took advantage of the new abilities used them to their fullest.

The last STE machine, the Mega STE, was a STE in a grey Atari TT case that ran at a switchable 16 MHz, dual-bus design (16-bit external, 32-bit internal), optional Motorola 68882 FPU, built-in 3½" floppy disk drive, VME expansion slot, a network port (very similar to that used by Apple's LocalTalk) and an optional built-in 3½" hard drive. It also shipped with TOS 2.00 (better support for hard drives, enhanced desktop interface, memory test, 1.44 MB floppy support, bug fixes). It was marketed as more affordable than a TT but more powerful than an ordinary ST.

  In 1990, Atari released the high-end workstation-oriented TT (32-MHz, 68030-based TT030). Originally planned with a 68020 CPU, the TT included improved graphics and more powerful support chips. The case was a new design with an integrated hard drive enclosure.

The final ST computer was the multimedia Falcon (also 68030-based, operating at 16 MHz, but with improved video modes and extensive custom chip provisions, particularly high-quality audio DSPs). Although 68030 microprocessor was capable of using 32-bit memory, the Falcon used a 16-bit bus which impacted performance, but also served to reduce its cost. In another cost-reduction measure, Atari shipped the Falcon in an inexpensive case much like that of the STE. After-market upgrade kits were available that allowed the Falcon to be put in a desktop or rack-mount case, with the keyboard separate.

Released in 1992, it was cancelled by Atari the following year. In Europe, C-Lab licenced the Falcon design from Atari and released the C-Lab Falcon Mk I (the same as Atari's Falcon except for some slight modifications to the audio circuitry), Mk II (as Mk I but with a 500 MB hard disk) and Mk X (as Mk II but in a desktop case).


The ST's low cost, built-in MIDI ports, and fast, low-latency response times made it a favorite with musicians.

The ST was the first home computer with built-in MIDI ports, and there was plenty of MIDI-related software for use professionally in music studios, or by amateur enthusiasts. The popular Windows/Macintosh applications Cubase and Logic Pro originated on the Atari ST. Another popular and powerful ST music sequencer application, Dr. T's KCS, contained a "Multi-Program Environment" that allowed ST users to run other applications, such as the synthesizer patch editing software XoR (now known as Unisyn on the Macintosh), from within the sequencer application.[1] Even today some people (such as Fatboy Slim) are still using the Atari ST for composing music.

Music tracker software was popular on the ST, such as the TCB Tracker, aiding the production of quality music from the Yamaha synthesizer ('chiptunes').

An innovative music composition program that combined the sample playing abilities of a tracker with conventional music notation (which was usually only found in MIDI software) was called Quartet (after its 4-note polyphonic tracker, which displayed one monophonic stave at a time on colour screens).

Due to the ST having comparatively large amounts of memory for the time, sound sampling packages became a realistic proposition. The Microdeal Replay Professional product featured a sound sampler that cleverly used the ST cartridge port to read in parallel from the cartridge port from the ADC. For output of digital sound, it used the on-board frequency output, set it to 128 kHz (inaudible) and then modulated the amplitude of that.

In addition to the sound sampling functionalities, the availability of software packages with MIDI support for music composition and efficient sound analysis contributed to make the Atari ST a forerunner of later computer-based all-in-one studios.

  Also popular on the ST was professional desktop publishing software, such as PageStream and Calamus; office tools such as word processors (WordPerfect, WordWriter ST and others), spreadsheets and database programs; and various CAD and CAM tools from amateur hobbyist to professional grade, all being largely targeted or even limited to high resolution monochrome-monitor owners.

Graphics programs such as NEOchrome, Degas & Degas Elite, Canvas, Deluxe Paint, and Cyber Paint featured advanced features such as 3D design, animation. One paint program, Spectrum 512, used palette switching tricks allowing the maximum number of colors to be displayed on-screen at once (up to 46 in each scan line - the STE never had a Spectrum4096, but other more minor applications filled this speciality niche, one even going so far as to trick the shifter into displaying a maximum 19200 colours).

3D computer graphics applications (like The Cyber Studio), brought 3D modelling, sculpting, scripting, and most important, computer animation (using delta-compression) to the desktop. Video capture and editing applications using special video capture 'dongles' connected using the cartridge port - low frame rate, mainly silent and monochrome, but progressing to sound and basic colour (in still frames) by the end of the machine's life.

  The Atari ST had a wide variety of languages and tools for development. 68000 assemblers (MadMac from Atari Corp, HiSoft's Devpac), Pascal (OSS Personal Pascal), Modula-2, C compilers (like Alcyon C, Lattice C, Megamax C, Mark Williams C, GNU C, Aztec C), LISP, Prolog, Logo and many others.

The initial development kit from Atari included a computer and manuals. At $5,000, this discouraged many from developing software for the ST. Later, the Atari Developer's Kit consisted of software and manuals (no hardware) for $300. Included with the kit were a resource kit, C compiler (first Alcyon C, then Mark Williams C), debugger, and 68000 assembler (plus the non-disclosure agreement).

The ST came bundled with a system disk that contained ST BASIC, the first BASIC for the ST. However, due to its poor performance, users favored other BASICs, such as GFA BASIC, FaST BASIC (notable for being one of the few programs to actually be supplied as a ROM cartridge instead of on disc) and the relatively famous STOS, a cousin of AMOS on the Amiga, and powerful enough that it was used (with a compiler, opposed to its usual runtime interpreter) for the production of at least two commercial titles and an innumerable host of good quality shareware and public domain games.

Even novelty tools such as SEUCK were available.

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

Notable individuals who developed games on the ST include Peter Molyneux, Doug Bell, Jeff Minter, Jez San, James Hutchby, Dimitri Koveos and David Braben. The first real-time 3D role-playing computer game, Dungeon Master, was first developed and released 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 enhanced graphics found in the ST machines, as did many arcade ports. One game, MIDI Maze used the midi ports to connect with other machines for interactive networked play. Games simultaneously released on the Amiga that had identical graphics and sound were often accused by computer game magazines of simply being ST ports.

  Utility software was available to drive hardware add-ons such as video digitisers. Office Productivity and graphics software was also bundled with the ST (HyperPaint II by Dimitri Koveos, HyperDraw by David Farmborough, 3D-Calc spreadsheet by Frank Schoonjans, and several others commissioned by Bob Katz, later of Electronic Arts).

There was a thriving output of public domain and shareware software which was distributed by, in the days long before public internet access, public domain software libraries that advertised in magazines and on popular dial-up Bulletin Board Systems.

Remarkably, a modest core fanbase for the system, supporting a dwindling number of good quality print magazines, survived to the mid 90s and the birth of the modern, publicly accessible internet as we know it. Despite the limited graphics, memory, and temporary hard storage capabilities of the system, several email, FTP, telnet, IRC, and even full-blown graphical world wide web browser applications are available and usable on the ST.

  In 1993, Atari cancelled development on the ST computers to focus on the Jaguar.

Following the exit of Atari from the computer market, Medusa Computer Systems manufactured some powerful 3rd-party Atari Falcon/TT-compatible machines that used 68040 and 68060 processors, based around multimedia (particularly audio, but also video), CAD and office uses.

Despite the lack of a hardware supplier, there is a small active community dedicated to keeping the ST platform alive. There have been advancements in the operating system, software emulators (for Windows, Mac & Linux), and some hardware developments. There are accelerator cards, such as the CT60 & CT63, which is a 68060 based accelerator card for the Falcon, and there is the Atari Coldfire Project, which aims at developing an Atari-clone based on the Coldfire processor. Milan Computer of Germany also makes 68040 and 68060-based Atari clones that can run either Atari TOS 4.5 or Milan Computer's MultiOS operating system.

  A number of machines were released in the ST family. Here they are, in rough chronological order after the original 520ST:
  520ST+ - Name for early 520STs with 1 MB of RAM, but without floppy disk  
  260ST - European name for the 520ST with 512 KB. Used after the release of the 520ST+ to differentiate the cheaper 512 KB models from the 1 MB models  
  520STM - a 520ST with a built-in modulator for TV output  
  520STFM - a 520STM with a newly redesigned motherboard in a larger case with a built-in floppy disk drive  
  1040STF - a 520STFM with 1 MB of RAM and a built-in double-sided floppy disk, but without RF modulator  
  1040STFM - a 520STFM with 1 MB of RAM and a built-in double-sided floppy disk with RF modulator  
  Mega ST (MEGA2, MEGA4) - 1040 with 2 or 4 MB of RAM, respectively, in a much improved "pizza box" case with a detached keyboard. Early models did not include the BLiTTER chip; most did. Included a real-time clock and internal expansion connector.  
  520STE and 1040STE - a 520STFM/1040STFM with enhanced sound, the BLiTTER chip, and a 4096-color palette, in the older 1040 style all-in-one case  
  Mega STE - same hardware as 1040STE except for a faster 16 MHz processor, in the TT case  
  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 (especially when rechargeable batteries of the time supplied insufficient power compared to the intended alkalines), they simply glued the lid of the battery compartment shut, and soon discontinued the machine.  
  ST Book (later version portable ST), vastly more portable than the STacy, but sacrificing several features in order to achieve this - notably the backlight, and internal floppy disc drive. Files were meant to be stored on a small amount (one megabyte) of internal flash memory 'on the road' and transferred using serial or parallel links, memory flashcards or external (and externally powered) floppy disc to a 'real' desktop ST once back indoors. The screen is highly reflective for the time, but still hard to use indoors or in low light (the idea of a switchable green LED backlight seeming not to have inspired the Atari technical department as it did many wristwatch manufacturers), it is fixed to the 640x400 1-bit mono mode (not even greyscale emulation of colour in low res is offered), and no external video port was provided. For its limitations, it gained some popularity as being the most utterly portable 'real' computer of the day (slim, light, quiet, reliable, and with a long battery life, even by today's standards for all 5), particularly amongst musicians already used to using the original computer and perhaps having lugged a STacy or even a full ST + Monitor + accessories rig on tour.  
  The design shipped in June 1985 to Atari User Groups and then in September 1985 for general retail sales as the 520ST. The machine had gone from concept to store shelves in a little under a year. Atari had originally intended to release versions with 128 KB and 256 KB of RAM as the 130ST and 260ST respectively. However, with the OS loaded from floppy into RAM, there would be little or no room left over for applications to run. The 260ST did make its way into Europe on a limited basis.

Early models shipped with TOS on disk, but were designed with ROM sockets to make for 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 to upgrade 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 520STM.

Atari had 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.

On the plus side, the ST was less expensive than most machines, including the Macintosh Plus, and tended to be faster than most (external link: price comparison). Largely as a result of the price/performance factor, the ST would go on to be a fairly popular machine, notably in 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.

  The ST featured a large number of ports mounted at the rear of the machine.
  Standard ports:  
  RS-232c serial port (DB25 male)  
  Centronics printer port (DB25 female)  
  joystick/mouse ports (DE-9 male)  
  MIDI ports (5-pin DIN)  
  ST-specific ports:  
  Monitor port (13-pin DIN)  
  ACSI (similar to SCSI) DMA port (for hard disks and laser printers)  
  Floppy port (to add a second floppy drive)  
  ST cartridge port (for 128 KB ROM cartridges)  
  Because of its bi-directional design, the Centronics printer port could be used for joystick input and several games made use of available adaptors that plugged into the printer socket, providing two additional 9-pin joystick ports.

Atari initially used single-sided disk drives that could store up to 360 KB. Later drives were double-sided versions that stored 720 KB. 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, for fear of alienating early adopters. ST magazines wishing to cater to the entire audience while still supplying a large amount of material on a single cover disc had to adopt innovative custom formats to work around this problem. Another sticking point was that while the Atari double-sided drive could read IBM-formatted disks, IBM PCs could not read Atari disks. This was a formatting issue that was later resolved by third-party software formatters and TOS upgrades (1.4 and higher).

  SF354 - Single-sided double-density 3½ floppy drive (360 KB)
  SF314 - Double-sided double-density 3½ floppy drive (720 KB)  
  SM124 - Monochrome monitor, 12" screen, 640x400 pixels, 70hz refresh  
  SM147 - Monochrome monitor, 14" screen, no speaker, replacement for SM124  
  SC1224 - Color monitor, 12" screen, 640x200 pixels plus speaker  
  SC1435 - Color monitor, 14" screen, stereo speakers, replacement for SC1224 (rebadged Magnavox 1CM135)  
  SM195 - Monochrome monitor, 19" screen for TT030. 1280x960 pixels. 70hz refresh  
  SH204 - External hard drive, 20 MB  
  Megafile 20, 30, 60 - External hard drive, Mega ST matching case  
  Megafile 44 - Removable cartridge drive, Mega ST matching case  
  SLM804 - Laser printer, connected through ACSI DMA port, used ST's memory and processor to build pages for printing  
  SLM605 - Laser printer, connected through ACSI DMA port, smaller than SLM805  
  The standard 8x8 pixel graphical character set for the ST (the main in-ROM "font" for GEM, and text-mode TOS operations) contains, following all the standard numbers, letters, symbols and accented characters, four unusual characters. These can be placed together in a square, forming a basic but recognisable facsimile of the face of J. R. "Bob" Dobbs, the supposed founder of the Church of the Subgenius.
  Jack Tramiel chose to include the Hebrew alphabet with ST's ROM character set because of his Jewish heritage.  
  Highly acclaimed IDM artists Mike Paradinas and Luke Vibert started out writing music on Atari STs.  
  Mike Oldfield's album "Earth Moving" stated in its sleeve that it was recorded using an Atari ST and C-Lab MIDI software.  
  In the Paris performance of Jean Michel Jarre's album "Waiting for Cousteau", musicians have attached Atari ST machines with unidentified MIDI software to their keyboards, as could be seen in the TV live show and video recordings.