# Atari ST
The Atari ST is a 16-bit home and small-business computer line built around the [Motorola 68000](https://www.edgepedia.org/motorola-68000) microprocessor, introduced by Atari Corporation at the Winter Consumer Electronics Show in Las Vegas in January 1985 and sold until 1993.[1](https://www.retroisle.com/atari/st/general.php) • [2](https://arstechnica.com/features/2005/12/total-share/) The name combined the memory size of the launch model ("520" for 512 KB) with "ST" for Sixteen/Thirty-two, referring to the 68000's 16-bit external bus and 32-bit internal registers.[1](https://www.retroisle.com/atari/st/general.php) The line became best known for its low price against the Apple Macintosh and for built-in MIDI ports that made it a computer of choice for late-1980s music studios.
| Key fact | Detail |
|---|---|
| Processor | Motorola MC68000 running at 8 MHz, with 192 KB of ROM (64 KB in early versions) and at least 512 KB of RAM[3](https://www.atarimania.com/documents/atari_520st_service_manual.pdf) |
| Display | Three modes: 320 × 200 pixels in 16 colors, 640 × 200 in 4 colors, and 640 × 400 monochrome[3](https://www.atarimania.com/documents/atari_520st_service_manual.pdf) |
| Operating system | TOS (Tramiel Operating System) with the GEM graphical desktop; first disk-based release May 29, 1985, first ROM-based release November 20, 1985[4](https://bruceatkinson.com/atari/history-atari-st-os.php) |
| MIDI | Two built-in MIDI ports on every ST, which PCWorld describes as a first for mainstream personal computers; a contemporary estimate put the ST's share of the MIDI computer market at 30–40%[5](https://www.atarimagazines.com/st-log/issue33/53_1_STEP_1_MAKE_MINE_MUSIC.php) • [6](https://www.pcworld.com/article/511497/inside_atari_1040st.html) |
| Launch price | 520ST complete system at £652 plus VAT in 1985, against £2,595 plus VAT for an equivalently equipped Apple Macintosh[7](https://nosher.net/archives/computers/atari_1024stfm_percw_may86) |
| 1040STF | 1986 model with 1 MB RAM and built-in floppy drive, launched at $999 with monochrome monitor and mouse[6](https://www.pcworld.com/article/511497/inside_atari_1040st.html) |
| End of line | Sales fell to 30,000 units in 1993; Atari was sold to hard-drive maker JTS in 1996[2](https://arstechnica.com/features/2005/12/total-share/) |
## Development and launch
Planning for the machine that became the ST began at Tramiel Technology in the spring of 1984, before Jack Tramiel acquired Atari's consumer business from Warner Communications. A small group of former Commodore employees defined an affordable new computer, with Shiraz Shivji leading the hardware effort and Leonard Tramiel closely involved in the operating-system choice.[8](https://bruceatkinson.com/atari/history-atari-st.php) The team considered [National Semiconductor](https://www.edgepedia.org/national-semiconductor) processors before settling on the 68000, a decision shaped by availability, price, and prototype performance as much as by the instruction set.[8](https://bruceatkinson.com/atari/history-atari-st.php)
The 520ST was introduced in January 1985 at the Winter Consumer Electronics Show in Las Vegas.[1](https://www.retroisle.com/atari/st/general.php) Atari sold about 100,000 ST computers in 1985, roughly half of them in the United States.[9](https://people.delphiforums.com/dpj/aone.htm) Price was the machine's central argument: a 1985 Personal Computer World advertisement listed a complete 520ST system, with mouse, monochrome monitor, 512 KB of RAM, and 500 KB disk drive, at £652 plus VAT, while an Apple Macintosh with the same components cost £2,595 plus VAT; the comparison was said to make the IBM PC and Macintosh appear "grossly overpriced".[7](https://nosher.net/archives/computers/atari_1024stfm_percw_may86)
## Operating system: TOS and GEM
The ST's software was divided into two layers. TOS, the Tramiel Operating System, provided the low-level routines, and GEM, the Graphics Environment Manager from [Digital Research](https://www.edgepedia.org/digital-research), supplied the mouse-and-windows desktop.[10](https://www.atari-wiki.com/index.php?title=The_Operating_System_of_the_Atari_ST) Atari had first planned to build the system on Digital Research's CP/M kernel, and the 520ST shown at the Winter CES 1985 ran a CP/M-based TOS, but from February 1985 the focus moved to the newer GEMDOS; Leonard Tramiel made the decision to go with GEMDOS in late January, taking the risk over the more mature CP/M-68K.[8](https://bruceatkinson.com/atari/history-atari-st.php) • [11](https://atari-wiki.com/index.php?title=The_Atari_ST_story)
The first machines shipped with a minimal boot-ROM that loaded TOS from floppy disk, because the full system would not fit in the available ROM; a disk-based release is dated May 29, 1985, and the first ROM-based release November 20, 1985 in Atari's 1986 GEMDOS reference manual.[4](https://bruceatkinson.com/atari/history-atari-st-os.php) Fitting the system into 192 KB of ROM required removing duplicate routines and inefficient layers, and disk-loaded TOS consumed RAM that would otherwise have been available to applications.[4](https://bruceatkinson.com/atari/history-atari-st-os.php) TOS continued to be developed from 1985 to 1992.[12](https://www.atari-wiki.com/index.php?title=TOS) GEMDOS's calls closely resembled MS-DOS calls despite the difference between the 68000 and the IBM PC's 8088, and the 1040STF's 720 KB drive could read, though not write, IBM-format disks.[13](https://www.atarimagazines.com/compute/issue73/insight_st.php) • [6](https://www.pcworld.com/article/511497/inside_atari_1040st.html)
## Hardware
The 520ST and 1040ST shared a common architecture: an 8 MHz MC68000, 192 KB of ROM, DMA support, and a bit-mapped video display using 32 KB of relocatable RAM.[3](https://www.atarimania.com/documents/atari_520st_service_manual.pdf) The original 520ST used an external power supply and an external 360 KB 3.5-inch floppy drive; the 1040STF integrated both into one case and doubled the RAM to 1 MB, launching in 1986 at $999 as a complete system with base unit, monochrome monitor, and mouse.[6](https://www.pcworld.com/article/511497/inside_atari_1040st.html) Atari announced the 1040STF at the Winter CES of January 9–12, 1986, and it reached the market shipped with 1 MB of RAM as standard equipment.[14](https://atari-computermuseum.de/1040st.htm)
Expansion ports ran along the right rear side: serial, parallel printer, a hard-disk port using Atari's proprietary ACSI interface (a derivative of SCSI), and an external floppy connector.[6](https://www.pcworld.com/article/511497/inside_atari_1040st.html) In late 1989 Atari released the 520STE and 1040STE, enhanced versions that expanded the color palette from 512 to 4,096 colors, added hardware scrolling, and introduced stereo 8-bit DMA sound with volume and tone control.[15](https://temlib.org/AtariForumWiki/index.php/Introduction_to_the_STE) The STE also added two 15-pin controller ports for paddles, light guns, and keypad joysticks.[15](https://temlib.org/AtariForumWiki/index.php/Introduction_to_the_STE) Later models included the Mega STE, the TT030, and the Falcon030, and the family kept the Atari ST brand alive until 1993.[16](https://leap-egypt.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608c3c4296fa2---39368588782.pdf)
## Music and MIDI
Atari included two built-in MIDI ports with every ST shipped, which PCWorld describes as a world first for mainstream personal computers.[6](https://www.pcworld.com/article/511497/inside_atari_1040st.html) The ports are five-pin DIN connectors, an IN port for data received and an OUT port for data transmitted, driven at the standard MIDI rate of 31.25 kbit/s by an MC6850 ACIA chip.[5](https://www.atarimagazines.com/st-log/issue33/53_1_STEP_1_MAKE_MINE_MUSIC.php) • [17](https://kagami.bg/en/academy/minitech/moduli/AtariST_Nostalgia.html) The combination of low price, mouse-driven interface, and built-in MIDI made the ST the computer of choice for musicians; one contemporary estimate put its share of the MIDI computer market at 30 to 40 percent, ahead of the Macintosh and PC clones.[5](https://www.atarimagazines.com/st-log/issue33/53_1_STEP_1_MAKE_MINE_MUSIC.php)
The ST became the platform where modern sequencer software took shape. Steinberg developed Pro-24 for the ST and then [Cubase](https://www.edgepedia.org/cubase) for the ST, Mac, and PC, while C-Lab followed a similar route from C64 sequencers to Notator and Creator on the ST, the line that became Emagic's Notator Logic.[18](https://www.musicradar.com/music-tech/the-whole-process-left-me-feeling-flat-and-empty-with-ai-now-threatening-to-make-the-daw-obsolete-is-it-finally-time-to-stand-up-to-the-tech-taking-the-very-soul-out-of-music-making) The 1040ST established itself in recording studios and on stage as a quasi-standard, and ST machines saw widespread use for audio production well into the late 1990s because of their stability and music software.[14](https://atari-computermuseum.de/1040st.htm) • [6](https://www.pcworld.com/article/511497/inside_atari_1040st.html)
## Market position and decline
The ST competed directly with the Commodore Amiga and the Macintosh, generally winning on price. In January 1986 Atari announced the 1040ST, cut $100 from both monochrome and color 520ST systems, and shifted the 520ST to mass-market outlets such as department stores.[19](https://www.atarimagazines.com/compute/issue71/electronics_show.php) British prices fell repeatedly: the 520STFM dropped to £299 by 1987, and the monochrome 1040ST system was reduced from $999 to $899 in the United States the same year.[20](https://www.atari-computermuseum.de/history_1987.htm) • [21](https://colorcomputerarchive.com/coco/Documents/Magazines/Compute%20%28Clean%29/Compute_Issue_083_1987_Apr.pdf)
Sales tailed off through the early 1990s, and only 30,000 ST units were sold in 1993. Atari fell into a severe cash-flow crisis as Nintendo took its console market share, and the company was sold to the hard-drive manufacturer JTS in 1996.[2](https://arstechnica.com/features/2005/12/total-share/) The machine retains an active community: new homebrew games and demos are still released for it, and modern FPGA recreations reproduce the cycle-exact 8 MHz 68000 with physical MIDI ports.[22](https://www.tomshardware.com/video-games/retro-gaming/atari-st-enthusiast-announces-the-minist-with-fpga-misterynano-core-and-black-tkl-case-priced-at-around-usd400-each-but-the-initial-run-is-a-mere-five-units)
## References
1. [Atari ST, Retro Isle](https://www.retroisle.com/atari/st/general.php)
2. [Total share: 30 years of personal computer market share figures, Ars Technica](https://arstechnica.com/features/2005/12/total-share/)
3. [Atari 520ST Service Manual, atarimania.com](https://www.atarimania.com/documents/atari_520st_service_manual.pdf)
4. [Creating the ST operating system, Atari Computers (Bruce Atkinson)](https://bruceatkinson.com/atari/history-atari-st-os.php)
5. [Step 1: Make Mine Music, ST-Log](https://www.atarimagazines.com/st-log/issue33/53_1_STEP_1_MAKE_MINE_MUSIC.php)
6. [Inside the Atari 1040STf, PCWorld](https://www.pcworld.com/article/511497/inside_atari_1040st.html)
7. [Atari advert: The new 1Mb 1040STF, nosher.net (Personal Computer World, May 1986)](https://nosher.net/archives/computers/atari_1024stfm_percw_may86)
8. [Creating the Atari ST, Atari Computers (Bruce Atkinson)](https://bruceatkinson.com/atari/history-atari-st.php)
9. [Atari Online News, Etc.](https://people.delphiforums.com/dpj/aone.htm)
10. [The Operating System of the Atari ST, Atari Wiki](https://www.atari-wiki.com/index.php?title=The_Operating_System_of_the_Atari_ST)
11. [The Atari ST story, Atari Wiki](https://atari-wiki.com/index.php?title=The_Atari_ST_story)
12. [TOS, Atari Wiki](https://www.atari-wiki.com/index.php?title=TOS)
13. [INSIGHT: ST: ST System Software, Inside Out, COMPUTE! June 1986](https://www.atarimagazines.com/compute/issue73/insight_st.php)
14. [Atari 1040ST, atarimuseum.de](https://atari-computermuseum.de/1040st.htm)
15. [Introduction to the STE, AtariForumWiki](https://temlib.org/AtariForumWiki/index.php/Introduction_to_the_STE)
16. [Atari 1040 ST games (document collection)](https://leap-egypt.com/wp-content/plugins/formcraft/file-upload/server/content/files/1608c3c4296fa2---39368588782.pdf)
17. [Atari ST: the musicians' machine (1985), KAGAMI Academy](https://kagami.bg/en/academy/minitech/moduli/AtariST_Nostalgia.html)
18. [With AI now threatening to make the DAW obsolete, MusicRadar](https://www.musicradar.com/music-tech/the-whole-process-left-me-feeling-flat-and-empty-with-ai-now-threatening-to-make-the-daw-obsolete-is-it-finally-time-to-stand-up-to-the-tech-taking-the-very-soul-out-of-music-making)
19. [A Turning Point for Atari? Report from the Winter CES, COMPUTE! April 1986](https://www.atarimagazines.com/compute/issue71/electronics_show.php)
20. [Die Geschichte der Marke Atari – Das Jahr 1987, atarimuseum.de](https://www.atari-computermuseum.de/history_1987.htm)
21. [COMPUTE! April 1987](https://colorcomputerarchive.com/coco/Documents/Magazines/Compute%20%28Clean%29/Compute_Issue_083_1987_Apr.pdf)
22. [Atari ST enthusiast announces the MiniST with FPGA, Tom's Hardware](https://www.tomshardware.com/video-games/retro-gaming/atari-st-enthusiast-announces-the-minist-with-fpga-misterynano-core-and-black-tkl-case-priced-at-around-usd400-each-but-the-initial-run-is-a-mere-five-units)
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*Topic: Encyclopedia › Technology and the built world › Computing and digital systems › Computer hardware › Personal computers & laptops*
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