--- title: Atari 520 ST / ST+ / STM categories: - Computers types: - Home Computer origins: - U.S.A. years: - '1985' cpus: - Motorola MC68000 params: name: 520 ST / ST+ / STM image: /media/museum/photos/atari_520st_system_1.jpg company: /companies/atari company_name: Atari specs: - label: NAME value: 520 ST / ST+ / STM - label: MANUFACTURER value: Atari - label: TYPE value: Home Computer - label: ORIGIN value: U.S.A. - label: YEAR value: '1985' - label: KEYBOARD value: Full-stroke keyboard with numeric and editing keypads - label: CPU value: Motorola MC68000 - label: SPEED value: 8 mHz - label: CO-PROCESSOR value: '''Shifter'' and ''Glue'' custom chips' - label: RAM value: 512 KB (520 ST/STM), 1 MB (520 ST+) - label: ROM value: 192 KB - label: TEXT MODES value: 40 or 80 columns x 25 lines - label: GRAPHIC MODES value: 320 x 200 / 640 x 200 / 640 x 400 dots - label: COLORS value: 16 among 512 (320 x 200) / 4 among 512 (640 x 200) / monochrome (640 x 400) this last mode needs a special monitor. - label: SOUND value: 3 voices, 8 octaves - label: SIZE / WEIGHT value: 47 (W) x 24 (D) x 6 (H) cm - label: I/O PORTS value: RGB, TV modulator (520STm), Cardridge, Midi (in/out), Centronics, RS232c, Hard Disk, Floppy Disk, Joystick, Mouse - label: BUILT IN MEDIA value: External 3.5'' 360 KB disk-drive (option) - label: OS value: TOS / GEM - label: POWER SUPPLY value: External power supply unit - label: PRICE value: £749 (1985, UK), £399 (1986, UK) tabs: - photos - adverts - hardware - emulators - links - docs forum_thread: 40 photos: - title: ATARI 520 ST subtitle: '' text: it has the same characteristics as the 130 ST and the 260 ST, save for its added memory image: /media/museum/photos/520st.jpg - title: 520 ST MOTHERBOARD subtitle: '' text: |- **(1)** SHIFTER custom circuit. Woks with the MMU to produce the video signal\ **(2)** 512 KB RAM memory chips (256K x 1 bit)\ **(3)** 2 x 6850 ACIA's. Manage asynchronous communications with keyboard, mouse, joysticks (first) and MIDI interface (second)\ **(4)** YM-2149 sound generator chip (3 tones generator + noise generator)\ **(5)** MMU custom circuit. Manages RAM address bus and video signal with the SHIFTER\ **(6)** Motorola 68000 microprocessor\ **(7)** GLUE custom chip. Manages the entire system and data transfer between various chips.\ **(8)** Western Digital 1772 floppy disk controller chip.\ **(9)** Multi-Function Peripheral 68901 chip. Performs a 8-bit parallel port, a built-in serial interface, timers and interrupts.\ **(10)** DMA controller chip. Oversees data transfer from F.D. and H.D. drives and various peripherals\ **(11)** 6 x ROM chips holding the BIOS and GEM operating system\ **(12)** ROM cartridge connector\ **(13)** Hard-disk unit DB19 connector\ **(14)** Floppy-disc unit 15-pin DIN plug\ **(15)** Modem/Serial DB25 connector\ **(16)** Printer/Parallel DB25 connector\ **(17)** RGB monitor DIN plug\ **(18)** RF modulator and TV output chinch plug\ **(19)** Musical interface MIDI in\ **(20)** MIDI out\ **(21)** Power DIN plug. Power is supplied by an external power supply unit\ **(22)** Power On/Off switch\ **(23)** System Reset switch\ **(24)** 2 x joystick plugs **Ari Feldman** specifies:\ The "Shifter" and "Glue" chips were not coprocessors in the traditional sense. The base ST models had four custom chips:\ \* Shifter - Video\ \* DMA - DMA and bus access\ \* MMU - Memory access\ \* Glue - "glues" the operation of the other three chips together\ Noe of these four chips could work independently. They were designed for very limited and specific functions and designed to only work with each other. For example, the Shifter woun't work without the MMU, etc.\ Coprocessors wouldn't be added to the ST line until 1987/88 when the BLITTER chip arrived, which was basically a hardware implementation of the ST's RasterOps routines. image: /media/museum/photos/atari_520_motherboard_1.jpg - title: REAR CONNECTORS subtitle: '' text: |- **(1)** 2 x joysticks connectors\ **(2)** Reset switch\ **(3)** Power On/Off switch\ **(4)** Power supply DIN plug\ **(5)** MIDI out\ **(6)** MIDI in\ **(7)** TV RF output\ **(8)** RGB video DIN plug\ **(9)** Printer DB25 connector\ **(10)** Modem DB25 connector\ **(11)** Floppy-disc unit plug\ **(12)** Hard-disk unit DB15 connector image: /media/museum/photos/atari_520st_back_1.jpg adverts: - title: UK ADVERT subtitle: '' text: |- One of the first advert for the Atari 520ST checked against an Apple Mac and an Apricot computer. Thanks to **Bradley Sturch** image: /media/museum/pubs/atari_520st_pub_s2.jpg hardware: - title: SF-354 subtitle: Single density disk-drive text: '' image: /media/museum/hardware/atari_st_sf354-diskdrive_1.jpg - title: SF-314 subtitle: Disk-drive text: '' image: /media/museum/hardware/atari_st-disk-drive_sf314.jpg - title: CUMANA DRIVE subtitle: '' text: '' image: /media/museum/hardware/atari_520_cumanadrive_1.jpg - title: SUPRADRIVE subtitle: 20 Mb hard-disk text: '' image: /media/museum/hardware/atari_supradrive_20mb.jpg - title: 170MB QUANTUM HARD-DRIVE subtitle: '' text: This unit has an ICD Host Adapter. image: /media/museum/hardware/atari_st_quamtum_hd170.jpg - title: ATARI MEGAFILE 30 subtitle: '' text: This hard-drive has a 30Mb capacity. image: /media/museum/hardware/atari_st_megafile30_1.jpg - title: INSIDE THE MEGAFILE 30 subtitle: '' text: |- **(1)** Seagate MFM 30 MB hard-disk Type ST-238\ **(2)** Power supply\ **(3)** Logical board\ **(4)** Power and disk access LED's image: /media/museum/hardware/atari_megast_insidemegafile_1.jpg - title: MEMORY EXPANSION subtitle: '' text: 512 KB to 2 MB memory expansion, depending of the memory chips used. image: /media/museum/hardware/atari_520st_memexp_1.jpg - title: ATARI UNIVERSAL MODEM subtitle: '' text: |- The SX212 modem was one of the rare Atari peripherals that could be used with all the Atari computers range, from the 400/800 series up to the Falcon. It had both the Atari I/O ports for the 8-bit systems and a standard RS-232 connector for ST's It was a 300/1200 baud modem compatible with the well-known Hayes 'AT' commands.\ Cable and software was sold separately, depending of the computer used. image: /media/museum/hardware/atari_520_modemsx212_1.jpg - title: SML-804 subtitle: Laser printer text: |- The SLM-804 was actually a Kyocera F1000 printer but without neither on-board processor and memory nor buttons other than the on/off switch. It was first delivered with the Mega ST but could be connected on all of the ST series computers through a dedicated interface box.\ The printer used the processing power and the RAM memory of the ST computer for printing at 8 pages per minute and 300 DPI. The paper tray held 250 sheets. Thanks to **Francois Michaud** who donated us this printer. image: /media/museum/hardware/atari_megast_slm804printer_s1.jpg - title: SMLC-804 subtitle: Laser printer interface text: This interface allowed the SML-804 printer to be connected to any Atari ST holding at least 1 MB RAM. image: /media/museum/hardware/atari_megast_slmcinterface_s1.jpg emulators: - title: Pacifist ! url: http://www.pacifist.fatal-design.com/ platform: MS DOS text: Pretty good emulator - title: Gemulator url: http://www.emulators.com/gemul8r.htm platform: Windows text: '' - title: MagiCPC url: http://www.application-systems.de/magicpc/index.html platform: Windows text: '' - title: SainT url: http://saint.atari.org platform: Windows text: The best Atari ST Emulator ! - title: Steem url: http://steem.atari.st/ platform: Windows text: Excellent emulator for 1040/520 STE ! - title: Tos2Win url: http://www.aixit.com/tos2win/ platform: Windows text: A good Atari GEM Emulator ! - title: MagiCMac url: http://www.application-systems.de/magicmac/index.html platform: Apple text: '' - title: NoSTalgia & PowerST url: http://users.skynet.be/sky39147/ platform: Apple text: '' - title: STonX Homepage url: http://www.complang.tuwien.ac.at/nino/stonx.html platform: Unix / Linux text: '' - title: Atari ST Emulator url: http://www.atari-st.lovely.net/ platform: Other platform text: Written in Java ! - title: ARAnyM url: HTTP://ARANYM.ATARI.ORG platform: Multiplatform text: Multiplatform project - title: Hatari url: http://hatari.sourceforge.net/ platform: Multiplatform text: Hatari is an Atari ST emulator for Linux, BSD, BeOS, Mac OS X and other systems that are supported by the SDL library. More precisely, Hatari is an adaption of the WinSTon source code to the SDL library. links: - title: Atari & Commodore Home Computer Museum url: http://www.best.com/~hmk/ text: '' - title: Atari Music Network url: http://www.atarimusic.net/ text: Atari Music Network welcomes and celebrates all vintage digital musicians no matter what their computer - title: Atari ST Demo History url: http://wwwbrauer.in.tum.de/~brandtf/ataridemos.html text: '' - title: Atari ST Download Area url: http://www.chebucto.ns.ca/Services/PDA/atari.shtml text: Atari 400/800/XL/XE & ST/TT/Falcon Software download page - title: ATARI.ORG url: http://www.atari.org/ text: Looking for something on any Atari machine ? Follow the links ! - title: Dead Hackers Society url: http://www.dhs.nu/ text: Atari demo scene - title: Little Green Desktop url: http://www.atari.st/ text: Largest Atari ST ressource! - title: Medusa computer url: http://www.kingx.com/kingx/medusa/thes.html text: You can still buy an Atari ST family clone computer - title: MiNTOS Distribution url: http://www.earth.ox.ac.uk/~steve/mintos.html text: '' - title: Musique.Atari.Org url: HTTP://MUSIQUE.ATARI.ORG text: Web site dedicated to the ATARI and the Music... - title: PLOPBOX - Atari music archive and jukebox url: http://www.plopbox.net/ text: listen to atari tunes directly from your browser - title: Polish Atari Wikipedia url: http://atariki.krap.pl text: A lot of info about Atari (in polish) - title: ST Anwender Bern url: http://my.blackpoint.ch/stab/ text: Atari ST Usergroup Bern (Swiss) - title: The Atari Historical Society url: http://www.atarimuseum.com/ text: The complete history of Atari Arcade and Home games and computers. Complete site with pictures, commercials (streaming), and full text articles. Amazing site ! - title: The Atari ST Quick FAQ url: http://www.megacom.net/~q-funk/ST/ text: '' - title: The Atari WebRing Homepage url: http://b.webring.com/hub?ring=atari text: Useful ! - title: The Ultimate ATARI Resource url: http://www.atari.org text: '' - title: What is TOS url: http://www.vanc.igs.net/~roughley/tos_main.htm text: '' - title: Index of -~archive-atari- url: http://www.umich.edu/~archive/atari/ text: '' - title: Web Wiz CAPTCHA url: http://www.webwizcaptcha.com text: French forum docs: - title: ATARI 520 ST OWNER'S MANUAL url: http://www.classiccmp.org/dunfield/atarist/index.htm cover: /media/museum/docs/couvs/atari_520st_user_doc.jpg text: |- [**ATARI 520 ST OWNER'S MANUAL**](http://www.classiccmp.org/dunfield/atarist/index.htm)written by Atari  compiled/archived by Daves Old Computers\  type of document : PDF\  size : 5 Mb\  source : [Daves Old Computers](http://www.classiccmp.org/dunfield) **... READ THE ONLINE VERSION BY CLICKING BELOW :** related: - /museum/atari-130-st-260-st - /museum/atari-4160-ste - /museum/atari-520-1040-ste - /museum/atari-520-1040-stf-stfm - /museum/atari-falcon-030 - /museum/atari-falcon-030-microbox - /museum/atari-fx-1-sparrow - /museum/atari-mega-st - /museum/atari-mega-ste - /museum/atari-st-book - /museum/atari-stacy - /museum/atari-stylus-st-pad - /museum/atari-tt-030 oc_id: 20 source: url: https://web.archive.org/web/20230602084718/http://www.old-computers.com/museum/computer.asp?c=20 date: '2023-06-02' --- The 520 ST featured same hardware basis and same amount of memory as the [260 ST](/museum/atari-130-st-260-st/). The main difference between them was the built-in ROM TOS operating system and GEM Graphics Interface. In fact, the Atari 520ST originaly came with the OS on floppy as the OS was not completly finished. Very shortly afterward they came with the OS on 6 ROM chips (TOS 1.0). It was first sold in Germany where it met a great success then released in the United States about six monts later. Colour and monochrome version were available. Sadly, users of the colour version couldn't expect programs written for the monochrome version to work until someone wrote an emulator allowing the software written for the monochrome version to run on a colour monitor. Atari was the first company to offer built-in MIDI ports. This made the computer very popular with musicians. One game even used the MIDI conectors (Midi Maze) to connect up to 16 computers together in a MIDI network. The **520 ST+** offered 1 MB of RAM instead of 512 KB. As the main board was designed to provide space for only 512 KB of RAM (16 x 41256 type chips), the second 512 KB bank chips were soldered on top of the original chips. Apparently, 1 Mb versions were sold as Atari 1040s in Australia... The model **520 STM** came with a built-in TV modulator allowing a direct connection with the TV-set. The original Atari 520 ST came with an external 360K single sided 3.5 floppy drive, the SF354. Most dealers either bundled it with separate power supply, or a much neater Cumana or Triangle branded drive at lower cost. --- More information from **Dan Osers**:\ Actually, there never was a colour vs. monochrome version. All ST models featured at least 2 colour and 1 monochrome setting. They were not interchangable, as the highest resolution was only available in monochrome.\ Hence a program has to have different versions (or fat binary) to work on either - but the system supported both. Many games would only run in colour mode, many pro apps only in hi-res mono. Colour monitors generally could not display the mono-hi-res and vice versa, though this was more of a limitation of TV / Monitor technology of the time. About fat binary apps, **Ari Feldman** adds:\ Atari ST apps were NOT "fat binaries" - e.g. two types of executables embedded in the same executables in the same way that apps written for the old MacOS were.\ Rather, most apps supported the ST's color and monochrome resolutions by using different Resource files (i.e. dialog, menu and alert box definitions). These were external files that resided on disc and were loaded in according to the screen resolution being used.\ Some games supported Monochrome directly by adding subroutines to detect what screen resolution was running and adjust themselves accordingly.