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A > ATARI  > 520 ST / ST+ / STM   

520 ST / ST+ / STM

The 520 ST featured same hardware basis and same amount of memory as the 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.

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i played first my 520 st later 520ste and then my 1040 which im sure had more ram. i played for hours and hours and hours i used to play Overdrive, and lots arcade games. i love the football player manager and kick off. later i got a pc and it was rubish compared to the atari, atari had major competition with amiga. me and my friends used to compare our atari v amiga and argue for hours on whose was best.

Tuesday 7th May 2013
dave (uk)

I read Enrique''s comment about an ST outrunning a PC in number crunching apps.

It reminded me of a time around 1991 when I had a graphic resembling an early screensaver running on an ST. A friend came over and seemed amazed at the speed of the travelling multi-coloured trailing lines moving around the screen. He said something to the effect that his PC couldn''t do that.

What amused me was the fact that the program had been written in Basic, a relatively slow running language.

Sunday 26th August 2012
Jim (Canada)

Army privates could buy them out of the PX for $721.00
There was a lot of great games that could be played on this machine, one that comes with most computers today is the standard chess master called chessmaster 2000 back then.

Wednesday 27th June 2012
Ed Daly (Washington, DC)


NAME  520 ST / ST+ / STM
TYPE  Home Computer
YEAR  1985
KEYBOARD  Full-stroke keyboard with numeric and editing keypads
CPU  Motorola MC68000
SPEED  8 mHz
CO-PROCESSOR  'Shifter' and 'Glue' custom chips
RAM  512 KB (520 ST/STM), 1 MB (520 ST+)
ROM  192 KB
TEXT MODES  40 or 80 columns x 25 lines
GRAPHIC MODES  320 x 200 / 640 x 200 / 640 x 400 dots
COLORS  16 among 512 (320 x 200) / 4 among 512 (640 x 200) / monochrome (640 x 400) this last mode needs a special monitor.
SOUND  3 voices, 8 octaves
SIZE / WEIGHT  47 (W) x 24 (D) x 6 (H) cm
I/O PORTS  RGB, TV modulator (520STm), Cardridge, Midi (in/out), Centronics, RS232c, Hard Disk, Floppy Disk, Joystick, Mouse
BUILT IN MEDIA  External 3.5'' 360 KB disk-drive (option)
POWER SUPPLY  External power supply unit
PRICE  £749 (1985, UK), £399 (1986, UK)

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