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Welcome to the Atari ST Alcove.

Click on one of the links at the upper left of this page to see various sub-indices, or read below for a brief description of the pedigree of this wonderful little microcomputer.

Atari TOS screenshot
The Atari ST used a licensed version of Digital Research's Graphical Environment Manager (GEM).

What is the Atari ST?

The Atari ST is a series of home computers made by Atari Corp. between the late 1980s and early 1990s. These machines competed most directly with the Commodore-Amiga for the home user market. The ST was also a popular machine amongst musicians because of its built-in MIDI ports. I remember reading in ST Format (a British ST magazine) that the group Queen used STs for their sequencing; whether that is an endorsement or not, I couldn't say. The vast majority of popular entertainment software releases from about 1987-1992 were converted to the Atari ST platform, so the system has a formidable software library behind it. Like the Amiga, the ST died at the hands of the PC and Mac platforms. Unlike the Amiga, it is most unlikely that a third party will ever resurrect the technologies used in the ST, for the simple reason that they were never REALLY ground-breaking from a technical perspective (they simply hit an attractive price-performance point), and the ST's two major niches - games and MIDI sequencing - have both been filled very well by dedicated systems. The Amiga was resurrected for systems based around interactive online services; it is difficult to see what similar embedded system role/s the ST could fill.

Depending on your geographical location, you may be more or less lucky as regards local supply of ST software, hardware and peripherals. In my home country (Australia), the ST was never a very popular machine; it was sold only in a few stores, and was almost entirely overshadowed by the Amiga 500, which was roughly the same price as the 1040ST here. In the ST's heyday, I also saw relatively little interest in the machine from the USA; most of the ST's userbase appears to have been spread throughout Europe, particularly the UK. Just about all the remaining ST supporters are in Europe.

What are the different models?

There were three basic flavors of the entry-level home-user ST. These were, in chronological order of introduction, the ST, the STFM and the STe. Each of these came in two varieties - the 520 (with 512Kb RAM) and the 1040 (with 1Mb RAM). The very earliest 520ST machines came with single-sided 3.5" floppy drives (a rarity!). If you are buying an ST for your collection of nostalgic computers, ensure that you get one with a double-sided disk drive.

The ST, STFM and STe have slightly different capabilities. All home-user ST units support three video modes; 320x200, 16-color, 640x200, 4-color and 640x400 monochrome. The original ST and STFM have a palette of 512 colors (three bits each for red, green and blue level); the STe supports a 4096 color palette, the same as the Amiga's. On the ST and STFM, a blitter (simple graphics coprocessor) is an optional extra; on the STe, it is standard. The STe also has easy-to-expand 30-pin SIMM sockets for up to 4Mb of internal RAM, and much more advanced sound capabilities. The original ST and STFM use the General Instruments AY-3-8910 (closely related to the Yamaha YM2203) three-channel tone generator, a very primitive audio output device which was also used in several 8-bit platforms including the Amstrad CPC series, the Sinclair ZX Spectrum +2 and +3, and some early 8-bit arcade games such as Capcom's 1942. The advantage of using this device is that because it doesn't use DMA, it is simple to design a circuit around it; unfortunately, it is a dreadful squeaker of a chip. The STe has stereo DMA 8-bit PCM audio, very similar to the Amiga's 4-channel DMA sound system.

There are other models of ST too, including lower-end versions of the 520ST (one with 128K RAM, one with 256K RAM), two portable versions of the machine and higher-end 68030-based machines such as the TT, but these are much rarer than the models listed above.

Comparison with the Commodore Amiga

Why make this comparison? The Amiga 500 and the Atari 520/1040 ST machines competed for the same market; the Amiga is (sort of) alive today, and the ST isn't, so it is interesting to see what qualities marked the ST for obsolescence. Also, it was long a bone of contention with Amiga owners that many Amiga titles were converted UP from the Atari ST versions - meaning they used 16-color graphics modes with 512-color palettes. Certain games originally written for the ST, particularly 3D polygon driving and role-playing games, performed VERY poorly on the Amiga because they were written with the ST's faster CPU in mind, and simply recompiled with a few small tweaks to make them Amiga-compatible. They might have been great games if the developers had added blitter support, but unfortunately they never quite made it.

In order to compare the Atari ST with the Commodore Amiga range, it is necessary to choose baseline systems for comparison. Because most Atari ST software was written with the 520/1040 ST/STFM models in mind, and because most Amiga 500 owners bought the A501 512K RAM expander/battery backed-up clock, I will compare the 1040ST with the Amiga 500 + A501 combination, with notes as appropriate.

Atari 1040ST
Commodore Amiga 500+A501
CPU 8MHz MC68000 7.14MHz MC68000, slowed down somewhat by buss contention
RAM 1Mb, quite costly to expand 1Mb, quite costly to expand
Storage DSDD 3.5" floppy drive; standard formatted capacity IBM-compatible 720Kb, up to 820Kb with custom disk formatter programs DSDD 3.5" floppy drive; standard formatted capacity (proprietary) 880Kb
Graphics resolutions 320x200, 16-color
640x200, 4-color
640x400, monochrome non-interlaced.

3 bits per color component giving a total palette of 512 colors.

No sprite hardware.

Very flexible graphics modes. PAL machines support 256 lines per frame (512 interlaced), NTSC machines support only 200 (400 interlaced).

4 bits per color component giving a total palette of 4096 colors.

At 320x200/320x256/320x400/320x512, the color depths supported are 2, 4, 8, 16, 32, 64 (halfbrite mode) and 4096 (hold-and-modify mode). 64 and 4096 color modes are somewhat limited.

At 640x200/640x256/640x400/640x512, the color depths supported are 2, 4, 8, 16.

The video ASIC supports sixteen 16-pixel-wide unlimited-height 3-color sprites.

Blitter Optional, not exploited by many programs Standard, used by many programs
Copper None Unique DMA-driven display-synchronized coprocessor capable of writing new values into (most) custom chip registers. This was used for effects such as faded color bars, switching resolutions, palettes or video memory pointers halfway through the screen, etc. On the ST, these effects had to be achieved by the main CPU executing a horizontal blank interrupt service routine.
Audio output Three-channel tone generator. All three channels are fed to a monaural amplifier. Four-channel 8-bit PCM digital audio. Two channels are fed to each of two amplifiers, with stereo RCA output jacks on the machine.
Connectivity Centronics-compatible parallel port, RS232-compatible serial port, MIDI in/out, cartridge port, external floppy drive, two digital joystick ports Centronics-compatible parallel port, RS232-compatible serial port, general-purpose expansion bus port, external floppy drive, two digital joystick ports and all original content herein is © Copyright 2001 by Lewin A.R.W. Edwards. "" is a trademark protected under U.S. and international law. Infringement or attempted dilution of the intellectual property rights held by Lewin A.R.W. Edwards will be prosecuted to the fullest possible extent.