Atari ST | Code Like It's 198x

At the Consumer Electronics Show in Las Vegas in January 1985, six months after he had bought Atari’s home computer business, Jack Tramiel showed a new computer under the slogan “Power without the Price”. Personal Computer News reported the 520ST as a 68000 machine running “a proprietary operating system that is still called TOS (Tramiel Operating System)”, with Digital Research’s GEM on top: “mice, windows, icons, handsome graphics, the whole Macintosh kit and caboodle. Wags around Las Vegas were calling the machines Jackintoshes.” The price was the point: “With 128K and 512K they will cost $399 and $699 respectively.”

The ST went from drawing board to shop in little more than a year, according to ST Format’s later history. In July 1985 Atari User reported that “the first major batches of Atari 520STs have begun arriving”, and that British buyers would pay £749.99 for the machine with a monochrome monitor. What they got was a fast processor with a plain screen, a three-voice sound chip and, built in, the MIDI In and Out ports that electronic instruments use. Those sockets took the ST into music studios.

Fast facts

Shown: Consumer Electronics Show, Las Vegas, January 1985. On sale in Britain from the summer of 1985.
Price: £749.99 for the 520ST with a monochrome monitor in 1985. The 520STFM sold for about £299 by 1988.
CPU: Motorola 68000 at 8 MHz.
Memory: 512K on the 520 models, 1MB on the 1040.
Graphics: 320×200 in 16 colours, 640×200 in 4, or 640×400 in monochrome, from a palette of 512. The STE raised the palette to 4,096.
Sound: Yamaha YM2149, a version of General Instrument’s AY-3-8910, clocked at 2 MHz: three square-wave voices and noise. The STE added 8-bit stereo sampled sound played by DMA.
Ports: MIDI in and out, a DMA port (ACSI) for hard discs, printer, serial, mouse and joystick.
Operating system: TOS with the GEM desktop, loaded from disc on the first machines and in ROM from 1986.

From 520ST to 1040STF

The first 520ST was, in ST Format’s description, “a collection of boxes”: the keyboard and processor, a separate disc drive and a separate power supply, with TOS loaded from disc every time the machine was switched on. Atari folded the pieces together quickly. The 520STM of early 1986 added a television modulator and put TOS in ROM. The 1040STF followed in 1986 with a megabyte of memory and the disc drive built into the case. Atari fixed its British price at under £1,000, and its advertisements in May 1986 recommended £799 plus VAT with a 12-inch monochrome monitor. “This isn’t just going to knock them over, it’s going to leave them for dead,” an Atari spokesman told Atari ST User.

Prices kept falling. Atari’s own advertisement in April 1986 offered the 520ST “for only £652” with a disc drive and monitor, and ST Format recalled that in February 1987 “the price of the 520 was dropped to £399”. By March 1988 mail-order dealers advertising in ACE were selling the 520STFM, with its built-in drive and modulator, for £299.

The machine that delegates nothing

The Commodore Amiga came out the same year with the same processor and the opposite design. The Amiga surrounded its 68000 with custom chips that drew, copied and played sound on their own. The ST kept almost everything on the processor.

Its screen is 32K of ordinary memory. Atari ST Internals records that “immediately after turning the ST on, an area of 32K bytes is initialized at the upper memory border as the video RAM”, and a pair of registers lets a program move it. The Shifter chip reads that memory and turns it into pixels, 16 colours at a time from a palette of 512. The original ST has no blitter to copy graphics and no co-processor to change colours down the screen. Every sprite, every scroll and every filled polygon is the 68000 moving words.

To pay for that, the processor runs slightly faster than the Amiga’s 7.09 MHz, and the figure was chosen rather than maximised. Atari ST Internals explains that the 68000 “can operate at different speeds” and that “the ST’s 8 mHz was chosen as a ‘middle of the road’ frequency to avoid losing data at higher frequencies”.

A blitter did arrive, in the Mega ST of 1987, two years after launch. In March 1987 Atari ST User reported that the chip, “fitted as standard in the Mega-STs, is running behind schedule”. It reached the ordinary home machines only with the STE at the end of 1989; the 520 and 1040 models sold until then had none.

That made the ST simpler to understand and harder to show off on. Effects that the Amiga scheduled onto its chips had to be timed out of one instruction stream on the ST. Demo programmers took that on. Reviewing the Union Demo in July 1989, ST Amiga Format found effects “that many still maintain are not possible such as fast, multi-plane parallax scrolling while playing a complex sound sample, as well as full overscan and sprites in the border”. Overscan meant filling the border that the hardware normally leaves blank.

Why MIDI was the whole argument

MIDI, the standard that lets electronic instruments exchange notes and controls, was part of the ST’s design from the start. Atari ST Internals describes two identical 6850 ACIA serial chips: “One of them communicates with the keyboard, mouse, joystick ports, and runs the clock … The second ACIA is used for operating the MIDI interface.” They sit side by side in the memory map at $FFFC00. A synthesiser was as much a part of the machine as the keyboard.

Atari was still leading with it in 1991: “MIDI expansion ports are fitted as standard,” its advertisements said. In December 1990 Atari ST User wrote that the MIDI ports had helped make the ST “the first choice for both professional and amateur musicians”, and that “Cubase, the Steinberg Pro 24 Sequencer, and Band in a Box, have given the ST a reputation second to none in the music arena”. ST Format later remembered Cubase’s release in September 1989 for its excitement and its £500 price.

Jean-Michel Jarre used a “small army” of STs to prepare his Paris concert of July 1990, Atari ST User reported, and not only for the music: “stage designs and story-boards for the show were also reputed to have been mapped out using the STs”. He worked mainly with C-Lab’s sequencers: “Jarre makes heavy use of C-Lab MIDI software, in particular Notator and Creator”.

The ST and the Amiga

In Britain the two machines were rivals for the same buyers, and for a while they shared a magazine. ST Amiga Format covered both until August 1989, when it split into ST Format and Amiga Format. In September 1988 it printed the sales claims side by side: “Official Atari figures say there are around 150,000 STs in the UK already, but independent estimates would put it at not much higher than 100,000.” Six months earlier CRASH had counted about 130,000 Amigas and STs together.

In its first issue, in August 1989, ST Format reckoned there were “around a million STs throughout the world”, with Germany the largest market, where STs were used “as professional tools”. It also admitted that “ST games players have long been waiting for Atari to produce a machine capable of giving the Amiga a run for its money”. Many Amiga games of the time were conversions of ST versions, and in October 1990 ACE’s Amiga column hoped that “the days of straight ST ports must be numbered”. ST Format reported that Populous, the biggest-selling game of 1989, sold 46,000 copies on the ST alone.

The STE and after

The STE, released at the end of 1989, was Atari’s answer. It added hardware scrolling a pixel at a time, a 4,096-colour palette, a blitter and stereo sampled sound played by DMA “at one of four constant rates between 6.25 and 50kHz”, mixed with the old Yamaha chip. ST Format’s verdict in November 1989 was measured: “this is not a radical rewrite of the ST’s specification”.

By March 1991 Atari was claiming “an installed user base of some half a million in this country alone”, and Peter Staddon of Atari UK told ST Format that “there are now two and a half million STs worldwide”. These are Atari’s own figures. The company moved on to the Falcon, and in August 1993 Atari ST User reported that Atari had “temporarily stopped production” of the STE “to enable them to concentrate on the Falcon”. Public sources do not give a date for the end of ST production.

Programming it

In 1988 Mandarin Software published STOS, “The Game Creator”, a BASIC for writing games by François Lionet, who went on to write AMOS for the Amiga. Games that wrote straight to the hardware were a worry when the blitter arrived: Atari ST User explained in 1987 that the chip sped up the operating system’s own graphics routines, so games such as Rainbird’s Starglider “will not be affected by the blitter”.

The demoscene still makes new ST productions, and parties such as Silly Venture in Gdańsk, Poland, are given over to Atari machines. The Hatari emulator runs ST, STE, TT and Falcon software on modern computers.

Sources

Amiga Computing, May 1990, p. 64: AMOS written by François Lionet, author of STOS, as set out in the Commodore Amiga entry.
Personal Computer News, issue 95, 19 January 1985, p. 1: the Las Vegas CES report, “Power without the Price”, TOS, GEM, “Jackintoshes” and the US prices.
Atari User, vol. 1 no. 3, July 1985, p. 8: the expected £749.99 price and the first batches of 520STs.
Atari ST User, vol. 1 no. 2, April 1986: the 1040ST’s UK price and the spokesman’s “leave them for dead”; Atari advertisement, the 520ST “for only £652”. Vol. 1 no. 3, May 1986: Atari advertisement for the 1040STF at £799 plus VAT with a monochrome monitor. Vol. 2 no. 1, March 1987: the Mega ST and its delayed blitter; Starglider and the blitter. Issue 55, September 1990: Jean-Michel Jarre, Notator and Creator. Issue 58, December 1990: the ST as “the first choice for both professional and amateur musicians”. Issue 90, August 1993: STE production stopped.
ACE, issue 6, March 1988: mail-order advertisement for the 520STFM at £299. Issue 37, October 1990: the Amiga column on “straight ST ports”.
CRASH, issue 50, March 1988, p. 32: “about 130,000 Amigas and STs in the country”.
ST Amiga Format, issue 3, September 1988: UK sales estimates. Issue 4, October 1988: STOS advertisement and review. Issue 13, July 1989, p. 38: “Demos Corner”, the Union Demo, and ST demos built on “regurgitated Rob Hubbard tunes”.
ST Format, issue 1, August 1989: the history of the ST, its launch price, the 520STM, 1040STF and 1987 price cut, and worldwide and German sales estimates. Issue 4, November 1989: the STE’s hardware. Issue 20, March 1991: Atari’s UK and worldwide figures. Issue 60, July 1994: timeline of the ST, including Cubase in September 1989 and Populous’s ST sales.
Atari Corporation advertisement, ST Format issues 24 and 25 (July and August 1991) and Your Sinclair issues 68 and 70: “MIDI expansion ports are fitted as standard”.
Atari ST Internals (Abacus Software, 1986): the clock (p. 11); the 2 MHz sound-chip clock (p. 15); the keyboard and MIDI ACIAs (pp. 41, 62); the YM-2149 (p. 48); the screen registers and 512-colour palette (pp. 56–57); the video RAM at power-on (p. 207).
Scott Sanders, The Atari Compendium: the screen modes; the Mega ST’s blitter; the STE’s 4,096-colour palette, fine scrolling and DMA sample rates.
Demozoo, “Silly Venture” party series (web, secondary): an Atari demoparty in Gdańsk. Hatari project website (web, secondary): an Atari ST, STE, TT and Falcon emulator.