Atari Sierra
32-bit personal computer | |
Release date | Prototype 1983 | - Project Cancelled
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Sierra was the code name for a
The graphics portion consisted of a two chip system called "Silver and Gold", Gold generated the video output while Silver was a
Sierra was bogged down since its inception through a committee process that never came to a consensus on the design specifications. A second project,
History
Earlier 8-bit designs
Atari's earlier consoles and computers generally used an off-the-shelf
In the
The much more powerful
Rainbow
By the early 1980s, a new generation of CPU designs was coming to market with much greater capability than the earlier 8-bit designs. Notable among these were the
Atari's Sunnyvale Research Lab (SRL),[b] run by Alan Kay and Kristina Hooper Woolsey, was tasked with keeping the company on the leading edge, exploring projects beyond the next fiscal year.[c] They began experimenting with the new 16-and 32-bit chips in the early 1980s. By 1982 it was clear Atari was not moving forward with these new chips as rapidly as other companies. Some panic ensued, and a new effort began to develop a working system.[6]
Steve Saunders began the process in late 1982 by sitting down with the guru of the 8-bit series chips.
Each rectangle in the display could be as large or small as required. One might, for instance, make a rectangle that was larger than the screen, which would allow it to be scrolled simply by updating the origin point in its description block. If this was moved off the screen, it would be ignored during drawing, meaning one could use rectangles as offscreen drawing areas and then "flip" them onto the visible screen by changing their origin point once the drawing was complete. Small rectangles could be used for movable objects whereas earlier Atari designs used custom sprite hardware for this task. Each of the rectangles had its own bit depth, 1, 2, 4 or 8-bit, and each one had its own color lookup table that mapped the 1, 4, 16 or 256 color registers of the selected bit depth onto an underlying hardware pallet of 4,096 colors. The data could be encoded using
Work on Rainbow continued through 1983, mainly by Saunders and Bob Alkire, who would continue developing the system on a large whiteboard. A polaroid image of the design was made after every major change.[12] A significant amount of effort was applied to considering the timing of the access process searching through the rectangles for a displayed pixel; it was possible to overload the system, asking it to consider too much memory in the available time, but that was considered suitable as this could be addressed in software.[13]
Jack Palevich produced a simulator of the system and George Wang of Atari Semiconductor produced a logic design.
Sierra
Sierra came about through a conversation between Alkire and Doug Crockford. Alkire borrowed Palevich's new Mac computer, using it to make block diagrams of a machine that slowly emerged as the Sierra effort.
The design, then, was more of an outline than a concrete design, the only portions that were positively selected was the use of Rainbow for graphics and a new synthesizer chip known as "Amy" for sound.[21] Tying all of this together would be a new operating system known as "Eva", although the nature of the OS changed as well. At least one design document outlining the entire system exists, referring to the platform as "GUMP", a reference to a character in The Marvelous Land of Oz.[22] The original design documents suggest different Sierra concepts aimed at the home computer market with a price point as low as $300 using a low power CPU, all the way through business machines, student computers and low-end workstations.[21] It was during this point that the wooden mockup was constructed.[23]
By early 1984 it was clear the project was going to be shut down, and the engineers began looking for other jobs.
Other designs
Sierra proceeded alongside similar projects within Atari being run by other divisions, including an upscale m68k machine known as
Work on the various Sierra concepts continued through 1983 and into 1984, by which point little progress had been made on the complete design. Several mock-ups of various complexity had been constructed, but no working machines existed. Likewise, little concrete work on the operating system had taken place, and the idea of using a
At the same time, teams of former Atari engineers were now working at the start-up computer companies Mindset and Amiga. Amiga, led by Jay Miner who had led the design of the original Atari HCS (Home Computer System--400/800) and the creation of the TIA for the Atari VCS (AKA 2600), had been making progress with their new platform, codenamed "Lorraine".[31] Lorraine was also based on the 68000 and generally similar to Sierra and Gaza in almost every design note, which is not surprising given that the teams originally came from the same company. By early 1984, Lorraine was farther along in design and nearly ready for production. Atari had already licensed the Lorraine chipset for a games console machine, and the Gaza team was told to drop their efforts and begin work on a desktop computer design using Lorraine, codenamed "Mickey" (semi-officially known as the Atari 1850XLD).[29]
Tramiel takeover
In July 1984, Jack Tramiel purchased Atari and the company became Atari Corporation. In a desperate measure to restore cash-flow, whole divisions of the company were laid off over a period of a few weeks.[32] This included the vast majority of the SRL staff. The Amy team convinced the Tramiels that their work could be used in other platforms, and their project continued. The rest of the Sierra team were scattered.
As a result, any progress on the Sierra platform ended, Gaza was completed and demonstrated and Mickey was completed, awaiting the Amiga chipset that would never arrive. The "Cray" development frame for Gaza and reused for Mickey was used by the Tramiel engineers to develop the Atari ST prototype. The company's option to use Lorraine for a games console also ended, and Amiga would later sign a deal with Commodore International to produce a machine very similar to Mickey, the Amiga 1000.[33] The Atari ST, Atari Corp's 68k-based machine, would be built with custom chips and off-the-shelf hardware, and was significantly less advanced than Sierra, GAZA or Mickey.
Description
As implemented, the Silver and Gold design was based on an internal buffer that constructed the screen one line at a time. This was an effort to relax the timing requirements between the
The system could be used to construct any display from 512 to 768 pixels wide and 384 to 638 lines high. The mode that it was designed to support was 640 x 480 at a maximum 8-bit color depth. The colors were selected from a
As implemented in Silver, the object buffer could contain up to twelve "objects" representing rectangular areas. This does not appear to be a design limitation, simply the implementation of this particular chip. Each of the object records contained a pointer to the location in memory for the underlying data. Using line-end interrupts, programs could modify these pointers on-the-fly as the screen was drawn, allowing the system to display different objects on each line. Similar techniques had been used in earlier Atari machines to increase the number of sprites on a single screen. Because Silver required control of the memory, it operated as the bus master and also handled
Notes
- ^ Some documents suggest "Rainbow" referred to AMY as well, others suggest otherwise.
- ^ Sometimes referred to as CRG, for Corporate Research Group.
- ^ One SRL employee stated the goal was to plan for the CES after the next one.
- ^ Saunders does not note who this guru was but later suggests it might have been Jim Dunion.[8]
- ^ Although some sources suggest that Rainbow and Silver/Gold were two different GPU systems, documentation from the era clearly shows the latter to be part of Rainbow.
- ^ There are numerous claims that Gaza was a dual-m68k machine, but this is unlikely due to the way these chips accessed memory. Comments by the engineers suggest the multiple CPUs are referring to co-processors in the traditional Atari usage of the term.
References
Citations
- ^ a b Montfort, Nick; Bogost, Ian (2009). Racing the Beam. MIT Press.
- ^ Crawford, Chris (1982). De Re Atari. Atari Program Exchange.
- ^ Johnson, Herbert R. (2011-10-13). "S-100 and the 8086".
- ^ Ken Polsson. "Chronology of Microprocessors". Processortimeline.info. Archived from the original on August 19, 2012. Retrieved 2013-09-27.
- ^ "National Semiconductor's Series 32000 Family".
- ^ Rainbow 2016, 10:00.
- ^ Rainbow 2016, 10:30.
- ^ Rainbow 2016, 25:30.
- ^ Rainbow 2016, 12:00.
- ^ Rainbow 2016, 31:15.
- ^ Rainbow 2016, 32:15.
- ^ Rainbow 2016, 14:00.
- ^ Rainbow 2016, 15:30.
- ^ Rainbow 2016, 16:10.
- ^ Rainbow 2016, 20:10.
- ^ Rainbow 2016, 21:00.
- ^ Rainbow 2016, 19:00.
- ^ Rainbow 2016, 32:45.
- ^ Rainbow 2016, 34:00.
- ^ Morrison 1983, pp. 6–7.
- ^ a b c Morrison 1983.
- ^ Goldberg & Vendel 2012, p. 732.
- ^ Rainbow 2016, 35:30.
- ^ Rainbow 2016, 39:15.
- ^ Rainbow 2016, 40:30.
- ^ Rainbow 2016, 41:00.
- ^ Goldberg & Vendel 2012, p. 733.
- ^ Knight, Daniel (10 January 2016). "The 1983 Home Computer Price War". Low End Mac.
- ^ a b Goldberg & Vendel 2012, p. 737.
- ^ AMY 1 Spec (PDF) (Technical report). Atari Semiconductor Group. 18 August 1983.
- ^ Goldberg & Vendel 2012, p. 708.
- ^ Goldberg & Vendel 2012, pp. 748–749.
- ^ Goldberg & Vendel 2012, pp. 745.
- ^ Wang 1983, 6.3.1.
- ^ a b Wang 1983, 2.
- ^ Wang 1983, 6.1.
Bibliography
- Goldberg, Marty; Vendel, Curt (2012). Atari Inc. Business Is Fun. Syzygy Press. ISBN 9780985597405.
- Morrison, Jerry (9 February 1983). Proposed Sierra Project Plan (Technical report). Atari.
- Bob Alkire and Steve Saunders (10 June 2016). Bob Alkire and Steve Saunders, Rainbow GPU (Audio). Antic Podcast.
- Wang, George (28 October 1983). The RAINBOW Gold Chip Specifications (Technical report). Atari.