Atari 800 Personal Computer System  


    Atari 800 Owners Manual   

    Atari BASIC

    Technical Data & Tear Down

    Atari 800 Expansion Bay

    Atari 800D Developer System

    Hardware Service Manual


(work in progress, updated 3/14/2019)





PART 1: Candy and Colleen…   the journey begins.


 So, you’ve heard about the famous Atari PCS’ (Personal Computer Systems) called the Atari 400 and the Atari 800.    Both had codenames:  Candy for the 400 and Colleen for the 800.  Internally their original model #’s were the C7000 for the Atari 400 and the C8000 for the Atari 800.  Their model #’s would be changed to be their price points:  $400 for the Atari 400 and $800 for the Atari 800.


 How did the Atari PCS computers come into existence?  Well, sit back and let’s take a walk back in time to 1977 and discuss their origins, the Atari 2600. The Atari 2600 VCS (Video Computer System) would make its debut in the summer of 1977 to rather surprised crowds at the Summer CES (Consumer Electronics Show) when Atari unveiled their marvel of technology.  It had been kept well hidden so as not to allow it to fall into the hands of Magnavox, who under a court settlement that Atari agreed to, would have access to any Atari technology in development up to a certain date.  So the Atari 2600 VCS would be shown after the date and freed Atari from having to turn over its technological wonder to Magnavox to exploit at Atari’s cost.


 While crowds were being amazed by the wonders of the Atari 2600 and retailers were crushing to place orders with Atari to get this incredible new video game console into their stores, Atari’s engineers who created the Atari 2600 VCS were happily smiling at how well received their new creation was, but not content with their creation. They wanted it to do more.


 Something they all wanted was character generation, better resolution graphics and more advanced features for input and storage. Steve Mayer, Larry Nicholson, Joe Decuir and Jay Miner all started to contemplate what would be possible.  Steve Mayer met with Nolan Bushnell and Joe Keenan and asked what they wanted this new system to be.  Nolan and Joe said they wanted it to be both a computer and a video game system.  They wanted a device to compete against Apple, but also wanted a device that would be a successor to the Atari VCS.


Project Colleen would be started.  Improve the TIA chip, the Television Interface Adapter which is the heart of the Atari 2600 VCS, allow it to display higher resolution graphics and more colors on the screen, give it Player Missile Graphics capabilities and other advanced functions. The CTIA would be born. (Computer Television Interface Adapter) and along with it a DMA (Direct Memory Access) chip called ANTIC which was short for the Alpha-Numeric Television Interface Chip.   For sound, Keyboard and communications the POKEY chip (Potentiometer Keyboard) chip was developed.   Rounding things out, these three custom chips would be put together with a full blown 6502C CPU chip and a 6520 PIA (Parallel Interface Adapter) which would interface the 4 front controller ports and allow high speed parallel I/O interfacing as well.


Later Atari would release an upgrade to the CTIA called the GTIA which would add more graphics modes and more colors to the Atari PCS computers.

 The new chipset was being defined and developed and the Mechanical engineers and Industrial Designers got to work to give these new devices a really great appearance.  John Ellis would define the overall designs of the system while Kevin McKinsey and Atari VCS case co-designer Douglas Hardy would design the looks for the Colleen and Candy. Kevin specifically wanted to give users a very familiar and friendly feel to the Colleen, so the design would be similar the home typewriters of the day.  The design worked out very well, hiding some of its more advanced capabilities such as its ROM access bay for Cartridge based software such as BASIC and the Talk and Teach cartridges.   Then with a few simple thumb latches the OS and Memory bay was revealed. Something the common user wouldn’t immediately notice was the built in Power-off safety switch in the front cartridge bay, once opened the Atari 800 would automatically turn off, once the door was closed to the cartridge bay, the system would boot back up.  A very smart feature to ensure no accidental insertion or removal of cartridges and/or OS or Memory modules might damage the system or possibly hurt the user.


The OS and Memory modules were located in a fortress of an expansion bay, surrounded by 2mm thick aluminum chassis which also doubled as part of the Atari 800’s case structure.  The expansion bays would be covered under a plastic guide cover which only exposed the expansion headers and completely separated the user from directly coming in contact with the electronics underneath. A very well thought out design which really differentiated the Atari 800 from other systems such as the Apple ][ and the early S-100 bus computers which exposed users to live current when the case was open and direct contact with all of the electronics and power components within the computers.


While these Expansion bays were innovative, they were also a major thorn in the over all design of the Atari 800 because at the time the FCC rules were so strict and Atari was so cautious to never violate them, to have a computer system with expansion bays that would emit large amounts of RF (Radio Frequency,) a form of electronic “noise” that could disrupt a Television signal and even create audio noise on nearby radios, was something Atari engineers couldn’t risk.  The solution – build a computer where almost all of its components would be encased inside an aluminum RF shield that was akin to an electronic EMP (electro magnetic pulse) bomb shelter, called a Faraday Cage.  And with it, its expansion modules would be inside plastic/metal enclosures nestled in an expansion bay with a top that also had an aluminum shield under it to cover and seal the expansion modules in their RF Tomb.  Talk about over engineering a solution.


Candy would have a scaled down, non-expansion bay version of this same RF cocoon as well. Atari engineers wanted slots, real slots, like Apple ][ type slots, but this didn’t happen.  Sadly the timing was just wrong for Atari, just as the Atari 400 and Atari 800 computers would begin production, the FCC in October 1979 would relax rules regarding Part 15 in regards to computers. This change in the FCC rule essentially freed Atari to be able to produce exactly the computer that the engineers had wanted from the very beginning of the project, ones with fully useable and externally accessible expansion slots.  It was too late, however. Once the Atari 400 and 800 were completed, Atari engineers Jay Miner and Joe Decuir had penciled out a block design for the next follow up to the Atari 400 and 800 that could be ready in 2-3 years.  It would be based on the stunningly powerful new Motorola 68000 processor and the Atari GTIA, ANTIC and POKEY chipset would all be enhanced further in the 16 bit realm of computing, giving Atari a future path to continue to be at the forefront of technology. Atari shot down this request from the two visionary engineers, since the new computers had just cost the company over $10 million in development and weren’t even on retailer shelves yet and Atari was unsure if this risky new venture into home PC’s was even going to see them recoup all of their R&D investment.  So the two engineers decided to wait till the Atari 400 and 800 began rolling off the assembly lines and then quit to move onto other ventures, but firmly committed to making the next generation computer a reality.  Eventually they did.  It’s called the Amiga.


Continue to Part 2...