Atari 1200 Prototype (October 82 Pilot)  

 

 

 

 

 

A300 Project

(Pre-1200 Designs)

 

 

 

 
 

 

 

  

 

 

 

The Atari 1200 Prototype
 



 The Atari 1200 and the finally Atari 1200XL have no real differences except in the label and the casing. The label lacks the XL (eXtended Line) designation and the case is a smooth finish instead of the rough finish on the sold versions of the XL's.    It is one of 250 October 1982 "PILOT RUN" units.

 

The original early designs of the 1200 (which was the Atari 1000 and 1000X and may be connected to a mysterious project called the A300, here below is a case which matches one of the artist renditions done by Regan Cheng on the proposed highly expandable Atari 1200/1000/A300

http://www.atarimuseum.com/computers/concepts/1200/A300-concept1-sketches.jpg

 

 


 For many years the Atari Museum has been tracking down the elusive "vapor" trail of what was the earlier Atari 1200 design (sometimes referred to as the Atari Z800, then as the Sweet-16 and also as the Atari 1000 and 1000X line.)    Finally during some research on the Atari 1400XL for a friend and fellow Atari enthusiast, information was stumbled upon... a lost treasure trove of materials pertaining to the very early designs of the Atari 1200XL called "Elizabeth".

Speaking with numerous Atari engineers, Dave Sovey in particular had informed the Atari Museum of a side by side "Sister Project" of the 1200XL and that there were actually two versions in development.      Several years later Dave's information had been verified when the Atari Museum found a copy of the Atari Sweet-16 Spec's, it was a very early document discussing an Atari 1200XL with much more expansion and capabilities then what eventually came onto dealer shelves in 1983.

The Atari prototypes came with an "X" designation, followed by a revision # and then followed by an A designation (whether A stood for Atari or for an Alpha version is unclear).     As shown in the above Revision Schedule, designs started in 3/26/82 and went into 5/13/82.   What's not shown is the date for revision X8A which was from other documents in early July 1982.  Another interesting note:  No Revision X7A, despite there being a full set of board layout drawings and schematics for it.

 

Interestingly enough, this above photo plot also from July 82 shows revision X10A which was nearly identical to what becomes the production Atari 1200XL motherboard.  Of unusual note is the project appears to have not one, but TWO codenames, apparently this is where the original S-16 (Sweet-16) project takes a fork in its design, rev X8A also says Elizabeth on it, but in a different location...    So far there is no revision X9A, it skips from X8A to X10A and then to final production.

 

This is the actual PCB layout of the revision X8A PCB for the Atari "Sweet-16".      This is where things get interesting.    Click on the above image to examine it more closely...    Note that the layout is entirely different from the production 1200XL computers.     Take particular note of the upper right corner of this PCB design - there is a 50 Pin header footprint and the traces all lead to the major IC's on the board which means this was the very first PBI (Parallel Bus Interface) which appears to have been meant as an internal device interface versus the later XL designs which brought the PBI directly out of the system to an Edge Connector.

Next thing to note is the Upper Center edge of the PCB, note the 2 DB-15 footprints versus an Atari SIO footprint.   This directly correlates with the early Atari Sweet-16 spec's document detailing the inclusion of 2 15 pin connectors to replace the original SIO and would allow for peripherals to automatically power up when the system powered up.

The departure from the X1A-X8A design to suddenly a radically different X10A design that appears at the same timeframe in July 1982 means that there must've been a side by side "Sister Project" of the Atari 1000 series being built and it moved into place to become the production machine leading to a disaster product launch for a system with plenty of sexy looks, but nothing under the hood, so to speak.

***Final Thoughts***

Several things we have to take away from the original 1200XL with the expansion header are this:

  • Every revision of the new 1200XL OS - Revision 10 (which was the replacement for the Atari 400/800 OS Revision B, never had any support for handling Parallel Devices.  Revision 11, which came out in the last several months of the Atari 1200XL production run (Jan 1983 to end of June 1983) also had no support for Parallel device handling.

  • We would have to assume the Expansion header was just buss line connections with no intelligent management of any devices connected to it.  So this could end up limiting its expansion capabilities similar to how the 800 even it if had more than one "Slot 3" would've had difficulty handling more than one expansion device board.

  • Atari's RF/EMI engineer noted that the X8A and earlier was very noisy.  So this too could lend to why the header is removed from the design.  

  • The 1200XL may have simply been a stop-gap release product and then 3 months after its release the more formalized designs of the "Surely" - the 600XL and the replacement for the 1200XL - the "Surley Plus" - the 800XL would now have all of the Parallel Device support and the design for an external Expansion System is also created.

 

The Atari Museum is currently investigating the possibility of having a PCB design firm that still works with physical Padmaster films to reproduce actual samples of the X8A revision motherboard, the real "Sweet-16" computer system to allow for further study and examination.

 

 

Are you a former Atari engineer?  Did you work on the Z800/1200/S16/S64/1000/1000x Project?   Do you have direct knowledge and/or information on this project?   If so, please contact the Atari Museum:   CLICK HERE