Williams Hardware Identification and Compatibility
Stargate, Robotron, Joust, Splat! and Sinistar CPU Boards

The games Stargate, Robotron, Joust, Splat! and Sinistar all share common CPU boards with 4 different revisions. This page allows you to identify them, view a high resolution image for comparison with your own boards and download the schematics pertaining to the particular board revision. Defender and Bubbles CPU boards are not covered here, for them see the main Williams Hardware compatibility page


R8948 (Revision -) CPU Board
Shipped with Stargate games only

View a high resolution image of the R8948 (Revision -) CPU Board
Identifiable by small daughterboard at the bottom of the board
and 5770-09656-00 etched above battery holder

Links for this PCB:
High Resolution Image (123kB)
Schematics (not online)

Note: The Stargate CPU BS.BA Inversion modification must be
carried out on all R8948 (Revision -) boards in order to use it
with later games (Robotron, Joust, Splat! and Sinistar).
R8731 (Revision B) CPU Board
Shipped with Stargate and Robotron games

View a high resolution image of the R8731 (Revision B) CPU Board
Identifiable by two wire BS.BA inversion factory modification
and 5770-09656-00 Rev. B etched above battery holder

Links for this PCB:
High Resolution Image (119kB)
Schematics (not online)

Note: This CPU is capable of running Stargate, Robotron,
Joust, Splat! and Sinistar without modification.




R8731 (Revision C) CPU Board
Shipped with Robotron, Joust and Sinistar games?

View a high resolution image of the R8731 (Revision C) CPU Board
Identifiable by 5770-09656-00 Rev. C etched above battery holder


Links for this PCB:
High Resolution Image (103kB)
Schematics (not online)

Note: This CPU is capable of running Stargate, Robotron,
Joust, Splat! and Sinistar without modification.
R8731 (Revision D) CPU Board
Shipped with Robotron, Joust and Sinistar games?

View a high resolution image of the R8731 (Revision D) CPU Board
Identifiable by inductors next to the PCB power connector
and 5770-09656-00 Rev. D etched above battery holder

Links for this PCB:
High Resolution Image (120kB)
Schematics (1.3MB)

Note: This CPU is capable of running Stargate, Robotron,
Joust, Splat! and Sinistar without modification.


Notes:

  1. The Stargate CPU BS.BA Inversion modification must be carried out on all R8948 (no revision) boards in order to use it with later games (Robotron, Joust, Splat! and Sinistar). If this is not done no damage will occur, however the boards will appear DEAD!

  2. Boards shipped with Stargate games had Decoder ROMs 4+5 fitted, however, all later games had Decoder ROMs 4+6 fitted. It may be the case that your PCB has different combinations of decoder ROMs due to incorrect replacement. Decoder ROMs work in the following combinations; 1+3, 2+3, 4+5 and 4+6. However RAM diagnostics may give incorrect information when using 1+3 and 2+3. Additionally, Decoder 1 will not work with cocktail games.

  3. Do not confuse the CPU boards for Stargate, Robotron, Joust, Splat! and Sinistar with Defender and Bubbles as although they look similar they will not work, it will appear as if the game were dead. Defender and Bubbles CPU boards are covered on the main Williams Hardware compatibility page.


Disclaimer: Although I have done my best to ensure that all information contained on this
page is correct, I can take no responsibility for damage to your game, its boards or yourself!