This kit is currently unavailable, if you are interested in buying one then please Email me to register. If there is enough interest then I may make another batch. In the meantime, feel free to use the information on this page to build your own for personal use only. Early Williams video games used battery backed-up CMOS RAM to hold bookkeeping data, game adjustments and high score tables, whilst this worked very well in the games when new it has proved problematic as these games become 20+ years old. This system gives the following problems: The high score table and settings can only be retained for the life of the battery. Many game boards I repair have anything from light to major acid damage. Many games are now powered by a retrofitted switching Power Supply which can cause problems with data retention due to the power up/down sequence.

My main goal for this project was to allow me to keep my high scores forever, however, it has the following bonus features:

• The high score table and settings are retained for 10+ years*.
• Acid damaged battery holders can just be removed and there will be no future acid damage problems.
• You have a modern reliable replacement for your hard to find CMOS RAM chip.
• The dataloss problem when using switching PSU's is eliminated.

* NOTE: The datalife of the NVRAM chips is 10+ years, however, certain game board failures can result in corruption of the data held within the NVRAM, therefore no guarantee of datalife can be given.

Stargate and later games (Robotron, Joust, Blaster etc) use the 5114/5514 (an 18 pin DIL-3 package) which is a 1K x 4bit SRAM device. We can remap its pinout to a more modern device, and here I have chosen to use an 8K x 8bit NVRAM. The daughterboards were designed to be fitted to dedicated games and so the unused portions of the NVRAM device are ignored, though you could bank switch the upper three (unused) address lines to give you up to 8 different sets of saved game data in a multigame environment.

Note that Bubbles has a unique boardset that had different pinouts on its ROM board to CPU board ribbon connector and that the CMOS RAM for Bubbles is 8 bits wide. To implement this Williams added a second 5114/5514 CMOS RAM chip. The daughterboards have the extra 4 data-lines, to use one on a Bubbles game simply use jumper wires to carry the D4 to D7 signal to the appropriate data lines of the extra CMOS RAM socket (or elsewhere). I will document this when I get a chance to test it on my Bubbles boards.

Schematic for the NVRAM Module Click image to enlarge		The schematic shows the pin to pin connections for the NVRAM module. Note the 4 pin socket which allows the 4 extra datalines to be connected to Bubbles boards, or these can be connected to a Robotron/Joust boardset to allow Bubbles to run. I built several of these NVRAM modules on veroboard for my own games. This is a very fiddly piece of soldering as the picture below illustrates, each one took several hours to make! I decided there had to be a better way so decided to design and manufacture some PCB's.
		The Prototype board built on veroboard! Click image to enlarge

Introducing the Williams NVRAM Module ....

The NVRAM Module is shown below, though may use a different (compatible) NVRAM depending on supply. Each kit will comprise a tested NVRAM module and a socket for the user to fit to their CPU board. These kits assumes starting off with a fully working boardset (or just a faulty CMOS RAM) and you are capable of desoldering the CMOS RAM chip and fitting a socket.

Since I have no control over your equipment or soldering skills I cannot provide any guarantees against bad soldering/desoldering on your part or faulty boards/PSU's.

The NVRAM module viewed from the top Click image to enlarge

The NVRAM module viewed from the bottom Click image to enlarge

Installing your NVRAM Module kit

The installation instructions here apply to Stargate, Robotron, Joust, Sinistar and Splat! CPU's.

Document Version: 2.00

The CMOS RAM socket location on the boardset Click image to enlarge		Step 1 - Locate your CMOS RAM chip: The picture shown left shows a typical Robotron boardset (in this instance in my Robotron Cocktail). The CMOS RAM chip is component 1C (an 18 DIL-3 package) located close to the opposite corner of the CPU board from the battery holder. In the picture we have an NVRAM module installed and highlighted within a red box to show the location. At this point you should remove any batteries fitted to your CPU board.
Remove the CMOS RAM and fit the socket provided Click image to enlarge		Step 2 - Fit the socket provided: Carefully desolder the CMOS RAM chip and fit the socket provided with the kit. Be careful to ensure that you do not damage any of the tracks on either side of the board or bridge anything with too much or stray solder as your game may not work if you do! Since I have no control over your equipment or soldering skills I cannot provide any guarantees against bad soldering/desoldering on your part or faulty boards/PSU's.
Fit the NVRAM Module to the CPU board Click image to enlarge		Step 3 - Fit the NVRAM Module to the Socket: Fit the NVRAM Module to the socket. Be careful to align the pins correctly. The NVRAM module should have the 4 holes (for Bubbles D4-D7) at the bottom and the notch in the NVRAM chip at the top as shown in the picture. Incorrect orientation may damage your board and/or the NVRAM module. Ensure that Q3, the transistor at the lower left side of the NVRAM Module does not foul it as sometimes they were left with long legs when installed at the factory. If you have to ease it to one side ensure that none of the legs are touching each other or anything else. Step 4 - Powering up for the first time: Nothing special to note here, on first power up the game will revert to factory settings and initialise the default high score table. Set up your game according to preference (difficulty, extra lives, free play etc). Now power the game off, wait a few minutes and then power it up to ensure the NVRAM module is working correctly.

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!