Eprom Replacement for Williams System 7-Pinballs
The motivation for this project was, that it is not always easy to buy and write the 2716 and 2532 Eproms, which were originally needed for System7 Pinball games. So we looked for an easy solution for this problem, let's see if we found one ;-)
The first step was to write the data, which was originally distributed over 4 individual Eprom-ICs into only one IC. We did this experiment with a Jungle-Lord pinball - the prototype looks somewhat experimental, but it works fine!
Now the second step: Todays EPROM-ICs are much more powerful than those which were used years ago, when System 7 pinballs were developed. So the idea was to write all data of ALL System 7 games ever produced into only one EPROM-Chip. This was possible and that's what the working prototype looks like:
There is a DIP-Switch in order to choose one of the games or a special test-EPROM which was written by Leon (Leons Homepage) .
The usage of this EPROM-replacement is very easy. First the CPU has to be removed from its socket. A special pin-socket on the bottom side of the replacement board has to be put into the CPU socket. The CPU itself is placed into another socket on top of the board. Beside these parts very few components are needed: The Eprom is a 27C2001 (256kByte), there is one logic-IC (4011), two resistor networks (pullups) and maybe a few capacitors in order to buffer the supply voltage, that's all!
Using this replacement you can get rid of all different Eproms - only one is needed and you can choose easily which game you would like to run. And this is the layout of the replacement board:
... and finally the circuit diagram:
If you are interested in the project or if you have some questions, please feel free to ask! My email is: .
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