Depending on when your machine was produced, some Data East games with the same title may have shipped from the factory with two different configurations. The display board may contain the software on either 2 2Mbit (256K 27C020) Eprom chips or only 1 4Mbit (512K 27C040) Eprom chip.
The 2 titles most commonly needed to check are Lethal Weapon 3 and Star Wars as the production run was changing during these 2 games. Normally games before LW3 are 2 chips, and games after SW, like Jurassic Park on up are 1 display rom. It’s always good to check though, cause operators did, alot of part swapping to keep their games earning on route.
You can purchase either version for the same machine. However, you will need to change a jumper setting if you don’t buy the configuration which your machine is already set up for. The jumper setting at R11 is how you set the game to look for 2Mbit or 4Mbit roms. If you are not comfortable soldering jumpers on your board, or do not want to modify your machine, I offer both versions available.
DMD Display Boards with part # 520-5055-00:
Shipped with jumper R11 installed, and use 2 2Mbit (256K) ROM chips in locations U12 (ROM0) and U14 (ROM1). Earlier PCB’s did not have ROM0 or ROM1 printed on the location.
DMD Display Boards with part # 520-5055-01:
Shipped with jumper R11 removed, and use only 1 4Mbit ROM chip in location ROM0
The “jumper” from the factory is actually a 0 ohm resistor, so if you do not have one handy, you can simply use a jumper wire.
Here is my board from Jurassic Park without the jumper installed: