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Data East, Sega, and late-model Stern Display ROM Jumper Info
NOTICE: For some very important information, please read the Technical Article Notice and Disclaimer, found on our Technical Articles Index page before performing any of the work described below. The information given below assumes you have read the Notice and Disclaimer first.
Some Data East, Sega, and late-model Stern pinball games may have shipped from the factory with TWO 2MB ROM chips used on the display unit. Updates to display ROM software may be available on ONE 4MB ROM chip, rather than TWO 2MB chips.
When replacing an original TWO-CHIP 2MB ROM SET with ONE 4MB ROM chip, you must remove the jumper at location R11 on the display unit PC board, otherwise the replacement chip will not work. Boards with part # 520-5055-00 shipped with jumper R11 in place, and were set up to use two 2MB ROM chips in locations ROM 0 (U12), and ROM 1 (U14).
Likewise, when replacing ONE 4MB ROM chip with TWO 2MB ROM chips, you must install a jumper at location R11, otherwise the replacement chips will not work. Boards with part # 520-5055-01 shipped with jumper R11 absent, and were set up to use one 4MB ROM chip in location ROM 0 (U12), and no ROM chip in location ROM 1 (U14).
For more details, see Data East Service Bulletin 38B.
A jumper is basically just a wire that connects two points on the board. The points are labeled on the PC board- label is usually located inbetween the two points, or dotted lines will outline the two points as labeled. The jumper may be just a simple bare wire, or a wire with white ceramic around the middle of it, or may look like a resistor.
For more details on jumpers and replacing/installing them, see our related Tech Article on Williams games by clicking here.
Programming your own? When combining the data from both chips into a single chip, data from ROM 1 (U14) is written into the lower half of memory in the single chip, and data from ROM 0 (U12) is written into the upper half of memory.
If you're uncomfortable doing this kind of work, we recommend leaving it to someone who is experienced. If you know which jumper needs to be set or removed, and don't know a local electronics technician, try taking the board to a local TV/VCR repair shop- they can do the work in a minute or two and may only charge $5 or $10.