I am trying to test a High Speed master display board. I only have an 11B MPU available to test with. I have this all setup on the bench. The MPU boots fine with F-14 Tomcat eproms and drives player 1, 2, 3 & 4 displays properly but I need to check the Match/Ball in Play display also. So I burned High Speed eproms but then the MPU won’t boot, the blanking stays low. Not sure if jumper configuration is correct or not. I know that the LEDs won’t work properly since High Speed is for an 11(nothing) MPU which has the 7 segment display instead of LEDs. The LEDs should all be on but they are not. All the address and data lines are good. I tried burning EPROMs in several different sizes of chips but get the same results. Anyone have any ideas on how to get this to work?

Thanks Chris, that’s what I thought too. Contacted a friend I do board work for a he had a High Speed MPU he needed fixed up so I got it to test with. It boots and all the displays work, yea. Now I will put my High Speed eproms in it and see what it does and go from there. When I get done testing with it I will clean it up, repair solenoid outputs not working, and install NVRAM and MOSFETS (for the lamp matrix). Pretty nice board compared to most I see, lol. Glad he had it.

To close this out, my High Speed eproms worked fine in the11b board, but it looks like I may have a bad U26 socket, which was causing the problem.