Hi Sjerpe, Is Leon's testrom passing the memory tests?

I coded Williams testroms myself which provide more thorough memory tests, as well as testing the IRQ generator, PIA initialization tests, switchmatrix input tests, socket 14 and 17 tests. Send me a PMwith your email address if you would like to try them (I am also from Holland).

Marco

Interesting....and with the 47K pull ups the gameroms are running fine?

Apparently, the 6808/6802 CPU is unable to drive the driverboard mounted 4k7 loads/pull ups at the databus. Is the 680x IC socket still okay? Solder connections and powerconnections also? 680x CPU is not an AMI branded one, these can show some odd behaviour when they are aging?!

What happens if you are testing the CPU board without a driverboard but with one or more additional 4k7 pull ups mounted on the cpu board. Just for a test. Maybe you can rule out a capacitive or other strange load caused by the driverboard...(however, this has Always been there before).

As Budwin already mentioned, probably due to save costs, Williams at some time removed the databus buffer IC's IC8 and IC9. Maybe an idea just to add these again?

Marco