I don't know if you guys have this same experience, but I haven't touched my 9010a for months. I went to fix my Midway Double Play last night and for some reason now this tester won't work. Just for no reason at all. AUUUGH! Fortunately, I happen to have my Fluke 90 series Z80 tester. I'm hoping someone on this list has had to become familiar with the 9010a service manual. If you feel like giving me a hand, you might want to refer to page 4-32 - 4-35. Here's the testing I've done so far. Symptoms - 9010a powers up but only displays a zero with an 'x' in the middle. The keyboard doesn't work except when toggling the probe pulses high or low. 9010a self test - won't respond to key presses. 90 series uP tests: Bus Test - Pass Ramp Test - Pass Memory Test - C000-FFFF Pass Memory Soak - C000-FFFF Fails - Hmmmmm. Is this normal? I/O verify - writes data to certain I/O addresses and then reads the data to check to see if it comes back the same. The Pod/Probe PIA section passes the I/O verify test (100C0 - 100C3) The Display/Keyboard section Fails the I/O verify test (10080-10081). The Magnetic Tape controller also fails (100A0 - 100A1). What appears to be happening is whatever gets written to the display/keyboard assembly will not get read back correctly. Here's something weird. If I do a write @ 10081 Data=00 (reset command to the display/keyboard) and loop it for a while, then immediately reset the "mainframe" (as they like to call it). For about a second the Normal display comes up and then blanks out. I can also send commands to the magnetic tape controller and it will rewind. So it seems like the 'writes' are all working, the reads are screwy. I'm mainly concerned about the keyboard/display assembly. Does anyone have any advice on this one? Could I have a bad ram chip somewhere? I already tried replacing the Z80 microprocessor. Thanks... Matt To UNSUBSCRIBE from techtoolslist, send a message with "UNSUBSCRIBE" in the message body to: techtoolslist-request@flippers.com. Please direct other questions, comments, or problems to jrr@flippers.com.