Stephen wrote: "
* between 37 and ground you should have clock for sure. * If I were you I would confirm that your frequency counter reads the correct result when the M100 is working. * not sure how your counter works.... * X1 is for the RTC, won't prevent start up * X2 is the 4.9152 MHz crystal. " I repeated my tests with the frequency counter, first verifying its operation by connecting to a known-good source of oscillation (Velleman PMK147'1). While connected to X2 with power on the frequency drifted from approximately 60 Hz to about 135 Hz, up and down. With power off the frequency returned to 0 Hz. I moved the counter contacts to pins 20 and 37 of the CPU. With power on I got 0 Hz. I will try replacing the X2 crystal next. -CH- Link to counter manual: https://drive.google.com/file/d/1Qpj-rVU-FyOG4KIyBXnG977CGlm0duFU/view?usp=sharing
