Time for the Real Work to Begin

Published Tuesday, July 17 2012

Last night was the big moment. I fired up the 11/35 for the first time with the CPU installed.

I’m pleased to report that nothing popped, no fireworks went off, and no magic smoke got out.

On the other hand, it did not work correctly, either. The processor starts up, the RUN light comes on, random(-ish) data is displayed on the ADDRESS and DATA lights, and that’s about all that I can make happen.

So now begins the really hard part, the logic debugging. I’ve started a thread over on Erik S. Klein’s Vintage Computer Forum to discuss what I’m seeing, with the hopes that the very smart (much, much smarter than I) DEC fiends over there will be able to offer insight into how I should proceed with debugging.

I am armed with the KD11-A Processor Maintenance Manual, the PDP-11/40 System Engineering Drawings, an 8-channel logic analyzer, an oscilloscope, a multimeter, my brain, and the Internet. This will by no means be easy, but it will definitely be educational, and probably fun and frustrating in equal parts. Let’s do this!