Thanks, Lou,
That's a very nice build that you did on your RAM board. I see from the schematic markups that it uses the 62256 chip also. (I assume that it's the same as the Cypress part.) It's nice to have some confirmation that it's popular. The PDP-8/a looks great.
Yeah, that little gotcha on the Douglas board--- The first time I plugged it in, I quickly discovered that the +15V supply had pulled down to +5V! Nice little robustness test for the PDP-8/m's switching regulators. Geez.
I'm envious of your PDP-8/a, with the RL8A controller, supporting the RL01/02 drive. Of course, there isn't an RL01/02 controller for the four-slot version of the Omnibus. I restored an RK8E controller board set and an RK05 drive to get OS/8 running. The RK8E does data break with the RAM board, of course. The drive needed a couple boards repaired, a power supply fixed, blower replaced, absolute filter replaced and foam replaced. Also made a prefilter assembly for it. Feel like I earned that sucker!
Thanks for the suggestion about writing up the memory diagnostics. I actually thought the same thing but the article was getting long and I wanted to get it out. I'll go back and add that and a few other things.
I appreciate your bringing Chuck Dickman's design and your fine project to my attention. I will add coverage of those to the article as well.
I have a few things on the projects list before I get back around to the PDP-8/m but will be bringing up an Extended Arithmetic Element set and a Power Fail/Autoboot for it in the near future. There is also that stuck bit in the 8K core board set to fix. And, there is a second RK05 sitting here, waiting to be restored. Not to mention the Tek 4012 graphics terminal begging for attention. So many toys, so little time. I guess you know the feeling.
Steve L.