Some DG 1200 progress

I found some appropriate C&K switches (7101 and 7205) in a bin at the local surplus electronics scrap place, $1 each - so I have a usable front panel. This is good because I really didn't want to cannibalize another perfectly good front panel. I also got a jarring reminder when installing them that my soldering skills have degraded over time. Thank god for solder-wyck :) I cleaned up the backplane and all edge connectors with progold, tested out the power supplies, and the machine sprang to life. It would appear that all the bulbs except the LSbit in the address row work, which is good as the bulbs seem pretty unobtanium. I'll keep digging to find a source of spares for the 2176D. The bulbs have no markings on them, but they are fed via an 11v supply. It looks like they are tied to ground via a 1K resistor which I'm guessing is a warming circuit. I do find it rather odd that they are soldered in place instead of socketed, and since the bulbs have no metal at all - just two very thin leads coming right out of the glass - they seem pretty fragile. I can deposit and examine correctly to all 4 cpu registers, but memory is a different story. There are a few spots in memory that I tested (at 100o for the one 8K stack and at 20000o for the other 8K stack) where I can deposit and read back as expected. However, there are a fair number of spots where if I deposit a value, the machine goes into run mode when I hit the deposit switch. Doesn't that sound more like a cpu card issue than memory or front panel? Next task is to try and decipher the documentation for the backplane and the J & P connectors, so I can tell from the schematics where things are supposed to be and where they go. The fun begins! Best, J