It turns out the KE15 registers are available on the main console, with a setting on the rotary 'select registers to display' switch. I was just being complete/thorough... :-) Oooh, thanks ever so much for turning that up!!! So that mystery panel seems to be a general panel, more associated with the but one quadrant is the KT15 memory management, one is the KA15 priority interrupt system, and there's general CPU/system stuff throughout (memory parity, power fail, instruction register). I'm not sure what it's formal name might be (I don't think it can be BA15, given all the CPU stuff that's in it). Very odd that the User's Handbook doesn't cover it when it covers the KT15, the KA15, etc, etc; the print set might be informative (now that I can see what's on that panel). Noel