Yes, that's the panel I found the picture of in the RSTS-11 brochure a while back: http://www.classiccmp.org/pipermail/cctalk/2016-November/029104.html The picture in the brochure is not very very hi-res, but Al Kossow recently located some original photos in the DEC section of the archive, and the image you sent the URL for is one of them. I've been puzzling over what this thing is. It looks 'kinda-sorta' like an RK11-C panel (the registers it shows are sort of the RK11 registers), but if you look at the print for the "RK11-C Indicator Connectors: RK11-C-23" (page 34 of the RK11-C Engineering Drawings PDF), you can see the pinout, and it doesn't match. E.g. look at the lower right line of lights on the panel: 4 bits of Bit Counter, a blank, 8 bits of Internal Word Counter, a blank, and three bits of Major State; now look at the RK11-C prints, connector B32: 4 bits of Bit Counter, 8 bits of Internal Word Counter, a blank, Postamble, Checksum, Data, Header, Preamble. Close, but different. One thing I have been wondering about is that "RK11-C" - that implies that there was a -B, etc. I wonder if this panel goes with one of them? (Or perhaps it is a custom prototype?) I have never been able to find out anything about an earlier version of the RK11: the earliest Peripherals Handbook that I have is the 1972 Red/White one, and it only talks about the -C. Also, the Spare Module Handbook (a fantastic resource, it lists the boards in almost every PDP-8/10/11 option) mentions the -C and -D, but no other ones. However, given the example of the KT11-B, which was totally unknown until the documentation for one showed up with the -11/20 in Arizona, thereby proving that there _was_ a KT11-B before the KT11-C (the -11/45's MMU), I would guess that there likely _was_ an RK11-B, and perhaps this panel goes with that (or an earlier one). Any further information would be most welcome. Noel