Really! :-) I can see a crystal on the cabkit, and if you look at the interface spec ('Microcomputers and Memories', 1982, pg. 628), it's clear it must use the External Clock for the baud rate to be switch selectable on the cabkit. That is the case for the KDJ11-B, which is why I assumed the same thing was the situation with the 11/23+. But it's not... Good question. I would assume in the 11/23+ print set, but I looked there, and couldn't find it. Maybe that print set (MP01236) is just for the CPU board itself, and there's some other print set for the larger system, including the cables, but I can't immediately think what I should look for. FWIW, the part number for the cabkit is 54-15422-01. (I think the 54- prefix means 'assembly', but I'm not sure. I should collect a list of all the DEC part prefixes - I looked, but there doesn't seem to be one.) Noel