From: Al Kossow
It is in the Dick Best Options and Modules List 197503
Ah, thanks for the pointer; I see it's listed as a "Memory Extension
Control" - not sure that tells me much, alas!
Interestingly, it's not in the earlier Options and Modules lists, e.g.
June '74, but the KS11 is in that earlier list, so the MX11's a later
addition.
Noel