AFAIK the only requirement for using a KK8-E in the 8/A chassis is that the M8320 timing generator board has to include a certain ECO. This is spelled out in the "PDP-8/A Operator's Handbook", p3-3. The rest of the 8/E board set is the same either way, and the modified M8320 still works in an 8/E chassis. I assume that at some point all the M8320s produced had this ECO and thus would work either way. This is the first I've heard about them having a special designation. The manual doesn't say specifically what the TG module ECO does, but it wouldn't surprise me at all if it had something to do with implementing NTS STALL. In any case the change can't have been too complicated since it could be done in the field as an ECO. Bob