Attached Processor Interface (3B-1A)

[segaloco]

Hello, I've just uploaded this new scan: https://archive.org/details/attached-processor-interface-3b-1a

After the link is a Western Electric pamphlet on the Attached Processor Interface, a unit designed for interconnecting a 3B processor with a 1A processor, with the expected use case being integration of 3B processors with existing 4ESS and 1AESS offices.  The document describes installation scenarios, the various registers and diagnostic interfaces, and provides references, a glossary, and a few other odds and ends.

I'm not entirely sure what to think of it, whether it would represent something between 4 and 5ESS or if it's a distinct attempt at retrofitting.  The first 5ESS was delivered July of 1981, so this postdates that by a few months.  However, I do find it interesting that mentions of the processor are just "3B Processor" in this pamphlet, as the 3Bs in use at the time, to my understanding, were the 3B20D and 3B20S, both of which are referred to by those specific names in other literature and are typically grouped under the 3B20 umbrella.  I don't know if 3B5 would've been in the picture at this point to necessitate the generality, or if on the flip side perhaps this was before any need to differentiate.  In any case, the nomenclature of 3B hardware is something I'm still trying to get a better timeline on.  For the record I have a document that predates this by 5 months proudly displaying "3B20S" on the cover as well as a later UNIX manual from 1983 specifically targeting the "3B5" by name.  I've also seen some pictures circulating of a Bell Laboratories pamphlet about the "3B20D" by name.  I hope as I find more Bell System materials from the years 1979-1982 I'll be able to form a clearer picture of the 3B computers in their infancy.

By the way, I may make a separate thread about it down the road when my backlog is cleaner, but I'm pretty much always accepting documents for scanning.  I can't do every single little piece of paper, but if you or someone you know is sitting on a cache of documents like this one from the Bell System, I'd happily pay the shipping both ways to ensure whatever it is gets preserved properly.  If I get scans going regularly enough too I'll just make a here's stuff I've scanned thread.