Strange third party board in PDP-11/45

-----Original Message----- From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mattis Lind via cctalk Sent: Monday, July 23, 2018 2:36 AM To: Noel Chiappa; General Discussion: On-Topic and Off-Topic Posts Subject: Re: Strange third party board in PDP-11/45 Here is how it is connected: https://i.imgur.com/4TEZoiO.jpg The sandwiched dual boards are i sitting in 27 / 26 AB. The board in 27AB was empty (quick glance), while the board in 26AB has a few TTL chips on it. Slot 26AB is the Unibus A slot, Slot 27 AB should be a terminator on Unibus B. (maybe there were terminating resistors on the second board. Didn't check in detail) Slot 28AB is Unibus B and goes to the DD11-C and the RK11-D backplanes. The hex ABLE/ ACT board sits in slot 21 which is the memory controller board for the MS11. It very much looks like it is a Cache board. But why have some one written "Not used" (Anv?nds ej) on it? I'll hope I find the documentation for it! /Mattis ----- I wonder whether this CACHE/45 can coexist with MS11 memory on the Fastbus itself, or is designed to _replace_ MS11 memory by accelerating access to Unibus-based memory? The available product literature doesn't clarify either way. paul