> Anybody knows, where to get a detailed description of the Q-Bus (elec. &
> mech)

A basic pinout of the Q-bus can be found at:

          ftp://sunsite.unc.edu/pub/academic/computer-science/history/
          pdp-11/hardware/qbus.backplane

If you're looking for details such as bus protocols, all the nitty-gritty
bus details, etc., because you're building a Q-bus interface card, a
good place to start would be any of the Q-bus processor manuals.  Others
have already recommended the KA630 manual, but I myself prefer the
description of the Q22-bus in the PDP-11/23 and /73 manuals, as there
are fewer typos :-).

> and of the MSCP-protocol ?

Up until a year or so ago, DEC would gladly sell you the QP905-GZ
"UDA50 Programmer's Document Kit".  It seems to no longer be officially
available, though it's possible that the component manuals
(AA-L619A-RK, "MSCP Basic Disk Function Manual", AA-L620A-RK, "Stor-
age Sys Diag & Util Protocol", and AA-L621A-RK "Storage Sys Unibus Port Des-
cription") are still orderable.

It's missing a few pages that have been "censored" as not being allowed
outside of DEC, but it's a good start if you're writing a device driver.
The Q-bus controller chapter is completely missing, but most of the
details there are either identical or extrapolatable from the Unibus part.

Most of the BSD MSCP device drivers are derived from one that Chris
Torek donated, and they are a good place to start learning if you
don't have the manuals.

Am I to assume that you're thinking about building a MSCP-emulating
Q-bus disk controller?

Tim. (shoppa@triumf.ca)