pdp11/84 PMI memory: What is the problem with Q bus?

[Noel Chiappa]

    > From: Chris Zach

    > Just checked the configuration and block mode DMA *is* off.

Interesting. So it's not bklock-mode on the QBUS which is screwed up, but
normal QBUS transfers. That jibes with the comment abour "gate array
incompatibilities" (which I take to mean "errors" :-).


    > was the 11/70's MASSBUS channels nothing more than RH11-C's attached to
    > the old FASTBUS on the 11/45 cpu core (which is what an 11/70 really
    > is, with cache) or did they port right to the memory box?

RH70's are totally different from RH11's - a hex card, and a couple of quads
- and the interface to the /70's memory system is totally different from the
RH11's (which goes to the UNIBUS):

   https://gunkies.org/wiki/RH70_MASSBUS_controller

It has interfaces to both the cache, and the memory bus (although the diagram
in the 11/70 CPU handbook shows it as only connected to the cache).

I didn't follow the "the old FASTBUS on the 11/45 cpu core (which is what an
11/70 really is, with cache)"; the 70's cache is what's connected to what
used to be the FASTBUS, the memory bus connects to the cache, IIRC.

	Noel