> From port-vax-owner-clowenst=ucsd.edu@netbsd.org Tue Sep 26 10:09 PDT 2000
> X-Sender: cmcmanis@208.226.86.10
> Date: Tue, 26 Sep 2000 10:16:54 -0700
> To: Jon Lindgren <jlindgren@slk.com>
> From: Chuck McManis <cmcmanis@mcmanis.com>
> Subject: Re: VAX 4000/200 issue resolved!
> Cc: port-vax@netbsd.org
> Delivered-To: port-vax@netbsd.org
> 
> At 05:54 AM 9/26/00 -0400, Jon Lindgren wrote:
> >It does?  Does that mean that the C/D connectors on my 4000/200 has DSSI
> >running down it?  How would that work?  Where would it terminate?
> 
> Yup. The signals go both to the connector next to the memory connector and 
> to the C/D connectors. When the CPU is installed in the BA215 or BA213 the 
> DSSI drives connect via a cable to the CPU, when the CPU is in a BA440 the 
> C/D slots connect up through the backplane into the top of the chassis. 
> Since there is a paddle board in there, and it is clearly designed to hook 
> up the DSSI drives, my only guess is that it gets used if you use the KA640 
> CPU in the BA440 chassis (was there ever a MicroVAX 3400 in the BA440?) The 
> bottom line is that is isn't used for the KA660.
> 
> >Don't the memory boards use the C/D connectors for additional lines, using
> >the 50 pin berg for actual data transfer?  How is this possible?
> 
> Most of the memory traffic goes over the 50 pin cable on the top. However, 
> I did notice that some third party MS650 memory would not work with the 
> KA660 installed, but with other memory cards it worked fine (these same 
> memory cards worked with the KA640 CPU)

As I recall the details of the CD-interconnect, nearly all of the
connections are from the bottom of one card to the top of the card
below it.  (assuming horizontal BA-23 orientation).  There are very few
signals bussed to slots further away than this.  Official DEC notation
is Side 1 for "top", Side 2 for "bottom"

So a CPU card in the first slot could communicate "up" to something in
the box, or "down" to a memory card.  .

    carl
--     
        carl lowenstein         marine physical lab     u.c. san diego
        {decvax|ucbvax} !ucsd!mpl!cdl                 cdl@mpl.ucsd.edu
                                                  clowenstein@ucsd.edu