ADV11-A vs. ADV11-C and 22-bit Bus - test-drb@ccmp.vtda.org

27 Jan 2018

...
  From: Mark Matlock 
...
     Any device which uses backplane pins BC1, BD1, BEl,
BF1 or DC1, 001,
    DEl, OF! 
Those last are probably typos for "DD1, DE1, DF1".

...
  Several other pins are also tied to ground on that
connector such as
 BC2, BJ1, and BT1. 
Yeah, those are all standard Q22 ground pins.

...
  When I look at the Board connector B pin C side 1
(component side) the BC1
 pin is tied to ground. .. So it looks like if I simply cut the trace
 between the BC1 finger and its connection to ground on the board it
 would become Q22 compatible.
 Is it that simple? 
That would be my take on it, yes.

As Jerry Weiss mentions, since it's not a DMA device, once you do that, it
should be Q22-capable; all QBUS devices are supposed (per the QBUS spec) to
use BBS7, along with BDAL0-12, to listen for register accesses, so the fact
that it's not listening to BDAL18-21 should not be an issue. 

(Odd factoid: various QBUS CPU's drive various combinations of BDAL13-21
during references to the I/O page; I forget the details off the top of my
head, but Dave Bridgham and I were just looking at that.)

	Noel