Is there a 3B1 StarLAN and tape backup unit "clash"?

[Peter Fales]

In article <35593 at cup.portal.com>, thad at cup.portal.com (Thad P Floryan) writes:
> kim at mathcs.emory.edu (Kim Wallen {Psy}) in <6479 at emory.mathcs.emory.edu>
> offers some 3B1 items for sale, and in the notice appears:
> 
> 	"... One 3B1 STARLAN card is modified so it doesn't clash with
> 	tape backup unit, second one is not.
> 
> Interesting.  I've been using tape backup and StarLAN and haven't experienced
> any problems.  Is the modification required for only certain ``REV.'' levels,
> or is there something insidious that will jump out and bite some day?

According to information I have (a several generation old copy):

"When the Release 1 NAU and the Tape Back-Up unit are in a UNIX PC, the
machine might crash leaving the following error messaes on the screen with
instructions to record the panic information and perform a hardware
reset.

Panic:  Page Fault in Kernel

To resolve this, the Tape Back-Up unit board should be in slot 1 (left-most
slot as seen from the back) and the NAU should be in slot 2.  If putting
the boards in the correct slots does not alleviate the problem, then a
47pf ceramic capacitor should be removed from the NAU.  (The 47pf ceramic
capacitor is only on the older versions of the NAU).


Here is my attempt to draw the associated diagram.

-------------------------------------------------------
|				STARLAN NAU
|	--IC--		--IC--
C
O	--IC--		--IC--
N
N	--IC--	O | |	--IC--
E		  ^
C	--IC--	  47pf	--IC--
T
O	--IC--		--IC--
R
|
--------------------------------------------------------
-- 
Peter Fales			AT&T, Room 5B-420
N9IYJ            		2000 N. Naperville Rd.
UUCP:	...att!ihlpb!psfales	Naperville, IL 60566
Domain: psfales at ihlpb.att.com	work:	(708) 979-8031