Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!hplabs!hpfcdc!hpfcmr!glen
From: glen@hpfcmr.HP.COM (Glen Robinson)
Newsgroups: comp.sys.hp
Subject: Re: Serious SCSI drive problems
Message-ID: <1080024@hpfcmr.HP.COM>
Date: 7 Jan 89 00:24:32 GMT
References: <6589@killer.DALLAS.TX.US>
Organization: HP Fort Collins, CO
Lines: 24

Actually, this is a formally escalated site.   A workaround
provided by an earlier contributor of putting the fast HP-IB
interfaces to interrupt level 3 (with the SCSI remaining at
interrupt level 4) fixed the customer to the best of my knowledge.

A modified SCSI daughter card has been sent to the CEC for 
delivery to the customer, and this should solve the problem.

For any interested folks, the problem was that the 98265-66501
(SCSI daughter card on the Human Interface Board) trashed an
internal buffer if polled during a transfer and it was not the
card that had requested an interrupt.  Polling followed an 
interrupt service request chain and if another card at the
same interrupt level had interrupted ---> garbaged data when the
(non-interrupting) SCSI card was polled in the chain.
This has been fixed with the 98276-66502 card.  

This is a fairly low incidence (but disastrous) bug because 
the population of users having the configuration is small.
If any readers fit that configuration, the workaround will work,
and you should notify your field engineer for a permanent fix.

Note that this problem is confined to the SCSI daughter card
part number 98265-66501 only.