Path: utzoo!utgpu!watmath!uunet!xanth!mcnc!ncsuvx!bu-cs!mit-eddie!andante!ulysses!att!mtunb!jcm
From: jcm@mtunb.ATT.COM (was-John McMillan)
Newsgroups: unix-pc.general
Subject: Combo Brd (Prev: Unix PC uugetty, Sun 3/50 or 4/110 getty)
Summary: Clarifies "Rev. F" trouble report
Keywords: uucp, cu, combo-boards
Message-ID: <1350@mtunb.ATT.COM>
Date: 3 Jan 89 14:41:39 GMT
References: <779@rush.cts.com> <295@arnold.UUCP> <453@uncle.UUCP>
Reply-To: jcm@mtunb.UUCP (was-John McMillan)
Organization: AT&T ISL Middletown NJ USA
Lines: 24

In article <453@uncle.UUCP> jbm@uncle.UUCP (John B. Milton) writes:
>In article <295@arnold.UUCP> dave@arnold.UUCP (Dave Arnold) writes:
>>In article <779@rush.cts.com>, bob@rush.cts.com (Bob Ames) writes:
>>> We've got uugetty on the AT&T (3.51, hardware flow control enabled,
>>> new combo PROM, HDB/BNU).
>>   ^^^^ What is a new combo PROM?  My Combo card causes my system
>>to hang when I use tty001 or tty002, do I need a hardware patch?
>
>This is NOT a rom upgrade, it is a replacement Zilog 8530 serial chip.
>It seems that Combo Boards Rev F. were made with a bad batch of chips.

If it was correctly explained to me a year ago: 
   Combo Boards of Revision Level "F" and newer were made with an
   altered oscillator logic that, belatedly, disclosed a Zilog serial
   chip defect.  The defect occurs as an occasional sustained "ringing"
   of the Special-Receive-Interrupt which can tie-up the system for
   seconds at a time, or can crash it (through Kernel-Stack exhaustion?).

No software work-arounds could cope with the ringing.  It is recommended
that the chip be replaced (via the HOTLINE?) if owner's of Rev F. and
newer combo-board's are experiencing multi-second system lock-ups or
crashes while doing UUCP's or upon receiving BREAK's on Combo-Ports.

JCM	-- att!mtunb!jcm	... speaking only for himself, if that.