Path: utzoo!utgpu!attcan!uunet!lll-winken!pacbell!att!mtunb!jcm
From: jcm@mtunb.ATT.COM (was-John McMillan)
Newsgroups: unix-pc.general
Subject: Re: AT&T UNIX PC Expansion Unit
Summary: Ouch!
Message-ID: <1540@mtunb.ATT.COM>
Date: 26 Jun 89 16:08:16 GMT
References: <12821@ea.ecn.purdue.edu>
Reply-To: jcm@mtunb.UUCP (John McMillan)
Organization: AT&T ISL Middletown NJ USA
Lines: 41

In article <12821@ea.ecn.purdue.edu> wieland@ea.ecn.purdue.edu (Jeffrey J Wieland) writes:
>We are trying to install one of these on a 3b1, but we are having
>problems getting some of the cards to work.  We have the following
>configuration:
...
>    In the Expansion Unit:
>
>Slot 5: Tape Controller
>Slot 6: EIA/RAM Combo Board
>Slot 7: EIA/RAM Combo Board (right hand slot, looking at back of unit)
>
>None of the EIA/RAM cards have memory installed.  The serial ports in
>the EIA/RAM cards in the Expansion Unit are not recognized by the
>system software.  This must have something to do with how the system
>identifies the cards to tell what hardware is installed.  The manual
>for the expansion does say that any ram cards must be installed in
>the internal slots, but we thought that we would be all right since
>there is no ram installed on these boards.  Is it possible to get 
>these cards to work in the expansion unit?  By the way, the tape
>drive controller card works fine.

	Much to my unpleasant surprise... a co-worker informed me that:
		
		The EIA/RAM cards fail in the expansion box.  He'd
		observed this and reported it as a bug when the
		expansion box was being tested.

	C.T. [who did the 3B1 chassis] did the EIA/RAM card engineering,
	BTW.

	My presumption is that the EIA/RAM card requires the External
	Memory Select line to be driven in order to do on-board
	decoding, and that the Expansion box doesn't drive this line.

	Best fix would be to get the EIA-ONLY boards.  Someone out
	there may be able to advise a hardware fix.... I only do
	software, if that.

	Last week's E-mail to you was bounced....  Sorry for the delay.

john mcmillan  -- att!mtunb!jcm -- Speaking for himself, only.