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From: fmcgee@cuuxb.ATT.COM (~XT6561110~Frank McGee~C23~L25~6326~)
Newsgroups: comp.sys.att
Subject: Re: 20Mhz 6386 memory blues
Summary: Macs use 1 Meg x 8 SIMMs
Message-ID: <4348@cuuxb.ATT.COM>
Date: 2 Dec 89 21:02:31 GMT
Expires: 21 Dec 89 00:00:00 GMT
References: <918@cwjcc.CWRU.Edu>
Reply-To: fmcgee@cuuxb.UUCP (Frank W. McGee)
Followup-To: comp.sys.att
Distribution: na
Organization: AT&T Computer Systems, Lisle, IL
Lines: 47

In article <918@cwjcc.CWRU.Edu> david@cwlim.INS.CWRU.Edu () writes:
>Why do AT&T machines always seem to be at the heart of the trouble?
>
>I have (I had no choice in the matter) AT&T 6386 20Mhz machine for
>my Novell file servers.  That might not be so bad in a normal situation, 
>but who's network is even remotly normal?  Anyway, I have had to put 
>more then one meg of RAM in each machine.  Presently, I have two Meg in
>one and four Meg in three others.  My machine with two Meg has decided
>to lock up on a regular basis--cause:  presumed memory.
>Two of the three machine with four Mag have it in 256k SIMMS, so the 
>card is full, and there is no expansion room and no trouble.  Well,
>I decided to put one Meg SIMMS in a servers to give it four meg with
>expansion room.  The memory has appeared to be totally compatable, it
>is 9 chips of 80 ns.  Macs love it (the only SIMM tester I have) but,
>the AT&T machine don't.  With 12 one meg SIMMS, I was only able to get 

I'd count the chips on your SIMMs again.  Macs use 1 Meg x 8 SIMMs,
not 1 Meg x 9 like the 6386.  I suppose if you stuck 1 Meg x 9's in
Mac the Mac would ignore the extra parity bits though.

As someone already pointed out, there are some early versions of the
AT&T memory cards that can't support 1 Meg SIMMs.  Believe it or not,
the easy way to tell if your card does is to look at the slot cover.
Cards that support 1 Meg SIMMs have holes in the slot cover.  The
holes are there to help dissipate all the heat created by 16 1 Meg
SIMMs.  There are also 120 ns versions of the card (for the 16 Mhz.
machines) and 100 ns. versions of the card (for the 20 Mhz. machines).
Make sure you aren't trying to use a 120 ns. card in a 20 Mhz.
machine; I've run into this one before with customers that have both
types of machines.

As for dip switch settings, I can pull up a few cheat sheets on how to
set them, and if enough people email me asking for them I can repost
them (they were posted here some time ago).

As for AT&T certified memory, the only AT&T certified memory is the
memory sold by AT&T.  You're looking for PEC 37716, it sells for $2900
U.S. list; it is 4, 1 Meg x 9 SIMMs.  However, at our site here we've
been using Toshiba SIMMs (THM91000S-10) without any problems.


Hope this helps you out,

-- 
Frank McGee, AT&T
Tier 3 Complementary Channel Sales Support
attmail!fmcgee