20Mhz 6386 memory blues

[david at cwlim.INS.CWRU.Edu]

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 
four to work in the AT&T machines.  The other would not allow the 
machine to boot, for that matter, they couldn't even pull up a display
or reset the keyboard (the three lights remain on.)  I have also noticed
that the settings I have gotten the card and memory to operate with, 
whether 256k SIMMS or 1 Meg SIMMS, unless there is the standard four
256k SIMMS, the switch setting on the card do not match the book.  I don't
get it.  I need to put some AT&T CERTIFIED memory in my file servers and
I don't know how to set the card to match the book and have the machine
operate.  I don't care at this point if I  have to pay more then the 
going rate to get proven AT&T 100% reliable memory, preferablly in
four meg SIMM modules.  Any information, help, or other information
anyone can provide would be greatly appreciated to the Nth degree.
Thank you.  
                                Dave

david at cwlim.ins.cwru.edu                     dwn at pyrite.som.cwru.edu


P.S.  I have notice some stand alone computers (the same internals) with
      one Meg straight from the warehouse have the same trouble booting.
      I suspect memory.  Perhaps a timing problem?