20Mhz 6386 memory blues

[george.p.wilkin]

>From article <918 at cwjcc.CWRU.Edu>, by 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.

The AT&T memeory board do NOT all support 1meg chips!  Some boards will
ONLY support 256K chips.  This is how I have surmized the distribution
of board types:
908 915   = 16Mhz  256K only
917       = 20Mhz  256K only
916       = 16Mhz  1meg or 256k
922       = 20Mhz  1meg or 256k
925       = 20Mhz  1meg or 256k

Again I THINK this is how they break out I AM NOT an OFFICIAL SOURCE!!

Can you put 1 meg chip into the earlier boards, maybe.
Will AT&T support anything other than their board?  My guess, based on
attempts such as yours, is no.

What's different??
The first mask had some faults(I was able to match boards by 'correcting'
them myself, of course voiding any warr.) and there are a number of 'white'
wire changes.  I also noticed that the 20Mhz machines and the 16Mhz machines
have different PALs in them(this is just on the Memory board) and that
some of the new boards have different PAL IDs.

How will I fix things to work?
Compare the working machines.... check PALs etc  check board types(on a yellow
tag and also on the mask) to see which ones are working.
Swap working boards into non-working systems. see if they come up..
A board that will not work in ANY system is one thing, one that works i 3 out of five is another.

Ask AT&T to fix them, Scream, kick yell....You have a 50-50 chance of getting
a new board install that WILL support 1 meg simms.


BTW
I have found that under UNIX(a little r goes here)  there can,(might) be
problem with core dumps if your memory board is too far out of sync with
your motherboard(ie. 908 memory board in a newer machine) so watch what kind
of replacement boards you get.

gpwilkin


Of course I don't speak for AT&T, just myself.
-- 
George Wilkin 	AT&T Network Systems,(IH MAIN BL)
                2000 N. Naperville Rd. Rm IH4A157
                Naperville, IL. 60566-7033
 att!ihlpf!gpw  work ph# (312) 979-4317