cbs+@cs.cmu.edu (Clauss Strauch) (12/20/90)
I would like to stick 32 MB of memory in a 4D/20. The prices that SGI charges for this memory are fairly high. Does anybody in netland have recommendations for third-party memory suppliers, warnings about possible pitfalls in doing such an upgrade, or other advice? -- Clauss Strauch Carnegie Mellon University cbs@cs.cmu.edu ...!harvard!cs.cmu.edu!cbs
operator@IRIS.KTH.DK (Martin Liversage) (12/20/90)
Clauss Strauch, I decided to summarize anyway.
Once in a while there are postings about how to upgrade the memory on
a 4D/20. I know that there has been several replies (and I have
benefitted from some of these), but I think it is time summarize once
again.
This information should be correct for both the 4D/20 as well as the
4D/25 (and perhaps, also other models) but I have only done the
upgrade on a 4D/20.
The 4D/20 has 16 memory slots. You get access to them by removeing the
right plastic cover and the metal shield underneath (box seen from the
front). The slots are in the upper, left corner (box now seen from the
right).
The slots have to be populated by SIMM's (some kind of industry
standard). I think 80 or even 100 ns is allright, but take a look at
the speed of your own SIMM's.
They should always be mounted in groups of four. In a plain 8 MB 4D/20
you have eight 1 MB SIMM's. They are placed in slots A and B in this
figure:
ABCD ABCD
ABCD ABCD
If you upgrade to 16 MB using eight more 1 MB SIMM's you simply insert
the new SIMM's in slots C and D. If you are going to mix different
SIMM's you should always have the the same type of SIMM in slots with
the same letter.
As far as I know, the SG 32 MB memory upgrade is sixteen 2 MB SIMM's,
and they are mounted in all the slots. Still not to difficult to
follow... is it? Now, I have been told (but haven't tried it) that it
is possible to mix 1 and 2 MB SIMM's. The important point is that the
2 MB SIMM's should be in the lowest numbered slots. To get 24 MB you
should populate the slots as shown (signatures are, 1 = 1 MB SIMM, 2 =
2 MB SIMM, 4 = 4 MB SIMM, . = empty slot):
2211 2211
2211 2211
The good news is that you can get 4 MB SIMM's from third-party
vendors outpricing the 2 MB SIMM's you can get from SG. To go to 32 MB
you mount eight 4 MB SIMM's like this:
44.. 44..
44.. 44..
The bad news is that you cannot mix 4 MB SIMM's with 1 or 2 MB SIMM's
(leaving with a lot of spare SIMM's) and even worse, not all 4 MB
SIMM's will function properly.
Among the 'good' SIMM's are SIMM's from Toshiba. They should look
something like (this information I got from message
<1990Sep14.204656.5216@eagle.lerc.nasa.gov> written by Chris Miller
<eagle!news@ucbvax.berkeley.edu>):
module ID tags: chip numbers:
-------------- --------- TOSHIBA
| TOSHIBA | | 9025AAA | TC514100J-80
| THM94000S-80 | | JAPAN | JAPAN 9020HDK
-------------- ---------
Among the 'bad' SIMM's are SIMM's from Hitachi:
chip numbers:
JAPAN R200
9026 2NN
HM514100JP8H
I have both 'good' and 'bad' 4 MB SIMM's in my 4D/20. The 'good
ones' are from Toshiba, and the 'bad ones'... I don't know, and I
don't want to take the box apart right know :) .
It is important that the 4 MB SIMM's in slot A are 'good'. Then you
are free to use 'bad' 4 MB SIMM's in the rest of the slots (this is
my experience), and it is possible to upgrade to 64 MB populating all
the slots with 4 MB SIMM's.
When you do the actual seating of the SIMM's you have to take
precautions (wearing a static strap, work on a static pad) not to
damage the memory. Sometimes you will have to reseat a module.
If a SIMM is not properly seated it will probably show up on the
diagnostics terminal (if you have one attached) during power on. Is it
the 'Walking bit' test it will fail? I've forgotten...
After a succesful power on you should enter the PROM monitor and issue
the 'hinv' command. This should tell you how much memory you have got
(or how much the 4D/20 believes it has). If this is correct you are
ready to boot UNIX.
On my system I have two problems. During the initial power on I get
an exception and a register dump on the console. Then the PROM monitor
'hinv' tells me that I have 0 MB of memory! Anyway, after I boot UNIX
everthing is fine, and the IRIX 'hinv' gives me the right amount of
memory. Still, a bit strange...
I hope this information is helpful to some of you, and that what I say
is indeed correct. It is after all only based on personal experience
with one machine.
Good luck with the upgrade, and thanks to Mark Leininger
<LEININGER@FNDCD.FNAL.GOV> for all his helpful advice.
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