SUMMARY: Sun 4/330 memory configuration

From: Martin Achilli (
Date: Wed Jan 22 1997 - 11:06:00 CST

Hello, sorry I'm a bit late..

I received a lot of help on this matter and would like to thank all
those who replied. The general opinion was that memory simms must be
added 8 at a time in a 4/330 since it has a 64 bit memory bus and 30
pin simms are 8 bits wide.
The 4/330 also supports 4Mb simms provided you have PROM revision 3.0.3
or later You can not mix 1Mb and 4Mb simms on the same board and you
have to set jumpers according to the simm size as explained in the
replies below.
The PROM settings for installed and tested memory do not seem to affect
whether the machine recognizes and uses the memory.
The configuration block settings also are not relevant.
I verified these last two facts on my 4/330, for other models and PROM
revisions things may be different.
As an update on a previous summary of mine I would like to include that
this machine is still running with a 6 ohm 20 watt resistor in series with
the 5 rear fans - reducing fan noise - and I have not had any problems.

Here is my original query:
> Hello Sun Managers,
> I have a Sun 4/330 with 16Mb RAM which I would like to expand to 20Mb.
> The setup is:
> CPU board in slot 0 with 8Mb RAM composed of 8 1Mb simms
> Sun "Single height parity memory board" (p/n 270-1711) with 8Mb in
> slot 4 composed of 8 1Mb simms (there are 16 simm slots on the board)
> I have the Sun 4/330 eeprom manual but I don't have a manual on the
> memory board, I searched via Altavista and in the SunManagers '94 and
> '95 archives but did not find much, my questions are:
> - can I install 4 additional 1Mb simms on the memory board or must I
> install 8 at a time ?
> - do I have to define the amount of memory on the board via PROM in
> the configuration block ? The address for the 4th board is set as 0x00
> (whereas from my PROM manual I think that it should be 0x02).
> Thanks in advance for any guru help..

and here are the most relevant responses:

Benjamin Cline:
You need to install SIMMS in blocks of 8. The 4/300 CPU has a 64-bit
memory bus, and because a 30 pin SIMM is only 8-bits wide, you need 8 of
them to work properly (8 X 8 = 64, of course :-).

Gary W. Cook:
You must install 8 SIMM's at a time. You can use either 1Mb or 4Mb SIMM's
with the 4/330. You can use 4Mb parts on the CPU if they are low profile
like the 1Mb parts. That requires moving a jumper next to the sockets and
that your boot PROM's be revision 3.0.3 or later. If you use 4Mb parts on
the memory expansion board, you also have to move a jumper on the memory
board. No mixing of 1Mb/4Mb parts on the same board.
The memory defined in the EEPROM is just for the amount to test when you
power up the system.

Glenn Satchell:
I have an old Sun Field Engineer's Handbook which has the info on the
330 cpu and memory boards. According to this (and this is _the_
hardware bible) the memory board can only have 8 or 16 simms installed,
and they must all be the same type (ie all 1 MB or all 4 MB).
There are two jumpers on the board j0901 is "in" for 8 simms and "out"
for 16 simms. j0902 is "in" for 1MB simms and "out" for 4MB simms.
While I've got the book out I may as well give you the motherboard
settings too. On the motherboard j1900 is "in" for 4MB simms and "out"
for 1MB simms. Looks like you must have 8 simms installed on the mother

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