Upgrade of 4/390-memory

[Ralf Bormann]

My boss asked me whether it is possible to upgrade the memory in our 4/390
to more than 56 MB.  Our current configuration is 32 MB, i.e. 8 MB on the
CPU-board and 24 MB on a separate memory board.

Some time ago, we upgraded some 4/330's by replacing the 8 1-MB simms of
the CPU-board by 8 4-MB simms.  Additionally, we had to set the 4-MB-simm
jumper.  Up to now we haven't had any problems with that configuration.

Though the CPU-boards of the 4/330 and the 4/390 are identical, the
situation for the 4/390 is a little bit more complicated (at least for me)
because of the separate memory board.  This board consists of 6 banks,
each one for 8 1-MB-simms.  And there is a jumper called "4 Meg".

I have two questions:

1. Is it possible to replace the 1-MB-simms of the CPU-board by
   4-MB-simms?

2. Ditto for the memory board.

Ralf Bormann                                e-mail : rbo at unido.uucp
University of Dortmund, IRB                          ..uunet!unido!rbo
P.O.Box 500500	                            BITNET : rbo at ddoinf6.bitnet
D-4600 Dortmund 50,  West Germany           voice  : +49 231 7552747