Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!rutgers!orstcs!guille.ECE.ORST.EDU!thallem
From: thallem@guille.ECE.ORST.EDU (Michael G. Lohmeyer)
Newsgroups: comp.sys.apollo
Subject: Re:  Various hardware hackins with DN420
Summary: memory boards in the 420
Message-ID: <16429@orstcs.CS.ORST.EDU>
Date: 3 Mar 90 20:52:56 GMT
References: <9003021407.AA18053@richter.mit.edu>
Sender: usenet@orstcs.CS.ORST.EDU
Reply-To: thallem@guille.ECE.ORST.EDU (Michael G. Lohmeyer)
Organization: Oregon State University, E&CE, Corvallis
Lines: 24

In article <9003021407.AA18053@richter.mit.edu> krowitz%richter@UMIX.CC.UMICH.EDU (David Krowitz) writes:
>By running the jumper program (in either /systest or /systest/ssr_util) you can
>see the various jumper configurations for the memory boards. It appears that
>you can have three boards in a DN420, although there are  3 different types of
>memory boards that were manufactured for the machine. The boards would all
>have to be of the same type. You can only run the node with a single display.
>Apollo's OS does not support multiple displays.

     It is not necessary that the boards all be the same type, just
compatible.  I am running a DN420 with two of the standard DN420 memory
boards in it, but I also added an extra meg of ram by using a 2 meg 
board out of a (unfortunately dead) DN660.  Yes, I said that I got only
an extra 1 Meg of ram from a 2 meg board meaning, of course, there
are problems with it.  The main point being that by using the jumper
program that David mentioned, I was able to set up the jumpers on the 
2 Meg board so that the DN420 at least recognizes part of the memory.
The reason why the 420 only sees the first meg of ram is because of the
way the memory is addressed (starting addresses of main memory, etc).
The jumper program will give you most the information you need to know
about the boards.

Mike Lohmeyer				thallem@ece.orst.edu
Oregon State University			(503) 737-9264	
Electrical & Computer Engineer Dept.