Putting two memory controllers on a 780?

[hartwell%shasta at sri-unix.UUCP]

From:  Steve Hartwell <hartwell at shasta>

One advantage to having 2 memory controllers is that you can interleave
memory, such that the 1st quadword comes from memory off of the 1st
controller, the 2nd quadword comes from memory off of the 2nd controller,
etc.  This balances the controller load, though it is difficult [for me,
anyway] to estimate the performance improvement in a paged environment,
though I suspect that it is worth it in most cases.

In order to interleave, you MUST have equal amounts of memory on both
controllers; in your case, 3.25Mb off each controller.  You must also
diddle the controller registers just before loading unix off of the
floppy, or autoconfig() will not "see" the 2nd bank of memory.  This
is done very easily by adding 2 DEPOSIT commands in the DEFBOO.CMD
file on the boot floppy.  I can send the magic numbers to anyone who
would like to have them.

Steve Hartwell, Stanford University