5 Feb
2015
5 Feb
'15
7:35 a.m.
I've been reading through the 11/45 manuals and
it seems these machines
are far more complex than I had imagined. Can anyone understand and
explain the unibus a / unibus b concept?
This is something I ought to figure out sometime too. AFAIK, it is only significant
if you have the special 11/45 memory boards (MOS or bipolar) in the CPU backplane.
For most applications (read : Anything you or I is going to do at the start), you
jumper the 2 Unibuses together with an M9200 in A/B of slots 26 and 27 of the
CPU backplane. This M9200 is just a narrower version of the M920, you can
probably drill out the rivets and remove the handle of an M920 to make one. I think
I did the reverse at one point.
If you do this, you can have standard Unibus memory boards on the Unibus, but they
don't go in the CPU backplane. I remember modifying a 4 slot backplane to have an MUD
slot (before I had even heard of an MUD slot) and fitting a 3rd party MOS RAM board.
Should I eliminate all this fancy bipolar and core memory and just use an
m7891? If I did, would it be on the fastbus, unibus a or unibus b and
would it even matter?
AFAIK, if you do that you have one bus, Unibus, and it works fine.
-tony