26 May
2016
26 May
'16
5:52 a.m.
There are jumpers on this card. W1, W2, W. I did
not find any
specific
examples online of scenarios for the jumpers
...
I think I get why one would remove the W2 jumper but if W1 is removed
(open) instead can someone give me an example scenario for when you'd
want to use this card "for beginning of non processor bus
termination".
Can someone give me an example of when you'd
do this?
The device the M9300 was invented for was probably the RH11-AB, which is
where one most often finds them. The RH11 is an UNIBUS device which is a
MASSBUS controller; the RH11-AB has connectors for _two_ UNIBI (so one
RH11-AB can be 'in' two PDP-11's at the same time; i.e. all the devices
connected to that controller can be accessed from either machine).
If it's only connected to a single CPU, though, what does one do with the
second UNIBUS? That's where the M9300 comes in. It simulated the
NPG-granting
section of a CPU, and when jumpered to do that, it goes at the _start_ of a
UNIBUS - e.g. the second UNIBUS in the RH11-AB. (Leave all the jumpers in,
and it functions like an M930, and can go at either end).
You can find a description of its use in the RH11-AB, as well as a
description of how the M9300 works, in the "RH11-AB Option Description"
document (available online), starting on page 4-32.
I can't conceive of any use for one in most PDP-11's, though (outside an
RH11-AB, of course).
Noel