10 Mar
2005
10 Mar
'05
3:30 p.m.
On Mar 10 2005, 14:18, willisjo at zianet.com wrote:
I did know about the serpentine weirdness. It caused
me a great deal
of
grief in getting the system to pass its self tests in
the beginning,
before
I stumbled (quite accidentally) across hamster's
digital$resources
page on Qbus. However, I think you may have hit on something. The
RQDX3 is
not at the end of the bus.
No, it's not that...
If memory serves (I'll verify this
after I get home from work today), the backplane arrangement is
something like this:
A B C D
+-------------------------------------+
| CPU |
+-------------------------------------+
| Memory |
+-------------------------------------+
| TQK50* | |
+-------------------------------------+
| M9047 | |
+-------------------------------------+
| RQDX3* | |
+-------------------------------------+
| DHV11 |
+-------------------------------------+
| ???? ** |
+-------------------------------------+
| | |
+-------------------------------------+
| | |
+-------------------------------------+
That's what's wrong. Assuming this is in a BA23, you don't have
interrupt or DMA grant continuity. The first three slots are Q22-CD
but (if this is a BA23) the fourth is Q22-Q22 so you need something in
the RHS (slots C+D) of row four:
A B C D
+-------------------------------------+
| CPU |
+-------------------------------------+
| Memory |
+-------------------------------------+
| TQK50* | |
+-------------------------------------+
| M9047 | RQDX3 |
+-------------------------------------+
| DHV11 |
That's the only reason you have a grant card; it is to sit next to a
dual-height card in a Q22-Q22 slot. If this were a BA123, you'd not
need it at all.
--
Pete Peter Turnbull
Network Manager
University of York
7228
days inactive
7228
days old
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