Strange idea in VAX

From: Ethan Dicks <>
Date: Tue Apr 2 17:19:53 2002

--- Sridhar the POWERful <> wrote:
> Ok. I wonder what would happen if I stuck a DWBUA in the BI cage of my
> VAX 7000-650, and added a UNIBUS cabinet, then I were to take a Qniverter
> and add a Qbus framebuffer?

You'd probably get bus timeouts. Does the DWBUA work in a VAX 7000? I
know it became an issue in machines newer than the 8800. I do not recall
where it falls off the trolley.

The tech manual for the DWBUA describes its requirement for Unibus boards.
I presume that *if* the DWBUA works as expected in the 7000 to begin with,
*and* the Qniverter doesn't violate any of the requirements of the DWBUA,
it would work, if the device driver didn't mind being stuffed into an
18-bit backplane vs 22-bit (and the mapping registers being different,
etc., from Qbus to Unibus). Analyzing how an RL11 vs an RLV21 is
set up by the VMS driver might be an interesting exercise to see how
it might behave. I presume the register model between those two
controllers is virtually the same; the difference would be the buses
and the mapping registers.

So presuming the hardware didn't glitch, you might be able to make it
work if the software doesn't throw a rod (or if you can modify/replace
the driver).


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Received on Tue Apr 02 2002 - 17:19:53 BST

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