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From: bin@rhesus.primate.wisc.edu (Brain in Neutral)
Newsgroups: comp.unix.wizards,comp.periphs
Subject: 18-bit Device on a MicroVAX II
Keywords: DMA device driver Q-bus
Message-ID: <349@rhesus.primate.wisc.edu>
Date: 26 Jul 88 13:30:38 GMT
Organization: UW-Madison Primate Center
Lines: 29


[Note: I'm posting this for someone else.  I'll forward replies, but
it would be better to send responses the the address below - Paul]
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18-bit Device on a Microvax II
keywords: DMA device driver Q-bus

We have built a Parellel DMA Interface in house.  We
have been unable to read anything from the device although
I have successful accessed the different registers on the
card.(I have verified this with a scope)  I get an interupt
and the word count goes to 0.

I am trying to determine if the Microvax II can handle an
18 bit device.  Is it necessary to have 22 bit addresses?
The board does not have any more room on it to add the 
wires that would be needed for 22 bit addressing.

Another thing I don't understand if your card accepts
22 bit address how do you get one.  From what I understand
you can't get one from ubasetup.  The bits above 18 tell
you the number of registers you need and the number of
BDP's what ever they are.

Thanks in advance for any ideas on this.

Cathy Accettura
Space Astronomy Lab University of Wisconsin
cathy@larry.sal.wisc.edu