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Date: Sat, 27 Sep 1997 05:55:43 -0500
To: Terry Lambert <tlambert@primenet.com>
From: Tony Overfield <tony@dell.com>
Subject: Re: INB question
Cc: hackers@FreeBSD.ORG
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References: <199709190659.QAA01136@word.smith.net.au>
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At 02:44 PM 9/19/97 +0000, Terry Lambert wrote:
>> > Yeah;  that's why I picked the extended MCA DMA ports for the detect;
>> > that, and I can do the probe non-destructively, with the expectation of
>> > a 0 bit in my data and no hardware configuratio changes resulting.
>> 
>> Where is the port exactly?  ie. is it likely to be sat on or masked 
>> over by an ISA device?
>
>Port 0x18 is the control, and port 0x1A is the data.

Port 0x18, on many systems, is an alias of port 0x08, which is 
the read-only DMA status register and the write-only DMA command 
register.  Likewise, port 0x1A is often an alias of the write-only 
port 0x0A DMA mask register.