Date: Thu, 09 Oct 1997 17:53:42 -0700 From: Julian Elischer <julian@whistle.com> To: mdean <mdean@best.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Reliable probing techiniques for isa bus? Message-ID: <343D7C95.52BFA1D7@whistle.com> References: <Pine.SGI.3.95.971009165204.26271A-100000@shellx.best.com>
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mdean wrote: > > If I have an isa card which occupies 16 ports but only uses 9 of them, I've > put in some debugging code to see what can be read from the card at boot > time. The read/write ports are random depending on what the card in > connected to, the control ports are write only, and so I am only left with > the other 5 ports on the card that aren't used and the pattern they are in. > Is it expected that you will always read 0xff from an unused port, because > that is what I am getting? welcome to the pleasures of ISA there is no answer.. yes the ports will read ff they will also read ff for any other device that does not use them :)
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