Date: Sat, 31 Oct 1998 21:03:38 -0800 From: David Greenman <dg@root.com> To: Greg Lehey <grog@lemis.com> Cc: John Polstra <jdp@polstra.com>, hardware@FreeBSD.ORG Subject: Re: Mixing 8- and 16-bit shared memory ISA cards Message-ID: <199811010503.VAA03108@implode.root.com> In-Reply-To: Your message of "Sun, 01 Nov 1998 15:25:39 %2B1030." <19981101152539.R28493@freebie.lemis.com>
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>> It affects all machines with ISA busses, not just early x86. > >What's the reason for it? Reason? Because it's PC hardware, that's why. :-) I think it has something to do with timing of the top 8bits of (the 24bit) address decoding and when the 8/16 bit select line is valid. The result is that the 8/16 bit selection ends up being segmented into 128KB chunks. ...something like that. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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