Date: Fri, 7 Apr 1995 16:04:01 -0700 (PDT) From: Terry Lee <teren@lyria.stanford.edu> To: Soeren Schmidt <sos@kmd-ac.dk> Cc: FreeBSD hackers <hackers@FreeBSD.org> Subject: Re: Intel 486"Enhanced Write Back" question Message-ID: <Pine.BSF.3.91.950407155946.25125B-100000@lyria.stanford.edu> In-Reply-To: <199504061849.AA09676@dkuug.dk>
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> I have these new 486 "enhanced writeback" CPU's lying around, but > I cannot use the WB feature. I've read that the CPU determines if > it shall work as a WB or WT chip by reading the level on some pin > on reset. This makes sense as old motherboard designs wouldn't > support this feature then. Now the question is which pin ?? B13 must be high. A10, A12, and B12 are also used to control cache flushes and the like. Looks like your motherboard needs to support it specifically. This is from the 486 databook which Intel will send you for free if you give them a call. Interesting that AMD uses B13 in their DX4 to specify clock triple or clock double mode. I N T E R N E T Terry Lee, Technical Director D E S I G N 745 Stanford Avenue, Palo Alto, California 94306 G R O U P 415 424 0747 voice 415 424-0751 fax http://www.mall.net terryl@cs.stanford.edu http://www.mall.net/terry
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