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Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!sgiblab!spool.mu.edu!bloom-beacon.mit.edu!news.kei.com!news.byu.edu!cwis.isu.edu!u.cc.utah.edu!cs.weber.edu!terry From: terry@cs.weber.edu (A Wizard of Earth C) Newsgroups: comp.os.386bsd.development Subject: Re: [FreeBSD 1.0R] DMA Problems? Date: 22 Dec 1993 05:06:02 GMT Organization: Weber State University, Ogden, UT Lines: 21 Message-ID: <2f8kjq$ft2@u.cc.utah.edu> References: <CI9EC4.AoB@genesis.nred.ma.us> <jmonroyCIB20s.FF8@netcom.com> NNTP-Posting-Host: cs.weber.edu In article <jmonroyCIB20s.FF8@netcom.com> jmonroy@netcom.com (Jesus Monroy Jr) writes: [ ... DMA in FDC driver ... ] > Previously I had stated that the problem stemmed from the > possibility that the "RAM refresh" process had priority > over the "FDC transfer". If this is true then (I beleive) > there is no way around this problem (except by new hardware). No. No way. Not a chance. The main interaction between memory refresh and DMA is that you can kill memory off and parity error yourself to death by holding the bus so long that refreshes get skipped. Dynamic RAM gets pissy when you skip its refresh. 8-). Terry Lambert terry@cs.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.