Date: Fri, 6 Nov 1998 11:19:05 -0500 From: Lee Cremeans <lee@st-lcremean.tidalwave.net> To: "Ron G. Minnich" <rminnich@Sarnoff.COM>, lcremean@tidalwave.net Cc: hackers@FreeBSD.ORG Subject: Re: Coprocessor board--which I/O method should I use? Message-ID: <19981106111905.A3375@tidalwave.net> In-Reply-To: <Pine.SUN.3.91.981106093938.28856A-100000@terra>; from Ron G. Minnich on Fri, Nov 06, 1998 at 09:41:12AM -0500 References: <19981106083018.B2926@tidalwave.net> <Pine.SUN.3.91.981106093938.28856A-100000@terra>
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On Fri, Nov 06, 1998 at 09:41:12AM -0500, Ron G. Minnich wrote: > > On Fri, 6 Nov 1998, Lee Cremeans wrote: > > The chip itself can handle 27 MBytes/s in single DES, 10 Mbytes/s in triple > > DES. THere's a data sheet for it if you want to see it; go look at > > www.hifn.com, it's the 7751. > > Right so what I'm saying is this: PII and other Intel-based motherboards > can only do PCI reads at 7 Mbytes/second. Intel bridges don't support > burst mode reads from the processor to PCI, even in cacheable space. So, > if you want to get that bandwidth from the board to main memory you're > going to have to have the board do PCI writes in DMA mode. This sort of > thing slightly complicates user-mode access. Exactly; in fact, DMA mode is the only one supported for actual work on this board. -- Lee Cremeans -- Manassas, VA, USA (WakkyMouse on DALnet and WTnet) A! JW223 YWD+++^ri P&B++ SL+++^i GDF B&M KK--i MD+++i P++ I++++ Did $++ E5/10/70/3c/73ac/95/96 H2 PonPippi Ay77 M | mailto:lcremean@tidalwave.net http://st-lcremean.tidalwave.net | Powered by FreeBSD 3.0-CURRENT To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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