Date: Wed, 17 Dec 1997 05:09:35 GMT From: jak@cetlink.net (John Kelly) To: Mike Smith <mike@smith.net.au> Cc: FreeBSD Hackers <hackers@FreeBSD.ORG> Subject: Re: 3com 3c509 card Message-ID: <349a59c3.99678713@mail.cetlink.net> In-Reply-To: <199712170334.OAA01300@word.smith.net.au> References: <199712170334.OAA01300@word.smith.net.au>
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On Wed, 17 Dec 1997 14:04:26 +1030, Mike Smith <mike@smith.net.au> wrote: >"AT Bus Design" (Edward Solari, Annabooks) BTW, I checked on getting that book and it seems to be no longer available. >Now, if you take into account just a little CPU overhead, interrupt >cycle overhead, metadata overhead, you will quickly see that you're >not going to route 4MB/sec aggregate traffic through anything on the ISA >bus, period. I seem to have one 486 board running at 12 MHz ISA and clock doubled 50/100MHz DX4-100 CPU will no apparent problems. This has reduced my (measured) 8 bit I/O cycle time to 0.65 usec. I don't have a suitable method for measuring the 16-bit cycle time, but I'm hoping for nearly 4MB through this supercharged bus in 16-bit mode. I'm only getting about 700K per card, so I don't think I need a full 4MB anyway. I might even be able to use five interfaces -- they won't be saturated all the time. >Personally, I'd recommend a 4-port Zynx card. I have a small truckload of SMC Ultras I need to use. John
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