Date: Sun, 28 Sep 1997 02:00:01 -0500 From: Tony Overfield <tony@dell.com> To: Mike Smith <mike@smith.net.au> Cc: hackers@FreeBSD.ORG Subject: Re: INB question Message-ID: <3.0.2.32.19970928020001.006ce080@bugs.us.dell.com> In-Reply-To: <199709190838.SAA02899@word.smith.net.au> References: <Your message of "Fri, 19 Sep 1997 08:49:37 %2B0200." <19970919084937.PR22228@uriah.heep.sax.de>
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At 06:08 PM 9/19/97 +0930, Mike Smith wrote: >> OTOH, 800000 transfers per second seem to support your figure. If the >> transfers are 16 bits wide, this would be ~ 80 % of the theoretical >> maximum. > >Read it again. 1.3MegaWords. Specifically, implying that it's making >1.3 million 16-bit I/O transactions per second, or 2.6MB/sec. > >Yes, this is substantially faster than I was expecting. 8) 16-bit ISA I/O cycles are not only wider but also faster than 8-bit ISA I/O cycles. Back when IDE drives were still attached to the ISA bus, a fast drive could transfer about 3.5MB/sec, but 2.5MB/sec or 2MB/sec was more typical. The speed depends on the chipset and the way that the BIOS programs the ISA timing options.help
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