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Date: Sun, 28 Sep 1997 02:00:01 -0500
To: Mike Smith <mike@smith.net.au>
From: Tony Overfield <tony@dell.com>
Subject: Re: INB question 
Cc: hackers@FreeBSD.ORG
In-Reply-To: <199709190838.SAA02899@word.smith.net.au>
References: <Your message of "Fri, 19 Sep 1997 08:49:37 +0200."             <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.