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From: keithe@tekgvs.LABS.TEK.COM (Keith Ericson)
Newsgroups: comp.unix.i386
Subject: Re: How to choose a new 386 UNIX PC...
Message-ID: <5914@tekgvs.LABS.TEK.COM>
Date: 11 Sep 89 17:25:03 GMT
References: <21969@cup.portal.com> <124379@sun.Eng.Sun.COM> <276@van-bc.UUCP> <570@tah386.manhattan.ks.us>
Reply-To: keithe@tekgvs.LABS.TEK.COM (Keith Ericson)
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 35

In article <570@tah386.manhattan.ks.us> terry@tah386.manhattan.ks.us (Terry Hull) writes:
>In article <276@van-bc.UUCP> sl@van-bc.UUCP (Stuart Lynne) writes:
>
>Who on the net has information about how much speed advantage
>following this advice will provide?
>...
>I'm really not interested in a theoretical answer.  I want to know
>what operations are noticably faster when using a higher bus speed.
>After all, if you do not notice the speed difference, who cares?


We spent quite a bit of time investigating video diplay performance
of various machines, bus speeds and display cards (VGA and EGA).

As important as bus speed was 8-bit versus (proper) 16-bit operation.
Also important was the quality of the display card's BIOS routines.  We
found some cases where others reported a particular card to be very
fast, yet our (non-BIOS-implemented, i.e., direct write to display
memory) tests showed them to be slower than others.

When the object of the game is to move large blocks of pixels around in
a hurry you _will_ notice the difference in bus speeds, word size, and
good software.  But if you're doing a lunch-break tape backup, the
performace of the disk controller card will be more important than
the bus speed.  ST-506 only puts out 5 Mbits/sec = 0.675 MBytes per
second anyway.  Even when your disk controller can keep up with this
rate (a 1:1 interleave) the bus will not be the limiting factor.
Even the fastest ESDI drives at 15 Mbits/sec=1.875 Mbytes/sec
shouldn't be choked by the bus speed.


kEITHe

My employer doesn't care about my opinions.
(Or at least now I'll find out if it does or not!)