How to choose a new 386 UNIX PC...

Keith Ericson keithe at tekgvs.LABS.TEK.COM
Tue Sep 12 03:25:03 AEST 1989


In article <570 at tah386.manhattan.ks.us> terry at tah386.manhattan.ks.us (Terry Hull) writes:
>In article <276 at van-bc.UUCP> sl at 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!)



More information about the Comp.unix.i386 mailing list