Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!bellcore!att!mcdchg!ddsw1!ddsw1!karl
From: karl@ddsw1.MCS.COM (Karl Denninger)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Dell 310 flame (of sorts)
Message-ID: <[2535e929:5977.7]comp.ibmpc;1@ddsw1.MCS.COM>
Date: 13 Oct 89 14:00:12 GMT
References: <8634@spool.cs.wisc.edu> <[2406.5]comp.ibmpc;1@point.UUCP>
Lines: 49

>-----
>Response 6 of 6 (5977) by wek at point.UUCP on Thu 12 Oct 89 09:33
>[Bill Kuykendall]
>(<Unknown> lines)
>
>>company, so I tried that in my DELL. Well it seemed quite compatable,
>>great setup in the ROM of the controller, but the DELL just could not
>>handle 1:1 interleave with this sucker. I got 54K (thats right)/sec. I
>>set it to 1:2 interleave and got 495K/sec (gosh its fun doing low level
>>formats of 300+meg hard disks repeatedly :-) ).  I took this hard disk
>>and controller over to my friend's 20Mhz Mylex 386 and did the 1:1
>>interleave and saw 990K/sec without buffers!!     Well I called up Dell
>
>The key to the discussion above is probably the Mylex board's bus speed, not
>the Dell's.  Many clone makers run the bus at the clock speed of the CPU. 
>Dell limits the bus speed to 8mz, to ensure compatibility with add-in cards.
....
>It isn't fair to judge a machine on it's performance with one high
>performance peripheral.  Drive controllers are designed to handle faster
>buses so that they can be used in unix boxes that really *are* io intensive
>and probably don't have a lot of other exotic peripherals.  

Sure it is!

The best systems, from any manufacturer, allow you to >choose< your bus wait
states and the like.  Our machines have this option in their CMOS setup, and
we (and our customers) use it to great advantage.

You simply set up for the fastest speed which your cards are rated for, or
if you feel lucky crank it wide open and then turn it down as problems
appear.

What makes this work well is that the bus settings are individual by type --
8 bit, 16 bit, and 32 bit slots all have their own, independant wait state
configuration.  This is a wonderful feature, and makes for >excellent<
performance.  We don't sell systems missing it (at least on the '386 side of
things; I haven't seen 80286 machines with this option yet).

Most C&T chipset machines can do this, IF you can figure out what to diddle.
The AMI BIOS has it built into the "advanced" setup pages.

Our boards honor the "0 wait state" line on the 16-bit bus, which tells
the system to ignore waits on that transfer.  Fast peripherals can yank on
that to get a 0 wait state transfer regardless of the CMOS settings.

--
Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910]
Macro Computer Solutions, Inc.		"Quality Solutions at a Fair Price"