Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!cs.utexas.edu!ut-emx!allred
From: allred@ut-emx.UUCP (Kevin L. Allred)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Mylex Motherboards - Why not?
Summary: I have a mylex 386sx -- Some BIOS shadowing conflicts
Message-ID: <17144@ut-emx.UUCP>
Date: 15 Aug 89 21:56:50 GMT
References: <4843@bgsuvax.UUCP>
Organization: UT-Austin, Dept. of Chem. Engr
Lines: 63

In article <4843@bgsuvax.UUCP>, bear@bgsuvax.UUCP (Michael D. Bear) writes:
> 
> 	I recently took a close look at a 386sx machine based on a Mylex
> motherboard.  I was fairly impressed with it, compared to what I've read
> on the net in the past.  My question is, why would you reccommend against
> a Mylex motherboard.  I have read bad reccommendations in the past, but no
> real reasons why.  Please respond with any experiences, good or bad.
> The machine I looked at, had Phoenix BIOS, Phoenix/VLSI chipset, 7 16 bit
> slots, and 1 8 bit slot, and appeared to be of the highest quality.
                         ^^
                         don't forget 1s and 1p too

I have one of these boards running in my system now.  It works almost
perfectly, so far.  I ran into shadow BIOS incompatibility, and it is
only a minor inconvenience, since I can map any memory not used for
shadowing out into the extended address space.  I have a rather
unusual hardware configuration, but judging by past posting the
shadowing incompatibility is probably the fault of the Pheonix BIOS
rather than the cards.  For your info, my configuration is:

	Mylex MXS-16 motherboard w/ 4MB (ie. 4 1MB 100ns SIMMS)
	Video-7 Fastwrite VGA card w/ 256KB and Magnovox Mono VGA monitor.
	Seagate ST02 SCSI host addaptor and ST296N 84 MB SCSI HD.

When I enable Video BIOS shadowing the ST02 can't find the HD.  I
tried changing the ST02 BIOS location to different places, but the
problem wouldn't go away.  My solution was to dissable video BIOS
shadowing (System BIOS shadowing works fine); remap the RAM out into
the extended memory space, and install the RAMBIOS driver shipped with
the Fastwrite in my config.sys file.  I wish I had a RAM installable
driver for the SCSI BIOS as maybe then I could get transfers to take
place fast enough to format the drive with a 1:1 interleave -- Oh well
450+ KBPS with a 2:1 interleve isn't slow, and a big RAM cache makes
the actual drive speed almost unimportant.  I don't know that not
having the SCSI bios in RAM is what is preventing the transfers from
going fast enough, but I do know that other people with 16MHz machines
have claimed to be able to get the 900+ KBPS transfer rates.  The
system has a Norton 4.5 Si rating of 16.(5-6) at 16MHz and about 11 at
8Mhz (you figure why it is not half).  I haven't had any normal DOS
software that wouldn't run.  I have run VMOS/3 which runs in protected
mode.  VMOS seems to work fairly well, but is not very robust -- It is
after all a young product.  I have been able to get 4 programs (the
machine wasn't anywhere near out of resources so I probably could have
started more) running simultaneously under VMOS -- some of them were
even games.  I wish I had UNIX to try out, but I'm waiting for GNU or
UNIX prices to drop.  I do know that Intel says their UNIX won't run
on a 386sx ( you figure the company that makes the processor would
know what to change :-).  I don't know about the other UNIX vendors.
I am happy with the Mylex board.  It is a good deal for a entry level
386 board.  I bought it from:

	MicroSource Distributors
	(800)-326-4276
	$483 0KB shipped 2nd day UPS.

PS.  If anybody has any suggestions for how to solve the shadowing
conflict or speed up the SCSI transfers, I would love to hear them.
Buying new cards isn't the solution I want to hear :-)
-- 

	Kevin Allred
	allred@emx.cc.utexas.edu
	allred@ut-emx.UUCP