putting a machine together, (now: MYLEX motherboards)

[Gordon W. Ross]

I will speak in defense of MYLEX since they've done well for me.
Too bad Jay Ts and Mark Hilliard have not had such good luck.

In article <190 at metran.UUCP> of comp.unix.i386,
	jay at metran.UUCP (Jay Ts) writes:
> I am using a home-built system based on Mylex's MI386-20 motherboard.
> My system passed BIOS tests OK, but wouldn't boot UNIX.  [It] freezes
> at the "Booting the UNIX System..." message from ISC's 386/ix.
[ He then describes his frustrating tech-support experience. ]
> [...]			 I simply cannot recommend Mylex
> products to *anyone* until they get their act together!

This hang-during-boot problem is mentioned frequently, and is not
specific to MYLEX boards.  It is (as I understand it) caused by the
BIOS setting the CPU status word to indicate presence of a math
co-processor when in fact the BIOS is just emulating its presence.
The AMI BIOS allows you to disable the "co-processor emulation"
feature.  I observed this problem while installing ESIX on my
MYLEX (AMI BIOS) machine.  With the AMI BIOS co-processor emulation
disabled, UNIX boots and runs flawlessly!

In article <110 at gizzmo.UUCP> of comp.unix.i386,
	mark at gizzmo.UUCP (Mark Hilliard) writes:
> This board has a NON-STANDARD caching system which is [incompatible] with
> MOST dual ported memory cards.  I have [extensively] tested Mylex boards
> and had BAD experiences with all of the caching boards. Some companies
> make custom work arounds for their cards to support the mylex board,
> but only a few.  I gave up on Mylex and started using AMI boards with
> NO problems with caching and dual ported memory.

I don't think there is any "STANDARD" caching system as far as
dual-ported memory cards are concern.  You should note, though that
MYLEX can provide you with a replacement for one of the PALs that
disables the cache for certain address ranges (you want it disabled
for the address range used by any memory-mapped I/O devices).
Alternatively, if your software supplier is cooperative, MYLEX does
clearly document in the hardware manual how software can enable or
disable the cache.  The driver software could be changed to disable
the cache while accessing the memory-mapped I/O device.

I am very happy with the MYLEX board.  I've never had difficulty with
their tech. support (though I've only called once with questions).
The board comes with very complete documentation written in English!
--
-- 
Gordon W. Ross / The MITRE Corporation / Bedford, MA 01730 (U.S.A.)
internet: gwr at linus.mitre.org	  uucp: {decvax,philabs}!linus!gwr