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From: kc@rna.UUCP (Kaare Christian)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Re: AT questions
Message-ID: <573@rna.UUCP>
Date: Fri, 21-Nov-86 11:50:31 EST
Article-I.D.: rna.573
Posted: Fri Nov 21 11:50:31 1986
Date-Received: Fri, 21-Nov-86 21:42:08 EST
References: <13210001@acf4.UUCP> <332@cartan.Berkeley.EDU> <419@catnip.UUCP>
Organization: Rockefeller Neurobiology
Lines: 60

>3. Can Xenix be run on any clone? Does it work well (i.e., is the total
>machine performance significantly reduced when two or more users or tasks
>are competing for CPU?).

When I reviewed SCO Xenix System V for PC mag last Spring I had three AT's
at my disposal:

	Mfr.			Disk Ctrl.	Speeds	Motherboard
	A Red River Tech	DTC		6,8,10	Chipset
	A PC Designs		WD		6,10	Random
	IBM			WD		6	Random

The Red River machine was the first on the market with the Chips and
Technology chipset, but today Red River is out of business.  Other
machines currently use the chipset. PC Designs is still in business,
and IBM is doing well.

Anyway I couldn't get  Xenix to *boot* from boot floppy on the RRT
machine until I swapped in a Western Digital controller. Then it booted
fine, and I was then able to replace the WD with the original DTC and
it still worked fine. Once running I could tar to/from floppy on RRT using
the DTC controller, so it isn't a gross problem, rather the original
system installation process picks up some subtle difference between WD
and DTC.

	Moral 1 : Although the DTC disk controller works with DOS, there
is some incompatibility with Xenix. Stay with the WD disk controller.

	Moral 2 : Apparently Xenix cohabitates well with the Chipset,
which is the basis of many current clone motherboards.

I also tried Xenix at all of the available speeds on all of the systems. It
booted from wini at all speeds, and worked reliably at all speeds.

	Moral 3 : Get a fast one. (Especially the disk. Do not even consider
	an XT type 60-90ms. disk. You need a 30-40ms. hard disk.)

As to performance, fast is better but even 6 MHZ is pretty respectable.
Some benchmark info appears in the article (PC Magazine, August 1986).
You can get a reprint from SCO. The bottom line is that a 10MHZ AT
running Xenix has about one half of the performance of a VAX 780: equal
integer performance, much slower floating point, slower I/O.  You could
support several people doing light work or one heavy user.

Based on my experiences, I believe that Xenix is compatible with most
clones, but of course you can get bitten. I had lots of spare widgets
around, which makes it easier to cobble something together when one
widget is slightly incompatible.

You should also keep in mind that Unix software is much better behaved
than DOS software. In the DOS world there were many programs that
wouldn't boot at above 6MHZ, programs like copy2pc and copywrite are
unbelievably machine specific, and copy protection gets you every other
time.  In the Xenix world, once the operating systems works your
compatibility problems are mostly over. In the DOS world booting DOS is
easy, but getting [ your favorite misbehaved/copy-protected DOS program ]
to work can be impossible.

Kaare Christian
cmcl2!rna!kc