Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!agate!ig!uwmcsd1!bbn!mit-eddie!killer!ninja!sys1!cpedev!neese
From: neese@cpedev.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: HD Controller advice
Message-ID: <-1025371@cpedev>
Date: 25 Feb 88 19:08:00 GMT
References: <23048@ucbvax.BERKELEY.EDU>
Lines: 22
Nf-ID: #R:ucbvax.BERKELEY.EDU:-2304800:cpedev:-1025371:000:1079
Nf-From: cpedev.UUCP!neese    Feb 25 13:08:00 1988


>I will soon be acquiring an 85 meg MFM hard drive which happens to have
>1250 cylinders.  I have heard that the 'standard' Western Digital controller
>for the PC/AT only supports up to 1024 cylinders.  Does anyone know of an
>MFM controller which will allow me to utilize all 1250 cylinders?  The
>controller must be Xenix compatible.

It sounds like you are only interested in Xenix so you don't need to worry
about the AT BIOS limitation of 1024 cylinders except at boot time.  SCO
Xenix, for example, uses the AT BIOS to load the kernel.  If the Xenix
kernel ever gets past the 1024th cylinder, you will not be able to boot.
Also you do need a controller that has a WD2010, or something equivalent
to be able to get past the 1024 cylinder hardware restriction.

>Also, what exactly is the difference between ESDI and the ST506 standard? Is
>it possible to use an ST506 drive with an ESDI controller?

ESDI and ST-506 are two very different standards.  No you cannot use an
ESDI controller with a ST-506 drive otr vice-versa.

						Roy Neese
					UUCP @	ihnp4!sys1!cpe!neese