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From: kls30@duts.ccc.amdahl.com (Kent L Shephard)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Mixing hard drive types: ESDI, MFM, IDE
Message-ID: <7apH02.W032201@JUTS.ccc.amdahl.com>
Date: 15 Nov 90 16:43:45 GMT
References: <5569@crash.cts.com>
Sender: netnews@ccc.amdahl.com
Reply-To: kls30@DUTS.ccc.amdahl.com (Kent L. Shephard)
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 50

In article <5569@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:
>kling@ICS.UCI.EDU (Rob Kling) writes:
>>Any comments/explanations about why there might be incompatibilities
>>if the appropriate drives are each connected to a proper controller for
>>that kind of drive?
>
>Simple, because ESDI, IDE, and ST412/506 use the same port addresses.  An IDE
>drive looks to your system like an ST412/506 drive to your system BIOS.
>
>What you could probably do is set your ST412/506 MFM controller card to the
>secondary port address, but then you have a problem of setting it to the
>second interrupt.  Not to mention that MS-DOS doesn't care to play with second
>controllers.

Wrong!  Buy a controller designed to act as a secondary controller in the
system.  It WILL work if the controller has its own bios.  Since the
device has its own bios MS-DOS WILL play with a secondary controller.

MS-DOS will play with ANYTHING provided you have a bios level driver or
an installable device driver.

I know because I have a DTC controller that works as the second controller
in my system and I've also designed a couple of interface boards for PC's
that were definitely non-standard and MS-DOS played just fine.

>
>Only big exception is SCSI.  Your SCSI host adaptors are designed to work with
>an existing ST412/506, ESDI, or IDE drive already in your system.

SCSI is a good option because, if you ever change computer systems (Mac
NeXT, Amiga, SUN) you can reuse the SCSI drive.

> 
>     // JCA
>
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--
/*  -The opinions expressed are my own, not my employers.    */
/*      For I can only express my own opinions.              */
/*                                                           */
/*   Kent L. Shephard  : email - kls30@DUTS.ccc.amdahl.com   */