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From: jca@pnet01.cts.com (John C. Archambeau)
Newsgroups: comp.os.minix
Subject: Re: problems with scsi
Message-ID: <2564@crash.cts.com>
Date: 7 May 90 07:16:02 GMT
Sender: root@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 49

root@johnbob.uucp writes:
>In article <90.124.00:35:40@ira.uka.de> wedeck@iravcl.ira.uka.de writes:
>>...
>>Since I have installed the SCSI Hostadapter it is completely impossible
>>to use Minix. When booting from floppy not even the boot-message of
>>Minix appears. Instead the BIOS prints out: PRESS A KEY TO REBOOT 
>>This effect happens with Minix 1.3 as well as with Minix 1.5.0.
>
>I couldn't use a scsi adapter in my machine.  I noticed that the card
>uses its own BIOS (copyright message appears when rebooting).  I figured
>it was using some nonstandard way to talk to the hardware.  If anybody
>knows that this is the case or knows a way around it, I'd like to hear
>from you.

The problem with SCSI in the IBM compatable domain is that everybody does it
differently.  Adaptec, Future Domain, Seagate, Western Digital, et. al. each
have a SCSI host adaptor, but the problem is that not a single one is
compatable with another.  There's no support for SCSI in any BIOS chip which
is why they have their own on-board BIOS.  The one that is supported the most
that I've noticed the the Adaptec.  It's the only one supported by SCO Xenix
at the present time.  WD provides a driver for their WD7000 under SCO Xenix,
but the documention from what I hear to install it is so poor that a lot of
users get frustrated and replace it with the Adaptec.

There's no standard spec for SCSI host adaptors in the IBM compatable domain. 
Unlike ST412/506, either the manufacturer of the host adaptor or software
maker provides you with a driver for the host adaptor, or you're up a creek.

Two problems I have with SCSI are this.  One, ESDI is faster by 50
percent and has a 16-bit bandwidth.  SCSI only has an 8-bit bandwidth and a 10
10 Mbit per second data transfer rate.

If you want performance, ESDI is the way to go.

Try and implement SCSI on Minix.  You're going to have one driver for every
manufacturer out there because EVERYBODY does it differently.  I can see it
now; adaptec.c, wd7000.c, futdomain.c, seagate.c.  Enough of this proprietary
bull.  That and getting the specs on the card on how to do it will be a pain. 
 
     // JCA

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