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From: iverson@xstor.UUCP (Tim Iverson)
Newsgroups: comp.sys.ibm.pc,comp.periphs.scsi
Subject: Re: MFM and SCSI together ?
Message-ID: <5@xstor.UUCP>
Date: 24 Mar 90 23:07:48 GMT
References: <1938@crash.cts.com>
Reply-To: iverson@xstor.UUCP (Tim Iverson)
Followup-To: comp.sys.ibm.pc
Organization: Storage Dimensions, Inc.
Lines: 60

>>tmottonen@cc.helsinki.fi writes:
>>
>> [paraphrased]	is it possible to have both a SCSI-adapter
>>			and an MFM-controller in the same machine?
>>
>>    Thanks, Teemu.

>jca@pnet01.cts.com (John C. Archambeau) replies:
>
>I don't know the idiosyncrasies of how a SCSI host adaptor works in a
>PC/AT/386, but I'm willing to bet that the host adaptor and ST412/506 MFM
>controller would have IRQ and port address wars ...
>... I personally wouldn't do it.  With respect to controllers, the rule of
>thumb is this...assume the manufacturer is stupid (or arrogant) and will not
>allow any way for you to have more than one drive controller in your machine.
>[... more mis-information deleted ...]
> 
>     // JCA
> ** ARPANET : crash!pnet01!jca@nosc.mil     | mine.  Bill Gates couldn't buy
> ** INTERNET: jca@pnet01.cts.com            | it, but he could rent it.  :)
> ** UUCP    : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca


I just couldn't pass this one up.  The scsi h/a would have IRQ and port wars
with an ST506 controller?  This is pure bullshit.  Most scsi host adapters
are *designed* to work in systems with existing ST506 controllers.  SCSI H/A
manufacturers are not arrogant idiots trying to lock you into their own
platform - for the most part they actually go out of their way to make sure
that their boards are comptible with existing platforms.  Because of this,
most H/As are easier to install and more reliable than their ST506
counterparts.

I have used Storage Dimensions' Data Cannon 800, Future Domain's TMC 830 and
MCS 350, and Adaptec's 1540 derivatives extensively.  I have played with
many others, but I do not posses sufficient information on them to provide
a recomendation.  This is what I can attest to:

	DC800	- very good for supported OSes.  SDI drivers support DOS
		and Novel only.  Low overhead, but no 1st party DMA.  DOS
		can run w/o SDI's SpeedStor driver, but you don't get added
		features (Erasable Optical support, fast compare after write,
		automatic reallocation of bad blocks on write, etc...).
		[BTW: I wrote the SpeedStor driver for the DC800 :-)].

	FutDom	- all products have serious bugs that require special driver
		workarounds (verify function doesn't work, randomly pokes
		bytes into memory under certain conditions, etc.)

	Adaptec	- high overhead (1ms per command?), but has 1st party DMA
		(good for UNIX - Novel support unknown) and is reliable.
		On board BIOS supports only 2 drives, but Adaptec driver
		will support 7.  SDI is working on adding 1540/1640 support
		to SpeedStor.

N.B.	I have cross-posted this to comp.periphs.scsi.  Hopefully, some
	of the knowledgeable people reading that group will deign to comment.


- Tim Iverson
  {decwrl,uunet}!xstor!iverson