Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!talgras!david
From: david@talgras.UUCP (David Hoopes)
Newsgroups: comp.periphs.scsi
Subject: Re: Always IN-2000 SCSI host adapter (the real story)
Keywords: Always SCSI disk drive controller host adapter
Message-ID: <90@talgras.UUCP>
Date: 7 Jun 91 15:46:30 GMT
References: <1991Jun06.204457.28453@xstor.com>
Reply-To: david@talgras.UUCP (David Hoopes)
Distribution: usa
Organization: Tallgrass Technologies Inc.
Lines: 63

In article <1991Jun06.204457.28453@xstor.com> iverson@xstor.com writes:
>
>Recently, it has come to my attention that the current BIOS in the Always
>IN-2000 SCSI host adapter no longer disables interrupts during transfers.
>And, despite other problems, seems to be marginally useful as a host
>adapter for a DOS only system.
>
> [ stuff deleted ]
>
>
>There are some problems: first, the board uses the WD33C93A SCSI chip.
>According to the opinion of others here more experienced with protocol
>chips, this is "not a good chip" (stated slightly more colorfully :-).

What is wrong with this chip.  Does it not work right?  Is it hard to
write drivers for?  Is it the wrong color?  We use this chip on some of
our scsi hardware and I have not heard of any trouble with them.

>
>The second problem is much greater: the external connector is not an
>accepted SCSI-1 or SCSI-2 connector.  It is a 25 pin Macintosh connector.

I am sure that someone will correct me if I am wrong, but I think that the
Macintosh style conector is an accepted SCSI-1 (I don't know about SCSI-2)
connector.  The way I understand it there are two types of conectors that
are covered in the spec.

>This isn't so bad until you realize that the 25 pin SCSI connectors usually
>used for the PC have term power and ground swapped w.r.t. the Mac cable.
>Connect the wrong cable by accident (perhaps by asking a different supplier
>for a 25 pin SCSI cable for your *PC*), and you could short-out something
>important, like your drive or your host adapter.
>

This I think is wrong.  I have taken the same drive with cable attached
and moved it from a Mac to my pc.  In fact that I why we choose to use
that conector on our SCSI host adapter, so that are tape drives could
be used on both PCs and Macs with the same cable.

Personally I like this conector better then the 50 pin conector.  The
little clips on the 50 pin conectors have a bad habit of wigeling loose.
That's a problem I have never had with the 25 pin conectors because they
have screws to hold them in place.


>
>Combine their average performance with poor integration and the sneaky
>interrupt disabling trick used in a previous BIOS, and I would call this the
>"Never IN-2000" instead of the "Always IN-2000".
>
>
>- Tim Iverson
>  iverson@xstor.com -/- uunet!xstor!iverson

I don't know anything about the Always IN-2000 and I am not defending it.  I
just question some of your arguments.


-- 
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David Hoopes                              Tallgrass Technologies Inc. 
uunet!talgras!david                       11100 W 82nd St.          
Voice: (913) 492-6002 x323                Lenexa, Ks  66214