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From: guyd@austin.ibm.com (Guy Dawson)
Subject: Re: A question about Adaptec 1542B/C (FAQ?)
Originator: guyd@pal501.austin.ibm.com
Sender: news@austin.ibm.com (News id)
Message-ID: <CAxn12.3J6D@austin.ibm.com>
Date: Thu, 29 Jul 1993 15:29:25 GMT
Distribution: inet
References: <235na7$gi@sauna.cs.hut.fi>
Organization: IBM Austin
Lines: 61
In article <235na7$gi@sauna.cs.hut.fi>, vendu@judge-dredd.cs.hut.fi (Tuomo Venalainen) writes:
> I'm sorry, if this is a FAQ...
>
> It looks like my old ESDI drive passed away. I'm going for SCSI. The
> question is, what are the differences between 1542B & 1542C? I could get
> 1542B for a reasonable price. Do you think I'm going to be happy with it?
The main difference is that the C is configured via s/w. The only jumpers
( DIP switch actually ) are to set the BIOS address and determine whether
the external SCSI port is always terminated or termination is controlled
in the config s/w. The C is also a little faster, has built in DOS support
for 7 disks and disks >1GB.
[ ROM V3.20 for the B support disk bigger than 1GB under DOS ]
The interface to the adaptor ( when bypassing the BIOS ) has a small change,
the mail box data structures used to communicate with the card need to be
set up earlier than is needed for the B. All the ???BSD systems & Linux
have been updated for this.
Early Cs have problems with sub-standard external cables - sub SCSI-2 spec that
is. The cables impedance is too low and this confuses the card. Later cards
have two resistors ( might be resistor & capacitor ) and three wires on the
non-component side - one wire connected to a pin on the external connector.
This slows down that line and gives the card a change to stabilise the
signals on the other bus lines.
I have a B and a C. I'm very happy with them. Until last night I considered
the C's s/w configuration 'nice'. Then I ran into a disk that cuased me no
end of grief. It was on the end of the external bus but would not work
unless the terminators were removed. I, of course, did not know this. Having
the configuration in s/w ment I could try lots of options very quickly...
If you can get the B at a good discount from the C, go for it. It's still a
good card...
>
> BTW, my box isn't connected to any network (at least not now), so I don't
> think I'll have to worry about NFS or anything in the near future.
>
> Another alternative would be a Buslogic SCSI adapter (don't know the model,
> sorry). It's claimed to be 100 % compatible with Adaptec's ASPI. Does any-
> one have experiences with their boards? I think I'd be able to try it and
> change it to 1542B/C in case I don't like it. Somehow, I think I should get
> a real Adaptec...
No experience with Buslogic so no comment!
>
> Thanks a lot in advance.
>
> Vendu
> vendu@niksula.cs.hut.fi
Guy
--
-- -----------------------------------------------------------------------------
Guy Dawson - Hoskyns Group Plc.
guyd@hoskyns.co.uk Tel Hoskyns UK - 71 251 2128
guyd@austin.ibm.com Tel IBM Austin USA - 512 838 2334