Date: Wed, 26 Aug 1998 11:18:19 +0200 (CEST) From: Wilko Bulte <wilko@yedi.iaf.nl> To: tlambert@primenet.com (Terry Lambert) Cc: joelh@gnu.org, dakott@alpha.delta.edu, hackers@FreeBSD.ORG Subject: Re: Adaptec 1542i Performance on -stable [was Re: SCSI Controller] Message-ID: <199808260918.LAA07176@yedi.iaf.nl> In-Reply-To: <199808260142.SAA00101@usr04.primenet.com> from Terry Lambert at "Aug 26, 98 01:42:28 am"
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As Terry Lambert wrote... > > > Many 1542s (particularly the B series) were very sensitive to poor > > > cabling and termination problems. > > > > I think there were also cabling sensitivities in the C series(?). > > Specifically, if you have a "B", and you enable the external SCSI > connector, you are required to attach an external SCSI terminator. On the B there is no such thing as enabling the external connector. It has resistor packs to be removed in order to use the external connector. Obviously the external connection needs termination in that case. > This goes for the 1742B, as well. There is no 1742B. Only a 174x and 174xA (x =[02] for (no)floppy interface). The 174x are all sensitive to using both internal and external cabling at the same time. For our Alphaservers we simply made that an unsupported config. In addition 174x are sensitive to which disks you use, some simply don't work, primarily the newer/faster ones. > For the "C", you can look at the SCSI connector; if there is not a pull-up > resistor soldered in as an obvious ECN afterthought, then you must use > an external terminator as well, AND you will be unable to use both > the internal and external connectors for devices, simultaneously. > > The "C" rev also broke "target mode" support; the controller will > support it, but it must have the pull-up, and the default ROMs > claim it is unsupported. Wilko _ ______________________________________________________________________ | / o / / _ Bulte email: wilko@yedi.iaf.nl |/|/ / / /( (_) Arnhem, The Netherlands WWW : http://www.tcja.nl ______________________________________________ Powered by FreeBSD __________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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