Date: Sun, 03 Nov 1996 23:06:19 -0700 From: Steve Passe <smp@csn.net> To: garycorc@mail.idt.net Cc: "Jordan K. Hubbard" <jkh@time.cdrom.com>, hardware@FreeBSD.org Subject: Re: OK, what's the deal with 2940W controllers and internal connectors? Message-ID: <199611040606.XAA01903@clem.systemsix.com> In-Reply-To: Your message of "Mon, 04 Nov 1996 00:46:03 EST." <327D831B.1D0D@mail.idt.net>
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Hi, > > use any 2 of the 3, both internal is fine as long as you don't use the > > external. As to termination, the card is at the end if using > > 1 cable (and thus should be terminated) and is in the middle if using > > 2 cables (any commbination) and should NOT be terminated. > > That explains it. Using one connector, the card terminates one end > of the SCSI cable. Using any two of the connectors, the card is > in the "middle" of the SCSI bus. But if you were to try to use > all three connectors, then you *would* have a "Y" cable situation, > which I'm sure would lead to all sorts of nasty reflections on > the bus (in certain/most cases at least). with the detail (for case of card in middle) stated by Justin: > with the controller termination set to high byte on, low byte off. this for the common case where you have wide devices on one cable and narrow on the other. If you used wide devices on both int/ext wide connectors both high/low would be off on the card. It is nothing more than another SCSI device, but one which happens to have 3 physical connectors for convenience. Electrically the 3 are one connector, just like any other SCSI device has. Think of them as the equivalant of the cable in an external SCSI cabinet. -- Steve Passe | powered by smp@csn.net | FreeBSD -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6.2 mQCNAzHe7tEAAAEEAM274wAEEdP+grIrV6UtBt54FB5ufifFRA5ujzflrvlF8aoE 04it5BsUPFi3jJLfvOQeydbegexspPXL6kUejYt2OeptHuroIVW5+y2M2naTwqtX WVGeBP6s2q/fPPAS+g+sNZCpVBTbuinKa/C4Q6HJ++M9AyzIq5EuvO0a8Rr9AAUR tBlTdGV2ZSBQYXNzZSA8c21wQGNzbi5uZXQ+ =ds99 -----END PGP PUBLIC KEY BLOCK-----
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