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From: jlohmeye@entec.Wichita.NCR.COM (John Lohmeyer)
Newsgroups: comp.periphs
Subject: Re: SCSI-II ID limits
Summary: Eight
Message-ID: <367@entec.Wichita.NCR.COM>
Date: 13 Jun 89 13:17:17 GMT
References: <4589@ihuxz.ATT.COM>
Reply-To: jlohmeye@entec.Wichita.NCR.COM (John Lohmeyer)
Organization: NCR, E&M Wichita - KS
Lines: 26

In article <4589@ihuxz.ATT.COM> bwf@ihuxz.ATT.COM (Fecht) writes:
>Has the SCSI-II std group decided how many hosts and targets
>I can put on the bus?  Are there any good trade articles on
>SCSI-II recently that I have missed?
>
>Thanks.
>Bill Fecht

The limit in SCSI-2 is eight.  The committee has a proposal to extend the
number of IDs to the bus width, which would mean that wide SCSI devices could
have 16 or 32 addresses available.  This has been designated a SCSI-3 proposal.
This idea works by assigning lower priority to the additional IDs than for
the first eight IDs.  Thus new and old devices can be mixed on the same bus--
old devices obviously won't know how to talk to the new ones, however.

There is a proposal which hasn't been formally submitted to the committee to
define a true 16-bit SCSI.  This would use one 68-conductor cable to support
a 16-bit data path allowing 16 devices.  The proposal is being developed by
several committee members, including myself.  I plan to write an article about
it when it is a little further along.

I've seen a few articles recently, but you would have to judge their "goodness"
by your needs.  I don't have a list of references, unfortunately.  I would
also appreciate a list of recent articles.

John Lohmeyer, Chairman X3T9.2 (SCSI)      J.Lohmeyer@Wichita.NCR.COM