JLOHMEYE at cossymwest.co.symbios.com
Thu Sep 26 08:56:00 PDT 1996
* From the SCSI Reflector (scsi at symbios.com), posted by:
* "Lohmeyer, John" <JLOHMEYE at COSSYMWEST.CO.SYMBIOS.COM>
>* From the SCSI Reflector (scsi at symbios.com), posted by:
>* Takaharu Ai <aiai at dsd.mei.co.jp>
>Does it means:
>-the SCSI-2 device can be used in the FAST-20 system
>-the negotiation of the nexus should be as FAST or slow synchronous
The SCSI-2 device should negotiate for slow synchronous. SCSI-2 does not
strictly prohibit single-ended Fast SCSI, but it recommends against it.
Some manufacturers of SCSI-2 devices read drafts of the SPI standard and
have implemented single-ended Fast SCSI (10 MegaRepetitions/Sec).
>-it does not influence the transfer rate of the other FAST-20 deviced?
Two Fast-20 (Ultra SCSI) devices on the same bus with one or more slower
devices should work okay. The Fast-20 devices should negotiate for
Fast-20 data rates when transferring between themselves. They will
negotiate slower rates with the other devices. Please note that the
Fast-20 bus rules must be met for this configuration to work. Some
manufacturers allow the system integrator to 'slow down' their Fast-20
device so it can be used on older buses -- it will then not negotiate for
a higher data rate.
John Lohmeyer E-Mail: john.lohmeyer at symbios.com
Symbios Logic Inc. Voice: 719-533-7560
4420 ArrowsWest Dr. Fax: 719-533-7036
Colo Spgs, CO 80907-3444 SCSI BBS: 719-533-7950 300--14400 baud
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