User guide

Overview, Continued
DSSI Bus
Function
The DSSI bus is a logical equivalent to the CI bus used on
larger Digital systems. The DSSI bus is used with low-end and
mid-range VAX systems.
The DSSI bus is a 50-conductor cable that allows one or more
hosts to communicate directly with storage devices. The hosts
and devices communicate through the SCA protocols. As many
as eight nodes (integrated storage elements and adapters) can
connect to one DSSI bus.
The DSSI bus located:
Inside an enclosure may be a flat ribbon cable or a round
bundle of twisted pairs
Between enclosures is a shielded, round cable
approximately one-half inch in diameter
ISE
An ISE is a DSSI device that contains an:
Embedded, intelligent controller
On-board Mass Storage Control Protocol (MSCP) server
Each ISE executes commands and transfers data independently
of other ISEs attached to the DSSI bus. Commands and data
are transferred over the DSSI bus in small packets, allowing
multiple ISE transfers to simultaneously complete successfully.
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