How do SCSI drives in the 3/160 tower communicate?

[Joe Smith]

In article <1990Sep12.175832.11438 at rice.edu> AKONSTAM at TRINITY.BITNET (AARON KONSTAM) writes:
>X-Sun-Spots-Digest: Volume 9, Issue 312, message 1
> Our 3/160 has two Micropolis 1355 internal
>disks in its tower together with an Emulex controller to control them.  We
>also have a WREN VI drive in a shoebox connected directly to the SCSI
>board in the tower with a ribbon cable.
>How are the the Micropolis 1355 which are supposed to be SCSI disk drives
>getting control signals from the SCSI bus?

They don't.  The Micropolis is an ESDI disk, not a SCSI disk.

The CPU talks to the SCSI host adapter via the VME bus.  The SCSI bus goes
from the host adapter, to the Emulex card, and to the embedded SCSI
controller in the WREN.  The Emulex MD21 disk controller translates the
SCSI commands the ESDI commands that the Micropolis disks understand.

The MD21 reports to the SCSI bus that it is a single SCSI controller with
2 logical units.  The WREN disk has a SCSI controller bolted to the disk;
it is set up as a controller with a single logical unit.  (If you have an
Adaptec ACB-4000 controller, it allows ST-506 disk to be connected to the
SCSI bus.)

Joe Smith (408)922-6220 | SMTP: jms at tardis.tymnet.com or jms at gemini.tymnet.com
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