sanjiv@bmers187.uucp (Sanjiv Khurana) (10/18/90)
Mac SCSI Expert Advice Needed
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Subject: how to reselect the Mac after disconnection.
The sequence of events on the SCSI bus is:
Mac gets bus
Mac selects device (ATN asserted)
Mac issues IDENTIFY message
Mac issues data transfer command
Device issues "SAVE DATA POINTERS" message
Device issues "DISCONNECT" message
<bus free, so far so good>
Device gets bus
Device attempts to reselect Mac
Mac ignores device completely
The problem is how to make the Mac respond to reselection. I can poll the
SCSI bus (using SCSIStat) but once I recognize that the device wants
to reselect, how do I tell the Mac that I want to acknowledge the
reselection? I need to assert the BSY line to acknowledge it, according
to the SCSI standard. Once that's done, the device will take over again, and
all's well.
I am working on a Mac II with the old SCSI manager and system 6.0.5.
Thanks for any advice...
If possible, please respond via e-mail to "gbrown@bnr.ca" (bitnet)
Gord Brown