149
STP2002QFP
Fast Ethernet, Parallel Port, SCSI (FEPS) - STP2002QFP
Sun Microsystems,
operation. After power-on, the D_ADDR register does not get self initialized.
Even software reset to SCSI CE does not initialize the D_ADDR register. At
such a time, or in a case where the previous transfer was started at an odd ad-
dress, the D_ADDR register may contain an odd number (if the previous
transfer was at an odd address, D_ADDR will contain an odd number for
sure).
When the D_ADDR register has an odd number, and D_BCNT register is
written to with a value of 1, a wrong byte could go out on the SCSI bus if this
was a SCSI write operation.
Work Around:
Make sure that the address register contains a value of 0, when D_BCNT is
being written. Suggested work around is to write 0 to D_ADDR register every
time a software reset is issued to SCSI CE, and then write D_BCNT before
writing to D_ADDR register.
9.1.2 FAS366 Core
9.1.2.1 Premature Deassertion of ATN
In message-out phase, the FAS366 deasserts the ATN signal in the middle of
the message out phase. The deassertion comes after the first byte of the mes-
sage is sent out on the SCSI bus. This problem shows up intermittently.
Work Around:
Use PIOs to the FAS366 while writing the message bytes of the message-out
phase to the FAS366.
9.1.2.2 Pre-Mature Assertion of ATN
The FAS366 asserts ATN in the middle of the data-in phase. This happens
when a set ATN command is stacked while the FAS366 is data-in phase.
Work Around:
Don’t stack set ATN command.
9.1.2.3 Mismatch Between the Number of REQs and ACKs on the SCSI Bus,
After External Bus Reset
After an external reset (SCSI bus reset) has been applied to the FAS366,
sometimes the number of REQs and ACKs in a request sense command do
not match. This causes the SCSI channel to hang.