Seagate Ultra 320 - Manual (Page 41)

Parallel SCSI Interface Product Manual, Rev. A ) 27
When information unit transfers are being used with synchronous transfers, the ATN receive setup time is the
minimum time required at the receiver between the assertion of the ATN signal and the negation of the ACK
signal corresponding to the last iuCRC transfer of an information unit to recognize the assertion of an attention
condition.
When information unit transfers are being used with paced transfers, the ATN receive setup time is the mini-
mum time required at the receiver between the assertion of the ATN signal and the assertion of the ACK signal
corresponding to the last iuCRC transfer of an information unit to recognize the assertion of an attention condi-
tion.
2.5.4 Bus clear delay
The maximum time for a SCSI device to stop driving all bus signals after:
1. The BUS FREE phase is detected (i.e., the BSY and SEL signals are both false for a bus settle delay).
2. The SEL signal is received from another SCSI device during the ARBITRATION phase.
3. The transition of the RST signal to true.
For item 1 above, the maximum time for a SCSI device to release all SCSI bus signals is 1200 ns from the BSY
and SEL signals first becoming both false. If a SCSI device requires more than a bus settle delay to detect
BUS FREE phase, it shall release all SCSI bus signals within a bus clear delay minus the excess time.
2.5.5 Bus free delay
The minimum time that a SCSI device shall wait from its detection of the BUS FREE phase (i.e., BSY and SEL
both false for a bus settle delay) until its assertion of the BSY signal in preparation for entering the ARBITRA-
TION phase.
2.5.6 Bus set delay
The maximum time for a SCSI device to assert the BSY signal and its SCSI ID after it detects a BUS FREE
phase for the purpose of entering the ARBITRATION phase.
2.5.7 Bus settle delay
The minimum time to wait for the bus to settle after changing certain control signals as specified in the protocol
definitions. Provides time for a signal transition to propagate from the driver to the terminator and back to the
driver.
2.5.8 Cable skew delay
The maximum difference in propagation time allowed between any two SCSI bus signals when measured
between any two SCSI devices excluding any signal distortion skew delays.
2.5.9 Chip noise in receiver
The maximum transition to transition time shift due to the internal physics of the receiving SCSI device circuitry.
2.5.10 Clock jitter
The maximum transition to transition time shift of SCSI bus signals caused by short term variations in the trans-
mitting SCSI device’s clock.
2.5.11 Crosstalk time shift
The peak-to-peak timeshift error on DB(0-15), P_CRCA, or DB(P1) caused by transitions on all other DB(0-
15), P_CRCA, or DB(P1) signals.