Quantum DLTtape DLT 4000, Product Manual

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SCSI Description
3-8 Quantum DLT 4000 Tape Drive
Table 3–4 SCSI Bus Timing Values
Timing Description Value Description
Arbitration Delay 2.4 µs Minimum time a SCSI device waits from asserting BSY
for arbitration until the DATA BUS can be examined to
see if arbitration has been won; there is no maximum
time.
Assertion Period 90 ns Minimum time a drive asserts REQ while using
synchronous data transfers; also, the minimum time
that an initiator asserts ACK while using synchronous
data transfers.
Bus Clear Delay 800 ns Maximum time for a SCSI device to stop driving all
bus signals after:
1. BUS FREE is detected.
2. SEL is received from another SCSI device during
ARBITRATION.
3. Transition of RST to true.
For condition 1, the maximum time for a SCSI device
to clear the bus is 1200 ns (1.2
µ
s) from BSY and SEL
first becoming both false.
If a SCSI device requires more than a bus settle delay
to detect BUS FREE, it clears the bus within a bus clear
delay minus the excess time.
Bus Free Delay 800 ns Maximum time a SCSI device waits from its detection
of BUS FREE until its assertion of BSY when going to
ARBITRATION.
Bus Set Delay 1.8 µs Maximum time for a device to assert BSY and its SCSI
ID bit on the DATA BUS after it detects BUS FREE to
enter ARBITRATION.
Bus Settle Delay 400 ns Minimum time to wait for the bus to settle after
changing certain control signals as called out in the
protocol definitions
.
Cable Skew Delay 10 ns Maximum difference in propagation time allowed
between any two SCSI bus signals measured between
any two SCSI devices.
1 Recommended Time.