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SCSI Description
Quantum DLT 7000 Tape System 3-9
Table 3–4 SCSI Bus Timing Values (continued)
Timing Description Value Description
Hold Time 45 ns Minimum time added between the assertion of REQ
or ACK and changing the data lines to provide hold
time in the initiator or drive while using standard
(slow) synchronous data transfers.
Negation Period 90 ns Minimum time that a drive negates REQ while using
synchronous data transfers; also, the minimum time
than an initiator negates ACK while using
synchronous data transfers.
1
Power-On to
Selection
10 s
1
Recommended maximum time from power
application until a drive is able to respond with
appropriate status and sense data to the TEST UNIT
READY, INQUIRY, and REQUEST SENSE commands.
Reset to Selection
Time
250
ms
1
Recommended maximum time after a hard RESET
condition until a drive is able to respond with
appropriate status and sense data to the TEST UNIT
READY, INQUIRY, and REQUEST SENSE commands.
Reset Hold Time 25 µs Minimum time for which RST is asserted; there is no
maximum time.
Selection Abort Time 200 µs Maximum time that a drive (or initiator) takes from its
most recent detection of being selected (or
reselected) until asserting a BSY response.
Selection Time-Out
Delay
250
ms
1
Recommended minimum time a SCSI device should
wait for a BSY response during SELECTION or
RESELECTION before starting the time-out procedure.
Transfer Period
2
Minimum time allowed between the leading edges of
successive REQ pulses and of successive ACK pulses
while using standard or fast synchronous data
transfers. The period range is 200 to 500ns minimum,
standard, or 100 to 500ns minimum, fast-
synchronous.
1
Recommended Time.
2
Set during an SDTR message.