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SCSI BUS
7-16 C156-E228-02EN
Table 7.7 Timing specifications (2 of 3)
No. Name Standard Timing specification
6 Bus Settle Delay 400 ns min. Minimum wait period between the time a particular
control signal condition changes and the time the bus
condition is stabilized.
7 Cable Skew Delay 3 ns max. Maximum allowable difference in transmission time
over the interface cable between any two bus signals
from any two SCSI devices.
8 Data release Delay 400 ns max. Maximum allowable period between the time an I/O
signal changes its status from false to true and the time
the INIT stops driving data bus signals.
9 Deskew Delay 15 ns min. Time for compensation for skew involved in bus signal
transmission.
10 Hold Time 16.5 ns min. In synchronous data transfer mode, the minimum time
during which the transfer data on the DATA BUS from
the leading edge of the REQ or ACK signal pulse must
be maintained to compensate for the hold time in the
SCSI device receiving data.
11 Negation Period 15 ns min. In synchronous data transfer mode, the minimum time
from the trailing edge of an REQ signal to the leading
edge of the next REQ signal, or from the trailing edge of
an ACK signal to the leading edge of the next ACK
signal.
12 Power-On to
Selection Time
10 sec max. Maximum time from when the TARG is turned on to the
time the TARG can post the correct status and sense data
for the TEST UNIT READY, INQUIRY or REQUEST
SENSE command.
13 Reset to Selection
Time
250 ms max. Maximum time from when the RESET condition (hard
RESET) is released to the time the TARG can post the
correct status and sense data for the TEST UNIT
READY, INQUIRY or REQUEST SENSE command.
14 Reset Hold Time 25µs min. The minimum time during which the RST signal must
be held true to create a RESET condition. A maximum
time is not defined.
15 Selection Abort
Time
200µs max. In a SELECTION or RESELECTION phase, the
maximum allowable period between the time the SCSI
device recognizes itself as selected and the time it
replies with a BSY signal.
16 Selection Timeout
Delay
250 ms min.
[Recommended
value]
In a SELECTION or RESELECTION phase, the
minimum time during which the INIT or TARG waits
for a BSY signal from the SCSI device to be selected
before it initiates timeout processing.