Seagate Ultra 160 ユーザーズマニュアル
20
Parallel SCSI Interface Product Manual, Rev. A )
2.5
SCSI bus timing
Unless otherwise indicated, the delay time measurements for each SCSI device, defined in paragraphs 2.5.1
through 2.5.60 shall be calculated from signal conditions existing at that SCSI device’s own SCSI bus connec-
tion. Thus, these measurements (except skew delay) can be made without considering delays in the cable.
Refer to the tables below for the actual timing values for these delays.
through 2.5.60 shall be calculated from signal conditions existing at that SCSI device’s own SCSI bus connec-
tion. Thus, these measurements (except skew delay) can be made without considering delays in the cable.
Refer to the tables below for the actual timing values for these delays.
Table 4:
SCSI bus control timing values in nanoseconds
[1]
Cable skew is measured at each SCSI device connection with the transmitted skew subtracted from the
received skew.
received skew.
[2]
This is a recommended time. It is not mandatory.
Timing description
Reference
Type
Timing
value (ns
unless
noted)
Arbitration delay
minimum
2.4 µs
Bus clear delay
maximum
800
Bus free delay
minimum
800
Bus set delay
maximum
1.6 µs
Bus settle delay
minimum
400
Cable skew
maximum
4
Data release delay
maximum
400
DIFFSENS voltage filter time
minimum
100 ms
Physical disconnection delay
minimum
200 µs
Power on to selection
maximum
10 s
QAS arbitration delay
minimum
1000
QAS assertion delay
maximum
200
QAS release delay
maximum
200
QAS non-data phase REQ(ACK) period
minimum
50
Reset delay
minimum
200
Reset hold time
minimum
25 µs
Reset to selection
maximum
250 ms
Selection abort time
maximum
200 µs
Selection time-out delay
minimum
250 ms
System deskew delay
minimum
45