Seagate Ultra 160 - Manual (Page 34)

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.
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.
[2]
This is a recommended time. It is not mandatory.
Timing description
Reference Type
Timing
value (ns
unless
noted)
Arbitration delay 2.5.1 minimum 2.4 µs
Bus clear delay 2.5.4 maximum 800
Bus free delay 2.5.5 minimum 800
Bus set delay 2.5.6 maximum 1.6 µs
Bus settle delay
2.5.7 minimum 400
Cable skew [1]
2.5.8 maximum 4
Data release delay 2.5.21 maximum 400
DIFFSENS voltage filter time 2.5.22 minimum 100 ms
Physical disconnection delay 2.5.24 minimum 200 µs
Power on to selection [2]
2.5.25 maximum 10 s
QAS arbitration delay 2.5.26 minimum 1000
QAS assertion delay 2.5.27 maximum 200
QAS release delay 2.5.28 maximum 200
QAS non-data phase REQ(ACK) period 2.5.29 minimum 50
Reset delay 2.5.42 minimum 200
Reset hold time 2.5.43 minimum 25 µs
Reset to selection [2]
2.5.44 maximum 250 ms
Selection abort time
2.5.46 maximum 200 µs
Selection time-out delay [2]
2.5.47 minimum 250 ms
System deskew delay 2.5.51 minimum 45