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Table 5:
SCSI bus data and information phase ST timing values
Timing description
ATN transmit setup time
ATN receive setup time
Cable skew
[2]
Receive assertion period
[3]
Receive hold time
[3] [4]
Receive negation period
[3]
Receive setup time
[3] [4]
Receive REQ(ACK) period tolerance
Signal timing skew
REQ(ACK) period
Transmit assertion period
Transmit hold time
[3] [4]
Transmit negation period
[3]
Transmit setup time
[3] [4]
Transmit REQ(ACK) period tolerance
SCSI bus timing values specified by the maximum transfer rate for the given range shall apply even if a
[1]
slower transfer rate within the given range is negotiated.
Cable skew is measured at each SCSI device connection within the same bus segment with the transmit-
[2]
ted skew subtracted from the received skew.
See Section 2.6 for measurement points for the timing specifications.
[3]
See Section 9.6 in the ANSI SCSI Parallel Interface-5 (SPI-5) specification for examples of how to calcu-
[4]
late setup and hold timing.
Table 6:
Miscellaneous SCSI bus data and information phase DT timing values
Timing description
Cable skew
[2]
REQ(ACK) period
Residual skew error
[3]
Skew correction range
[4]
Signal timing skew
Strobe offset tolerance
SCSI bus timing values specified by the maximum transfer rate for the given range shall apply even if a
[1]
slower transfer rate within the given range is negotiated.
Parallel SCSI Interface Product Manual, Rev. A )
Reference
2.5.2
2.5.3
2.5.8
2.5.30
2.5.31
2.5.34
2.5.35
2.5.36
2.5.48
2.5.41
2.5.55
[2]
2.5.56
2.5.58
2.5.59
2.5.60
Reference
Type
2.5.8
max
2.5.41
nom
2.5.45
max
2.5.49
min
2.5.48
max
2.5.50
max
Timing values for negotiated transfer rate in
nanoseconds unless otherwise noted
Type
Asynch
min
90
min
45
max
4.0
min
N/A
min
N/A
min
N/A
min
N/A
min
N/A
max
8.0
nom
N/A
min
N/A
min
N/A
min
N/A
min
N/A
max
N/A
Timing values for negotiated transfer rate in nanoseconds
unless otherwise noted
[1]
Fast-10
Fast-20
Fast-40 Fast-80
4.0
3.0
2.5
200
100
50
N/A
N/A
N/A
N/A
N/A
N/A
26.8
13.4
6.7
N/A
N/A
N/A
Fast-5
Fast-10
Fast-20 Fast-40
33
33
21.5
17
17
8.5
4.0
4.0
3.0
70
22
11
25
25
11.5
70
22
11
15
15
6.5
1.1
1.1
1.1
8.0
8.0
5.0
200
100
50
80
30
15
53
33
16.5
80
30
15
23
23
11.5
1.0
1.0
1.0
Fast-160
2.5
2.5
25
12.5
N/A
±
0.15
N/A
±
3.45
[5]
3.35
4.85
N/A
±
0.125
[1]
19.25
6.75
2.5
6.5
4.75
6.5
4.75
1.1
4.5
25
8.0
9.25
8.0
9.25
1.0
Fast-320
2.5
6.25
±
0.20
±
3.45
[5]
4.85
±
0.125
21
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