Seagate Ultra 160, Ultra 320 manual Scsi bus data and information phase ST timing values

Table 5:	SCSI bus data and information phase ST timing values
				Timing values for negotiated transfer rate in
				nanoseconds unless otherwise noted [1]
Timing description		Reference	Type	Asynch	Fast-5	Fast-10	Fast-20	Fast-40
ATN transmit setup time		2.5.2	min	90	33	33	21.5	19.25
ATN receive setup time		2.5.3	min	45	17	17	8.5	6.75
Cable skew [2]		2.5.8	max	4.0	4.0	4.0	3.0	2.5
Receive assertion period [3]		2.5.30	min	N/A	70	22	11	6.5
Receive hold time [3] [4]		2.5.31	min	N/A	25	25	11.5	4.75
Receive negation period [3]		2.5.34	min	N/A	70	22	11	6.5
Receive setup time [3] [4]		2.5.35	min	N/A	15	15	6.5	4.75
Receive REQ(ACK) period tolerance		2.5.36	min	N/A	1.1	1.1	1.1	1.1
Signal timing skew		2.5.48	max	8.0	8.0	8.0	5.0	4.5
REQ(ACK) period		2.5.41	nom	N/A	200	100	50	25
Transmit assertion period [2]		2.5.55	min	N/A	80	30	15	8.0
Transmit hold time [3] [4]		2.5.56	min	N/A	53	33	16.5	9.25
Transmit negation period [3]		2.5.58	min	N/A	80	30	15	8.0
Transmit setup time [3] [4]		2.5.59	min	N/A	23	23	11.5	9.25
Transmit REQ(ACK) period tolerance		2.5.60	max	N/A	1.0	1.0	1.0	1.0

[1]SCSI bus timing values specified by the maximum transfer rate for the given range shall apply even if a slower transfer rate within the given range is negotiated.

[2]Cable skew is measured at each SCSI device connection within the same bus segment with the transmit- ted skew subtracted from the received skew.

[3]See Section 2.6 for measurement points for the timing specifications.

[4]See Section 9.6 in the ANSI SCSI Parallel Interface-5 (SPI-5) specification for examples of how to calcu- late setup and hold timing.

Table 6:	Miscellaneous SCSI bus data and information phase DT timing values
				Timing values for negotiated transfer rate in nanoseconds
				unless otherwise noted [1]
Timing description		Reference	Type	Fast-10	Fast-20	Fast-40	Fast-80	Fast-160	Fast-320
Cable skew [2]		2.5.8	max	4.0	3.0	2.5	2.5	2.5	2.5
REQ(ACK) period		2.5.41	nom	200	100	50	25	12.5	6.25
Residual skew error [3]		2.5.45	max	N/A	N/A	N/A	N/A	±0.15	± 0.20
Skew correction range [4]		2.5.49	min	N/A	N/A	N/A	N/A	±3.45 [5]	± 3.45 [5]
Signal timing skew		2.5.48	max	26.8	13.4	6.7	3.35	4.85	4.85
Strobe offset tolerance		2.5.50	max	N/A	N/A	N/A	N/A	±0.125	±0.125

[1]SCSI bus timing values specified by the maximum transfer rate for the given range shall apply even if a slower transfer rate within the given range is negotiated.

Parallel SCSI Interface Product Manual, Rev. A ) 21