Seagate Ultra 160, Ultra 320 manual Transfer period factor relationships, Synchronous

2.12.5Transfer period factor

The Transfer Period Factor field selects the transfer period and determines which transfer rate’s timing values in Tables 5, 6, 7, and 8 shall be honored, provided that REQ/ACK OFFSET is greater than 00h. The field val- ues are defined in Table 14.

Table 14: Transfer period factor

Value	Description	Message	Transfer rate
00h - 06h	Reserved	N/A	N/A
07h	Transfer period equals 3.125 ns	PPR	Fast-320
08h	Transfer period equals 6.25 ns	PPR	Fast-160
09h	Transfer period equals 12.5 ns	PPR	Fast-80
0Ah	Transfer period equals 25 ns	PPR, SDTR	Fast-40
0Bh	Transfer period equals 30.3 ns	PPR, SDTR	Fast-40
0Ch	Transfer period equals 50 ns	PPR, SDTR	Fast-20
0Dh - 18h	Transfer period equals the TRANSFER PERIOD FACTOR x 4	PPR, SDTR	Fast-20
19h - 31h	Transfer period equals the TRANSFER PERIOD FACTOR x 4	PPR, SDTR	Fast-10
32h - FFh	Transfer period equals the TRANSFER PERIOD FACTOR x 4	PPR, SDTR	Fast-5

Table 15 shows which transfer period factors may be used with different types of transfer agreements, provided REQ/ACK OFFSET is greater than 00h.

Table 15:	Transfer period factor relationships
			Transfer agreement
Value
	Synchronous	Paced	Data group		Information	ST data	DT data
					unit
00h - 06h				Reserved
07h - 08h	NS	M	NS		M	NS	M
09h	M	NS	O		O	NS	M
0Ah	M	NS	O		O	O	O
0Bh	M	NS	O		O	O	O
0Ch	M	NS	O		O	O	O
0Dh - 18h	M	NS	O		O	O	O
19h - 31h	M	NS	O		O	O	O
32h - FFh	M	NS	O		O	O	O

Table abbreviations are defined as follows:

M = Mandatory: Support for the indicated transfer agreement shall be implemented if the indicated transfer period factor is implemented.

O = Optional: Support for the indicated transfer agreement may be implemented if the indicated transfer period factor is implemented.

NS = Not Supported: The indicated transfer agreement shall not be allowed if the indicated transfer factor is selected.

Table 20 defines valid combinations of TRANSFER PERIOD FACTOR and other fields.

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