Asus PCI-DA2200, Руководство пользователя

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Appendix D
187
ASUS PCI-DA2100/PCI-DA2200 User’s Manual
Appendix D Sync. Clock Period/Frequency
Changes to the SCSI Synchronous Clock Period of each SCSI target is
a low-level control of the SCSI controller chip. There is no other
selectable option. Only the Synchronous Clock Period is available in
this field.
To calculate the Synchronous Clock Period, refer to the “Sample
equation” to get the correct Synchronous Clock Period.
Sample equation:
In this example,
where “20.8Mhz”
is called the
Synchronous
Clock Frequency,
and “12” is called
the Synchronous
Clock Period.
Synchronous
Clock Period
Synchronous
Clock
Frequency
Synchronous
Clock Period
Synchronous
Clock
Frequency
10* 40 62 4.0
11* 30 75 3.3
12* 20 88 2.8
15 16.6 100 2.5
18 13.8 110 2.2
25 10.0 120 2.0
31 8.0 135 1.8
37 6.7 0 Asynchronous
43 5.8
50 5.0
∗ These three clock periods aren’t in accordance with the sample
equation; they are specially defined in the SCSI-3 specification.
Mhz
ns
ns Mhz
8 . 20
10 4 12
1
4 12
1
12
10 4 10 8 . 20
1
4 8 . 20
1
9
9 6
=
× ×
=
×
=
× × ×
=
×
−
−