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Intel
®
413808 and 413812 I/O Controllers in TPER Mode
October 2007
Developer’s Manual
Order Number: 317805-001US
133
Address Translation Unit (PCI-X)—Intel
®
413808 and 413812
2.12.5
External Clock Driver (CR_FREQ[1:0])
When the internal PCI Clock outputs are not sufficient, an external clock driver can be
used to supply additional PCI Clocks. To facilitate the use of an external driver, the
CR_FREQ[1:0]
pins are driven based on the settings in the PCI-X capability field (bits
19:16) in the
“PCI Configuration and Status Register - PCSR”
. These output pins can be
connected to a PCI-X clock driver to select the desired bus frequency.
Table 22. CR_FREQ[1:0] Encoding
PCSR[19:16]
(PCIX Init
Pattern)
PCSR[10]
(P_M66EN)
CR_FREQ[1:0]
Bus Frequency
Bus Mode
1111
0
11
33 MHz
Conventional PCI
1111
1
10
66 MHz
Conventional PCI
1110
-
10
66 MHz
PCI-X
1101
-
01
100 MHz
PCI-X
1100
-
00
133 MHz
PCI-X