Intel 31154 PCI-X Clocking Modes, Secondary Bus Frequency Initialization, PCI/PCI-X Interface

PCI/PCI-X Interface

Table 8.	PCI-X Clocking Modes
	PCI-X Mode	PCI Mode	PCIXCAP (pin on	P_M66EN
			PCI connector)
	Not capable	33 MHz	GND	GND
	Not capable	66 MHz	GND	Not connected
	PCI-X/66 MHz	33 MHz	Pull down	GND
	PCI-X/66 MHz	66 MHz	Pull down	Not connected
	PCI-X/133 MHz	33 MHz	Not connected	Ground
	PCI-X/133 MHz	66 MHz	Not connected	Not connected

Table 9.	Secondary Bus Frequency Initialization
S_M66EN		S_PCIXCAP	S_MAX100	Conventional PCI	PCI-X Frequency	Typical Slot
				Frequency		Loading1
Ground		Ground	–	33 MHz	Not capable
Not connected		Ground	–	66 MHz	Not capable
Ground		Pull-down	–	33 MHz	PCI-X 66 MHz	Typical setting for
						four slots
Not connected		Pull-down	–	66 MHz	PCI-X 66 MHz
Ground		Not connected	1	33 MHz	PCI-X 100 MHz
Not Connected		Not Connected	1	66 MHz	PCI-X 100 MHz	Typical setting for
						two slots
Ground		Not Connected	0	33 MHz	PCI-X 133 MHz
Not Connected		Not Connected	0	66 MHz	PCI-X 133 MHz	Typical setting for
						one slot
NOTE:
1. Simulation is suggested for any deviation from typical slot loading recommendations.

Intel® 31154 133 MHz PCI Bridge Design Guide Design Guide 33