Intel PCI Circuit Control Word 21h, 20 D0 Power Word 22h high byte, 21 D3 Power Word 22h low byte

EEPROM Interface

5.6.19Circuit Control (Word 21h)

This word is loaded into the Circuit Control Register (CIRC) for setting PCI-X driver strength. See Table 5-2and Table 5-3for suggested values.

Note: PCI-X is not applicable to the 82540EP/EM, 82541xx, and 82547GI/EI.

5.6.20D0 Power (Word 22h high byte)

If the signature bits are valid and Power Management is not disabled, the value in this field is used in the PCI Power Management Data Register when the Data_Select field of the Power Management Control/Status Register (PMCSR) is set to 0 or 4. This indicates the power usage and heat dissipation of the networking function (including the Ethernet controller and any other devices managed by the Ethernet controller) in tenths of a watt. For example:

If word22h = 290E, POWER CONSUMPTION (in 1/10W, hex), then:

bits 15:8 = 29h Power in D0a, 29h = 4.1W

bits 7:0 = 0Eh Power in D3h, 0Eh = 1.4W

5.6.21D3 Power (Word 22h low byte)

If the signature bits are valid and Power Management is not disabled, the value in this field is used in the PCI Power Management Data Register when the Data_Select field of the Power Management Control/Status Register (PMCSR) is set to 3 or 7. This indicates the power usage and heat dissipation of the networking function (including the Ethernet controller and any other devices managed by the Ethernet controller) in tenths of a watt as described in Section 5.6.20.

5.6.22Reserved Words (23h - 2Eh)

Words 23h through 2Eh of the EEPROM are reserved areas for the 82541ER.

5.6.23Reserved Words (23h - 2Fh)

Words 23h through 2Fh of the EEPROM are reserved areas for the 82544GC/EI.

112 Software Developer’s Manual