Intel PCI-X, Intel Gigabit Ethernet Controllers manual Eeprom Device and Interface

				EEPROM Interface
Table 5-1. Component Identification
	Stepping	Vendor ID	Device ID	Description
	82541GI-B1	8086h	1076h	Cooper
	82541GI-B1	8086h	1077h	Mobile
	82541PI-C0	8086h	1076h	Cooper
	82541ER-C0	8086h	1078h	Cooper
	82540EP-A	8086h	1017	Desktop
	82540EP-A	8086h	1016	Mobile
	82540EM-A	8086h	100E	Desktop
	82540EM-A	8086h	1015	Mobile

Note: These Ethernet controllers also provide identification data through the Test Access Port (TAP).

5.3EEPROM Device and Interface

The EEPROM access algorithm, programmed into the Ethernet controller, is compatible with most, but not all, commerically available 3.3 V dc Microwire* interfaces and serial EEPROM devices with a 1 MHz speed rating. Ethernet controllers are compatible with two sizes of 4-wire serial EEPROM devices1. If ASF mode functionality is desired, a 4096-bit serial NM93C66 compatible EEPROM can be used. Otherwise, a 1024-bit serial NM93C46 compatible EEPROM can be used. Both EEPROMs are accessed in 16-bit words; the larger has 256 words while the smaller has 64 words. Refer to the appropriate Ethernet controller’s design guide for recommended EEPROM manufacturers.

An Ethernet controller automatically determines which EEPROM it is connected to and sets the EEPROM SIZE field of the EEPROM/FLASH Control and Data Register (EEC.EE_SIZE) field appropriately. Software can use this field to determine how to access the EEPROM using direct access. Note that different EEPROM sizes have different numbers of address bits and therefore must be accessed with a slightly different serial protocol. Software must be aware of this if it accesses the EEPROM using direct access.

1.The 82544GC/EI only supports one size of EEPROM. Refer to the 82544GC Gigabit Ethernet Controller Datasheet and Hardware Design Guide (AP-427) for more information.

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