Appendix (82540EP/EM and 82545GM/EM Differences)

Note: Though the 82540EP/EM supports devices with up to 512 KB of memory, smaller devices may also be used. Accesses to memory beyond the FLASH device size results in access wrapping as only the lower address bits are utilized by the FLASH.

The 82540EP/EM does not provide an interface for performing an “Erase” operation to the serial Flash device. Flash write operations must be performed to an initialized or pre-erased Flash device. If in-circuit erase is required, an external source (such as hardware's software-definable pins) can be used to drive the Flash pins to perform the erase operation.

B.2.2 No TBI/Internal SerDes Interface

The 82540EP/EM does not support a TBI/internal Serdes interface. As a result, all TBI/internal SerDes-related registers (for example, RXCW) should not be used.

B.2.3 Single-Port Functionality

The 82540EP/EM and the 82545GM/EM do not have the dual-port functionality of the 82546GB/EB. As a result, the 82540EP/EM and the 82545GM/EM appear as single PCI bus devices.

B.2.4 32-Bit PCI Support

No developer impact.

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Software Developer’s Manual

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Intel PCI-X manual No TBI/Internal SerDes Interface, Single-Port Functionality, 4 32-Bit PCI Support