Motorola MCP750 Installation And Use Manual page 59

Functional Description
3
!
Caution
3-6
Every MCP750 is assigned an Ethernet station address. The address is
$08003E2xxxxx, where xxxxx is the unique 5-nibble number assigned to
the board (that is, every board has a different value for xxxxx).
Each MCP750 displays its Ethernet station address on a label attached to
the base board in the PMC connector "keepout" area just behind the front
panel. In addition, the six bytes including the Ethernet station address are
stored in an SROM off the DECchip Ethernet controller. That is, the value
08003E2xxxxx is stored in SROM, where xxxxx is a unique 5-nibble
number for the board.
These bytes are stored in bytes 0x4 through 0x19 in the Ethernet SROM.
The Ethernet information in the SROM is stored in DEC Version 3 format.
For further information on this subject, refer to the Digital Semiconductor
21x4 Serial ROM Format, Version 3.03 document, listed in
Related Documentation.
Use extreme caution when viewing the contents of the Ethernet SROM via
the PPCBUG SROM command. If the contents are modified incorrectly
this could cause the PPCBUG Firmware Ethernet Drivers to work
incorrectly.
Note: When the board is shipped from the factory, it should contain the
proper SROM data for the MCP750, which has 10/100 Base-T
Ethernet connections. There should not be a need to change the
SROM contents.
For the pin assignments of the 10/100 Base-T connector, refer to
4-11. Refer to the BBRAM/TOD Clock memory map description in the
MCP750 Series Single Board Computer Programmer's Reference Guide
(MCP750A/PG) for detailed programming information.
Computer Group Literature Center Web Site
Appendix B,
Table