The Serial EEPROM

@xbox

Published in 

xbox

 · 20 Feb 2024

written by Michael Steil, 26 June 2002

The Xbox stores some permanent information such as the serial number, the HD key and the region code in a 256 byte serial EEPROM accessible through the SMBus as device 0x54. Accessing the EEPROM data is quite straightforward: The address of the value is passed as the SMBus command, and the data (either 8 or 16 bits wide) as the SMbus data.

Two routines that read bytes from and write bytes to the serial EEPROM and do no error handling are shown below:

void EepromWrite8(unsigned char address, unsigned char value) { 
    SMBusWriteCommand(0x54, address, false, value); 
} 

void EepromRead8(unsigned char address, unsigned char value) { 
    SMBusReadCommand(0x54, address, false, &value;); 
}