Avago Technologies LSI53C895A - Manual (Page 84)

2-58 Functional Description
2.4.2 No Download Mode
When MAD7 is pulled up through an external resistor, the automatic
download is disabled and no data is automatically loaded into chip
registers at power-up. The Subsystem ID and Subsystem Vendor ID
registers are read only, per the PCI specification, with a default value of
0x1000 and 0x1000 respectively.
2.5 Alternative SSVID/SSID Loading Mechanism
Programming the PCI Subsystem ID and Subsystem Vendor ID registers
can be accomplished in the LSI53C895A without the use of a serial
EEPROM. This alternative loading mechanism is the only way to set the
SSVID/SSID registers to something other than the default value, except
through Serial EEPROM download.
Please see Section 2.4, “Serial EEPROM Interface,” for additional
information.
Table 2.8 Mode A Serial EEPROM Data Format
Byte Name Description
0xFB SVID(0) Subsystem Vendor ID , LSB. This byte is loaded into the least significant
byte of the Subsystem Vendor ID register in the appropriate PCI
configuration space at chip power-up.
0xFC SVID(1) Subsystem Vendor ID, MSB. This byte is loaded into the most significant
byte of the Subsystem Vendor ID register in the appropriate PCI
configuration space at chip power-up.
0xFD SID(0) Subsystem ID , LSB. This byte is loaded into the least significant byte of
the Subsystem ID register in the appropriate PCI configuration space at
chip power-up.
0xFE SID(1) Subsystem ID, MSB. This byte is loaded into the most significant byte of
the Subsystem ID register in the appropriate PCI configuration space at
chip power-up.
0xFF CKSUM Checksum. This 8 bit checksum is formed by adding, bytewise, each byte
contained in locations 0x00–0x03 to the seed value 0x55, and then taking
the 2’s complement of the result.
0x100–0xEOM UD User Data.