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Table 2.8 mode c serial eeprom data format, Mode c serial eeprom data format – Avago Technologies LSI53C876E User Manual

Page 69

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Serial EEPROM Interface

2-47

The format of the serial EEPROM data is defined in

Table 2.8

. If the

EEPROM is not present, or the checksum fails, the

Subsystem ID

and

Subsystem Vendor ID

registers read back all zeros. At power-up or hard

reset, only five bytes are loaded into the chip from locations 0xFB
through 0xFF.

The

Subsystem ID

and

Subsystem Vendor ID

registers are read only, in

accordance with the PCI specification, with a default value of all zeros.

Before implementing Mode C, contact LSI Logic for additional
information.

Table 2.8

Mode C Serial EEPROM Data Format

Byte

Name

Description

0x00–0xFA

UD0

User Data.

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 or hard reset.

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 or hard reset.

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 or hard reset.

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 or hard reset.

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–EOM

UD

User Data.