Intel E7220 LF80564QH0778M Data Sheet

Document Number: 318080-002

137

 includes the checksum values for 

each section defined in the 128 byte ROM.

Checksums are automatically calculated and programmed by Intel. The first step in 
calculating the checksum is to add each byte from the field to the next subsequent 
byte. This result is then negated to provide the checksum.

Example: For a byte string of AA445Ch, the resulting checksum will be B6h.

AA = 10101010 

44 = 01000100

5C = 0101100

AA + 44 + 5C = 01001010
Negate the sum: 10110101 +1 = 101101 (B6h)

Also available in the memory component on the processor SMBus is an EEPROM which 
may be used for other data at the system or processor vendor’s discretion. The data in 
this EEPROM, once programmed, can be write-protected by asserting the active-high 
SM_WP signal. This signal has a weak pull-down (10 kΩ) to allow the EEPROM to be 

programmed in systems with no implementation of this signal. The Scratch EEPROM 
resides in the upper half of the memory component (addresses 80 - FFh). The lower 
half comprises the Processor Information ROM (addresses 00 - 7Fh), which is 
permanently write-protected by Intel.

7:0

One Byte Checksum of the Feature Data Section

00h- FFh: See 

 for calculation of the value

Header

0Dh

Processor Data 

15h

Processor Core Data

24h

Cache Data

31h

Package Data

37h

Part Number Data 

6Fh

Thermal Ref. Data

73h

Feature Data

7Fh