82 Datasheet
System Management Feature Specifications
6.2 Processor Information ROM
An electrically programmed read-only memory (ROM) provides information about the Itanium 2
processor. The checksum bits for each category provide error correction and serve as a mechanism
to check whether data is corrupted or not. This information is permanently write-protected.
Table 6-4 shows the data fields and formats provided in the memory.
Note: The data, in byte format, is written and read serially with the most significant bit first.
Table 6-3. EEPROM SMBus Addressing on the Itanium
®
2 Processor
Address
(Hex)
Upper
Address
1
NOTES:
1. Though this addressing scheme is targeted for up to four-way MP systems, more processors can be supported by using a
multiplexed (or separate) SMBus implementation.
Processor Select
Memory
Device
Select
Read/
Write
Device Addressed
Bits 7–4
(SMA1)
Bit 3
(SMA0)
Bit 2
Bit 1 Bit 0
A0h/A1h 1010 0 0 0 X Scratch EEPROM 1
A2h/A3h 1010 0 0 1 X Processor Information ROM 1
A4h/A5h 1010 0 1 0 X Scratch EEPROM 2
A6h/A7h 1010 0 1 1 X Processor Information ROM 2
A8h/A9h 1010 1 0 0 X Scratch EEPROM 3
AAh/ABh 1010 1 0 1 X Processor Information ROM 3
ACh/ADh 1010 1 1 0 X Scratch EEPROM 4
AEh/AFh 1010 1 1 1 X Processor Information ROM 4
Table 6-4. Processor Information ROM Format (Sheet 1 of 4)
Offset/
Section
# of
Bits
Function Notes Examples
Header
00h 8 Data Format Revision Two 4-bit hex digits Start with 00h
01h 16 EEPROM Size Size in bytes (MSB first) Use a decimal to hex
transfer; 128 bytes =
0080h:
• 02h[7:4] = 0000
• 02h[3:0] = 0000
• 01h[7:4] = 1000
• 01h[3:0] = 0000
03h 8 Processor Data Address Byte pointer, 00h if not present 0Eh
04h 8 Processor Core Address Byte pointer, 00h if not present 17h
05h 8 Processor Cache Address Byte pointer, 00h if not present 28h
06h 8 Processor Data Address Byte pointer, 00h if not present 37h
07h 8 Part Number Data Address Byte pointer, 00h if not present 3Eh
08h 8 Thermal Reference Data
Address
Byte pointer, 00h if not present 63h
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