82374EB Datasheet, PDF (94/208 Pages) Intel Corporation – SYSTEM COMPONENT (ESC)

82374EB 82374SB
3 7 3 APICID I O APIC IDENTIFICATION REGISTER
Address Offset
Default Value
Attribute
Size
00h
00h
Read Write
32 Bits
This register contains the unit’s 4-bit APIC ID The ID serves as a physical name of the I O APIC Unit All APIC
units using the APIC bus should have a unique APIC ID The APIC bus arbitration ID for the I O unit is also
writtten during a write to the APICID Register (same data is loaded into both) This register must be pro-
grammed with the correct ID value before using the I O APIC unit for message transmission
Bit
Description
31 28 Reserved
27 24 I O APIC Identification This 4-bit field contains the I O APIC identification
23 0 Reserved
3 7 4 APICID I O APIC IDENTIFICATION REGISTER
Address Offset
Default Value
Attribute
Size
01h
00h
Read Only
32 Bits
The I O APIC Version Register identifies the APIC hardware version Software can use this to provide compati-
bility between different APIC implementations and their versions In addition this register provides the maxi-
mum number of entries in the I O Redirection Table
Bit
Description
31 24 Reserved
23 16 Maximum Redirection Entry This field contains the entry number (0 being the lowest entry) of the
highest entry in the I O Redirection Table The value is equal to the number of interrupt input pins
minus one of this I O APIC The range of values is 0 through 239 For the ESC this value is 0Fh
15 8 Reserved
7 0 APIC VERSION This 8 bit field identifies the implementation version The version numbers are
assigned for 82489DX and APIC as follows
0Xh ^e 82489DX
1Xh ^e APIC
20 – FFh ^e Reserved
For the ESC the current value is 11h
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