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MP Configuration Table
Version 1.4 4-9
Table 4-5. Intel486 and Pentium Processor Signatures
Family Model
Stepping
a
Description
0000 0000 0000 Not a valid CPU signature.
0100 0000 and 0001 xxxx Intel486 DX Processor
0100 0010 xxxx Intel486 SX Processor
0100 0011 xxxx Intel487 Processor
0100 0011 xxxx IntelDX2™ Processor
0100 0100 xxxx Intel486 SL Processor
0100 0101 xxxx IntelSX2™ Processor
0100 1000 xxxx IntelDX4™ Processor
0101 0001 xxxx Pentium Processors (510\60, 567\66)
0101 0010 xxxx Pentium Processors (735\90, 815\100)
Values not shown are reserved for future processors.
Refer to the documentation of each new processor for its family and model values.
1111 1111 1111 Not a valid CPU signature. Indicates a processor that is not
an Intel architecture-compatible processor (a graphics
controller, for example)
a
Intel releases information about stepping numbers as needed.
Table 4-6. Feature Flags from CPUID Instruction
Bit Name Description Comments
0 FPU On-chip Floating
Point Unit
The processor contains an FPU that supports the Intel387
processor floating point instruction set.
1–6 Reserved.
7 MCE Machine Check
Exception
Exception 18 is defined for machine checks, including CR4.MCE for
controlling the feature. This feature does not define the model-
specific implementations of machine-check error logging reporting
and processor shutdowns. Machine-check exception handlers may
have to depend on processor version to do model-specific
processing of the exception or test for the presence of the standard
machine-check feature.
8 CX8 CMPXCHG8B
Instruction
The 8 byte (64 bits) compare-and-exchange instruction is supported
(implicitly locked and atomic). Introduced by the Pentium
processor.
9 APIC On-chip APIC Indicates that an integrated APIC is present and hardware enabled.
(Software disabling does not affect this bit.)
10–31 Reserved.