Intel MultiProcessor Intel486 and Pentium Processor Signatures, Bit Name Description Comments

MP Configuration Table

Table 4-5. Intel486 and Pentium Processor Signatures

Family	Model	Steppinga	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	The processor contains an FPU that supports the Intel387
		Point Unit	processor floating point instruction set.
1–6			Reserved.
7	MCE	Machine Check	Exception 18 is defined for machine checks, including CR4.MCE for
		Exception	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	The 8 byte (64 bits) compare-and-exchange instruction is supported
		Instruction	(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.

Version 1.4 4-9