Extended Functions - AMD -K6-2/450 - MHz Processor Application Note

23913A/0—November 2000

Extended Functions

Function 8000_0000h — Largest Extended Function Input Value
Input: EAX = 8000_0000h
Output: EAX = Largest function input value recognized by the CPUID instruction
EBX = Reserved
ECX = Reserved
EDX = Reserved
Function 8000_0000h returns a value in the EAX register that indicates the largest
extended function value recognized by the processor.
Function 8000_0001h — AMD Processor Signature and Extended Feature Flags
Input: EAX = 8000_0001h
Output: EAX = AMD Processor Signature
EBX = Reserved
ECX = Reserved
EDX = Extended Feature Flags
Function 8000_0001h returns two values — the AMD Processor Signature and the
Extended Feature Flags. The AMD processor signature is returned in the EAX
register and identifies the specific processor by providing information regarding its
type — generation/family, model, and revision (stepping). The information is
formatted as follows:
EAX[3–0] Stepping ID
EAX[7–4] Model
EAX[11–8] Generation/Family
EAX[31–12] Reserved
The extended feature flags are returned in the EDX register and indicate the
presence of specific features found in AMD processors. In most cases, a '1' indicates
the feature is present, and a '0' indicates the feature is not present. Table 32 on
page 76 contains a list of the currently defined extended feature flags for the AMD-K6
family of processors. Reserved bits will be used for new features as they are added.
Appendix A
Preliminary Information
Embedded AMD-K6™ Processors BIOS Design Guide
75