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New Instructions 3-29

18524C/0—Nov1996 AMD-K5 Processor Technical Reference Manual

3.3.1 CPUID

mnemonic opcode description

CPUID 0FA2h Identify processor

Privilege: CPL=0

Registers Affected: EAX, EBX, ECX, EDX

Flags Affected: none

Exceptions Generated: Real, Virtual-8086 mode—none

Protected mode—none

The CPUID instruction identifies the type of processor and the features it supports.

A 0 or 1 value written to the EAX register specifies what information will be

returned by the instruction.

The processor implements the ID flag (bit 21) in the EFLAGS register. By writing and

reading this bit, software can verify that the processor will execute the CPUID

instruction.

For detailed instructions on processor and feature identification see the AMD Proces-

sor Recognition application note, order# 20734.

Table 3-8 outlines the AMD-K5 processor family codes and model codes with the

CPU clock frequencies (MHz), bus frequencies (MHz), and P-rating strings (“Pxxx”).

Table 3-8. CPU Clock Frequencies, Bus Frequencies, and P-Rating Strings

Family Code Model Code CPU Frequency (MHz) CPU Bus Frequency (MHz)

P-Rating String (“Pxxx”)

75 50 P75

90 60 P90

100 66 P100

90 60 P120

100 66 P133

120 60 P150

133 66 P166

Notes:

1. The CPUID instruction does not return a P-Rating string.

— This table does not constitute product announcements. Instead, the information in the table represents possible product offerings.

AMD will announce actual products based on availability and market demand..

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