Intel 253666-024US Computer Hardware User Manual


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3-184 Vol. 2A CPUID—CPU Identification
INSTRUCTION SET REFERENCE, A-M
The Processor Brand Index Method
The brand index method (introduced with Pentium
®
III Xeon
®
processors) provides
an entry point into a brand identification table that is maintained in memory by
system software and is accessible from system- and user-level code. In this table,
each brand index is associate with an ASCII brand identification string that identifies
the official Intel family and model number of a processor.
When CPUID executes with EAX set to 1, the processor returns a brand index to the
low byte in EBX. Software can then use this index to locate the brand identification
string for the processor in the brand identification table. The first entry (brand index
0) in this table is reserved, allowing for backward compatibility with processors that
Figure 3-9. Algorithm for Extracting Maximum Processor Frequency
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