Request type 1 was introduced in the Pentium® processor and is supported by all subsequent IA32 processors (as well as the later 486 models). When the input value in EAX = 1 (i.e., request type 1), the processor returns the following items of information:
Prior to the advent of the Pentium® 4 processor, the information shown in Figure 59-2 on page 1448 is returned in EAX. With the advent of the Pentium® 4 processor, the information shown in Figure 59-3 on page 1448 is returned in EAX. Table 59-2 on page 1449 defines the processor type field values.