The Unabridged Pentium 4 IA32 Processor Genealogy

Pentium® Flavors

The Pentium® processor evolved through three basic incarnations (there were many speed variations of each):

• The initial version was the P5. It implemented neither the Local APIC nor the MMX instruction set. It was the first IA32 processor that had separate code and data caches (each 8KB in size).

• The P54C version was the first IA32 processor to implement the Local APIC. Its FSB arbitration scheme supported dual P54C processors on the FSB.

• The P55C version was the first IA32 processor to implement MMX. It also doubled the size of the code and data caches from 8KB to 16KB each.