Re: P R = Page Ranking (PR)
AMD used P R on K5's, most K7's, and now most K8's. People used to jokingly call it "Pentium Rating" when it really stood for "Processor Rating" or "Performance Rating", since you could generally guess the equivalent Intel by taking the P R and comparing it to the clock speed of Intel's Pentium line.
Example: AMD Athlon XP 1500+ <-- P R, suggests that it's roughly equivelent to a 1500MHz Intel Pentium 4. But now, even though Pentium is dead, AMD is still continuing with P R's. I have an AMD Athlon X2 5000+ EE.
Intel is even using it's own form of P R with its new chips (although they refer to them as "Processor Numbers"). Example: Intel Core 2 Duo T7500.
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