Processor Performance Rating (PR or P-Rating), often mistaken for "Pentium Rating", was a rating system that allowed various x86 manufacturers to gauge the performance level of their microprocessors against equivalent Pentium-level performance. PR specifications were finalized on January 25 and were introduced on February 5, 1996 in a collaborated effort by AMD, IBM, SGS-Thomson, and Cyrix to provide a way to report processor performance.

With the introduction of K6 in 1997, AMD extended this rating system by introducing PR2, comparing models against Intel's Pentium II models.

Measuring P-Rating

Performance rating was obtained by:

1. Obtain a representative target system that supports both the Pentium and Cyrix/IBM/AMD processor (e.g. Am5x86 / K5).
2. Run Winstone 96 using the Pentium Processor and record the scores for the various frequencies.
3. Defragment the hard disk after each test run
4. Replace the Pentium processor with target processor (e.g. Am5x86).
5. Run Winstone 96 using the target processor and record the score for this processor.
6. Compare the Winstone 96 score you get against the Pentium processors. The target processor's P-Rating is based on the highest freqeucny of the Pentium processor that the target processor's Winstone score surpasses.

Documents

• /IBM Microelectronics: Four companies announce new, simplified method for consumers to measure microprocessor performance in PCs
• /Processor Performance Rating (P-rating) Specification