P rating

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The P-Rating or Performance Rating or Pentium Rating is a "unit" with which the speed of a processor is compared with that of a correspondingly clocked Pentium processor (Pxx). 'Normal' office applications were used for the comparison. The floating-point performance was usually far below that.

The rating was first used by AMD for the Am5x86 , later also by Cyrix for the Cyrix 5x86 and by NexGen ( NexGen Nx586 ) in order to better compete with the Pentium of that time . With the MII (later 6x86MX), Cyrix was the last manufacturer to use this comparison.

Due to the use of different architectures and bus speeds, the Intel processors could not only be compared with one another in terms of their clock rate. Therefore, Intel developed the iCOMP Index , which is based on a number of benchmark applications (including CPUmark32, Norton SI-32, SPECint_base95, SPECfp_base95). Since this was based heavily on floating point functions, in which Intel was the leader in the x86 CPUs, the advantage should also be documented.

With the NetBurst architecture of the Pentium 4 and its high clock rates, Intel again switched to clock frequencies as the unit of measurement. In order to remain comparable, AMD later established a similar name, called QuantiSpeed , with the Athlon XP , which is based on the clock rate of the Pentium 4.

Examples

A 486 (an Am5x86- P75) runs at 133 MHz and is about as fast as a Pentium processor at 75 MHz . The 486 has a Pentium rating of 75. The rating is here in the name (...- P75).

An AMD Athlon processor with the rating “2000+” should therefore be as fast or faster than a Pentium 4 processor with 2000 MHz. Officially, however, the P-Rating is not used for comparison with the clock rates of the P4 from the competitor, but rather for comparison with the Athlon of the Thunderbird series from the company.