In a radical departure for Intel, it is not a low-power version of the desktop-oriented Pentium 4, but instead a heavily modified version of the Pentium III design (itself a modified form of the Pentium Pro). Essentially, it is a P-III core with a Pentium-4 bus interface and twice as much cache: 64k primary (as compared to the P-III's 32k, the P-4's 8k or the Athlon's 128k) and 1MB secondary (as compared with the 256k or 512k in the P-III, P-4 and Athlon). The usually power-hungry secondary cache uses an innovative access method to avoid switching on any parts of it not actually being accessed.
The Pentium M is optimised for power efficiency, which is vital in the mobile sector due to its impact on battery life. Running with very low power consumption and much less heat output than desktop processors, the Pentium M runs at a lower clock speed than the contemporary Pentium 4 desktop processor series, but with similar performance. The processor forms part of the Intel Centrino platform.
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