The New Dothan, Or The Evolution Of Banias
With regard to its processor design, Dothan doesn't boast revolutionary new features as its predecessor Banias did a year ago. Here, we'd like to remind you, above all, of the "intelligent circuitry" found with the 1 MB L2 cache. With Banias, this is what allows only 1/32 of the entire L2 cache to be continually active, and this supposedly contributes to the lower power consumption of the chip. Logically, Intel also uses this clever circuitry design for the 2 MB cache of the new mobile chip.
The data prefetch unit also had to be reworked since the caveat of doubling the cache size without modifying the data prefetch unit entails the risk of cache misses or invalid cache data. In such a case, the CPU's perfrmance would not increase significantly.
What's revolutionary is the fabrication technology that Intel uses, because Dothan is Intel's first mobile CPU that is manufactured with the 90-nm process. The new fabrication technology lets the CPU run with lower operating voltage, which has a positive effect on power consumption. Speaking of operating voltage - on the Pentium M, each of the Speedstep increments have one voltage/frequency pair, those of the Dothan now boast four. These are designated by VID#A, VID#B, VID#C and VID#D. In other words, Intel now introduces multiple voltage IDs (VIDs), first encountered with Northwood's C1 Stepping, to its mobile CPUs as well. Starting now, four variants with different VIDs, or differently specified supply voltages, are available per CPU model.
|Intel Pentium M 755|
|2.0 GHz||1.340 V||1.324 V||1.308 V||1.276 V|
|1.8 GHz||1.292 V||1.276 V||1.276 V||1.244 V|
|1.6 GHz||1.244 V||1.228 V||1.228 V||1.196 V|
|1.4 GHz||1.196 V||1.180 V||1.180 V||1.164 V|
|1.2 GHz||1.148 V||1.132 V||1.132 V||1.116 V|
|1.0 GHz||1.100 V||1.084 V||1.084 V||1.084 V|
|800 MHz||1.052 V||1.036 V||1.036 V||1.036 V|
|600 MHz||0.988 V||0.988 V||0.988 V||0.988 V|
Four variants of the Pentium M 755 will be available, each with a different VID.
According to Intel, the advantage of multiple VIDs is that a higher yield can be guaranteed for production. Multiple VIDs should not be of much interest for end users, since they ultimately buy notebooks with the CPUs and don't need to worry about the input voltage of the processor. For overclockers, however, the variant with VID#D will be interesting, since this also runs stably with low supply voltages.