5. The 855 Chipset Family

The attempt to prolong battery operating time with the help of "intelligent" energy saving technologies falls flat if there's no chipset to go along with the processor that knows how to do the job.

In time for the launch, Intel offers two chipsets (Northbridges) with the 855PM (Odem) and the 855GM (Montana-GM) and combines these with the Southbridge ICH4-M, the mobile variant of the ICH-4.

The Northbridge 855PM and ...

The 855PM (Odem) is meant to be the link to a dedicated GPU via an AGP 4x port, while 855GM (Montata-GM) comes with Intel's own integrated 3D-decellerator. Both Northbridges support DDR memory, have a mobile-optimized memory controller and communicate with the Pentium-M processor over its 400 MHz (100 MHz QDR, P4-style) low-power processor system bus.

... the corresponding Southbridge ICH4-M.

The I/O controller hub ICH-4M offers USB 2.0, two Ultra ATA-100 channels, AC97 sound and a modem, to name some of the more important features. As is usual with the Southbridges of Intel's mobile chipsets, it is also responsible for managing the various power-saving mechanisms, such as Quickstart, Deep Sleep, Deeper Sleep and the new Improved Enhanced SpeedStep of the Pentium-M.

Up to now, the only thing that's known about Improved Enhanced SpeedStep is that the processor recognizes further modes that lie somewhere between Performance mode and Battery Optimized mode - similar to AMD's PowerNow and Transmeta's LongRun. Intel has given no details about the core frequencies and core voltages that the Pentium-M uses in these modes.