The chip's Southbridge lacks direct support for Serial ATA - a real shortfall at the moment. Intel plans to include its ICH5 chip with the new Canterwood and Springdale chipsets. This will contain two ports for Serial ATA hard drives in addition to its well-known Ultra ATA/100 controller.

VIA has similar plans and SiS is working on the SiS964 - also with an integrated Serial ATA controller. A Serial ATA controller will also feature in the soon-to-be-released R659 chipset with four Channel PC 1200 RDRAM support.

But even if the chipset is not yet ready for Serial ATA, all manufacturers have grafted a separate Serial ATA controller on their boards. Only low-budget and OEM boards will have to make do without Serial ATA completely; most motherboards you find in the stores include add-on controllers.

200 MHz FSB And Hyper-Threading

Up to now there are no plans for the SiS655 to support the 200 MHz front side bus speed for the forthcoming Pentium 4 models, even though the P4SDX from Asus is already working at these speeds.

In our view, it should be possible to update the data sheets and enable 200 MHz relatively quickly, although SiS and the motherboard manufacturers should highlight the difference with a modified or even new model number. There was some confusion about the Hyper-Threading upgrade on the SiS648.

Support for Hyper-Threading has since become an indispensable feature, since all future Pentium 4 processors will use this technology. Behind Hyper-Threading is the Pentium 4's ability to convince the operating system that it is dealing with two processors, so that the operating system sends threads to both virtual processors (known as dispatching). The Pentium 4 is able to organize and process the threads and the resulting commands in such a way as to achieve a degree of "real" parallel processing. This was previously only possible with an expensive multiprocessor system.