SiS 963 chip

The South Bridge

As we stated earlier, motherboard manufacturers have two South Bridge’s to choose from for SiS 648: SiS 963 or SiS 961. The SiS 961 chip is borrowed from the SiS 645/SiS 645DX chipsets, and as such will likely only be used on SiS 648 motherboards intended for the value market. When the SiS 648/SiS 961 combination is used, bandwidth between the North Bridge and South Bridge is 533MB/sec, the same figure available on SiS 645/SiS 645DX. If SiS 963 is implemented, bandwidth jumps to 1GB/sec between both chips. In order to support this, SiS had to add a few pins to SiS 963, so it isn’t pin-compatible with the SiS 961 South Bridge.

Bandwidth

In particular, the pathway between the North Bridge and South Bridge is 16-bits wide and operates at 533MHz when the SiS 963 chip is used. Like SiS 645, the link between both chips is bi-directional. This means that two independent pathways have been implemented. One connection can send data from the SiS 648 chip to SiS 963, while the second pathway can simultaneously send data to SiS 648 by way of the SiS 963 South Bridge. In comparison, both Intel’s 845E and VIA’s own P4X333 chipsets offer 266MB/sec between both chips (although VIA’s recently announced P4X400 chipset offers 533MB/sec of bandwidth).

Other Peripherals

One new feature SiS 963 adds is support for the new USB 2.0 protocol. Offering up to 480MB/sec of bandwidth, USB 2.0 offers 40 times more performance than USB 1.1. Of course, USB 2.0 is backwards compatible with USB 1.1 devices; no new cables or connectors are necessary. Up to six USB devices are supported by the South Bridge.

Besides the new USB controller, SiS 963 also has a new IEEE-1394a “Firewire” controller. This is welcome news to the A/V world, as many consumer electronics devices have already implemented Firewire connections. In particular data rates of 100/200/400MB/sec are supported. Besides connecting your digital camcorder, the Firewire support SiS 963 offers can also be used to connect PCs without additional hardware. The Firewire controller built in to SiS 963 supports up to three devices.

Like SiS 961, dual hard drive controllers are implemented in SiS 963, although ATA/133 hard drives are now officially supported by the chipset. The onboard audio (six-channel) and networking from SiS 961 are also rolled into SiS 963.