From Silicon Integrated Systems:
SiS 180 RAID Controller: The SiS180 is a PCI to Serial ATA and Parallel ATA controller. It supports one parallel IDE channel and two SATA ports. The PCI interface is PCI2.3 compliant and 33MHz clock timing. The SATA interface meet Serial ATA 1.0 specification and transfer rate is 1.5Gb/s. The DMA transfer rate by SATA is up to 150MB/s. The hard drive on SATA channel of SiS180 can be selected as the system boot-up drive. Because most of the hard drive operation is running on the boot-up drive, the system can get the speed benefit of SATA.