http://download.intel.com/design/chipsets/embedded/datashts/319537.pdf 查了一下P15的系統晶片組US15的功能 "Ultra DMA: Synchronous DMA protocol that redefines signals on the PATA cable to allow both host and target throttling of data and transfer rates up to 100 MB/s. Ultra DMA 100/66/33 are supported."