Primary/Secondary Master/Slave PIO The four PIO (Programmed Input/Output) fields sets a PIO mode (0-4) for each of the four IDE devices that the onboard IDE interface supports. Modes 0 through 4 provide successively increased performance. In Auto mode, the system automatically determines the best mode for each device. The choice: Auto, Mode 0, Mode 1, Mode 2, Mode 3, Mode 4. Primary/Secondary Master/Slave UDMA Ultra DMA/33 implementation is possible only if your IDE hard drive supports it and th