<< you're talking about the udma mode. Mode 5 = ATA100, mode 4 =ATA66, etc. It has nothing to do with sharing resources, like an IRQ. >>
I partially agree with this statement, I think you are talking about mode 5 instead of channel 5, as via 686B has 2 bus master IDE controllers, and "bus master" means the IDE controller is equipped with its own DMA hardware, so it should not use the slave DMA resources on the motherboard, which is also known as DMA0-7
However, I think for most common modern southbridges, each IDE controller have only got 1 set of DMA and IRQ hardware, which means if two devices are using the same channel as master and slave, they do share the DMA, IRQ, and the available bandwidth. If the master and slave both try to use the IDE channel, the slave will back off for the master. So there is a possibility that the two drives are sharing resources without knowing ur drive config
If I am spreading false info, please let me know.
Now for my question Pyramix, how do u know both ur drive are DMA enabled even the DMA option is device manager is not available?