DMM32AT_AI_HI_CHAN_REG
outb(last_chan, dev->iobase + DMM32AT_AI_HI_CHAN_REG);
outb(0xff, dev->iobase + DMM32AT_AI_HI_CHAN_REG);
aihi = inb(dev->iobase + DMM32AT_AI_HI_CHAN_REG);