/* send start address */
waport = DMA2_CHN(chan - 4);
outb(waport, phys>>1);
outb(waport, phys>>9);
outb(dmapageport[chan], phys>>16);
outb(dmapageport[chan], phys>>17);
/* send count */
nbytes >>= 1;
outb(waport + 2, --nbytes);