//! initialize DMA to use phys addr 84k-128k
void flpydsk_initialize_dma ()
{
   outportb (0x0a,0x06);   //mask dma channel 2

   outportb (0xd8,0xff);   //reset master flip-flop

   outportb (0x04, 0);     //address=0x1000
   outportb (0x04, 0x10);

   outportb (0xd8, 0xff);  //reset master flip-flop

   outportb (0x05, 0xff);  //count to 0x23ff (number of bytes in a 3.5" floppy disk track)
   outportb (0x05, 0x23);

   outportb (0x80, 0);     //external page register = 0

   outportb (0x0a, 0x02);  //unmask dma channel 2
}