Int 13 Fn 1C  U - Esdi Fixed Disk - ???                                    [d]

   AH = 1Ch
   AL = subfunction (01h-06h)
   DL = drive (80h,81h)
   ???

Return: ???

Note:  these functions perform a controller command 0612h without DMA

See Also: AX=1C08h,PORT 3510h"ESDI"