Int 14 Fn 1646  - Digiboard - Ccb Command - Set Interrupt To Host Mask     [S]

   AX = 1646h
   BL = bits to set
   BH = bits to clear
   CL = byte 1
   DX = port number (00h-03h) (04h-43h for XAPCM232.SYS)

Return: AH = status
       00h successful
       80h error
       FFh error

See Also: AH=16h"Digiboard",AX=1647h