Int 14 Fn 19  - Digiboard Digichannel Pc/x* - Special Character Interrupt  [S]

   AH = 19h
   BL = flag
       00h disable special character interrupt
       FFh enable interrupt
   DX = port number (00h-03h) (04h-43h for XAPCM232.SYS)

Return: AH = status
       00h successful
       FFh failed

See Also: AH=1Ah"Digiboard"