INT 14 - MultiDOS Plus 4.0 IODRV - GET AND RESET PORT LINE STATUS
        AH = 08h
Return: AL = line status (see AH=03h)
        AH destroyed
Notes:  the port number is stored at offset BEh in the Task Control Block
        on every line status change, the line status is ORed with the line
          status accumulator; this function returns the accumulator and clears
          it
SeeAlso: AH=04h"MultiDOS",AH=07h"MultiDOS",INT 15/AH=13h"MultiDOS"