Int 14 Fn 09  - Multidos Plus Iodrv - Reset Port Status                    [S]

   AH = 09h

Return: modem status byte cleared

Note:  the port number is stored at offset BEh in the Task Control Block

See Also: AH=04h"MultiDOS",AH=07h"MultiDOS",INT 15/AH=13h"MultiDOS"