INT 14 - PC-MOS/386 v5.01 $serial.sys v5.04 - DISABLE PORT
        AH = 11h
        DX = port number
Return: AL = status
            00h successful
            01h IRQ for port is shared
            02h IRQ was reserved
SeeAlso: AH=04h,AH=05h,AH=12h"PC-MOS"

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