INT D4 - PC-MOS/386 v5.01 - GET PORT AND BAUDRATE INFORMATION
        AH = 20h
        BX = task ID (FFFFh for current task) (see AH=19h)
Return: CF clear if successful
            CX = port number (0000h if none)
            DI:SI = baudrate (if CX nonzero)
        CF set on error
            AX = error code (see INT 21/AH=59h)
Program: PC-MOS/386 is a multitasking/multiuser MS-DOS-compatible operating
          system by The Software Link, Inc.
SeeAlso: INT 14/AH=0Ch"FOSSIL"

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