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        Issue handle generic IOCTL request (INT 21h, 440Ch)

        This function uses an open device handle to request a device
        driver to perform code page switching or to get/set device
        information.

        Entry:
          AX = 440Ch
          BX = Handle
          CH = Category (Type of device)
                 0: Unknown (if device type not known)
                 1: a COMx device
                 3: CON
                 5: a LPTx device
          CL = Function within category
                 Category 3 & 5:
                   4Ch: Prepare start
                   4Dh: Prepare end
                   4Ah: Select (Set) code page
                   6Ah: Query (Get) selected code page
                   6Bh: Query prepare list
                 Category 3:
                   5Fh: Set display information
                   7Fh: Get display information
          DS:DX = Address of packet
        Return:
          CF = 1
               AX = Error code
          CF = 0
               No error