Function 3300h          Get Ctrl-C Check Flag

    Returns the status of the Ctrl-C checking.

        Entry   AX = 3300h

        Return  DL = 0 | 1   BREAK flag is off | on

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    If the Ctrl-C (Ctrl-Break) flag is off, DOS checks for Ctrl-C
    keystrokes only while processing I/O functions 01h through 0Ch.
    If the flag is on, DOS checks for Ctrl-C while processing other
    system functions.