DOS Fn 0bH: Check Input Status

                                                         Compatibility: 1.0+ 
 Expects: AH    0bH
 Returns: AL    0ffH if a character is available from the Standard Input
                0    if no character is available
    Info: Checks the status of the Standard Input.

          If Ctrl-Break is detected, INT 23H is executed.

   Notes: ■ Use before Fns 01H, 07H, and 08H to avoid having DOS wait for a

          ■ This is a simple, non-destructive way to check for Ctrl-Break
            during long calculations or other processing that does not
            normally look for input.  It lets the user abort from such a

See Also: INT 16H
          Character I/O Functions
          DOS Functions