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  Function 0CH (decimal 12) clears the keyboard buffer in RAM and then
  invokes one of five DOS functions: function 01H, 06H, 07H, 08H, or 0AH.
  The AL register is used to select which of these functions will be
  performed after the keyboard buffer is flushed. With the keyboard buffer
  clear of extraneous characters, function 0CH forces the system to wait for
  new input before it acts on the invoked function.

  Because function 06H is supported, the follow-up service need not be
  keyboard input: It can be display output.