INT 15 - OS HOOK - KEYBOARD INTERCEPT (AT model 3x9,XT2,XT286,CONV,PS)
        AH = 4Fh
        AL = hardware scan code
        CF set
Return: CF set
           AL = hardware scan code
        CF clear
           scan code should be ignored
Note:   called by INT 9 handler to translate scan codes; the INT 09 code does
          not examine the scan code it reads from the keyboard until after
          this function returns.  This permits software to rearrange the
          keyboard; for example, swapping the CapsLock and Control keys, or
          turning the right Shift key into Enter.
SeeAlso: INT 15/AH=C0h