INT 2F U - DOS 3+ internal - DELAY
        AX = 1224h
        SS = DOS DS (must be using a DOS internal stack)
Return: after delay set by INT 21/AX=440Bh, unless in server call
          (INT 21/AX=5D00h)
Note:   delay is dependent on the processor speed, and is skipped entirely if
          inside a server call
SeeAlso: INT 21/AH=52h