INT 16H 12H: Query Extended Keyboard Shift Status

                                                                   [XT] [AT]
 Expects: AH    12H
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 Returns: AX    KbdShiftFlags101Rec (status of Ctl, Alt, Ins, etc)
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    Info: Returns the current status of the shift keys and 'lock' states.
          This is similar, but not exactly the same as the word at
          0040:0017 in the BIOS Data Area.

   Notes: ■ The low-byte of the return value (AL) is identical for this fn
            and INT 16H 02H.  Only the high byte (AH) is encoded with
            additional information.

See Also: INT 16H (BIOS keyboard services)
          ROM-BIOS Functions
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