Int 16  - Keyboard - Get Keystroke                                         [!]

   AH = 00h

Return: AH = BIOS scan code
   AL = ASCII character

Notes: on extended keyboards, this function discards any extended keystrokes,
     returning only when a non-extended keystroke is available
   the BIOS scan code is usually, but not always, the same as the hardware
     scan code processed by INT 09.  It is the same for ASCII keystrokes
     and most unshifted special keys (F-keys, arrow keys, etc.), but
     differs for shifted special keys.

See Also: AH=01h,AH=05h,AH=10h,AH=20h,INT 18/AH=00h