[XT] [AT]
Expects: AH    11H
Returns: ZF    ZR = no keys in buffer
NZ = key is ready
AH    (if ZR) scan code
AL    ASCII character code or extended ASCII keystroke
Info: This is identical to INT 16H 01H, except that it does not perform
"extended key filtering" to map 101-key 'board keystrokes to
84-key 'board equivalents.

See Also: INT 16H (BIOS keyboard services)
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INT 16H 11H: Query Extended Keyboard Status / Preview Key