Int 4A/AH=01h

AH = 01h

Return:
ZF set if no keystroke available
ZF clear if keystrokes in buffer
AX = next keystroke (AH=00h for ASCII keys -- no scan code)

See Also: AH=00h - AH=02h - AH=03h - AH=04h - Category: Vendor-specific BIOS Extensions - Int 4Ah - T