INT 18 - NEC PC-9800 series - KEYBOARD - CHECK FOR KEYSTROKE
AH = 01h
Return: ZF set if no keystroke available
ZF clear if keystroke available
AX = keystroke
SeeAlso: AH=02h,INT 16/AH=01h

See also: 1800

1801 - NEC PC-9800 series - KEYBOARD - CHECK FOR KEYSTROKE