Int 14 Fn 20  - X00 Fossil - Destructive Read With No Wait                 [S]

   AH = 20h
   DX = port number

Return: AH = 00h if character was available
       AL = next character (removed from receive buffer)
   AX = FFFFh if no character available

See Also: AH=0Ch,AH=21h"X00"