Int 21 Fn 4406  - Dos 2+ - Ioctl - Get Input Status                        [D]

   AX = 4406h
   BX = file handle

Return: CF clear if successful
       AL = input status
       00h not ready (device) or at EOF (file)
       FFh ready
       AH may be destroyed (refer to note)
   CF set on error
       AX = error code (01h,05h,06h,0Dh) (see #1366 at AH=59h/BX=0000h)

Notes: files may not register as being at EOF if positioned there by AH=42h
   under DOS 5.0, on a successful return, AH contains either the next
     character which will be read or 1Ah if at EOF; under a Windows95
     DOS box, AH seems to be either unchanged or 00h
   this function was not supported by Digital Research's DOS-Plus
BUG:   the CLOCK$ device under DR DOS 3.41 always indicates 'Ready'; this was
     corrected in v5.0

See Also: AX=4407h,INT 2F/AX=122Bh