INT 21 - DOS 1+ - CHARACTER INPUT WITHOUT ECHO
        AH = 08h
Return: AL = character read from standard input
Notes:   Break are checked, and INT 23 executed if detected
        standard input is always the keyboard under DOS 1.x, but may be
          redirected under DOS 2+
        if the interim console flag is set (see AX=6301h), partially-formed
          double-byte characters may be returned
SeeAlso: AH=06h,AH=07h,AH=0Ah,AH=64h