INT 21 - DOS 1+ - DIRECT CHARACTER INPUT, WITHOUT ECHO
        AH = 07h
Return: AL = character read from standard input
Notes:  does not check  Break
        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=08h,AH=0Ah