Konsole should be able to represent control characters (e.g. STX, ETX, DLE, etc). Ideally it would either print the unicode character instead (e.g. ␂, ␃, etc.) or draw box containing the character code in matrix form (e.g. [0 0 0 2], [0 0 0 3], etc. )) which is how gnome-terminal does it.

How to test:
    echo '\02'
    echo '\03'

Expected:
    ␂
    ␃

Got:
    <nothing visible>
    <nothing visible>