> The only things, that can protect you - change you product as frequently, as
> possible, add new features, new ideas and didn't try to obtain superprofit.
> If you need really protected product for security applications - use special
> security designed chips, not wide available microcontrollers.

Very seldom is it worthwhile to crack a code-protected chip.  While the
software in many chips has $1000's of dollars of engineering invested in
it, the designer has access to knowlege and information NOT contained
within the chip (e.g. info about debug modes, etc.)  In many cases, it's
better to rewrite software from scratch than to reverse-engineer what's
there, especially if it's necessary to make any changes.

The one time code-cracking is profitable (which is what made the 16X84's such
a nice target) is when the contents of the chip are worth more than the device
in which it's embedded.  For example, in a Satellite TV decoder, the contents
of the chip may be worth thousands of dollars even though the decoder itself
may be worth only a few hundred.

Note that the 16C84/16F84 may in fact be no easier to break than other 16Cxx
parts; the big reason it got cracked was the value of the broadcast satellite
signals.