Hi babar,

How are you doing?

Even hacker's hacking tricks are hijacked by senior hackers. ha..ha..ha..

I have a suggestion, since Atmel89C2051 is 20pin chip, it is (relatively) easy to make someone fool. Remove the part number from top of the IC, print some other number on the chip, such as 74LS374 or 74ALS245 etc. Empty one big electrolytic capacitor container, put the crystal into that container, and filled it up with silicon rubber. Now your circuit will look like quite different. It may offer you atleast some further protection, and will take longer for anyone to reach upto the bottom of your design. This is just an idea, you can develop your own idea of course.

Rauf