Since ATMEL introduced AT89Sxx, they marked AT89Cxx as "obsolete" or "not for new designs" or something like that. Furthermore, they even remove the product from their product lists. However, AT89Cxx is still available in market, and the date mark is 04xx, which means it is produced in 2004. Then a question came to me: Who made these ICs?? ATMEL himself?? the doubt came to me because when I used these newly come AT89Cxxs, their reliability sucks. I only used them for less than 100 cycles e/p and they start to fail on verification. I don't know whether the problem is locally or worldwide. Off course, I have switched to newer AT89Sxx, which is more reliable then the AT89Cxx I bought from the same shop, but the question still bother me.