I made the circuit and it is working but I have some questions:

-the first question about the crystal frequency for at89s8253
which value is the best for it for putting it in the circuit programming.

-the second question is about the saftware for the programming when I write for the microcontroller the window that showing it writting it appear there was some byte error and I don't know what it mean ???

thanks for reading and taking some of your time

your brother/khalid