thanks for your reply Purohit....

something i want to ask are...

1)i do know the website is providing the hex file... but how do i burn the hex file to the microncontroller? do i need to do that?

2)http://www.kmitl.ac.th/~kswichit...gm30a.html
this website is regarding AT89S51 or?

3)ISP means we can use PC to burn our program to AT89S51 instead of programmer device?

thanks again~