Is it possible to write a byte recieved through serial communication to Flash memory of AT89S52? I tried to write a bootloader kind of program in which AT89S52 receives a byte from serial communication(from RS232 of PC through MAX232) and writes to Flash memory (say from 80H, from next location where my original program ends). I flashed this program using a development board with ISP which I know works fine. But all I could find was FF. Is this kind of self programming possible with AT89S52?

Regards