Hi,Dear All; Sorry.I posted this message again because this is the detailed informaiton of my project. I want to write a program to modify the data in AT93C46(EEPROM IC)by controlling the MCU via RS232 interface from the PC.Do you have any application notes on this subject? And any example codes? Can I implement it with the Hyper Terminal? The MCU I am using is AT89C51/52 by Atmel Corp. Thanks in advance.