plz plz

i wanted to control a devices like fan or light, using mcu and the signal will be receive by the mcu came from the pc ,in the serial port.......but i dont know how to prog it for serial port to detect...
plz plz

i wanted to control a devices like fan or light, using mcu and the signal will be receive by the mcu came from the pc ,in the serial port.......but i dont know how to prog it for serial port to detect...
explain

i am working in arm7/ 9 boards.. IDE IS keil3 version.. in all sample program..they given the retarget option.. what is the need of that..
explain

i am working in arm7/ 9 boards.. IDE IS keil3 version.. in all sample program..they given the retarget option.. what is the need of that..
code explaination

Hi can anyone tell me the basics of what this code is doing? I know it is writing to eeprom but is it writing a byte at a time and incrimenting the address? EECSN is the eeprom pin. #define...