I have the C program written below to be compiled and progrmmed using uvision2 C51. #include <at898252.H> // Routine for time delay void delay(unsigned long n) { unsigned long temp; for (temp=0;temp<n;temp++); } void main (void) { while (1) { P1=0x00; // Turn ON LED diodes delay(6000); // Time delay P1=0xff; // Turn OFF LED diodes delay(6000); // Delay } } But nothing is happening to my LEDs, in fact nothing work. The Hex filed generated by keil is in fact wrong. Can someone tell me how to do it right? How can i set up my target and output? Please i need help.