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help on output port programming

Hi all! I m a SY E&C student. And m working on a microcontroller based project.The one i m using is AT89C2051. To test it i wrote a sample program and loaded it in the controller using a universal programmer. The sample program would write a low to P1.3 continuously using an infinite loop. but wen i started the controller after making all the external hardware connections(reset and crystal oscillator , Vcc and GND) instead of showing logic low it gives me +5V only at pin P1.3. Can anybody help me troubleshoot it?