Nikhil, I am assuming you are using hi-tech before void main() Add this and try again #include Andre Abelian -----Original Message----- Hello everybody, I am using a PIC18F452 chip but cannot get it working :( My interfacing follows: VDD=5V VSS=0V (GND) The MCLR\ pin is connected to the ground via capacitor and to the source (VDD) via the resistor. The clock is 12 MHz between the OSC1 and OSC2 pins, each of which has a 33pF capacitor to ground. The program is simply this: void main() { TRISB=0; PORTB=0xAA; while(1) /* do nothing */ ; } I compile it using MPLAB C compiler and program the pic using LabTool 48 Programmer. I think the program does not run at all not even the TRISB=0 line because the PORTB pins do not seem to be configured for output even. (The pins take any voltage I give them) The MPLAB IDE simulator (MPLAB SIM) runs the program nicely though. I would be grateful if somebody could help! Thank you, Nikhil -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu