Recently I was designing a PCB for my project using 89c51. I am using a 12V battery to run motor and 7805 to give 5V to 89c51. When going to ARES for PCB designing I realised the VCC pin of 89c51 is not connected to output of 7805. While this pins are hidden in ISIS. How do I unhide this hidden VCC and GND pins to manually connect them to output and COM of 7805?
In order to see the hidden pins and the nets they are connected to you should double click the microcontroller and then click the hidden pins button.
There is no need to unhide the power pins, just connect the 5v regulator output to the Vcc net and the regulator ground to a GND net.
To place a Vcc terminal (the upwards pointing triangle) select the terminals menu, place a POWER terminal and double click it to select Vcc net. For the ground terminal just place a GROUND terminal, it's already connected to the GND net.
Then when you open the ARES layout you will see the following connections from the regulator to the microcontroller power supply pins