Companies that manufactor semiconductors, ic's, microprocessors, transistors
Most of these sites have data books or data sheets which describe how each device works. The data books tell what each pin on the device is used for. The data books also show where the pin is located on the device. Say you had a LM7805 which is a IC that used to provide a regulated 5 volt power supply. The data sheet on the LM7805 which pin on the device gives the +5 volt out put, which pin is hooked to ground, and which pin is hooked to the + input voltage.
Say you had a LM7805 which is a IC that used to provide a regulated 5 volt power supply. The data sheet on the LM7805 which pin on the device gives the +5 volt out put, which pin is hooked to ground, and which pin is hooked to the + input voltage.