A 150R resistor acts as a current limiting resistor for each display. PIC ports have a maximum sourcing current of 40mA ( the maximum current for the LED display is 200mA so it is the PIC that R1 is protecting, not the display.)
PIC16C54 dual dice electronic project circuit
An electronic dice project circuit can be designed in various modes , using logic circuit or using microcontrollers . This electronic project is based on the PIC16C54 microcontroller , manufactured by Microchip . This project is a simple dual dice electronic project , that use few external electronic parts and LED displays , to generate ( simulate ) dices .
As you can see in the schematic circuit , the main advantage of this electronic dice project is that this circuit require few external electronic parts ( like many of the microcontroller based projects ) .