This code will make an Arduino Uno (or Nano) behave like an Rockwell 10939/10941 chipset. The Arduino will output the character data sent from any CPU/MPU to the Serial connection.
This project has been developed to debug the data coming from an Gottlieb System 80B pinball machine as the display was not working properly.
This project can also be used to drive an alternative display based on LCD or LEDs. The code should be changed to make this work. See this blog post for more information.
Make sure to change the code reading from the port registers when using any other Arduino (compatible) board other than the Arduino Uno or Nano as this code directly uses the values present in the port registers.