private void doVersion(String[] arguments) {
    if (arguments.length != 1) {
      printError("Invalid command syntax");
    }

    print("Post Room Computer : Version 1.1 (July 2008)");

    System.exit(0);
  }
  private void doAuthor(String[] arguments) {
    if (arguments.length != 1) {
      printError("Invalid command syntax");
    }

    print("Post Room Computer : By Richard Walton");
    print("Based on work by Dr. Hugh Osborne");

    System.exit(0);
  }
  private void doHelp(String[] arguments) {
    if (arguments.length != 1) {
      printError("Invalid command syntax");
    }

    print("Post Room Computer Help File:");
    print("Usage: java -jar path/to/postroom.jar -[option]");
    print("[option]");
    print(" h | help                        : Show help file");
    print(" v | version                     : Show version number");
    print(" a | author                      : Show author");
    print(" f [format] -i <filename>        : Assemble file");
    print(" f [format] -i <filename>  -e    : Assemble file and execute");
    print(" f [format] -i <filename>  -e -o : Assemble file, execute, and save trace information");
    print("[format]");
    print(" a | absolute                    : Absolute Address Machine");
    print(" r | register                    : Register Address Machine");

    System.exit(0);
  }
  private void printError(String error) {
    print("ERROR: " + error);
    print("For help use <postroom.jar> -help");

    System.exit(-1);
  }