private void assemble() {
    if (sourceFile == null) {
      printError("-i : No source file specified");
    }

    if (assembler == null) {
      printError("-f : No format specified");
    }

    print("...Assembling " + sourceFile.getName());

    assembler.assemble(sourceFile);

    print("..." + assembler.getErrors().length + " error(s) found");

    try {
      PrintWriter output = null;

      if (!assembler.hasErrors()) {
        if (!machineCode) {
          print("...saving .pco file");

          output = new PrintWriter(new FileWriter(baseFileName + ".pco"));

          for (Instruction instruction : assembler.getInstructions()) {
            output.print(instruction.getInstruction());
            output.println(" ;" + instruction.getSourceCode());
          }
        } else {
          print("Machine code file varified");
        }
      } else {
        print("...saving .err file");

        output = new PrintWriter(new FileWriter(baseFileName + ".err"));
        for (AssemblyError error : assembler.getErrors()) {
          output.println(error.toString());
        }
      }

      if (output != null) {
        output.close();
      }
    } catch (IOException e) {
      printError(e.getMessage());
    }
  }
  private void doInput(String[] arguments) {
    if (arguments.length < 2) {
      printError("-i : No filename specified");
    }

    if (arguments[1].endsWith(".pco")) {
      machineCode = true;
      assembler = new MachineCodeAssembler();
    } else {
      if (!new File(arguments[1]).exists()) {
        print("...no file extension specified.  Guessing .pca");

        arguments[1] = arguments[1] + ".pca";
      }
    }

    try {
      sourceFile = SourceFile.load(arguments[1]);
      baseFileName = arguments[1].substring(0, arguments[1].lastIndexOf("."));
    } catch (IOException e) {
      printError(e.getMessage());
    }
  }