   return 0.95 <= vSync && vSync <= 1.20 && 0.95 <= hSync && hSync <= 1.05;
 }
 
+#if hasSerial
 void doCommand(char line[])
 {
   switch (toupper(line[0])) {

  // Wait for Loader to be running
  delay(1000);
}

// Because the Arduino doesn't have enough RAM to buffer
// a complete GT1 file, it processes these files segment

    Serial.println(": L        Start Loader");
    Serial.println(": P        Transfer object file from PROGMEM");
    Serial.println(": U        Transfer object file from USB");
    Serial.println(": .<text>  Send text line as ASCII key strokes");
    Serial.println(": T        Enter terminal mode");
    Serial.println(": W/A/S/D  Up/left/down/right arrow");
    Serial.println(": Z/X      A/B button ");
    Serial.println(": Q/E      Select/start button");
