Shift register method: A method whereby data is written into an internal shift register for lighting a single horizontal row of LEDs. Data display within the shift register is performed via designation from an external device. Display and control are synchronized, making this method compatible with simple gradation displays. However, LED timing is performed externally, increasing the processing load vs. the memory method.
Memory method: A method of writing two screen's worth of display data to an internal memory (RAM) circuit. The data written to the memory circuit is automatically displayed via a lighting circuit. Since lighting operations are processed automatically, there is no need for external processing. This reduces the processing load. If fixed characters are used, many units or multiple-step units can be controlled by a simple control device.