The 9666A was a ruggedized terminal for use on factory floors. It was called the "Operator Interface Unit" (OIU). The 9666A has a 12-inch color screen with a resolution of 640 x 400 dots. The 9666A could operate in temperatures up to 60 degrees Celsius. Its NEMA 12 enclosure was dust and drip resistant. The 9666A came with an HP-HIL interface for connecting to keyboards, mice and tablets.