The Mark 1, and later the Mark 1A, Fire Control Computer was a component of the Mark 37 Gun Fire Control System deployed by the United States Navy during World War II and up to 1969. It was used on a variety of ships, ranging from destroyers (one per ship) to battleships (four per ship). The Mark 37 system used tachymetric target motion prediction to compute a fire control solution. Weighing more than 3000 pounds (1363 kilograms), the Mark 1 itself was installed in the plotting room, a water tight compartment that was located deep inside the ship's hull to provide as much protection against battle damage as was possible.