Electronics aboard a boat usually refers to the marine navigation and communication electronics found at the helm. Until the last couple of decades, each individual function had its own readout or screen. Today, multi-function devices, or MFDs, pull together the signals from radars, depthsounders, GPS receivers, infared and closed-circuit cameras, engine and generator inputs, and many others. All this information can be displayed in numerous ways on the MFD screen. The information on a single screen at the lower helm can be duplicated on a screen at the upper helm, and it is not unusual to have multiple screens at either location.