The NRL electrical output charge storage tube differs from other types in that the reading time can be extended to hours or even days, yet the decay of the stored pattern is negligible. Electric charge storage with two stable equilibrium voltages makes this extended read time possible at a residual gas pressure as high as

mm Hg. The capabilities of this device are illustrated by the fact that it has been used to capture a single frame of a television picture. The reproduced picture contained tones, four levels, at approximately 300 line resolution. The tube is constructed with two magnetically focused and deflected guns, one for writing and the other for reading. Therefore this tube is not well adapted to computer application because the registration between the guns is not exact. It can be used for scan conversion, for signal integration, for capturing single transients, and for temporary storage of patterns, for example, maps and math-function curves.