are constructed from their differences with great efficiency, either as printed tables or as a ."

In February 1950, in a Radio Corporation of America (RCA) advertisement in Popular Science magazine describing a new "memory" vacuum tube it had developed, RCA stated: "the results of countless computations can be kept 'on file' and taken out again. Such a 'file' now exists in a 'memory' tube developed at RCA Laboratories. Electronically it retains