Useless machine

More elaborate devices and some novelty toys, which have an obvious entertainment function, have been based on these simple useless machines.

[4] Minsky's mentor at Bell Labs, information theory pioneer Claude Shannon (who later became an MIT professor himself), made his own versions of the machine.

[3] Minsky also invented a "gravity machine" that would ring a bell if the gravitational constant were to change, a theoretical possibility that is not expected to occur in the foreseeable future.

[8][9] (Both companies were later to be co-defendants in landmark litigation initiated by Theodor Geisel ("Dr. Seuss") over copyright issues related to figurines.

)[10][6] Both the plain black box and the bank version were widely sold by Spencer Gifts, and appeared in its mail-order catalogs through the 1960s and early 1970s.