Electro-mechanical arcade games

Periscope, an example of an early Sega electro-mechanical arcade game.

Electro-mechanical arcade games (often abbreviated EM games) are what arcades used to have before the invention of solid state electronic games (which use solid-state electronics like transistors, integrated circuits, printed circuit boards and microcontrollers.) An electro-mechanical game is any coin operated game that has neither a microprocessor (nor an approximation of one with logic gates like SHARK Jaws, Computer Space, and others used), or a proper monitor. An electro-mechanical game is run through switches, relays, motors, and lights. Any electronic circuitry in the machine will be very simple.

The most common type of electro-mechanical games were early Pinball machines—all of them up to the late seventies were electromechanical (the industry switched to microprocessors around 1978 or so). Other electro-mechanicals include most early slot machines and Pachinko machines, although the earliest ones were completely mechanical.

These games had one big problem: they broke down all the time. This is why you never see any electro-mechanicals anymore (aside from a few really old Skee Ball machines). The mean time between failures on most of these machines could be measured in days. Some were more reliable than others, but in general the more complex ones were constantly failing. Any individual game may have hundreds of moving parts, which were often subject to abuse. This makes functioning electro-mechanicals very rare today.