In what two decades did an  electronic, digital or computer device that outputs a video signal or visual image to display a video game that one or more people can play, become popular?
1970s and 1980s
Video game console
A video game console is an electronic, digital or computer device that outputs a video signal or visual image to display a video game that one or more people can play.
Early history of video games
The history of video games spans a period of time between the invention of the first electronic games and today, covering a long period of invention and changes.
 Video gaming would not reach mainstream popularity until the 1970s and 1980s, when arcade video games, gaming consoles and home computer games were introduced to the general public.
 Since then, video gaming has become a popular form of entertainment and a part of modern culture in most parts of the world.
 The early history of video games, therefore, covers the period of time between the first interactive electronic game with an electronic display in 1947, the first true video games in the early 1950s, and the rise of early arcade video games in the 1970s ("Pong" and the beginning of the first generation of video game consoles with the Magnavox Odyssey, both in 1972).
 During this time there were a wide range of devices and inventions corresponding with large advances in computing technology, and the actual first video game is dependent on the definition of "video game" used.
Electronic drum module
An electronic drum module is an electronic or digital music device in an electronic drum kit that serves as the central processing unit and sound module.
 The drum module creates or produces the drum kit sounds or other sounds selected by the drummer.
 By itself, a drum module cannot play or sound drum beats.
 It only produces drum sounds when a performer strikes electronic drum pads or acoustic drum kit instruments that have electronic "triggers" (or sensors) attached to them.
 When the electronic drum pads or trigger-equipped instruments are struck, this sends a signal to the drum module, which produces the corresponding electronic drum sound (or other sound).
 Even when drum pads and/or triggers are connected to a drum module, the drum module by itself does not make any audible sound.
 Like other electronic instruments such as the synthesizer, the drum module only outputs an electronic signal.
 The performer can hear this signal by connecting headphones to the drum module (i.e., for individual practice) or by plugging the drum module into a amplifier and loudspeaker or PA system for audible practice or live performances.
 The drum module's output signal can also be patched into an audio console for concerts or sound recording.
 The nomenclature varies (see below).
 For example, electronic drum modules are called "percussion sound modules" in the case of Roland Corporation, or sometimes simply modules.
 A common colloquial term for this device is drum brain.
 (see below). Clean feed (television)
In television technology, a clean feed is a video signal that does not have added graphics and text.
 This video signal is used in sport production to allow different television stations to add their own digital on-screen graphic image on a common signal, or in news broadcasting to produce two or more different streams, each one with the same picture but in different languages. Video display controller
A video display controller or VDC (also regularly called display engine, display interface) is an integrated circuit which is the main component in a video signal generator, a device responsible for the production of a TV video signal in a computing or game system.
 Some VDCs also generate an audio signal, but that is not their main function. Flicker fixer
A flicker fixer or scan doubler is a piece of computer hardware that de-interlaces an output video signal.
 The flicker fixer accomplishes this by adjusting the timing of the natively interlaced video signal to suit the needs of a progressive display Ex: CRT computer monitor.
 Flicker fixers in essence create a progressive frame of video from two interlaced fields of video. Video synthesizer
A video synthesizer is a device that electronically creates a video signal.
 A video synthesizer is able to generate a variety of visual material without camera input through the use of internal video pattern generators.
 It can also accept and "clean up and enhance" or "distort" live television camera imagery.
 The synthesizer creates a wide range of imagery through purely electronic manipulations.
 This imagery is visible within the output video signal when this signal is displayed.
 The output video signal can be viewed on a wide range of conventional video equipment, such as TV monitors, theater video projectors, computer displays, etc. Composite monitor
A composite monitor is any analog video display that receives input in the form of an analog composite video signal to a defined specification.
 A composite video signal encodes all information on a single conductor; a composite cable has a single live conductor plus earth.
 Other equipment with display functionality includes monitors with more advanced interfaces and connectors giving a better picture, including analog VGA, and digital DVI, HDMI, and DisplayPort; and television (TV) receivers which are self-contained, receiving and displaying video RF broadcasts received with an internal tuner.
 Video monitors are used for displaying computer output, closed-circuit television (e.g. security cameras) and other applications requiring a two-dimensional monochrome or colour image. Video-signal generator
A video signal generator is a type of signal generator which outputs predetermined video and/or television oscillation waveforms, and other signals used in the synchronization of television devices and to stimulate faults in, or aid in parametric measurements of, television and video systems.
 There are several different types of video signal generators in widespread use.
 Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses (in analog) or sync words (in digital).
 Generators of "composite" video signals (such as NTSC and PAL) will also include a colorburst signal as part of the output. Analog Protection System
The Analog Protection System (APS), also known as Copyguard, is a DVD copy prevention system originally developed by Macrovision.
 Video tapes copied from DVDs encoded with APS become garbled and unwatchable.
 The process works by adding pulses to analog video signals to negatively impact the AGC circuit of a recording device.
 In digital devices changes to the analog video signal are created by a chip that converts the digital video to analog within the device.
 In DVD players trigger bits are created during DVD authoring to inform the APS that it should be applied to DVD players analog outputs or analog video outputs on a PC while playing back a protected DVD-Video disc.
 In set top boxes trigger bits are incorporated into Conditional Access Entitlement Control Messages (ECM) in the stream delivered to the STB.
 In VHS alterations to the analog video signal are added in a Macrovision-provided “processor box” used by duplicators.