and looked to develop that into a home version, which was released in 1975. The first consoles were capable of playing only a very limited number of games built into the hardware. Programmable consoles using swappable ROM cartridges were introduced with the Fairchild Channel F in 1976, though popularized with the Atari 2600 released in 1977. Handheld consoles emerged from technology improvements in handheld electronic games as these shifted from mechanical to electronic/digital logic, and away from light-emitting diode (LED) indicators to liquid-crystal displays (LCD) that resembled video screens more closely. Early examples include the Microvision in 1979 and Game & Watch in 1980, and the concept was fully realized by the Game Boy in 1989. Both home and handheld consoles have become more advanced following global changes in technology. These technological shifts include including improved electronic and computer chip manufacturing to increase computational power at lower costs and size, the introduction of 3D graphics and hardware-based graphic processors for real-time rendering, digital communications such as the Internet, wireless networking and Bluetooth, and larger and denser media formats as well as digital distribution. Following the same type of Moore's law progression, home consoles are grouped into generations, each lasting approximately five years. Consoles within each generation share similar specifications and features, such as processor word size. While no one grouping of consoles by generation is universally accepted, one breakdown of generations, showing representative consoles, of each is shown below. Types Most consoles are considered programmable consoles and have the means for the player to switch between different games. Traditionally, this has been done by switching a physical game cartridge or game card or through using optical media. It is now common to download games through digital distribution and store them on internal or external digital storage devices. Dedicated consoles were very popular in the first generation until they were gradually replaced by second generation that use ROM cartridges. The fourth generation gradually merged to optical media. It is now common to download games through digital distribution and store them on internal or external digital storage devices. Some consoles are considered dedicated consoles, in which games available for the console are "baked" onto the hardware, either by being programmed via the circuitry or set in the read-only flash memory of the console. Thus, the console's game library cannot be added to or changed directly by the user. The user can typically