Arcade Games and the Earliest Home Emulators
The idea of emulation in computer science dates back to the 1950s, but it was some time before emulation would be practical for video games (which can be traced back to 1962's Spacewar!). Early arcade games and home units in the 1970s were crude enough that savvy fans could reverse-engineer and build their own versions of Home Pong or other popular games – an example of hardware emulation.
By the beginning of the 1980s, video games had become increasingly lucrative, and emulation threatened game manufacturers. Pirates used hardware emulation to make convincing clones of Nintendo's most popular Game & Watch units (portable, one-game precursors to the Game Boy), while other blockbuster arcade games of the time, such as the puzzle game Tetris, were also prominent victims of illegal emulation.
The Golden Age of Emulation: the 8- and 16-Bit Eras
The 1980s saw video game systems designed for home use, using separate game cartridges, proliferate and begin to supplant arcades in popularity. The Atari 2600, Nintendo Entertainment System, and Sega Master System dominated this era of 8-bit video game systems. By the early 1990s, The Super Nintendo and Sega Genesis battled for supremacy in the 16-bit console wars.
Personal computers were becoming powerful enough that software emulation of these early games was becoming possible. These worked by using ROM images (copies of the data from a game cartridge's Read-Only Memory chip) of old games. But as with the hardware emulators of the 1980s, these ROMs were very often illegal copies, which game publishers tried to suppress.
By the late 1990s, there was an explosion of emulators, as game libraries grew and computers got faster – and became internet-ready. One of the earliest NES emulators, NESticle, was soon followed by RockNES, Genecyst (emulating the Genesis), ZSNES, and Snes9x (emulating the Super NES), just to name a few. Sites such as Zophar's Domain made emulators and ROM images more widely available online.
Emulators have been less successful at duplicating games from the era of three-dimensional games for technical reasons – emulators such as Mupen64 (duplicating Nintendo 64 on Linux, Windows, and Mac) required top-of-the-line computers, and still could only run a few ROMs without glitches. And as systems became harder to reverse-engineer and emulate accurately, emulator development was dampened by legal action, such as when commercial PlayStation emulator Bleem! was bankrupted by a lawsuit brought by Sony.
That aside, emulation serves an important purpose in many current-generation game consoles, helping expand backward-compatibility. The Nintendo Wii emulates the hardware of the earlier Nintendo GameCube, and has a Virtual Console which emulates many systems from earlier eras, such as NES, SNES, Nintendo 64, Sega Genesis, TurboGrafx-16, and Neo Geo. Gamers are legally able to purchase and download ROM images of games first made for those systems.
Early models of the PlayStation 3 contained the same hardware as earlier PlayStations, although current production models are unable to play PS and PS2 games. The PlayStation Portable, however, does have software emulation allowing it to play some original PlayStation games. Similarly, the Xbox 360 achieves some backwards-compatibility with original Xbox games through software emulation and an added hard drive.
The State of Emulation Today
Thanks to legal concerns, and the technological barriers to emulating current systems, video game emulation remains a pastime mostly for nostalgic hobbyists. Nevertheless, emulation does provide a way for younger gamers to appreciate older hits, and video game scholars also use emulators to preserve the digital culture of yesteryear.