Video game console emulator
A video game console emulator is a type of emulator that allows a computing device to emulate a video game console's hardware and play its games on the emulating platform. More often than not, emulators carry additional features that surpass limitations of the original hardware, such as broader controller compatibility, timescale control, easier access to memory modifications, and unlocking of gameplay features. Emulators are also a useful tool in the development process of homebrew demos and the creation of new games for older, discontinued, or rare consoles.
The code and data of a game are typically supplied to the emulator by means of a ROM file or an ISO image. While emulation software itself is legal as long as it doesn't infringe copyright protections on the console, emulating games is only so when legitimately purchasing the game physically and ripping the contents. Freely downloading or uploading game ROMs across various internet sites is considered to be a form of online piracy, and users may be sued for copyright infringement.
History
By the mid-1990s, personal computers had progressed to the point where it was technically feasible to replicate the behavior of some of the earliest consoles entirely through software, and the first unauthorized, non-commercial console emulators began to appear. These early programs were often incomplete, only partially emulating a given system, resulting in defects. Few manufacturers published technical specifications for their hardware, which left programmers to deduce the exact workings of a console through reverse engineering. Nintendo's consoles tended to be the most commonly studied, for example the most advanced early emulators reproduced the workings of the Nintendo Entertainment System, the Super Nintendo Entertainment System, and the Game Boy. The first such recognized emulator was released around 1996, being one of the prototype projects that eventually merged into the SNES9X product. Programs like Marat Fayzullin's iNES, VirtualGameBoy, Pasofami, Super Pasofami, and VSMC were the most popular console emulators of this era. A curiosity was also Yuji Naka's unreleased NES emulator for the Genesis, possibly marking the first instance of a software emulator running on a console. Additionally, as the Internet gained wider availability, distribution of both emulator software and ROM images became more common, helping to popularize emulators.Legal attention was drawn to emulation with the release of UltraHLE, an emulator for the Nintendo 64 released in 1999 while the Nintendo 64 was still Nintendo's primary console – its next console, the GameCube, would not be released until 2001. UltraHLE was the first emulator to be released for a current console, and it was seen to have some effect on Nintendo 64 sales, though to what degree compared with diminishing sales on the aging consoles was not clear. Nintendo pursued legal action to stop the emulator project, and while the original authors ceased development, the project continued by others who had gotten the source code. Since then, Nintendo has generally taken the lead in actions against emulation projects or distributions of emulated games from their consoles compared to other console or arcade manufacturers.
This rise in popularity opened the door to foreign video games, and exposed North American gamers to Nintendo's censorship policies. This rapid growth in the development of emulators in turn fed the growth of the ROM hacking and fan-translation. The release of projects such as RPGe's English language translation of Final Fantasy V drew even more users into the emulation scene. Additionally, the development of some emulators has contributed to improved resources for homebrew software development for certain consoles, such as was the case with VisualBoyAdvance, a Game Boy Advance emulator that was noted by author Casey O'Donnell as having contributed to the development of tools for the console that were seen as superior to even those provided by Nintendo, so much so that even some licensed game developers used the tools to develop games for the console.
On April 17, 2024, Apple began allowing emulators on the App Store, lifting a ban that had lasted nearly 16 years. Following this decision, numerous emulators such as Delta, Sutāto, and RetroArch appeared on the store.
Methods
Emulators can be designed in three ways: purely operating in software which is the most common form such as MAME using ROM images; purely operating in hardware such as the ColecoVision's adapter to accept Atari VCS cartridges, and mixed.An emulator is created typically through reverse engineering of the hardware information as to avoid any possible conflicts with non-public intellectual property. Some information may be made public for developers on the hardware's specifications which can be used to start efforts on emulation but there are often layers of information that remain as trade secrets such as encryption details. Operating code stored in the hardware's BIOS may be disassembled to be analyzed in a clean room design, with one person performing the disassembling and another person, separately, documenting the function of the code. Once enough information is obtained regarding how the hardware interprets the game software, an emulation on the target hardware can then be constructed. Emulation developers typically avoid any information that may come from untraceable sources to avoid contaminating the clean room nature of their project. For example, in 2020, a large trove of information related to Nintendo's consoles was leaked, and teams working on Nintendo console emulators such as the Dolphin emulator for GameCube and Wii stated they were staying far away from the leaked information to avoid tainting their project.
Once an emulator is written, it then requires a copy of the game software to be obtained, a step that may have legal consequences. Typically, this requires the user to make a copy of the contents of the ROM cartridge to computer files or images that can be read by the emulator, a process known as "dumping" the contents of the ROM. A similar concept applies to other proprietary formats, such as for PlayStation CD games. While not required for emulation of the earliest arcade or home console, most emulators also require a dump of the hardware's BIOS, which could vary with distribution region and hardware revisions. In some cases, emulators allow for the application of ROM patches which update the ROM or BIOS dump to fix incompatibilities with newer platforms or change aspects of the game itself. The emulator subsequently uses the BIOS dump to mimic the hardware while the ROM dump is used to replicate the game software.
ROM files and ISO files are created by either specialized tools for game cartridges, or regular optical drives reading the data. As an alternative, specialized adapters such as the Retrode allow emulators to directly access the data on game cartridges without needing to copy it into a ROM image first.
Perspectives
Outside of official usage, emulation has generally been seen negatively by video game console manufacturers and game developers. The largest concern is the nature of copyright infringement related to ROM images of games, typically distributed freely and without hardware restrictions. While this directly impacts potential sales of emulated games and thus the publishers and developers, the nature of the value chain of the industry can lead to potential financial harm to console makers. Further, emulation challenges the industry's use of the razorblade model for console games, where consoles are sold near cost and revenue instead obtained from licenses on game sales. With console emulation being developed even while consoles are still on the market, console manufacturers are forced to continue to innovate, bring more games for their systems to market, and move quickly onto new technology to continue their business model. There are further concerns related to intellectual property of the console's branding and of games' assets that could be misused, though these are issues less with emulation itself but with how the software is subsequently used.Alternatively, emulation is seen to enhance video game preservation efforts, both in shifting game information from outdated technology into newer, more persistent formats, and providing software or hardware alternates to aged hardware. Concerns about cost, availability, and longevity of game software and console hardware have also been cited as a reason for supporting the development of emulators. Some users of emulation also see emulation as means to preserve games from companies that have long-since gone bankrupt or disappeared from the industry's earlier market crash and contractions, and where ownership of the property is unclear. Emulation can also be seen as a means to enhance functionality of the original game that would otherwise not be possible, such as adding in localizations via ROM patches or new features such as save states. In November 2021, Phil Spencer stated that he hoped for video game companies to eventually develop and propagate legal emulation which would allow users to play any game from the past that they already owned a copy of, characterizing it as "a great North Star" for the industry to aim towards in the future.
Legal issues
United States
As computers and global computer networks continued to advance and become more popular, emulator developers grew more skilled in their work, the length of time between the commercial release of a console and its successful emulation began to shrink. Fifth generation consoles such as Nintendo 64, PlayStation and sixth generation handhelds, such as the Game Boy Advance, saw significant progress toward emulation during their production. This led to an effort by console manufacturers to stop unofficial emulation, but consistent failures such as Sega v. Accolade 977 F.2d 1510, Sony Computer Entertainment, Inc. v. Connectix Corporation 203 F.3d 596, and Sony Computer Entertainment America v. Bleem 214 F.3d 1022, have had the opposite effect, which has ruled that emulators, developed through clean room design, are legal. The Librarian of Congress, under the Digital Millennium Copyright Act, has codified these rules as allowed exemptions to bypass technical copyright protections on console hardware. However, emulator developers cannot incorporate code that may have been embedded within the hardware BIOS, nor ship the BIOS image with their emulators.Unauthorized distribution of copyrighted code remains illegal, according to both country-specific copyright and international copyright law under the Berne Convention. Accordingly, video game publishers and developers have taken legal action against websites that illegally redistribute their copyrighted software, successfully forcing sites to remove their titles or taking down the websites entirely.
Under United States law, obtaining a dumped copy of the original machine's BIOS is legal under the ruling Lewis Galoob Toys, Inc. v. Nintendo of America, Inc., 964 F.2d 965 as fair use as long as the user obtained a legally purchased copy of the machine. To mitigate this however, several emulators for platforms such as Game Boy Advance are capable of running without a BIOS file, using high-level emulation to simulate BIOS subroutines at a slight cost in emulation accuracy.
Newer consoles have introduced one or more layers of encryption to make emulation more difficult from a technical perspective but also can create further legal challenges under the DMCA, which forbids the distribution of tools and information on how to bypass these layers. The Nintendo Switch emulator Yuzu had been sued by Nintendo because the group behind the emulator had provided such information on how to obtain the required decryption keys, leading the group to settle with Nintendo and removing the emulator from distribution. Forked projects from Yuzu since appeared, taking the route of informing users what decryption items they would need but otherwise not stating how to acquire these as to stay within Nintendo's stance against emulation and copyright infringement.