This page is for software emulating gaming consoles. For a general overview of virtualization, see Virtualization.
Emulation is the replication of the same or different hardware via either hardware or software. Emulating a system within another system has significant performance penalties due to the need of conversion through an interpreter, as systems such as PC, Android, PlayStation, Atari, and NES all have significantly different hardware and instruction sets. Running a game intended for one type of device on fundamentally different hardware therefor requires emulating most if not all of the original hardware, such as Sega Mega Drive and Genesis Classics running the Sega Genesis title Sonic the Hedgehog (1991) on modern PCs. The performance penalty incurred is directly related to how accurate the emulation is, and emulators targeting as accurate behaviour as possible of the emulated hardware often requires an order of magnitude of more processing power.
- Emulation General Wiki - A large wiki dedicated to video game emulation
- Video game console emulator
- List of video game emulators
Usage of emulation
To run software using an emulator, one usually needs the following:
- Emulator program binaries for the host platform
- Original software, copies of which are sometimes called "dumps"
- BIOSes or firmware copies, when applicable
Emulation is an extremely cost-effective way to distribute old games for more recent hardware, so it increases chances of old games being officially re-released. Re-releases / remakes using emulators are gaining ground and visibility on official stores.
- Gametap (now defuncted) offered emulated games.
- On consoles, Nintendo's Virtual Console and Sony's PS2 Classics are emulation-based services
- DOSBox is used by Steam and GOG.com for almost all DOS games
- Neo Geo games available on Humble Bundle are pre-configured emulator+game packages.
Emulation-based official releases almost always fail to provide the following information, that PCGamingWiki game pages may document:
- compatibility with any other emulator 
- emulator release used, hardware configuration for PC games
- exact version of the game: PAL/NTSC release, World/USA/Japan/Europe/other release, disk/CD version, etc.
Emulation had struggled to prove itself as a legal option for preservation before the precedent Bleem! vs Sony case .
Game companies often fail to properly preserve their titles and document them for later generations.
Currently, emulators are considered legal to develop and to distribute, as long as they are not bundled with copyrighted software.
Emulation allows modifying or extending the behavior of the original software, for instance:
- Upscaling - increasing game resolution and usage of custom textures for 3D hardware-rendered games.
- Netplay - for games that originally offered couch co-op.
- Mods - game mods and translations, via unofficial patches
- TAS - input-based gameplay record and playback. Emulators can be very convenient for speedruns and TAS (Tool Assisted Speedruns) in particular.
- Hardware customization - DOS games on GOG.com or Steam are pre-configured, however guest sound card or the display device, since these are virtual and handled by the emulator. This is explained in greater detail in the DOSBox article. The Dolphin emulator also allows for CPU overclocking among other hardware customization.
Official re-release dumps of original software can be DRM-free, however if the dumps are encrypted and obfuscated, they are likely tied to the bundled emulator. DRM-free dumps can be used in other emulators that can offer more features than the bundled emulator.
Unobfuscated DRM-free emulation-based releases are the most convenient way to acquire a license for old console-based games that are no longer sold in their original format.
An alternative is to buy the original game, and dump it using an appropriate device. However, it could be less than obvious depending on the hardware/game, and making private backups is not something that every jurisdiction in the world allows.
Identifying emulators and dumps
One can try to check the game installation directory for an executable file that looks like an emulator name or short name. If you find such a file, you may be able to then identify the emulator version by checking the binaries properties, such as the Product Description on Windows (right click > properties). Most of the time, the packaged emulator will be a custom one, though, so it is not obvious to know what it actually is and how accurate it is.
Some emulators have a built-in database of game dumps they know of, which allows precise identification of a game or software by automatically comparing the entries in the database against a file provided by the user.
MAME is one of the emulators with such functionality.
Here is an example with Altered Beast from SEGA Mega Drive & Genesis Classics (dumps are in the "uncompressed ROMs" installation subfolder):
mame64.exe -romident ALTEREDB_UE.68K Identifying ALTEREDB_UE.68K.... ALTEREDB_UE.68K = mpr-12538f.ic1 megadriv:altbeast Altered Beast (Euro, USA)
This tells us that this is compatible with MAME and that the game dump corresponds to the Europe (Megadrive) and USA (Genesis) release of Altered Beast (and we don't have the japanese release available). "megadriv" is the name of the emulation driver, "altbeast" the short name defined in MAME for the entry.
Note that MAME database does not keep track of bad dumps, which are discarded when found. If a bad dump was found, "NO MATCH" would have been the output. Bad dumps are bad copies or hacks, however, MAME and other emulators may be able to run them.
List of PCGW emulator pages
- Ars Technica - Accuracy takes power: one man’s 3GHz quest to build a perfect SNES emulator - last accessed on 2022-09-17
- "It doesn't take much raw power to play Nintendo or SNES games on a modern PC; emulators could do it in the 1990s with a mere 25MHz of processing power. But emulating those old consoles accurately—well, that's another challenge entirely; accurate emulators may need up to 3GHz of power to faithfully recreate aging tech."