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A ROM image, or ROM file, is a computer file which contains a copy of the data from a read-only memory chip, often from a video game cartridge, or used to contain a computer's firmware, or from an arcade game's main board. The term is frequently used in the context of emulation, whereby older games or firmware are copied to ROM files on modern computers and can, using a piece of software known as an emulator, be run on a different device than which they were designed for. ROM burners are used to copy ROM images to hardware, such as ROM cartridges, or ROM chips, for debugging and QA testing.
ROMs can be copied from the read-only memory chips found in cartridge-based games and many arcade machines using a dedicated device in a process known as dumping. For most common home video game systems, these devices are widely available, examples being the Doctor V64, or the Retrode.
Dumping ROMs from arcade machines, which are highly customized PCBs, often requires individual setups for each machine along with a large amount of expertise.
While ROM images are often used as a means of preserving the history of computer games, they are also often used to facilitate the unauthorized copying and redistribution of modern games. Viewing this as potentially reducing sales of their products, many game companies have incorporated so-called features into newer games which are designed to prevent copying, while still allowing the original game to be played. For instance, the Nintendo GameCube used non-standard 8 cm DVD-like optical media, which for a long time prevented games stored on those discs from being copied. It was not until a security hole was found in Phantasy Star Online Episode I & II that GameCube games could be successfully copied, using the GameCube itself to read the discs.
SNK also employed a method of copy prevention on their Neo Geo games, starting with The King of Fighters in 1999, which used an encryption algorithm on the graphics ROMs to prevent them from being played in an emulator. Many thought that this would mark the end of Neo Geo emulation. However, as early as 2000, hackers found a way to decrypt and dump the ROMs successfully, making them playable once again in a Neo Geo emulator.
Another company which used to employ methods of copy prevention on their arcade games was Capcom, which is known for its CPS-2 arcade board. This contained a heavy copy protection algorithm which was not broken until 7 years after the system's release in 1993. The original crack by the CPS2Shock Team was not a true emulation of the protection because it used XOR tables to bypass the original encryption and allow the game to play in an emulator. Their stated intent was to wait until CPS-2 games were no longer profitable to release the decryption method (three years after the last game release).The full decryption algorithm was cracked in 2007 by Nicola Salmoria, Andreas Naive and Charles MacDonald of the MAME development team.
Another copy prevention technique used in cartridge-games was to have the game attempt to write to ROM. On an authentic cartridge this would do nothing; however, emulators would often allow the write to succeed. Pirate cartridges also often used writable chips instead of ROM. By reading the value back to see whether the write succeeded, the game could tell whether it was running from an authentic cartridge. Alternatively, the game may simply attempt to overwrite critical program instructions, which if successful renders it unplayable.
Some games, such as Game Boy games, also had other hardware such as memory bank controllers connected to the cartridge bus. The game would send data to this hardware by attempting to write it to specific areas of ROM; thus, if the ROM were writable, this process would corrupt data.
Capcom's latest arcade board is the CPS-3. This was resistant to emulation attempts until June 2007, when the encryption method was reverse-engineered by Andreas Naive. It is currently implemented by MAME and a variant of the CPS-2 emulator Nebula.
Video game console emulators typically take ROM images as input files.
ROM images are used when developing for embedded computers. Software which is being developed for embedded computers is often written to ROM files for testing on a standard computer before it is written to a ROM chip for use in the embedded systems.
The lifespan of digital media is rarely great. While black-and-white photographs may survive for a century or more, many digital media can become unreadable after only 10 years. This is beginning to become a problem as early computer systems may be presently fifty or sixty years old while early home video consoles may be almost thirty years old. Due to this aging, there is a significant worry that many early computer and video games may not survive without being transferred to new media. So, those with an interest in preservation are actively seeking older arcade and video games and attempting to dump them to ROM images. When stored on standardized media such as CD-ROMs and DVD-ROMs, they can be copied to future media with significantly reduced effort.
The trend towards mass digital distribution of ROM image files, while potentially damaging to copyright holders, may also have a positive effect on preservation. While over time many original ROM copies of older games may deteriorate, be broken or thrown away, a copy in file form may be distributed throughout the world, allowing games which would otherwise have been lost a greater chance of survival.
Once games have been made available in ROM format, it is possible for users to make modifications. This may take the form of altering graphics, changing game levels, tweaking difficulty factor, or even translation into a language for which a game was not originally made available. Hacks can often take humorous forms, as is the case with a hack of the NES version of Mario Bros. , titled Afro Mario Brothers, which features the famous brothers wearing Afro haircuts. The Metroid Redesign mod is a hack of Super Metroid that revamps the game and adds new objectives.
A large scene has developed to translate games into other languages. Many games receive a release in one part of the world, but not in another. For example, many role-playing video games released in Japan go unreleased in the West and East outside Japan. A group of fan translators will often translate the game themselves to meet demand for titles. For example, the 1995 game Tales of Phantasia was only officially released in Japan; DeJap Translations translated the game's on-screen text into English in 2001. Further to this, a project called Vocals of Phantasia was begun to translate the actual speech from the game. An official English version was not released until March 2006, some five years after the text translation was released. Another example was that of Mother 3, a Japan-only sequel to the cult-favorite Earthbound. In spite of massive fan response and several petitions for an English translation, the only response from Nintendo was that Mother 3 would be translated and released in Europe, which it never was. Instead, the fan website Starmen.net undertook a massive translation project and released the translated version of Mother 3 in October, 2008. The translation was praised by fans and even employees from Nintendo, Square Enix, and other industry professionals.
The Japanese N64 game Dōbutsu no Mori (Animal Forest) has also been translated into English. The game was originally only released on N64 in Japan, but it was ported to GameCube and renamed Animal Crossing.
Hacks may range from simple tweaks such as graphic fixes and cheats, to full-blown redesigns of the game, in effect creating an entirely new game using the original as a base.
Image files derived from computer tape are known as tape images, while those derived from floppy disks and CD-ROMs (and other disk formats) are known as disk images. Images copied from optical media are also called ISO images, after one of the standard file systems for optical media, ISO 9660.
Creating images from other media is often considerably easier and can often be performed with off-the-shelf hardware. For example, the creation of tape images from games stored on magnetic tapes (from, for example, the Sinclair ZX80 computer) generally involves simply playing the magnetic tape using a standard audio tape player connected to the line-in of a PC sound card. This is then recorded to an audio file and transformed into a tape image file using another program. Likewise, many CD and DVD games may be copied using a standard PC CD/DVD drive.
The Atari 7800 ProSystem, or simply the Atari 7800, is a home video game console officially released by the Atari Corporation in 1986. It is almost fully backward-compatible with the Atari 2600, the first console to have backward compatibility without the use of additional modules. It was considered affordable at a price of US$140.
The Intellivision is a home video game console released by Mattel Electronics in 1979. The name Intellivision is a portmanteau of "intelligent television". Development of the console began in 1977, the same year as the introduction of its main competitor, the Atari 2600. In 1984 Mattel sold their video game assets to a former Mattel Electronics executive and investors that would become INTV Corporation. Games development started in 1978 and continued until 1990 when the Intellivision was discontinued. From 1980 to 1983 over 3 million Intellivision units were sold.
The Neo Geo, stylised as NEO•GEO, also written as NEOGEO, is a cartridge-based arcade system board and fourth-generation home video game console released on April 26, 1990, by Japanese game company SNK Corporation. It was the first system in SNK's Neo Geo family. The Neo Geo was marketed as 24-bit; its CPU is technically a 16/32-bit 68000-based system with an 8/16-bit Z80 coprocessor, while its GPU chipset has a 24-bit graphics data bus.
The Magnavox Odyssey 2, also known as Philips Odyssey 2, is a second generation home video game console that was released in 1978. It was sold in Europe as the Philips Videopac G7000, in Brazil as the Philips Odyssey and in Japan as Odyssey2. The Odyssey 2 was one of the major three home consoles prior to the 1983 video game market crash, along with Atari 2600 and Intellivision.
UAE is a computer emulator which emulates the hardware of Commodore International's Amiga range of computers. Released under the GNU General Public License, UAE is free software.
MAME is a free and open-source emulator designed to recreate the hardware of arcade game systems in software on modern personal computers and other platforms. The intention is to preserve gaming history by preventing vintage games from being lost or forgotten. The aim of MAME is to be a reference to the inner workings of the emulated arcade machines; the ability to actually play the games is considered "a nice side effect". Joystiq has listed MAME as an application that every Windows and Mac gamer should have.
The BallyAstrocade is a second-generation home video game console and simple computer system designed by a team at Midway, at that time the videogame division of Bally. It was originally announced as the "Bally Home Library Computer" in October 1977 and initially made available for mail order in December 1977. But due to production delays, the units were first released to stores in April 1978 and its branding changed to "Bally Professional Arcade". It was marketed only for a limited time before Bally decided to exit the market. The rights were later picked up by a third-party company, who re-released it and sold it until around 1984. The Astrocade is particularly notable for its very powerful graphics capabilities for the time of release, and for the difficulty in accessing those capabilities.
Visual Pinball is a freeware and source available video game engine for pinball tables and similar games such as pachinko machines. The software is composed of an editor and the simulator part itself. It runs on Microsoft Windows. The program is also able to operate with Visual PinMAME, an emulator for ROM images from real pinball machines.
In video gaming, a fan translation is an unofficial translation of a video game made by fans.
Multi Emulator Super System (MESS) is an emulator for various consoles and computer systems, based on the MAME core. It used to be a standalone program, but is now integrated into MAME. MESS emulates portable and console gaming systems, computer platforms, and calculators. The project strives for accuracy and portability and therefore is not always the fastest emulator for any one particular system. Its accuracy makes it also useful for homebrew game development.
The CP System II or CPS-2 is an arcade system board that Capcom first used in 1993 for Super Street Fighter II. It was the successor to their previous CP System and Capcom Power System Changer arcade hardware and was succeeded by the CP System III hardware in 1996, of which the CPS-2 would outlive by over four years. The arcade system had new releases for it until the end of 2003, ending with Hyper Street Fighter II.
The CP System III or CPS-3 is an arcade system board that was first used by Capcom in 1996 with the arcade game Red Earth. It was the second successor to the CP System arcade hardware, following the CP System II. It would be the last proprietary system board Capcom would produce before moving on to the Dreamcast-based Naomi platform.
ROM hacking is the process of modifying a ROM image or ROM file of a video game to alter the game's graphics, dialogue, levels, gameplay, and/or other elements. This is usually done by technically inclined video game fans to breathe new life into a cherished old game, as a creative outlet, or to make essentially new unofficial games using the old game's engine.
Homebrew is a term frequently applied to video games or other software produced by consumers to target proprietary hardware platforms that are not typically user-programmable or that use proprietary storage methods. This can include games developed with official development kits, such as Net Yaroze, Linux for PlayStation 2 or Microsoft XNA. A game written by a non-professional developer for a system intended to be consumer-programmable, like the Commodore 64, is simply called hobbyist.
Retrogaming, also known as classic gaming and old school gaming, is the playing or collecting of older personal computer, console, and/or arcade video games in contemporary times. Usually retrogaming is based upon systems that are obsolete or discontinued.
A game backup device, formerly usually called a copier and more recently a flash cartridge, is a device for backing up ROM information from a video game cartridge to a computer file called a ROM image and playing them back on the real hardware. Recently flash cartridges, especially on the Game Boy Advance and Nintendo DS platforms, only support the latter function; they cannot be used for backing up ROM data. Game backup devices also make it possible to develop homebrew software on video game systems. Game backup devices differ from modchips in that modchips are used in conjunction with systems that use generally available media such as CDs and DVDs, whereas game backup devices are used with systems that use cartridges.
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 the limitations of the original hardware, such as broader controller compatibility, timescale control, greater performance, clearer quality, easier access to memory modifications, one-click cheat codes, 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 more rare consoles.
In computing, an emulator is hardware or software that enables one computer system to behave like another computer system. An emulator typically enables the host system to run software or use peripheral devices designed for the guest system. Emulation refers to the ability of a computer program in an electronic device to emulate another program or device. Many printers, for example, are designed to emulate HP LaserJet printers because so much software is written for HP printers. If a non-HP printer emulates an HP printer, any software written for a real HP printer will also run in the non-HP printer emulation and produce equivalent printing. Since at least the 1990s, many video game enthusiasts have used emulators to play classic arcade games from the 1980s using the games' original 1980s machine code and data, which is interpreted by a current-era system.
Atari System refers to two arcade system boards introduced in 1984 for use in various arcade games from Atari Games. Two versions of the board were released, Atari System 1 and Atari System 2.
Video game preservation is a form of digital preservation applied to the video game industry. Such preservation efforts include archiving development source code and art assets, digital copies of video games, emulation of video game hardware, maintenance and preservation of specialized video game hardware such as arcade games and video game consoles, and digitization of print video game magazines and books prior to the Digital Revolution.
Fans of classic games argue that emulation preserves video arcade games, many of which would otherwise be approaching extinction.
MAME is strictly a non-profit project. Its main purpose is to be a reference to the inner workings of the emulated arcade machines. This is done both for educational purposes and for preservation purposes, in order to prevent many historical games from disappearing forever once the hardware they run on stops working.
[T]he archivists feel that the more copyable something is, the more likely it's going to survive in the long term.