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A ROM image, or ROM file, is a
computer file A computer file is a computer resource for recording data Data (; ) are individual facts, statistics, or items of information, often numeric. In a more technical sense, data are a set of values of qualitative property, qualitative or quant ...
which contains a copy of the data from a
read-only memory Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing sof ...
chip Chip may refer to: Food * Chip (snack type) A chip (American English and Australian English) or crisp (British English) is a snack food in the form of a crisp, flat or slightly bowl shaped, bite-sized unit. Some chips can be made into Dish (f ...
, often from a
video game cartridge A game cartridge, usually referred to in context simply as a cartridge, cart, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, electron ...
, or used to contain a computer's
firmware In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and soft ...
, or from an
arcade game An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily game of skill, games of skill and in ...

arcade game
's
main board A motherboard (also called mainboard, main circuit board, system board, baseboard, planar board, logic board, or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It holds and allows communic ...
. The term is frequently used in the context of
emulation Emulation may refer to: Computing *Emulator, imitation of behavior of a computer or other electronic system with the help of another type of computer/system **Video game console emulator, a program that allows a personal computer or video game co ...
, whereby older games or firmware are copied to ROM files on modern computers and can, using a piece of software known as an
emulator In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run so ...
, be run on a different device than which they were designed for. ROM burners are used to copy ROM images to
hardware Hardware may refer to: Technology Computing and electronics * Computer hardware, physical parts of a computer * Digital electronics, electronics that operate on digital signals * Electronic component, device in an electronic system used to affect e ...

hardware
, such as ROM cartridges, or ROM chips, for
debugging In computer programming Computer programming is the process of designing and building an executable In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, caus ...

debugging
and
QA testing
QA testing
.


Creation

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 The Doctor V64 (also referred to simply as the V64) is a development Development or developing may refer to: Arts *Development hell Development hell, development purgatory, development limbo, or production hell, is a media Media may refe ...
, or the
Retrode The Retrode is a USB adapter for legacy video game#REDIRECT Video game A video game is an electronic game that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, key ...
. Dumping ROMs from arcade machines, which are highly customized
PCBs A polychlorinated biphenyl (PCB) is an organic chlorine compound with the formula C12H10−''x''Cl''x''. Polychlorinated biphenyls were once widely deployed as dielectric In electromagnetism Electromagnetism is a branch of physics i ...

PCBs
, often requires individual setups for each machine along with a large amount of expertise.


Copy protection mechanisms

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 The is a home video game console A home video game console is a video game console that is designed to be connected to a display device, such as a television, and an external power source as to play video games. Home consoles are generall ...

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 In computer security, a vulnerability is a weakness which can be Exploit (computer security), exploited by a threat actor, such as an attacker, to cross privilege boundaries (i.e. perform unauthorized actions) within a computer system. To exploit ...
was found in
Phantasy Star Online Episode I & II ''Phantasy Star Online'' is an online role-playing video game, role-playing game (RPG) developed by Sonic Team and published by Sega in 2000 for the Dreamcast. It was the first Online game, online RPG for Video game console, game consoles; playe ...
that GameCube games could be successfully copied, using the GameCube itself to read the discs.
SNK is a Japanese video game hardware and software company. It is the successor to the company Shin Nihon Kikaku and presently owns the SNK video game brand and the Neo Geo Neo Geo is a family of video game hardware developed by SNK. On the mar ...
also employed a method of copy prevention on their
Neo Geo Neo Geo is a family of video game hardware developed by SNK is a Japanese video game hardware and software company. It is the successor to the company Shin Nihon Kikaku and presently owns the SNK video game brand and the Neo Geo video game ...
games, starting with ''
The King of Fighters ''The King of Fighters'' (''KOF'') is a series of fighting game A fighting game (also known as versus fighting game) is a video game genre that involve combat between pairs of fighters with game elements such as blocking, grappling, cou ...
'' 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 A hacker is a person skilled in information technology who uses their technical knowledge to achieve a goal or overcome an obstacle, within a computerized system by non-standard means. Though the term ''hacker'' has become associated in popula ...
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 is a Japanese video game developer and publisher. It has created a number of List of best-selling video game franchises, multi-million-selling game franchises, with its most commercially successful being ''Resident Evil'', ''Monster Hunter'', ...

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 MAME (originally an acronym An acronym is a word In linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), gestu ...

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 The or CPS-3 is an arcade system board that was first used by Capcom in 1996 with the arcade game ''Red Earth (video game), Red Earth''. It was the second successor to the CP System arcade hardware, following the CP System II. It would be the las ...
. This was resistant to emulation attempts until June 2007, when the encryption method was
reverse-engineered Reverse engineering (also known as backwards engineering or back engineering) is a process or method through the application of which one attempts to understand through deductive reasoning Deductive reasoning, also deductive logic, is the proces ...

reverse-engineered
by Andreas Naive. It is currently implemented by
MAME MAME (originally an acronym An acronym is a word In linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language), gestu ...

MAME
and a variant of the CPS-2 emulator Nebula.


Uses


Emulation

Video game console emulator A video game console emulator is a type of emulator In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest'' ...
s typically take ROM images as Input (computer science), input files.


Software ROM

ROM images are used when developing for Embedded system, 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.


Digital preservation

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.


Hacks and fan translations

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. ROM hacking, Hacks can often take humorous forms, as is the case with a hack of the Nintendo Entertainment System, NES version of ''Mario Bros.'', titled ''Afro Mario Brothers'', which features the famous brothers wearing Afro, 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 translation, 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 calle
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 (series), 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 Nintendo 64, 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 (video game), 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.


Similar image types

Image files derived from Magnetic tape data storage, 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 Research, 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.


References

{{reflist


External links


Nintendo's Intellectual Property FAQ


* [http://www.worldofspectrum.org/EmuFAQ2000/EmuFAQ_Y2KAddendum2.htm EmuFAQ Addendum - The Question of ROMs] Computer memory Embedded systems Firmware Video game emulation