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Clone (computing)
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In computing, a clone is hardware or software that is designed to function in exactly the same way as another system.[1] A specific subset of clones are remakes (or remades), which are revivals of old, obsolete, or discontinued products.
Motivation
[edit]Clones and remakes are created for reasons including competition, standardization, availability across platforms, and as homage. Compatibility with the original system is usually the explicit purpose of cloning hardware or low-level software such as operating systems (e.g. AROS and MorphOS are intended to be compatible with AmigaOS). Application software is cloned by providing the same functionality.
Commercially-motivated clones are made often during a competitor product's initial successful commercial run, intentionally competing with the original and trying to participate in their success.
Hardware
[edit]
Hardware clones
[edit]When IBM announced the IBM PC in 1981, other companies such as Compaq decided to offer clones of the PC as a legal reimplementation from the PC's documentation or reverse engineering. Because most of the components, except the PC's BIOS, were publicly available, all Compaq had to do was reverse-engineer the BIOS. The result was a machine with similar performance and lower price than the machines cloned. The use of the term "PC clone" to describe IBM PC compatible computers fell out of use in the 1990s; the class of machines it now describes are simply called PCs, but the early use of the term "clone" usually implied a higher level of compatibility with the original IBM PC than "PC-Compatible", with (often Taiwanese) clones of the original circuit (and possibly ROMs) the most compatible (in terms of software they would run and hardware tests they would pass), while "legitimate" new designs such as the Sanyo MBC-550 and Data General/One, while not infringing on copyrights and adding innovations, tended to fail some compatibility tests strongly dependent upon detailed hardware compatibility (such as ability to run Microsoft Flight Simulator, or any software that bypassed the standard software interrupts and directly accessed hardware at the expected pre-defined locations, or—in the case of the MBC-550 for example—wrote diskettes which could not be directly interchanged with standard IBM PCs).
While the term has mostly fallen into commercial disuse, the term clone for PCs still applies to a PC made to entry-level or above standard (at the time it was made) which bears no commercial branding (e.g., Acer, Dell, HP, IBM). This includes, but is not limited to, PCs assembled by home users or corporate IT departments. (See also White box (computer hardware).)
There were many Nintendo Entertainment System hardware clones due to the popularity and longevity of the Nintendo Entertainment System.
Hardware remakes
[edit]Examples for hardware remakes include recent home computer remakes.
A special kind of hardware remakes are emulators which implement the hardware functionality completely in software. For instance, the WinUAE emulator software tries to behave exactly like a physical Amiga.
Software
[edit]Software can be cloned by reverse engineering or legal reimplementation from documentation or other sources, or by observing a program's appearance and behavior. The reasons for software cloning may include circumventing undesirable licensing fees, acquiring knowledge about the features of the system or creating an interoperable alternative for an unsupported platform. GNU, a clone of UNIX, was motivated by a need of the free software movement for an operating system composed of entirely free software.
In the United States, the case of Lotus v. Borland allows the functionality of a program to be cloned so long as copyright in the code and interface is not infringed.
Yet, the public interface may also be subject to copyright to the extent that it contains expression (such as the appearance of an icon). For example, in August 2012, Electronic Arts, via its Maxis division, put forth a lawsuit against Zynga, claiming that its Facebook game, The Ville, was a direct clone of EA's own Facebook game, The Sims Social. The lawsuit challenges that The Ville not only copies the gameplay mechanics of The Sims Social, but also uses art and visual interface aspects that appear to be inspired by The Sims Social.[2][3][4] The two companies settled out of court on undisclosed terms in February 2013.[5]
Examples of software cloning include the ReactOS project which tries to clone Microsoft Windows, and GNU Octave, which treats incompatibility with MathWorks MATLAB as a bug.[6]
Video games
[edit]Since the start of the video game industry, clones of successful concepts and games have been common. The first influential first-person shooter, Doom, led in the 1990s to the creation of a new genre dubbed as Doom clones. In the 2000s, the open world action-adventure Grand Theft Auto inspired the creation of many Grand Theft Auto clones.
Software remakes
[edit]Remakes of software are revivals of old, obsolete, or discontinued software.
A good share of software remakes are fangames of computer games and game engine recreation made by the fan community as part of retrogaming, to address e.g. compatibility issues or non-availability of the original, e.g. a shutdown server gets substituted with a server emulator.
Since the 2000s there has been an increasing number of commercial remakes of classical games by the original developer or publisher for current platforms as the digital distribution lowers the investment risk for niche releases.[7] When enhanced in some way (audio, graphics, etc.) new releases might be called "high definition" release or "special edition"; an example is The Secret of Monkey Island: Special Edition.[8][9]
Other uses of the term
[edit] |
Databases
[edit]A database clone is a complete and separate copy of a database system that includes the business data, the database management system software and any other application tiers that make up the environment. Cloning is a different kind of operation to replicate and backup, in that the cloned environment is both fully functional and separate in its own right. Additionally, the cloned environment may be modified at its inception due to configuration changes or data subsetting.
Desktop
[edit]Since 2010, clone computing, in the sense of replicating a session on a host computer in a virtual instance in the cloud, has been introduced. This allows the user to have access to a copy of their PC's desktop on any other computing device such as a tablet computer, a personal computer running any operating system, WebOS, smartphones, etc.
The clone computer replicates, runs, and is always available through a series of cloud servers. Unlike remote management software, clone computing has no dependency on the host computer.
Disk cloning software
[edit]Disk cloning is the process of copying the contents of one computer hard drive to another disk or to an "image" file. Typically, the contents of the first disk are written to an image file as an intermediate step, and the second disk is loaded with the contents of the image. A cloned drive can replace the original, rather than simply containing backup copies of files.
Cloning software replicates the operating system, drives, software and patches of one computer for a variety of purposes, including setting up multiple computers, hard drive upgrades, and system recovery in the event of disk failure or corruption.[10]
Programming
[edit]In computer programming, particularly object-oriented programming, cloning refers to object copying by a method or copy factory function, often called clone or copy, as opposed to by a copy constructor. Cloning is polymorphic, in that the type of the object being cloned need not be specified, in contrast to using a copy constructor, which requires specifying the type (in the constructor call).
See also
[edit]References
[edit]- ^ clone /n./ "An exact duplicate: "Our product is a clone of their product." Implies a legal reimplementation from documentation or by reverse-engineering" from the Jargon File
- ^ Griffen, Daniel Nye (2012-08-06). "EA Sues Zynga, But Deeper Social Issues Threaten". Forbes. Retrieved 2012-08-07.
- ^ Brown, Nathan (2012-01-25). "How Zynga cloned its way to success". Edge. Archived from the original on Jul 9, 2012. Retrieved 2012-08-07.
- ^ Jamison, Peter (2010-09-08). "FarmVillains". SF Weekly. Archived from the original on Aug 2, 2012. Retrieved 2012-08-07.
- ^ Cifaldi, Frank (2013-02-15). "EA and Zynga settle The Ville copycat case out of court". Gamasutra. Archived from the original on February 17, 2013. Retrieved 2013-02-15.
- ^ 11. Porting programs from MATLAB to Octave "There are still a number of differences between Octave and MATLAB, however in general differences between the two are considered as bugs."
- ^ Walker, John (2007-11-22). "RPS Exclusive: Gabe Newell Interview". Rock, Paper, Shotgun. Retrieved 2013-06-28.
The worst days [for game development] were the cartridge days for the NES. It was a huge risk – you had all this money tied up in silicon in a warehouse somewhere, and so you'd be conservative in the decisions you felt you could make, very conservative in the IPs you signed, your art direction would not change, and so on. Now it's the opposite extreme: we can put something up on Steam, deliver it to people all around the world, make changes. We can take more interesting risks.[...] Retail doesn't know how to deal with those games. On Steam [a digital distributor] there's no shelf-space restriction. It's great because they're a bunch of old, orphaned games.
- ^ "The Secret of Monkey Island: Special Edition Tech Info". GameSpot. Archived from the original on April 2, 2010. Retrieved November 15, 2011.
- ^ Onyett, Charles (June 2, 2009). "E3 2009: The Secret of Monkey Island: Special Edition Preview". IGN. Retrieved November 15, 2011.
- ^ "Definition of cloning software". PCMAG. Retrieved 2023-08-29.
Clone (computing)
View on Grokipediafrom Grokipedia
In computing, a clone is an exact duplicate or close imitation of a digital or physical entity, such as a storage device, software application, or hardware system, often created to replicate functionality, facilitate backups, or enable compatibility.[1] This concept encompasses various applications, from duplicating entire hard drives bit-by-bit to producing compatible computer systems that mimic established architectures.[2]
One of the most common uses of cloning in computing is disk cloning, which involves copying the complete contents of a storage drive—including the operating system, applications, files, partitions, and metadata—to another drive, typically for backup, system migration, or forensic analysis.[3] Unlike simple file copying, disk cloning creates a sector-by-sector replica that can be bootable and functional on the target device, often using specialized software like Clonezilla for Linux or Carbon Copy Cloner for macOS.[2] This process is essential for upgrading hardware, such as migrating from a traditional hard disk drive (HDD) to a solid-state drive (SSD), while preserving all data and settings without reinstallation.[3]
Historically, the term "clone" gained prominence in the 1980s with PC clones, referring to IBM-compatible personal computers built by third-party manufacturers like Compaq, Dell, and HP to replicate the IBM PC's x86 architecture, allowing them to run the same MS-DOS and Windows software.[1] These clones democratized computing by making affordable alternatives to IBM's proprietary systems, establishing the open PC standard that dominates the industry today.[2]
In software development, cloning can denote application clones, which are programs designed to emulate the features of popular software, often as free or open-source alternatives for cost savings or cross-platform compatibility—examples include Inkscape as a clone of Adobe Illustrator.[1] Additionally, in version control systems like Git, cloning creates a local copy of a remote repository, enabling developers to work independently while syncing changes.[2] More specialized contexts include cloning data structures in programming, where an exact copy of objects or arrays is made to maintain structure and contents without altering the original.[4]
Cloning also appears in cybersecurity, where malicious actors may clone devices, identities, or networks to deceive systems or users, though legitimate uses focus on security testing and redundancy.[5] Overall, cloning enhances efficiency, reliability, and scalability in computing environments, from individual user backups to enterprise deployments.[3]
Fundamentals
Definition and Motivation
In computing, a clone refers to hardware or software designed to replicate the functionality, interface, or behavior of an original system, component, or application, often to achieve interoperability or exact duplication without relying on the proprietary elements of the source.[1] This replication can encompass full systems, such as personal computers compatible with an established architecture, or individual applications that mimic user interfaces and operations to support similar workflows.[2] The goal is typically to produce a functional equivalent that operates seamlessly with existing ecosystems, including peripherals, software libraries, or data formats, thereby extending accessibility beyond the original vendor's control.[6] Key motivations for creating clones include reducing costs through competitive manufacturing and avoiding expensive proprietary licensing fees, which allows broader market entry for smaller vendors.[7] For instance, clones enable the preservation of platform availability for legacy software by maintaining compatibility with outdated but essential applications, preventing obsolescence in specialized industries.[8] Standardization drives further adoption, as clones facilitate market expansion by promoting open architectures that encourage innovation and economies of scale, while non-commercial efforts often stem from homage to influential designs or the desire to democratize access to restricted technologies.[8] An example is the ReactOS project, an open-source initiative aimed at providing a free operating system compatible with Windows applications and drivers, motivated by the need for a trustworthy, license-free environment to run proprietary software without vendor lock-in.[9][10] Ethically, cloning raises considerations around intellectual property, distinguishing legitimate replication for interoperability—such as through clean-room reverse engineering to ensure compatibility—from infringement that copies protected elements like source code or trademarks.[11] While clones can enhance accessibility and foster competition, they must navigate copyright, patent, and trade secret laws to avoid unauthorized duplication, with U.S. doctrines like fair use permitting limited analysis for compatibility purposes but prohibiting direct copying of creative expressions.[11] This balance supports innovation in open ecosystems while protecting creators' rights against exploitative replication.[11]Historical Context
The concept of cloning in computing emerged in the 1970s and 1980s through efforts to emulate mainframe systems on more accessible hardware, enabling broader adoption of computing resources beyond proprietary environments. One early example was the 1973 SCAMP prototype developed by IBM, which emulated the IBM 1130 minicomputer to run APL software, demonstrating the feasibility of hardware emulation for cost-effective alternatives to large-scale mainframes. This period laid groundwork for compatibility-focused duplications, as organizations sought to replicate functionality without full reinvention. A pivotal development occurred in 1981 with the release of IBM's Personal Computer (PC), which was quickly followed by the first legal compatible clone in 1983 from Compaq Computer Corporation. Compaq's Portable PC reverse-engineered IBM's BIOS to achieve full compatibility while navigating intellectual property restrictions through clean-room techniques, marking it as the inaugural 100% IBM-compatible machine. This innovation ignited the "clone wars," a surge of competing PC manufacturers that eroded IBM's market dominance from over 80% in the early 1980s to less than 20% by the late 1980s, commoditizing personal computing and fostering industry standardization. In the 1980s and 1990s, cloning expanded into consumer electronics and software, with unauthorized hardware clones of Nintendo's Famicom (known internationally as the NES) proliferating in Asia to offer affordable gaming amid regional distribution barriers. These Famiclones, often produced in Taiwan and China, replicated the console's architecture using off-the-shelf components, enabling widespread access to popular titles without official licensing. Concurrently, software cloning gained momentum through the GNU Project, announced by Richard Stallman in September 1983, which aimed to create a free Unix-like operating system by developing compatible tools and libraries, emphasizing open-source principles to counter proprietary restrictions. From the 2000s onward, open-source initiatives further advanced OS cloning, exemplified by ReactOS, which originated in 1996 as the FreeWin95 project to reimplement Windows 95 functionality from scratch and evolved into a broader Windows NT-compatible system. Legal precedents also shaped practices, notably the 1995 Lotus Development Corp. v. Borland International, Inc. ruling by the U.S. Court of Appeals for the First Circuit, which held that replicating a software's menu command hierarchy for compatibility purposes did not constitute copyright infringement, thereby affirming the legitimacy of interface cloning. The U.S. Supreme Court affirmed this decision in a 4-4 tie, influencing subsequent compatibility efforts. By the 2010s and into 2025, cloning proliferated in mobile ecosystems through custom Android ROMs, such as LineageOS (forked from CyanogenMod in 2016), which modify and extend the open-source Android base to support diverse devices and user preferences, sustaining innovation amid rapid hardware turnover. These developments reflect cloning's role in democratizing access, with ongoing projects like GrapheneOS emphasizing privacy-focused variants based on Android 16 as of November 2025.[12]Hardware Cloning
Hardware Clones
Hardware clones in computing are physical devices engineered to replicate the core architecture, input/output ports, and firmware—such as the Basic Input/Output System (BIOS)—of an original hardware platform, ensuring binary compatibility that allows unmodified software from the source system to execute seamlessly. This replication typically involves using off-the-shelf components where possible, combined with reverse-engineered elements to mimic proprietary aspects, thereby enabling cost-effective production without licensing agreements. Unlike software-based emulation, hardware clones produce tangible, standalone machines that function as drop-in replacements for the originals.[8] A landmark case of hardware cloning emerged with the IBM Personal Computer (PC) in the early 1980s, where competitors produced compatible systems to capitalize on the platform's growing software ecosystem. The Compaq Portable, announced in November 1982 and first shipped in March 1983, marked the inaugural fully compatible IBM PC clone; it featured an Intel 8088 processor, identical expansion slots, and ports, but achieved BIOS compatibility through a $1 million clean-room reverse-engineering effort that avoided direct copying of IBM's copyrighted code. This approach involved one team documenting the BIOS functionality without viewing the source, followed by a separate team implementing it from scratch, ensuring legal viability. Subsequent clones from companies like Phoenix Technologies further standardized this process, flooding the market with compatible systems. By the late 1980s, hundreds of manufacturers worldwide were producing IBM PC clones, with Gartner estimating in 1988 that consumers purchased 1.5 clones for every genuine IBM PC.[13][14][15] The proliferation of IBM PC clones dramatically commoditized personal computing, driving down prices from over $3,000 for a fully configured original IBM 5150 in 1981 to under $1,000 for equivalent clones by the mid-1980s, making the technology accessible to businesses and consumers alike. IBM's decision to use non-proprietary components and an open architecture facilitated this cloning wave, though it sparked patent disputes over elements like the bus design; these were largely resolved through licensing and the company's strategic pivot away from dominating hardware production. This shift empowered the industry standard, with clones outselling IBM systems and fostering explosive growth in PC adoption.[15][7] Beyond PCs, hardware cloning appeared in console gaming with unlicensed replicas of Nintendo's Famicom (Japan) and NES (international markets) during the 1980s and 1990s, particularly in regions with lax intellectual property enforcement. Devices like the PolyStation emulated the original's 8-bit Ricoh 2A03 CPU and Picture Processing Unit (PPU) using cloned chipsets or integrated "NES-on-a-chip" solutions, preserving cartridge compatibility for authentic games while often bundling pirate copies. These clones, produced in Taiwan and distributed globally, bypassed Nintendo's lockout mechanisms and enabled affordable access in emerging markets, though they faced crackdowns as patents expired in the early 2000s.[16]Hardware Remakes
Hardware remakes in computing refer to modern hardware designs that replicate the functionality of vintage systems, typically using field-programmable gate arrays (FPGAs) or custom integrated circuits to achieve compatibility with original software and peripherals while leveraging contemporary manufacturing for enhanced reliability and performance.[17] Unlike exact physical duplicates of obsolete components, these remakes prioritize cycle-accurate reproduction of original circuitry at the logic gate level, ensuring low-latency operation and minimal deviation from the source hardware's behavior.[18] Prominent examples include the MiSTer FPGA platform, initiated in 2017 by developer Alexey Melnikov, which utilizes the Terasic DE10-Nano development board to recreate systems such as the Amiga 500, Atari ST, and various arcade machines through community-developed FPGA cores.[19] Similarly, the Analogue Pocket, released in December 2021, is a handheld device engineered with an FPGA to natively support original Game Boy, Game Boy Color, and Game Boy Advance cartridges, featuring a high-resolution display and adapters for other legacy portables like the Neo Geo Pocket.[20] More recent developments include the Analogue 3D, an FPGA-based remake of the Nintendo 64 that began shipping on November 18, 2025, and the SuperStation One, a MiSTer-based console released in 2025.[21][22] These platforms maintain backward compatibility by directly interfacing with authentic media, bypassing the interpretive layers of software emulation. The core process involves programming FPGAs to mimic the original hardware's digital logic, enabling cycle-accurate emulation where each clock cycle matches the timing of the vintage system, thus avoiding the overhead and potential inaccuracies of CPU-based simulation.[23] This hardware-level recreation supports parallel processing of components like video, audio, and input subsystems, resulting in superior fidelity for timing-sensitive applications.[18] Advantages of hardware remakes include exceptional accuracy and responsiveness, often surpassing software alternatives in replicating subtle behaviors such as sprite flicker or audio artifacts, while offering modern upgrades like HDMI output and reduced power consumption.[19] However, limitations encompass higher development complexity, requiring specialized expertise in hardware description languages, and elevated costs—MiSTer setups typically range from $200 to $500, compared to inexpensive software emulators—along with dependency on ongoing community support for core updates.[17] The field has seen a resurgence in the 2020s, fueled by retro gaming enthusiasm, with the global FPGA consoles market valued at $236.9 million in 2025 and projected to grow significantly.[24]Software Cloning
General Software Clones
General software clones are programs or systems developed to replicate the application programming interfaces (APIs), user interfaces, or behavioral characteristics of proprietary software or operating systems, primarily to achieve compatibility and enable the execution of existing applications on alternative platforms.[1] These clones often emerge as open-source initiatives aimed at providing cost-free alternatives or preserving legacy software support without direct reliance on original vendor code. By mimicking core functionalities, they facilitate interoperability while navigating intellectual property constraints.[2] A prominent example is ReactOS, an open-source operating system project initiated in 1998 (with roots in a 1996 effort to clone Windows 95) that seeks binary compatibility with Microsoft Windows NT, allowing it to run Win32 applications and drivers natively.[25] Similarly, AROS, started in 1995, is an open-source reimplementation of the AmigaOS API designed to support Amiga legacy software on modern hardware through portable, hardware-independent code.[26] MorphOS, developed since 2000 for PowerPC-based systems, clones AmigaOS behaviors and interfaces to maintain compatibility with Amiga applications, emphasizing efficiency on limited hardware.[27] The legal landscape for software cloning in the United States was shaped by the 1995 Supreme Court case Lotus Development Corp. v. Borland International, Inc., which ruled that the menu command hierarchy in Lotus 1-2-3 constituted an uncopyrightable "method of operation," permitting competitors to replicate such user interfaces without infringement.[28] In contrast, the European Union's Directive 2009/24/EC on the legal protection of computer programs explicitly permits reverse engineering, including decompilation, to observe, study, or test software elements necessary for achieving interoperability with other programs, thereby supporting interface cloning for compatibility purposes. To mitigate copyright risks, developers of general software clones frequently employ clean-room reverse engineering, a process where one team analyzes and documents the target software's external interfaces without accessing its source code, and a separate team independently implements compatible functionality from those specifications. This method has been integral to projects like the GNU Project, launched in 1983 by Richard Stallman, which produced compatible duplicates of Unix utilities—such as compilers and text editors—through reimplementation to foster a free Unix-like operating system.[29]Video Game Clones
Video game clones are titles that replicate the core mechanics, genres, or assets of successful originals, often developed by independent or smaller studios targeting mobile platforms or niche markets to capitalize on established popularity.[30] These clones typically vary elements like artwork, narrative, or level design while preserving the fundamental gameplay loop, distinguishing them from outright piracy.[30] A prominent early example is the wave of first-person shooter clones inspired by id Software's Doom (1993), which popularized fast-paced 3D action and maze-like levels. Raven Software's Heretic (1994) exemplifies this trend, adapting Doom's engine and shooting mechanics into a fantasy setting with magic-based weapons and medieval enemies, while introducing features like an inventory system.[31] Similarly, open-world crime games proliferated following Rockstar Games' Grand Theft Auto series, with Volition's Saints Row (2006) iterating on vehicular combat, gang warfare, and urban exploration in a fictional city, though it emphasized more exaggerated, humorous elements.[32] The rise of mobile gaming after 2010 amplified cloning practices, as low barriers to entry enabled rapid development and distribution via app stores. Dong Nguyen's Flappy Bird (2013), a simple endless flyer, sparked hundreds of imitators in 2014, with 95 iOS clones released in a single 24-hour period and an average of 60 uploaded daily to Apple's App Store—one every 24 minutes.[33][34] These often reskinned the core tapping mechanic with themes like celebrities or animals, dominating free game charts and highlighting how clones could quickly saturate markets.[33] Legal challenges have shaped the landscape, as seen in Electronic Arts' 2012 copyright infringement lawsuit against Zynga, alleging that The Ville (2012) copied distinctive elements like character animations and social interactions from The Sims Social (2011).[35] The case, which included Zynga's countersuit over hiring practices, settled in 2013 with both parties dropping all claims, underscoring tensions over protectable creative assets versus unpatentable mechanics.[36] Economically, clones foster genre proliferation by validating and refining popular formulas, encouraging competition that evolves titles like battle royales from PUBG inspirations.[30] However, they often lead to brand confusion for originals, inflating marketing costs and eroding trust among players, with indie developers reporting over 30 clones per hit title on platforms like Google Play.[37] App stores frequently issue takedowns for blatant copies, as with Apple's removal of Wordle imitators in 2022, balancing proliferation against IP enforcement.[37] By 2025, AI-assisted tools have accelerated copycat development, enabling rapid generation of concepts, sprites, and prototypes from existing game descriptions, further intensifying these dynamics in indie and mobile sectors.[38]Software Remakes
Software remakes refer to re-releases or community-driven projects that reconstruct original software, typically games, using contemporary technologies to enhance graphics, user interfaces, audio, or compatibility with modern hardware and operating systems, while preserving the core mechanics and content of the source material.[39][40] A prominent example is Monkey Island 2: LeChuck's Revenge Special Edition, developed and published by LucasArts in 2010 as an updated version of the 1991 adventure game, featuring redrawn high-resolution visuals, full voice acting, and point-and-click controls alongside an option to toggle back to the original pixel art and interface for backward compatibility.[41][42] This edition maintained the narrative and puzzles of the original while adapting it for platforms like Windows, PlayStation 3, and iOS.[42] Another key instance is ScummVM, an open-source initiative launched in 2001 that reimplements the SCUMM engine used in 1990s LucasArts adventure titles such as The Secret of Monkey Island and Day of the Tentacle, enabling these games to run on current operating systems like Windows, macOS, and Linux without requiring the original executables beyond data files.[43][44] ScummVM supports over 100 classic graphical adventures by emulating their interpreters, thus extending their lifespan through community contributions and cross-platform portability.[43] Development of software remakes often involves source porting, where developers modify and recompile the original source code to support new environments, as seen with the 1997 release of the Doom engine code by id Software, which spurred community ports like ZDoom and GZDoom that added features such as higher resolutions and multiplayer enhancements while retaining compatibility with legacy Doom levels (WAD files).[45][46] In contrast, full rewrites reconstruct the software from the ground up without relying on the original code, typically through reverse engineering assets and logic, allowing for more extensive overhauls like modern physics or UI redesigns but increasing development time and risk of fidelity loss.[47] By 2025, software remakes have become a dominant force in the retro gaming market, driven by nostalgia and preservation efforts amid a broader resurgence in classic titles, with libraries increasingly filled by such updates as a cost-effective strategy for publishers to capitalize on enduring franchises.[48][49] For instance, the 2019 Resident Evil 2 remake, rebuilt in Capcom's RE Engine with third-person over-the-shoulder gameplay and photorealistic visuals while homageing the 1998 original's survival horror elements, has sold over 16 million units worldwide, underscoring the commercial viability of blending homage with modern profitability.[50][51]Specialized Applications
Disk and Storage Cloning
Disk cloning refers to the process of creating a bit-for-bit replica of a hard disk drive (HDD), solid-state drive (SSD), or storage partition, duplicating all data sectors including the operating system, applications, files, and system configurations for purposes such as backups, system migrations, or large-scale deployments.[52] This sector-level replication ensures the clone is bootable and functionally identical to the source, distinguishing it from file-level copying that omits hidden system elements.[53] Key tools for disk cloning include open-source options like Clonezilla, which has been available since 2005 and supports imaging and cloning for Linux, Windows, and other systems, enabling efficient bare-metal backups and multicast deployments for multiple machines.[54] Commercial alternatives, such as Acronis True Image—first released in 2001—offer advanced features like incremental cloning, which updates only changed sectors in subsequent clones to reduce time and storage needs.[55] Technically, disk cloning relies on imaging algorithms that replicate data at the block level; for instance, the Unixdd command performs raw, sector-by-sector copies by reading from the source device (e.g., /dev/sda) and writing to the target (e.g., /dev/sdb), making it a foundational tool for precise duplication in Linux environments.[56] Cloning tools must handle partition schemes like Master Boot Record (MBR), which supports up to four primary partitions and is limited to 2 TB disks, or GUID Partition Table (GPT), which allows unlimited partitions and larger capacities via UEFI integration.[57] Additionally, bootloaders such as GRUB require post-clone reconfiguration to update device paths and ensure the replica boots correctly, often involving manual installation on the target disk's boot sector.[58]
Applications of disk cloning span system recovery, where clones serve as immediate failover options to restore operations after hardware failure, and software testing environments, allowing isolated replicas for debugging without risking production data.[59] By 2025, modern tools integrate TRIM support for SSDs during and after cloning, issuing trim commands to mark unused blocks and prevent write amplification that could degrade performance on the target drive.[60]
Database Cloning
Database cloning refers to the process of creating an independent, point-in-time copy of a database instance or schema, enabling isolated environments for development, testing, or disaster recovery without impacting the production system. These clones often incorporate anonymized or masked data to protect sensitive information while preserving the database's structure and functionality for realistic simulations. This technique supports high availability by allowing rapid failover setups and facilitates schema evolution in non-production settings.[61] Key methods for database cloning include logical and physical approaches. Logical cloning involves exporting the database schema and data at the application level, such as through SQL dumps, which allows for platform-independent transfers but can be time-intensive for large datasets. For instance, in PostgreSQL, the pg_dump utility creates a consistent logical backup by generating an SQL script or custom archive that can be restored to a new database instance using pg_restore, ensuring compatibility even during concurrent operations.[62] In contrast, physical cloning operates at the block or file level, copying binary data files directly for faster replication within the same environment. Oracle introduced snapshot-based physical cloning in the 2000s, leveraging storage snapshots to create space-efficient clones of database volumes, which became prominent with Oracle Database 10g in 2005 for rapid test environments.[63] Modern tools have streamlined database cloning in cloud environments. AWS RDS supports snapshot cloning since its 2009 launch, allowing users to create read-only or writable replicas from automated or manual DB snapshots with minimal downtime, typically completing in minutes for terabyte-scale databases.[64] Similarly, MySQL's Clone Plugin, introduced in version 8.0.17 in 2019, enables efficient physical cloning of InnoDB data locally or remotely via the CLONE statement, supporting replication setup and reducing provisioning time compared to traditional backups. Best practices emphasize data masking during cloning to ensure compliance with regulations like GDPR, enacted in 2018, by replacing personally identifiable information with fictitious yet realistic values in non-production clones, thereby minimizing privacy risks in testing scenarios.[65][66] By 2025, AI-optimized cloning in cloud database management systems, such as Oracle's Autonomous Database, employs zero-copy techniques to instantiate clones in seconds, enhancing agility for AI workloads by avoiding full data duplication.[67]Desktop and Environment Cloning
Desktop cloning, also known as virtual desktop cloning in the context of Virtual Desktop Infrastructure (VDI), refers to the process of replicating graphical user interfaces, user configurations, and virtual desktop sessions across multiple machines or instances to provide identical environments for users.[68] This technique enables efficient deployment of personalized desktops without recreating each one from scratch, often using linked clones that share base virtual disks with a parent image to conserve storage while allowing user-specific changes.[69] A prominent early example is Windows MultiPoint Server 2010, designed for educational settings to support multiple simultaneous user sessions on a single physical machine, effectively cloning session environments for shared access among students and teachers.[70] In VDI, tools like Citrix XenDesktop, introduced in the 2000s and evolved into Citrix Virtual Apps and Desktops, facilitate cloning through Machine Creation Services (MCS), which provisions virtual desktops by creating full or fast clones from a master image, ensuring consistent user interfaces across deployments.[71] These systems allow administrators to replicate desktops rapidly, supporting persistent or non-persistent modes where clones reset or retain user data as needed.[72] Technically, desktop cloning relies on profile synchronization mechanisms, such as roaming user profiles integrated with Active Directory, to replicate user settings, preferences, and application data across cloned sessions, preventing inconsistencies in multi-user setups.[73] In cloud environments, Azure Virtual Desktop, launched in 2019, enables on-demand cloning via golden images and automated scaling of session hosts, creating replicas that deliver identical desktops without manual intervention.[74] Desktop cloning has become essential for remote work scalability, with VDI adoption surging over 30% in 2020 amid the shift to distributed teams, driving the global VDI market from $11.7 billion in 2020 to a projected $30 billion by 2026.[75][76] By 2025, integrations with zero-trust security models enhance cloned sessions by enforcing continuous verification and micro-segmentation, as seen in Azure Virtual Desktop implementations that align with Microsoft's zero-trust framework for secure remote access.[77]Object Cloning in Programming
Object cloning in programming is the process of creating a duplicate of an object instance to enable independent state management, preventing modifications to the original from affecting the copy. This mechanism is essential for operations requiring isolated data manipulation, such as in concurrent programming or when passing objects to functions. Cloning can be shallow or deep: a shallow clone copies only the object's top-level fields, sharing references to nested objects, while a deep clone recursively duplicates all nested structures, ensuring complete independence. Shallow cloning is faster and sufficient for simple objects, but deep cloning is necessary when nested modifications must not propagate.[78] In Java, the standard approach involves implementing the Cloneable marker interface and overriding the protected Object.clone() method from the Object class, which by default performs a bit-by-bit shallow copy of the object's fields. For deep cloning, the overridden method must manually recurse through fields, cloning mutable nested objects like collections or arrays to avoid shared state. This design, introduced in Java 1.0, requires careful handling to ensure thread safety and correctness, as the clone() method is not declared to throw CloneNotSupportedException unless explicitly checked.[79][80] Python's copy module offers standardized functions for cloning: copy.copy() creates a shallow copy by invoking the object's copy() method if defined, otherwise performing a basic duplication, while copy.deepcopy() generates a deep copy via deepcopy(), recursively cloning all components. The deepcopy implementation uses a memoization dictionary to detect and handle circular references, preventing infinite recursion by mapping original objects to their copies during traversal. This approach, part of Python's standard library since version 2.0, balances generality with efficiency for common data structures like lists and dictionaries.[78] Implementation challenges in object cloning include managing circular references in deep copies, where self-referential structures risk infinite loops; mitigation typically involves a visited set or memo to track processed objects, as seen in Python's deepcopy. Performance is another concern, with deep cloning exhibiting O(n) time complexity—linear in the total number of elements in the object graph—due to the full recursive traversal, contrasting with O(1) for shallow copies in fixed-size objects. In languages without built-in support, improper handling can lead to memory leaks or unintended sharing.[78][81] Language-specific variations address these issues differently: C++ relies on user-defined copy constructors, special member functions that initialize a new object from an existing one, often requiring explicit deep copying of pointers or containers to manage resources like dynamic memory. This follows the rule of three (or five in C++11+), ensuring balanced resource handling for custom types. In Rust, the Clone trait defines a clone() method for explicit duplication, deriving implementations automatically for structs when possible, providing zero-cost abstractions for Copy types (shallow, bit-wise) while enforcing safety for heap-allocated data through ownership rules. By emphasizing compile-time checks, Rust avoids runtime errors common in manual cloning approaches.[82]Virtualization and Cloud Cloning
In virtualization and cloud computing, cloning refers to the process of creating identical copies of virtual machines (VMs), containers, or cloud instances to enable scalable infrastructure management, such as load balancing across servers, isolated testing environments, or rapid disaster recovery setups. This technique allows administrators to instantiate multiple replicas from a single template or snapshot, minimizing manual configuration and ensuring consistency in deployment. For instance, in virtual desktop infrastructure, cloning a parent VM can provision hundreds of user sessions simultaneously while sharing underlying resources to optimize storage and performance.[83][84] Key technologies for virtualization cloning emerged in the late 1990s and early 2000s, with VMware vSphere introducing VM cloning capabilities shortly after its founding in 1998, evolving to include linked clones that reference a parent VM's disk for space-efficient duplication without full data replication.[85] In containerization, Docker's 2013 release popularized cloning via thecommit command, which captures a running container's state into a new image for subsequent run operations, facilitating lightweight, portable replicas.[86] Similarly, Amazon Web Services (AWS) launched EC2 in 2006 with Amazon Machine Images (AMIs) as the mechanism for cloning instances, allowing users to bundle and replicate entire server configurations across regions for high availability.[87]
Cloning processes often leverage snapshots to accelerate creation, capturing a VM's state at a point in time and deriving clones from it, which can reduce provisioning from hours of full copies to mere minutes through delta disk techniques that only track changes.[88][84] In orchestrated environments, Kubernetes ReplicaSets, introduced in 2015, automate pod cloning by monitoring and scaling replicas to maintain a desired count, ensuring fault tolerance in container clusters without manual intervention. These methods build on foundational disk cloning for efficiency, as snapshots typically rely on underlying storage-level copies.[89]
By 2025, advancements in serverless and edge computing have extended cloning to functions-as-a-service platforms, such as AWS Lambda's SnapStart feature, which snapshots initialized execution environments to cut cold-start latencies by up to 10x for Java functions, enabling near-instantaneous replica invocation in distributed workloads. In hybrid cloud setups, edge cloning deploys low-latency replicas of VMs or containers closer to data sources, addressing post-2023 trends toward decentralized processing for IoT and real-time analytics while integrating with central clouds for orchestration. In 2025, containerized solutions have become essential for edge deployments, enabling efficient cloning of containers closer to data sources.[90][91][92] These developments enhance scalability in multi-cloud environments, reducing downtime and costs through automated, on-demand duplication.References
- https://doomwiki.org/wiki/Doom_source_code