Emulation:  Right or Wrong?
aka "The EmuFAQ"


copyright (c) 1999 Sam Pettus (aka "the Scribe"), all rights reserved

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Module One:  The Emulator
Part 2 - Developing an Emulator
When crime is finally outlawed, then only criminals will live in America.
From an anonymous Internet posting
OverClocked #80, "Mysterious Ways" © 2000 David Lloyd


     The time is the wee hours of the morning.  The setting is inside the confines of a small, darkened room.  Crumpled printouts and soft drink cans are overflowing out of a small wastepaper basket, while a medium-sized contingent of insects and various rodents are feasting upon the remains inside an ever-growing pile of take-out food containers in a far corner.  The human occupant of the room appears unconcerned; in fact, he has been working for days, and has taken to humoring himself by making sure that some morsels are left behind for his small guests.  The erstwhile hacker takes the last swig from his drink, crushes the can, and then throws it at the basket.  It bounces off of the top and into a nearby pile of junked computer hardware, but by this time he has turned back to his console and is concentrating intently on the computer code on which he is working.  Beside him are two monitors - one showing various bits of screen garbage and the other showing a videogame display.  The latter is connected to a strange-looking device sitting on a nearby table.  In another life it might have been an older model computer, videogame console, or some other piece of computer hardware.  Today it has been stripped to the bare boards, data lines, and power leads, and has enough logic probes and other such monitoring devices attached to make it look like some weird Kafkaesque mutation of its former self.
     Suddenly, there is flickering on the monitor screen that was displaying the garbage but a few moments ago.  The hacker looks up with furrowed brow, preparing to swear profusely.  The screen goes black for a few seconds, and then a display pops up.  It is an almost perfect match for the one next to it - the one coming from the Rube Goldberg box on the table.  The young man is overjoyed - he kicks back in his chair away from his console and into another pile of parts behind him.  The resultant crash startles his little guests and they scamper off, but he is no longer paying attention to them; the young man has become excited by the almost-matching displays.  He grins, begins laughing, and then raises his clenched fist into the air, exclaiming, "That's it!  I did it!"
     Sound familiar?  This scene, or something vaguely similar to it but probably less dramatic, is familiar to anyone who has worked on a computer project for an extended period of time and has been played out by many a emulator developer around the world.  It doesn't matter if the place is a converted garage and the young man is an American teenager, or if the place is an apartment inside a Tokyo high rise and the young Japanese man is shouting "Yatta! Yatta!" over and over again to the irritation of his neighbors, or if the place is a college dorm somewhere in Mannheim and the awed German college student at the console can do nothing but whisper "Mein Gott!" in reverent awe.  It really doesn't matter either if the unusual device on the table used to be an Amiga computer, or a Sega Master System, or even an Hewlett-Packard scientific calculator in a former life.  Another triumphant milestone in the emulation community has been achieved.  Somewhere out there in the murky shadows and backwaters of the computer underground, another privately developed emulator has been born.
     We've already seen that emulation is a legitimate use for a computer.  We have established that emulation in one form or another has been with us for many years.  That now leads us to the question that all developers who are not affiliated with original product vendors must ask themselves:  "Is it legal for me to develop an emulator?"


     "The introduction of videogame emulators represents the greatest threat to date to the intellectual property rights of videogame developers."  So says Nintendo concerning emulation in their industry, but the same can be said for other computer industries as well; the operating system industry (Microsoft Windows and SoftWindows), the computer hardware industry (Gateway 2000 and WinUAE), and so on.  Nintendo should know - they are one of the biggest vendors in the videogame industry and have a widespread reputation for having a hair-trigger legal attitude in this regard.  Other companies within this and other related industries have also expressed concern over the growing popularity of emulation and taken legal action on their own, and the process will no doubt continue.  Why?  Do they just like picking on people who like "old stuff" or "cool cross-platform tools," or is there something else involved?  There are a number of concerns, but almost all of them can be grouped together under the legal term that Nintendo employs in its emulation policy statement - intellectual property rights.
     So what is intellectual property?  At the risk of oversimplifying the legal definition, let's reduce the concept to its fundamentals.  Intellectual property is one or more unique creations that belong to you and nobody else.  They can be anything, so long as you can demonstrate that said items are unique.  These items embody an particular set of ideas or productions to which you own all legal rights.  They do not necessarily have to be created by you; they may have been produced by someone in your employ or under contract for you, known in legal circles as a "work for hire," or you may have bought the rights to them from another party, which is commonly referred to as a "technology transfer."  Regardless of how you obtained the ownership of these items, your intellectual property rights imply that these creations are yours and yours alone to do with as you please, and nobody else has the right to do anything with them without your express consent.  Governments around the world recognize the concept of intellectual property rights, and it is usually embodied in one of three forms:  the patent, the copyright, and the trademark.


     Patents are awarded to creations of the hand.  Again, at the risk of oversimplification, patents are used to provide legal protection to any type of device that can be created or any process of creation in and of itself.  Just take a moment to look around you.  Many of the physical objects you see are covered by some kind of patent, or may have been produced using some kind of patented process.  Not everything is covered, though, because patents do not cover generic concepts or manufacturing methods.  For example, just about all of the parts inside your computer are patented and many of the components on the individual boards also have patents, whereas the chair upon which you are seated is probably not patented. There is no such thing as an "implied" patent; you must apply for a patent before you can enjoy the rights and benefits of patent protection. There is no such thing as "fair use" of patented material, as this runs counter to the exclusive nature of patent protection.  It should also be noted that governments tend to be quite stringent when it comes to awarding patents; you must prove that your device or process is either a unique creation or a creation that uses existing resources in a new and unique way.
     In the computer industry, patents used to be limited to hardware, but recent changes in federal law allow patents to cover software as well.  These are awarded under certain limited conditions; for example, a patent can be used to protect a piece of software if it contains a unique process like the mathematical algorithms used in compression software, or aids in the working of a unique process within the hardware itself.  The main reason behind this change is that patent protection gives software developers, owners, and vendors more legal leverage than does copyright protection - copyrights only protect the expression of the concept (the code as a whole) and not the many processes it might enable.
     In the United States, patents are governed under the terms of the U.S. Patent Act (35 USC).  The United States is also a signatory to the internationally recognized Patent Cooperation Treaty, which means that it honors the patents of other countries and they honor U.S. patents in return.  United States law was recently changed with regards to the lifetime of a patent; as a result, patents now last twenty years from the date of original application (not the date the patent was granted, as was previously the case).  Extensions are sometimes granted under certain circumstances, but the maximum length of extension cannot by law exceed five years from the end of the original patent.  Patents are further governed in the United States under the terms of the Intellectual Property Rights Act (37 CFR).  For more information, you can drop by the official web site of the U.S. Patent and Trademark Office.
     The University of California at Berkeley has a course on intellectual property rights which I highly recommend to anybody who might be attending that institution.  I have borrowed from their course outline to present the major points with regards to patent protection and the computer industry:

     What is patentable?

  1. Machines (any system or other apparatus that can be programmed).
  2. Manufactured devices (internal hardware and external accessories used in conjunction with a system).
  3. Processes (a series of operational steps to be performed on or with the aid of a machine).
     What is not patentable?
  1. "A compilation or arrangement of data independent of any physical element." (something stored inside a system, such as a database or other similar compendium of data)
  2. "A known machine-readable storage medium encoded with data representing creative or artistic expression." (these are considered literary creations, and program source code is the prime example)
  3. "A data structure independent of any physical element." (data tables, linked lists, etc.)
  4. "A process that does nothing more than manipulate abstract ideas or concepts; e.g. a process consisting solely of the steps one would follow in solving a mathematical problem." (generic mathematical equations, as opposed to a mathematical process created to serve a unique purpose)
     What are the advantages of patent protection?
  1. Coverage is quite broad, protecting against almost all forms of  independent development.
  2. Patents prohibits other individuals or organizations from laying claim to the same invention.
  3. Deterrent factor of patents is their chief value - it's harder to fight or circumvent a patent than any other form of intellectual property protection.
     What are the disadvantages of patent protection?
  1. Application and processing costs are high.
  2. Duration of patent protection is relatively short.
  3. Totality of invention is disclosed once application is made (this is a requirement under current patent law).

     Copyrights are awarded to creations of the mind.  These include but are not limited to such forms of expression as printed matter, music, and all forms of audiovisual production.  Examples include books, poems, essays, epics, songs, works of art, musicals, movies, television shows, plays, animation, and so on.  With regards to the computer industry and at the risk of oversimplifying things again, copyright protection is usually limited to any and all types of computer code and digital audiovisual works:  programs, programming languages, program source code, specialized databases, expert systems, unique sound and/or graphic creations, specialized computer software (such as but not limited to games, applications, and operating systems), and any digital reproduction of the old-style media mentioned earlier.
     There are two forms of copyrightImplied copyrights cost nothing and are assumed at the moment of creation, but are difficult to prove and protect.  On the other hand, statutory copyrights are granted by a government copyright office (usually for a small fee) and ensure full legal protection for said work under applicable laws.  In the United States, copyrights are awarded and protected under the terms of the U.S. Copyright Act (17 USC), which itself is in sync with the internationally recognized Berne Convention for the Protection of Literary and Artistic Works (828 UNTS 221).  It is important to note that the provisos of Berne do not require the inclusion of a copyright notice within a work to qualify for copyright protection, as was previously the case under the old 1976 U.S. Copyright Act.
     As a general rule, copyrights for all commercial works, which are regarded as "works for hire" by copyright law, that were created on or after 1 January 1978 last for the lifetime of the copyright holder plus an additional seventy-five years.  As an aside, this includes all personal computer programs and practically all videogame releases, and only excludes a mere handful of of pre-1978 concepts for mainframes and early arcade videogames that are still in use today.  Extensions are no longer granted for copyrighted works except for items that were copyrighted before 1978, but these can only be extended for a maximum of seventy-five years before they expire.  Some of the exceptions that I named are protected by copyright, but not all may have been extended (you need to check with the original vendor or copyright owner for more details).  Just like patents, copyrights are further governed in the United States under the Intellectual Property Rights Act (37 CFR).  For more information, you might want to drop by the official web site of the U.S. Copyright Office.
     Again, as with the patent, I have borrowed from the Berkeley course outline and adopted their format to note the distinctions with regards to copyright protection and the computer industry:

     What is copyrightable?

  1. Videogames, computer software, sound recordings, works of art (graphics), and other audiovisual forms of expression.
  2. Any old-style media that can be digitally reproduced (in such cases, the original copyright protections apply to the digital reproduction as well).
     What is not copyrightable?
  1. Everything that is a work of authorship, regardless of whether or not the author is known, is copyrightable (this tends to cover the ground that patent protection does not).
  2. Copyrights protect the means and manner of expression, not the idea or thought itself (this is the fundamental difference between copyrights and patents).
     What are the advantages of copyright protection?
  1. Easy and quick to obtain, as opposed to a patent.
  2. No substantive examination required before granting.  In contrast, the patent process is quite rigorous and requires exhaustive proof of uniqueness.
  3. Minimal cost to obtain and maintain.
  4. Long-lived - about three times longer than patent protection.
     What are the disadvantages of copyright protection?
  1. Independent development is permitted, thus allowing others to create and release similar products.
  2. Reverse engineering is permitted, thus allowing others to learn the ideas and concepts that underlie your work.
  3. Burden of proof to show infringement lies with the copyright holder.

     Trademarks are awarded to creations of the marketplace.  These include but are not limited to names, terms, corporate "mascots," and advertising gimmicks such as corporate logos and other such graphics designs.  The core idea behind a trademark is that it creates a unique image or association within the mind of a consumer that is linked to a particular company or company product.
     A trademark has the longest life of any form of intellectual property protection.  They are initially granted for a term of ten years, but they become incontestable after the fifth continuous year of use.  Some countries require periodic proof-of-use or maintenance fees, but the general rule-of-thumb is that trademarks last forever unless they fall into disuse.  It is up to the owner to show proof-of-use and continue using it in a proper manner, otherwise it passes back into the public domain.  In such cases, the trademark is said to have been abandoned, and anybody can then use it or register it themselves.  Even so, limited forms of public domain use of a registered trademark are acceptable (i.e. no license from the owner) so long as the owner deems the use to be noninfringing - that is, it doesn't harm the image that the trademark is supposed to represent.  In these cases, the use must somehow acknowledge its owner, and there are specific ways of doing so that are laid out under law.
     Patents and trademarks usually go hand-in-hand - you patent a product or process, then create a trademark to advertise it.  The Landham Act (15 USC 1051-1127) is the key law within the United States that governs trademarks; they are also covered to a large extent by the same laws that govern patents (35 USC, 37 USC), and the same international treaties also apply.
     My copy of the Berkeley course outline does not cover trademarks; nevertheless, I have adopted their format to note the distinctions with regards to trademark protection and the computer industry:

     What can be trademarked?

  1. Unique or invented words or terms.
  2. Unique number and letter combinations that would rarely appear in normal or mathematical use.
  3. Unique graphic images (logos, characters, mascots, etc.).
  4. Unique objects (subject to size and other restrictions).
  5. Unique uses for a generic word or term (e.g., Microsoft Windows™ is a piece of computer software, as opposed to a generic architectural construct).
     What cannot be trademarked?
  1. Generic numbers and mathematical equations.
  2. Generic words and terms (provided that the intended use is clearly generic in nature).
  3. Generic graphics and geometric symbols.
     What are the advantages of trademark protection?
  1. Longest life of any intellectual property protection - trademarks last forever.
  2. Can provide protection to any product that includes the trademark in some form.
  3. Can be as stringent as a patent with regards to use and proper licensing.
     What are the disadvantages of trademark protection?
  1. Must be constantly maintained; burden of proof-of-use lies with the owner.
  2. Weakest form of intellectual property protection; covers only marketing concepts and not always the product itself.
  3. Subject to certain forms of unlicensed public domain usage.
     For further inquiries regarding the appropriate federal statutes of U.S. law that govern copyrights, patents, and trademarks, I recommend consulting the Internet version of the United States Code (USC).  This is the codex that contains all federal laws that govern the United States of America, and it serves as the basis for the Code of Federal Regulations (CFR).  There are several different sites and mirrors available, but the website of the Cornell University School of Law is a good place to start.  A somewhat more user-friendly site with great background data (but limited only to intellectual property issues and associated sidebars; it does not contain the entire USC) is BitLaw: A Resource on Technology Law.


     "So why should I care about all this legal claptrap?" the more impatient among you are probably screaming by now.  "I just wanna program a emulator, not go to law school!"  If you're going to write an emulator, then you're going to be walking all over one or more of these forms of legal protection for the original vendor and software developers.  "How?" you may ask?  Let's see just how that can happen with videogame emulators, since these are the cause of emulation's current woes.
     A videogame console, be it the standalone coin-op type found in the arcades or the ubiquitous book-sized boxes found in people's homes, is an extremely complicated piece of engineering.  You have to have the code for the game(s) that it will run for starters.  Next, you have to have the hardware that will make it possible for users to play the game(s) the way you intended.  You have to have a way to store the game inside the console; likewise, you need some kind of processing hardware to interpret and execute the many lines of code within the game(s).  You have to have some kind of method to generate a visual display.  Said output must properly project the imagery that the game is creating in such a fashion so that it will not cause the user to suffer eye strain or possible seizures.  Sound is not a necessary requirement but is extremely desirable, since it adds to the impact of the gaming experience on the user.  You must have some kind of control interface so the user can interact with the game; this can vary wildly depending on the hardware and/or intended experience(s) involved.  Finally, if the console is designed to handle more than one kind of game, you will need what the legal profession terms a "delivery system."  This is a means whereby your game(s) can be stored outside of the console until such time as gameplay is desired, at which time they can be connected to or inserted within the console in order to deliver the game code into the console's hardware for execution.
     Wow, that's quite a tall order, isn't it?  That involves a lot of specialized knowledge in order to make such a piece of computer hardware a reality.  This is where intellectual property rights become involved.  It really doesn't matter what kind of emulator you are designing for whatever system you have in mind to emulate - you have to do it in such a way as to avoid infringing upon the intellectual property rights of the original vendor and its licensees.  Remember our discussion of patents, copyrights, and trademarks?  Here is where all of that "legal claptrap" comes into play.

The key word in all of this is process.  Remember, patents are used to protect a vendor-specific product or process.  Patents are more protective than are copyrights; therefore, vendors will almost always try to use patent violation as the chief means of prosecution whenever they accuse an emulator developer of stealing their intellectual property.  Software developers for vendor products are limited to claims of copyright violation unless they can establish that their code either contains a unique process or can be linked to a vendor-specific process within the hardware, in which case they also qualify for patent protection.  Filings for trademark violation are problematic at best, due to the nature of the beast and the concept of "fair use" (which we shall discuss at a later time).  To wit, patents provide the heaviest legal protection for a vendor product, followed next by copyrights, and last and least by trademarks.
     You ever wondered why vendors chase after unlicensed developers of emulators regardless of their design?  You ever wonder why software companies tend to frown on any modification of their titles?  You ever wonder why certain companies are quick to claim violation of the computer code inside their proprietary hardware?  Patents and copyrights are the chief reasons why.  Patents are now the main assault weapons in the original vendor's arsenal, and patent protection packs some pretty heavy caliber.  In comparison, copyrights have the status of a rapid-firing pistol with a large magazine - copyright protection packs a sustained punch, although not nearly that which patents provide.  Trademarks, by their very nature, are naught but a derringer in a vendor's potential legal assault on an emulator developer - only one shot, but sometimes that shot can kill you.  Their greatest role is played in validating claims of software piracy, but there is one specific case in which trademark infringement can be used against an emulator developer, and we will discuss it at the appropriate time.
     The primary problem for an emulator author is finding a means to duplicate the vendor's patent-protected custom processes in such a way as to not violate those patents.  The only legal recourse for doing so without a vendor license is a technique known as reverse engineering.  This is the creation of a device or piece of code that duplicates the function of a given process while at the same time not being an exact copy of the original.  The most common interpretation of this within the computer industry is that your process can work like the original vendor's, but it cannot contain any of the vendor's proprietary hardware or software.  It can be put inside similar packaging with a somewhat similar-sounding name and interface in a similar way as the original, but it can't be a perfect clone.  In other words, it might look like a duck, walk like a duck, swim like a duck, and quack like a duck, but it's not a real duck under those feathers.  Bear in mind, though, that if a reverse engineered process successfully duplicates the function of a patented process but is not or cannot be proven to be an independent creation, then the original vendor will consider it illegal and respond in kind.
     Frequently the situation will arise where a developer cannot surmount a certain technical problem, or decides not to develop their own reverse engineered code for any number of reasons.  Instead, they opt to obtain a legal copy of a vendor creation for use in their own product.  This is where vendor licensing comes into play.  In this situation, an emulator author opts not to duplicate a certain process.  The developer may elect to license the process from the vendor; they pay for the right to use that vendor-developed process in their product.  They can also elect to require the user to purchase these materials directly from the vendor or one of its licensees in order to get the developer's product up and running.  Regardless of the form it takes, vendor licensing is a universally accepted practice within the computer industry and one to which most vendors do not object. In effect, it is a recognized legal technology transfer between the original patent holder and the licensor or user who wishes to employ a patented process to suit their own needs.


     So let's assume that an independent developer has found some means of surmounting the many legal and technical obstacles in order to create a working emulator.  How can the original vendor deal with its release?  How can the developer combat the almost certain lawsuit that will be thrown his or her way?  Does it matter whether or not the emulator is commercially released, or just handed out free in the public domain?  Can the original vendor find some way to take advantage of the situation to its profit, or do we end up with nothing but a shouting match and lots of flame email?  In short, just what is at stake with the release of an independently developed emulator?  That's a good question, and that is what we shall look at next.


1.    According to Nintendo, what represents the greatest single threat to the videogame industry?  Why?

2.    What is "intellectual property?"  How is one entitled to intellectual property rights?

3.    What is the main hurdle one must overcome to have his or her creation qualify for intellectual property protection?

4.    How do governments protect intellectual property rights?  To what areas do these protections apply?

5.    What are two different forms of protection for a work considered to be an expression?  Which is preferable?  Why?  Give examples of each.

6.    How does each form of intellectual property protection relate to the computer industry?

7.    What two forms of intellectual property protection can be used to cover computer software?  How can it qualify for both?  Why would you want to use one as opposed to the other?

8.    What form of intellectual property protection is said to last forever?  Is this true, or not?  Explain why.

9.    Which two forms of intellectual property protection usually go hand-in-hand?  Why?

10.  What are two methods developers of so-called "clone products" can use to avoid intellectual property disputes?

11.  In your own words, describe the best way developers have found to produce a clone product while at the same time avoiding legal hassles from the original vendor.  How has this technique been justified in the courts?

12.  If the developer of a clone product cannot surmount certain technical obstacles, then what can they do?  Describe several methods of employing this alternate technique.

13.  Is it legal for an end user to develop an emulator "for private use only?"  How about "as a backup for the original console?"

14.  Apply the concept of intellectual property to the two Amiga-based examples given in the introduction.  What are the various ways in which intellectual property rights were honored, abused, or violated?


1.    In your own words, describe how you as a vendor could pursue somebody who has violated your intellectual property rights by releasing an emulator.  Give specific examples as to how you would achieve this.

2.    In your own words, describe how you as a developer could create an emulator that would not infringe upon the intellectual property rights of a vendor.  Give specific examples as to how you would achieve this.

The EmuFAQ (c) 1999 Sam Pettus - section last revised 10 March 2000