An introduction to emulation, discover what emulation is, and how emulation works, and how emulation is helping to preserve videogames for future generations

AN INTRODUCTION TO EMULATION
Last Updated: 13th April 2010

So, what is emulation?

Emulation, simply put, means one that one type of electronic hardware, ie a PC computer, can, using emulation software or hardware, operate as another type of electronic hardware, which could be a different type of computer, console, or an arcade machine.My site's focus is on the emulation of the hardware found inside arcade videogame cabinets, which can be run on a modern PC, allowing your computer to run the original game code for 100's of arcade videogames.

How does it work?

Hmm, difficult to explain, but emulation software essentially contains all of the components, generally IC's and CPU's, that make up the hardware it is emulating.Although these only exist as virtual components within a software enviroment, each part behaves in the same way as the real thing, or least that is what the developer is hoping to achieve.

What use is it to me?

With just the emulated hardware, probably not very much, as hardware is no good without software.The hardware inside a real videogame cabinet may be used for many different games, and so contains the necessary processors to display graphics, run the game code, decode the controls, and of course provide sound, just like the inside of your PC, but unlike your PC the game is generally not read from a harddisk, or even a floppy disk but from chips called ROMs (Read Only Memory), each game is usually supplied as a series of these chips, each holding a different part of the game, graphics data, sound samples, game code, and so on.By changing these chips, different games designed for that hardware can be played.This is why you sometimes find a videogame in an arcade which is running a different game to that of the cabinet it's in.The ultimate version of a multigame cabinet is of course one using the Jamma standard, which allows any compatible Jamma game board to be used on a game cabinet based on the Jamma standard.

So how can you use these 'ROM' chips inside your PC?

As they are, of course you can't, what we need is the the information which is stored on each chip, and this is what a ROM image is.Basically a ROM image is a file which contains all of the data which was stored on the original ROM chip.To create ROM images special hardware is used to extract the code from many different types of chips, so a complete 'ROM set' can be made of all the chips which formed the code for a particular game.Now we have the ROMs in the form of a file which a PC can understand, we can add this to the hardware emulator, which will thinks it's reading the code straight from the original game ROMs.This is why, when you play a game under emulation, that it appears to be exactly the same as the original playing, assuming that the ROMset and hardware emulator are complete.

How can ROM images help preserve real coin-op games?

If you are lucky enough to own a real coin-op videogame, you obviously want to look after it, but just like any other electronic item, it will with age eventually break down.Just think how often you see a PacMan or Galaxian game in an arcade nowadays, I haven't for years!.As with any electronic item, repair is only possible if parts are available, and as most manufacturers only support their products for about 5 years, it becomes increasingly difficult with age.Of course some parts are fairly standard and still used today, joysticks, monitors etc, so easily available, but for things like game board ROM failures, it's a different story, as of course each contains a part of a unique game, and you need to find the exact same game ROM to replace it, if you can't, then the game is effectively incomplete and will not work.Fortunately, what is now available thanks to emulation projects, is a huge archive of romsets for hundreds of arcade games, the code of which can be burned onto new eprom chips, which are available.In this way new ROMs for every archived game can be created, which would otherwise not be available, hence helping to preserve arcade games.

Is it Legal?

This is a rather difficult area in the emulation world, but the emulator is generally judged to be legal, although certain videogame manufacturers have tried to claim otherwise.ROM images are an altogether different situation, as you'll understand having read the terms and conditions of entry to the rom archive.Basically, if you own the actual coin-op videogame hardware, be it the complete cabinet, or just the insides, or a licenced commercial emulator, then owning backup ROM images for your own personal use for that game is normally accepted as being legal.In otherwords, it is illegal to own ROM images for a game which you do not actually own.Hopefully, the videogame companies will realise that most of the ROM images are for games they made years ago, which haven't earn't them any money in a long time, and so will licence the ROM images for use with emulators, some videogame authors or manufacturers have already done this, but until this or an alternative solution is found, then the use of ROM images is illegal unless you own the original game in some format.