What Are Mame CHDs?

Installing CHD Files

A CHD file for MAME should also include a ROM file. The ROM file contains a copy of the firmware stored on the arcade game's circuit board. When you install the game in the MAME folder on your computer, place the ROM file in the 'ROMS' folder, then create a new folder with the same name as the ROM. For example, the name that MAME recognizes for the game 'Killer Instinct' is 'kinst.' Place the ROM file -- 'kinst.zip' -- in the 'ROMS' folder and move the CHD file to a new folder called 'kinst' in the 'ROMS' folder.

Games With CHD Files

Many of the arcade games created during the mid-1990s and later that are supported by MAME have CHD files. Some of these games include 'Beatmania,' 'Area 51,' 'Killer Instinct,' 'Street Fighter III,' 'BioFreaks' and 'Gauntlet: Dark Legacy.' Generally, MAME is unable to run a game that does not include the corresponding CHD file.

Legality

Unless the copyright holder has released an arcade game into the public domain, the code stored in a CHD file is proprietary and protected by law. You cannot download or share CHD files containing code from arcade games unless you are the copyright holder or you have the copyright holder's permission to do so.

Compression

The CHD file format uses a form of lossless compression to reduce the size of the file while retaining all of the original data. This means that you should not compress a CHD file using a utility such as WinZip or WinRAR and run it in MAME, because MAME must then decompress the file twice to run it, and this can cause severe performance issues.