How to Get CHD Files to Work With MAMEby Alan Donahue ; Updated September 22, 2017
CHD files are content files that store graphics, sounds, video and gameplay for a MAME ROM. The ROM file is the backbone of the game, but 90 percent of a game cannot be played with the CHD file. CHD files are only required for newer MAME games, but if you have the CHD files for your game, it is easy to make it compatible with the MAME emulator that you use. The process is all about categorizing and organizing your MAME files.
Open the "ROMS" folder in the main folder for your emulator. This is usually found in the "Program Files" section of your hard drive.
Locate the game ROM for which you have the CHD files. Write down the exact title of the game.
Right-click in the "ROMS" folder and select "Create New Folder." Title the folder exactly the same as the game folder you are using. For example, if the game "Jurassic Park" has its ZIP folder labeled "jp1993" then create another folder entitled "jp1993."
Cut and paste your CHD files into the new folder you just created. Each game usually only has one CHD file, but some could have two to three files.
Open the MAME emulator you use. Select the ROM for which you created the new folder. Now the software will automatically associate the CHD file with the ROM file.