.CHD File Extension
File TypeMAME Hard Disk Image
What is a CHD file?
A CHD file is an arcade game disk image used by some MAME (Multiple Arcade Machine Emulator) games. It contains a compressed version of the entire contents of an arcade machine's hard disk. CHD files must be used in conjunction with a game .ROM to load an arcade game.
To load a MAME arcade game, you must typically place its CHD file in a directory that has the same name as the corresponding ROM's filename prefix. For example, if you have a ROM named mygame.zip, a CHD file named mygame.chd, and a ROM directory named Roms, you will typically store the ROM and CHD file in the following locations:
Other emulators require users to store all CHD files in one generic directory, often named Rom.
Some CHD files are large in size because the original arcade hard disk they were created from was also large in size. Even though CHD files are compressed, they may still take up large amounts of disk space.
How do I open a CHD file?
CHD files are not meant to be opened. Instead, you should place your CHD files in the directory your MAME system uses to load CHD files. In most cases, this is a folder named for the game the CHD file is meant to be used with. Refer to your emulator's documentation for more-specific instructions.