CHD stands for Compressed Hunks of Data. Originally developed by the MAME (Multiple Arcade Machine Emulator) team for preserving massive arcade hard drives, the format has since been adopted by the console emulation community.
Think of a CHD file as a ZIP file specifically designed for disc images. It compresses the game data while keeping it playable. Unlike a standard ZIP or RAR file, which you have to extract before playing, emulators can read CHD files directly.
Not all emulators are created equal. Here is the 2025 compatibility table for CHD files:
| Emulator | CHD Support | Accuracy | Performance | Best For | | :--- | :--- | :--- | :--- | :--- | | Mednafen/Beetle Saturn | ✅ Perfect | 99% (Gold standard) | Moderate (needs 2GB+ RAM) | Purists & RetroArch users | | Kronos | ✅ Perfect | 95% | Good (OpenGL/Vulkan) | Windows & Linux users | | Yaba Sanshiro 2 | ✅ Perfect | 85% | Excellent (runs on phones) | Android, low-power PCs | | BizHawk | ✅ Perfect | 98% | Moderate | TAS & debugging | | SSF (modern fork) | ✅ Good | 90% | Good | Windows classic UI | sega saturn chd roms
Recommended Setup (Beginner): Download RetroArch + Beetle Saturn core. Load your CHD file directly (no cue sheet needed). Ensure your BIOS files (sega_101.bin, mpr-17933.bin) are in RetroArch’s system folder.
Recommended Setup (Power User): Use Kronos standalone. It supports upscaling, texture replacement, and runs CHD games like Panzer Dragoon Saga at 4K/60fps.
Converting games one by one is tedious. If you have many games, you can use a script or a frontend tool. The most popular user-friendly tool is CHDman GUI (found on GitHub), which provides a drag-and-drop interface for the command-line tool. CHD stands for Compressed Hunks of Data
The command to convert CD images to CHD is createcd.
The Syntax:
chdman createcd -i "INPUT_FILENAME.cue" -o "OUTPUT_FILENAME.chd"
Example:
chdman createcd -i "Game.cue" -o "Game.chd"
Note: If the filename has spaces, you must put it in quotes.
One of the most exciting developments in Saturn preservation is the rise of ODEs (Optical Drive Emulators). Devices like the Fenrir (for 20-pin and 21-pin Saturn models) and the Satiator (plugs into the Video CD card slot) now support CHD files natively via firmware updates.
Why load CHD on real hardware?
CHD is a lossless compression format. It uses algorithms like FLAC for the audio tracks. This means the game is byte-for-byte identical to the original disc when emulated. You aren't "downgrading" the quality; you are simply storing it more efficiently.