So open that folder full of dusty ZIPs, download chdman , and start converting. Your hard drive—and your future self—will thank you. Last updated: 2025. Emulation tools on Windows 11, macOS Sonoma, and Linux (Proton/Steam Deck) confirmed working.
Introduction: Why Change Your ROM Format? For decades, the .zip file has been the standard container for arcade ROMs (MAME) and disc-based game images. It’s convenient, reduces file size, and is universally supported. However, as emulation has evolved, a new champion has emerged for disc-based games: CHD (Compressed Hunks of Data) .
PS2 .iso files inside ZIPs work, but the PS2 emulator PCSX2 has only experimental CHD support. The standard is still .iso or .gz . Stick to CHD for CD-based systems (PS1, Sega CD, etc.).
chdman createcd -i game.cue -o game.chd -c cdlz (CD LZMA) # Balanced chdman createcd -i game.cue -o game.chd -c lzma (Generic) # Smallest, slowest If you have an old CHD (version 1-3), update it to version 5 for better performance:
Absolutely none. CHD uses lossless compression for game data and lossless FLAC for CD audio. Your game will be bit-for-bit identical to the original disc.
The workflow is trivial once automated: