: If you have a collection of ISOs, you can use the chdman tool (part of the MAME distribution) to convert them yourself. Use the command chdman createcd -i "game.iso" -o "game.chd" for the best results.
After testing 50+ PSP games across real hardware (PSP-3000 with ARK-4 CFW), PPSSPP on a Steam Deck, and RetroArch on a Raspberry Pi 5, the answer is clear: psp chd internet archive better
The format is widely considered a superior archival and emulation format for PlayStation Portable (PSP) games compared to traditional ISO or CSO formats due to its lossless compression and significant storage savings . While PSP games were originally distributed as UMD ISOs, the Internet Archive hosts extensive collections of these games in CHD format, particularly those using Zstd compression, to balance data integrity with accessibility. Why CHD is Often "Better" : If you have a collection of ISOs,