Many users maintain a "complete PSP archive" as a personal backup. While a full PSP ISO Redump set exceeds 1.2 TB, a well-compressed CSO set can shrink to under 600 GB—far more manageable.
Two free tools dominate this space:
Copy one CSO to your PSP memory card or open it in PPSSPP. If it lags on original PSP, re-compress at level 1 or 2. On PPSSPP, even level 9 runs flawlessly. cso psp archive
Understanding the CSO PSP Archive Format For enthusiasts of the Sony PlayStation Portable (PSP), managing storage has historically been a challenge due to the proprietary and often expensive Memory Stick Pro Duo cards. The format emerged as the community's primary solution for archiving and playing games more efficiently. What is a CSO File? Many users maintain a "complete PSP archive" as