A .cso file is a compressed version of a standard .iso disk image. It was the first widely adopted compression method for PSP games.
Use a small free tool called (Windows) or MaxCSO (Mac/Linux). Drag your ISO, choose compression level (9 = smallest, 1 = fastest), and get a CSO in seconds. cso psp archive free
In the early years of the PSP's lifecycle, storage was a premium commodity. Standard PSP Memory Sticks were expensive and limited in capacity, making the raw 1.8GB size of a full UMD image (ISO) impractical for many users. The CSO format solved this by utilizing DEFLATE compression Drag your ISO, choose compression level (9 =
: Open the app and navigate to the folder where you saved your .cso files. Launch : Click the game icon to start playing immediately. ⚠️ Important Considerations The CSO format solved this by utilizing DEFLATE
CSO (Compressed ISO) is a highly compressed file format primarily used for PlayStation Portable (PSP) game archives to save space on memory cards. While a standard ISO is an uncompressed disc image, a CSO uses lossless compression—meaning no game data is removed—but the file size can be reduced by up to 50% depending on the compression level used. Key Benefits of CSO Storage Efficiency