The Sony PlayStation Portable (PSP), released in 2004, remains one of the most successful handheld gaming consoles. Its games were distributed on Universal Media Discs (UMDs), which store data in an ISO 9660-based format. Over time, the need to store, manage, and transfer PSP game backups led to the development of PSP ISO compressor tools. These utilities reduce the file size of raw PSP ISO images using various compression algorithms, custom lossless methods, and removal of dummy data. This paper provides a detailed technical examination of PSP ISO compression, explores popular tools (CSO, DAX, JSO, ZSO), analyzes compression ratios and performance trade-offs, discusses legal implications, and evaluates the ongoing relevance of such tools in the era of flash storage and high-capacity memory cards.
Decompression on PSP works on-the-fly: when the game requests sector X, the CFW’s ISO driver decompresses only the block containing that sector and caches it. psp iso compressor
: A classic, lightweight Windows tool that supports batch conversion between ISO, CSO, JSO, and DAX formats. The Sony PlayStation Portable (PSP), released in 2004,