This ISO is for preservation only. You must own a legitimate copy of Minecraft (any platform) per the original homebrew license.
This typically refers to a specific update of a fan-made mod or port. These updates often add things like: Crafting systems. New textures and block types. Improved performance for the PSP's limited RAM. How to Use Minecraft ISOs on PSP minecraft psp 574 download iso exclusive
Because these are unofficial ports, they are typically distributed as files rather than standard ISOs, as they must run through the PSP's "GAME" directory on custom firmware. This ISO is for preservation only