Flash0: The internal partition holding core OS files.
Flash1: The partition for user settings and registry.
Flash2: The partition used for PSN DRM and activation data.
Flash3: A mostly unused partition.
IdStorage: A secure area containing unique console keys, region data, and MAC addresses.
Target ID: A region identifier stored in IdStorage.
Memory Stick PRO Duo: Sony’s proprietary memory format.
MS Adapter / SD Card Adapter: Third-party plastic sleeves that let you put standard MicroSD cards into your PSP instead of tracking down original Memory Sticks.
Cluster Size: The size of data blocks on your memory card. The PSP reads games fastest when formatted with 64k clusters, but the PSP’s built-in format option only uses 32k.