What will the PSP use for memory storage without a writeable disc?

The PSP will make use of Sony's Memory Stick format, small rewriteable Flash ROM cards about the size of a stick of bubble-gum. This format will mostly be used for the same uses as the Memory Card for PlayStation and PlayStation 2: game character and progress saves, user-created data, online downloaded content, and system profiles and hardware drivers. The Memory Stick media will also be used to store separate audio and video files for those who use the handheld's additional multimedia features. The specific Memory Stick format to be supported by PSP is the Memory Stick PRO Duo format, which also makes it compatible with the standard Memory Stick Duo format.  more