==== Pinout ====
[[File:Psp-info-memory-stick-pins.png|right|frame|pin numbers for Memory Stick]]
The below table describes the full pinout of the Memory Stick running in parallel mode. For serial communication (which the PSP uses), pins 3, 5, and 7 are open.
Both Pin 1 and Pin 10 will be connected to VSS.
==== Filesystem ====
In the root folder of the Memory Stick, there are three entries that concern the PSP. The first is <code>MEMSTICK.IND</code> (or <code>MSTK_PRO.IND</code>), which seems to be an indication that the stick is formatted. The second is the directory <code>PSP</code>, which itself contains directories for the different types of data used by the PSP. These subdirectories are not mandatory, and may be simply missing if the appropriate media type is not stored on the media. The third root-level directory of interest to the PSP is <code>MP_ROOT</code>, which stores video, and should only contain a single directory with the name <code>100mnv01</code>.
Note that for the directory structure illustrated below, not all directories are required to be present:
* <code>PSP</code>
** <code>GAME</code> - Contains PSP software to be run directly, in the form of <code>*.PBP</code> files
*** <code>UPDATE</code> - Official firmware updates should be placed here
** <code>MUSIC</code> - Audio tracks in .mp3 format - only one level of subdirectories is supported by the music player
** <code>PHOTO</code> - Image files in .jpg format - only one level of subdirectories is supported by the image viewer
** <code>SAVEDATA</code> - Savegame data - Each game creates a subdirectory with its product code (e.g. ILJS00002) in the following format:
*** <code>ILJS00002</code> - product code
**** <code>ICON0.PNG</code> - A still picture icon in PNG format (24bpp, 144x80 standard, or 300x170 maximum)
**** <code>ICON1.PMF</code> - (Optional) Animated version of the icon (file format still unknown)
**** <code>PIC1.PNG</code> - A fullscreen background picture for the file manager in PNG format (24bpp, 480x272)
**** <code>SND0.AT3</code> - (Optional) Background music to play in the file manager, ATRAC3plus encoded in WAV (max 500kb and 55 seconds)
**** <code>PARAM.SFO</code> - Metadata about the game as a PSF file with a category of MS
** <code>SYSTEM</code>
*** <code>BROWSER</code>
* <code>MP_ROOT</code>
** <code>100MNV01</code> - Video clips for playback in the music player - according to the PSP manual, these must be MPEG-4 (h.264/AVC MP Level 3) with a maximum bitrate of 768kbps, and named m4vnnnnn.mp4 with nnnnn being a 5-digit number - thumbnails can be optionally included with the same filename and extension of .thm
* <code>HIFI</code> - Used for DRM-protected ATRAC3 files
* <code>CONTROL</code> - Used for DRM-protected ATRAC3 files
** <code>PACKAGES</code>
*** <code>PKGxxxxx</code> - Contains <code>package.xml</code>, which is song information in an XML format that works similar to ID3v2 tags
* <code>DCIM</code> - Used by the Sony Cybershot Camera to store photos in JPEG format
* <code>MISC</code> - Used by the Sony Cybershot Camera, ignored by the PSP