2.71 SE ("Special Edition") is an unofficial firmware version. It combines the best features of the official v2.71 firmware with comprehensive homebrew support, and was the first custom firmware designed to be installed as a genuine system firmware in the flash memory of your PSP.

3.02, 3.03, 3.10, 3.30 and 3.40 OE ("Open Edition") are unofficial firmware versions, based on the official firmwares with the same numbers. They combine the best features of the official firmwares (including PSOne emulation) with comprehensive homebrew support. They are designed to be installed as a complete replacement firmware for your PSP.

The future of these firmwares is unclear, since the author, Dark AleX, announced his retirement from the PSP homebrew scene in July 2007.

A Brick is a PSP that has been broken, such that it now has no more function than a household brick. Usually a bricked PSP can turn on for a few seconds, but nothing appears on the screen before it powers off again.

Bricks are usually the result of failed downgrade attempts, or flash memory experiments gone wrong. The two main ways to restore a brick are to send it back to Sony under warranty, or to fit a modchip and restore the flash memory that way.

DevHook is a homebrew application that allows you to emulate other firmware versions. So, for example, you could pretend that your v1.5 PSP was actually a v3.00, including all of the features of the higher firmware.

DevHook revolutionised the homebrew scene, because for the first time, it was possible to keep a v1.5 PSP for homebrew purposes, but still be able to run commercial UMD games that required a higher firmware version to run.

This is just another term for downgrader.

A downgrader is a piece of homebrew software that allows you to install a lower version of the PSP firmware than the version that is currently installed on it. Normally, this is not allowed by Sony, but homebrew developers have discovered ways around that restriction.

Although downgrading will remove some official firmware features from your PSP (for example, downgrading from v2.0 to v1.5 would remove the official web browser, because v1.5 did not have a web browser built in), it can be desirable, because it is often easier to run homebrew on lower firmware versions. Also, homebrew often offers alternative versions of the official features.

The most popular firmwares to downgrade to are v1.5 and v2.71.

• A firmware update
• A homebrew application
• An official game demo

The full filename is usually EBOOT.PBP, and you'll usually place the EBOOT.PBP file in its own subfolder, under the /PSP/GAME/ folder on your memory stick.

eLoader is a homebrew application that is designed to allow you to run other homebrew applications on your PSP. In essence, eLoader bridges the gap between exploits (which just open a small crack to allow unofficial code to run on the PSP), and homebrew applications (which expect a certain standard environment in which to run).

On PSP firmwares higher than v1.5, a loader such as eLoader or HEN is necessary to enable the bulk of homebrew to be run.

An exploit is a way of tricking computer code to do something that it is not supposed to do. In the PSP homebrew context, we use exploits to fool the PSP into allowing us to run unofficial software.

Famous exploits on the PSP have included image exploits (where special data is inserted into TIFF images, to fool the TIFF-viewing software to start running program code), and game exploits (where bugs in the game-save data processing in Grand Theft Auto: Liberty City Stories and Lumines were used to run code).

Firmware is simply the system software of the PSP, the program code that is responsible for providing all the official system features, such as the music player and the web browser.

Different PSP firmware versions have different capabilities, both officially, and for running homebrew. See "The Basics" in the FAQ for more details.

1. Flash homebrew is homebrew that is written to run in the PSP's Macromedia Flash interpreter. Macromedia Flash is a popular web-based software format, used mainly for games and fancy graphical effects. PSPs from version 2.70 upwards are capable of running most simple Flash programs, using the official system software.
2. Flash memory is the internal PSP system memory, that holds the system software and persistent user settings (like wallpaper choice, or network settings). To downgrade a PSP, or significantly alter the system settings, full write access to the flash memory is required. Usually, this requires full kernel access. Flash1, the memory containing the settings, is usually easier to access than Flash0, which contains the system software. Note that experimenting with modifying your flash memory contents can easily brick your PSP if you don't know exactly what you're doing.

Homebrew Enabler - HEN is a homebrew loader for v2.71, 2.80, 3.03 and 3.50 PSPs, that works by patching the system software in memory (so it is not permanent) to allow it to run homebrew applications direct from the XMB.

Homebrew is simply defined as software produced by unofficial developers. For a more complete definition, see the FAQ section "The Basics".

Initial Program Loader - the IPL is the part of the PSP's system software that is first run during the boot-up process, and is responsible for loading the rest of the system software.

The IPL is stored in a separate part of flash memory to the rest of the system software, and special techniques are required to modify it. IPL is most often discussed when talking about downgraders, and presents a challenge because if the IPL version does not match the version of the rest of the system software, a brick will occur.

International Standards Organisation - in the PSP world, ISO is short for ISO 9660, which is a standard published by the ISO to describe a standard format for disk images. PSP ISOs are files, containing an image of the contents of a UMD disk - most usually, a UMD game.

Sharing ISOs of games or movies that you do not own is invariably illegal, and not endorsed by the homebrew community.

An ISO Loader is a homebrew application that allows you to run ISO images as if the UMD disk that they contain was inserted in your PSP's UMD drive.

Using ISO Loaders for games that you do not own is illegal, and in some countries (including the USA, it is believed) , it is illegal even for games that you do own.

In the PSP sense, kernel is a level of access privileges in the system software. Ordinarily, software runs in user mode, which has restricted access to the system resources. In theory, user mode programs are unable to cause any permanent damage to the system.

Kernel mode is the privilege level that the system software runs at, which allows access to do virtually anything to the system. Gaining access to kernel-level privileges is the Holy Grail of homebrew software - with kernel mode, it is possible to write faster emulators, and to directly control the hardware, for example to write Universal Remote Controller software.

Kernel mode is also generally required to run a downgrader.

KXploit is a method devised for running homebrew on firmware v1.5 PSPs. It works by tricking the PSP, with a folder containing a "%" character in its name, which contains an EBOOT that contains no code, but valid metadata about the application, and a second folder, with the same name but no "%" character, containing the actual application code.

The method works because the PSP validates the % folder, then attempts to run it. But it strips out the '%' character by accident, and so runs the other folder instead.

KXploit is patched by Sony in firmware versions v1.51 and later, and so cannot be used for non-1.5 PSPs.

A modchip is a hardware modification, made to a games console to allow it to perform unauthorised operations - for example, running pirated copies of games.

There is only one commercially-available modchip for the PSP, and its name is Undiluted Platinum (UP). The UP chip works by adding a second flash memory to the PSP, which can be used to install a different firmware version alongside the original. This lets you have a dual-boot PSP, for example firmware 1.5 for homebrew, and the latest firmware for UMD games.

UP also allows you to backup and restore the contents of flash memory, so it can be used to recover your PSP if it was bricked by a bad flash modification.

UP cannot be installed on motherboard models TA-082 or later.

You may see the code numbers TA-079, TA-081, TA-082, TA-086 being discussed. These are the code numbers for different PSP hardware revisions, with TA-079 being the original hardware, and TA-086 being the latest.

The numbers lower than TA-082 are generally the most sought-after, because TA-082 and later are harder to downgrade, and are not able to have a modchip installed. Just about all new PSPs now come with TA-082 or TA-086.

Universal Media Disk - UMD is a proprietary Sony optical disk format, a little like a cut-down DVD disk. All commercial PSP games and videos come on UMD disks.

VSH is simply another name for the XMB. It is the name used internally by Sony software to describe the operating mode where the XMB is displayed. Because the XMB is allowed to alter system settings, VSH mode has slightly more access to the system resources than software that is running in GAME mode. Therefore, homebrew exploits that allow the system to be exploited in VSH mode are generally more useful than those that are found in games. VSH exploits are also typically more convenient to use.

xLoader is a version of eLoader, included in the "Kriek" eLoader release, that runs on v2.80 PSPs only. The advantage of xLoader is that it patches the PSP's system software in RAM (so it is non-permanent), to allow homebrew to be run (via eLoader) directly from the XMB.

xLoader has slightly lower compatibility with homebrew applications than eLoader, but it also has a few advantages - such as greater access to the flash0 system memory than eLoader has.

Most older homebrew has to be patched with the PatchSFO program before it will run on xLoader.