What is a PSP?

The PSP can play video games, video, and digital audio, as well as display digital photos. Instead of being distributed on traditional ROM cartridges with battery-backed RAM for saves, games and other content are sold on Sony's new 1.8 GB Universal Media Discs (UMDs). The Memory Stick Duo (regular or Pro, but the high-speed mode of high-speed Sticks is not supported) is used for storing saved games and moving multimedia to the PSP from other devices. Other notable features of the PSP include WiFi wireless networking support (including a web browser in version 2.0 of the firmware), a rechargeable and removable battery, 4.3 inch, similar to the connectivity feature of the Game Boy Advance and GameCube.

Homebrew definition

In May 2005, it was found that PSPs using the 1.00 version of the firmware (meaning Japanese PSPs that were not updated to the latest firmware) could execute unsigned code. What this meant in practice was that these PSPs could run homebrew software, as the mechanism for checking to make sure that software has been approved by Sony hadn't yet been activated. Later on, in June 2005, it was discovered that software could also be run on 1.50 PSPs via an exploit. Homebrew software cannot be run on versions 1.51, 1.52, and 2.00 of the PSP firmware. Users wishing to run such software can choose not to upgrade, but future game titles for the PSP will require version 2.00, and the upgrade will be included with the games themselves. This has been circumvented by an application that can trick the PSP into showing a desired version but acting as a 1.5 machine.