PSP Homebrew
From PHWiki
PSP Homebrew has been around since the first exploit in the 1.00 firmware was discovered. Note that there is cureently ALMOST NO REASON TO UPGRADE A 1.0 OR 1.5 PSP, with the Device Hook psp loader being able to run most newer firmware versions in ram without updating the psp. Also understand that there is currently no way to return to older firmwares once 3.10 or above has been installed.
Official Sony Firmware Homebrew Support
PSP version 1.0 can run unencrypted eboot files without any patching at all.
PSP version 1.5 must be in kxploit form with two files HOMEBREW and HOMEBREW%. Corrupted data will be generated.
PSP versions 1.51/1.52 CANNOT run homebrew. 1.51/1.52 users must upgrade to 2.0 and use those methods or downgrade to 1.5.
PSP version 2.0 can use hombrew with the tiff exploit or the GTA eLoader
PSP versions 2.0, 2.01, 2.5, 2.6 can use homebrew with OLD VERSIONS of GTA with the GTA eLoader. There is a new tiff exploit for those with a newer copy, however
PSP versions 2.7/2.71 can also run homebrew with said exploit, run 2.71 SE, or use a downgrader.
PSP version 2.80 can be downgraded and run homebrew. Homebrew doesn't run nativly, but can once you've run the HEN application.
PSP versions 2.81/2.82 can't run homebrew or be downgraded.
PSP version 3.03 can be downgraded, but you need an unpatched copy of GTA:LCS.
Modified Firmwares
Dark Alex has released "open editions" of Sonys official firmware, these allow you to get all of the features of the newest firmware versions (Web Browser, Sony PSX emulator, Flash support, ect) while still allowing you to run homebrew eboots as if you had firmware version 1.0 installed. These custom firmware editions also have a revocery mode built in in case your firmware gets damaged.
Version 3.03 OE C is generally considered stable
Version 3.10-3.30 OE have bugs that cause random instabilities, but they're not too serious as many people used these firmwares.
Version 3.40 OE is supposed to have the instabilities fixed, but because it's new it's yet to be tested thoroughly
