The Playstation Portable has a long history that can be divided up into categories. The PSP has kept people interested due to its homebrew. Homebrew is applications made to run on the PSP through unassigned code, often made through the community, not companies. Homebrew is able to run on particular firmware versions that have security holes in which unassigned code can be run through an eboot file. Firmware is the software version of the PSP, which gets regular updates from Sony for fixing security holes and adding new features.
Throughout PSP history, there has been many firmware updates. The first firmware version was 1.00 for Japan PSPs only. This version has very little security and easily allowed homebrew to run through the XMB. The XMB is the opening menu of the PSP when it is turned on. There is also firmware version 1.50 which was released for the US. This firmware had a small security fix, but within weeks an exploit was found to run homebrew on it as well. These two firmwares were known as homebrew friendly versions throughout PSP history. Future firmwares versions, such as 1.51, 1.52, 2.00, 2.01, 2.50, 2.60, 2.70, 2.71, 2.80, and 2.81, didn’t support homebrew that could be loaded in the XMB until recent exploit discoveries.
Firmware versions 1.51 and 1.52 never have, and never will have homebrew support. The security has been patched up and any exploits used in other firmwares either were patched up, or are not featured in the firmware. For example, firmware version 2.00 has a TIFF overflow exploit that none of the other firmwares have because 2.00 introduced the internet browser. When Sony introduces new features, it often brings in new security problems that newer firmware versions fix. Any firmware that is adding a .01 to the previous firmware version number is a security fix. For example, firmware versions 1.51, 2.01, and 2.71 only gave security patches and no new features to the previous firmware version.
As said before, firmware version 2.00 has a TIFF exploit that allows homebrew. This exploit allows a downgrader to run so that the user can return to firmware version 1.50. The firmware version 2.00 however does not have kernel access, which limits the homebrew that can run on it. Firmware versions such as 2.01, 2.50, and 2.60 do not have any exploits that can allow homebrew through the XMB. However with a game known as GTA Liberty City Stories, unassigned code could be used using an eloader. The eloader is a game save that the GTA game loads and brings up a program that allows homebrew. Like firmware version 2.00, this too has a downgrader, which is often used to revert back to firmware version 1.50. Firmware versions 2.00, 2.01, 2.50, 2.60, 2.80, and 2.81 are known as non-homebrew versions. They are updated firmware versions that do not allow homebrew to load in the XMB.
Two particular firmware updates are considered limited homebrew versions. Firmware versions 2.70 and 2.71 have the ability to load homebrew through the XMB with the help of the PIFF exploit. Even though homebrew can be run, kernel mode is still blocked off due to previous security patches. This allows some homebrew to be run; however other homebrew that requires kernel mode can not be used. The PIFF exploit allows data to be written to the flash0 and flash1 of the PSP, which is why some people prefer these firmware versions to others. Firmware versions 2.70 and 2.71 are known as the limited homebrew versions allowing some, but not all, homebrew to run.
The PSP has a long history of updates from Sony, however each firmware update has its own story from its security fixes and new features, to new exploits found from the new features. There are three types of firmware versions that Sony has made. There are the homebrew friendly firmware versions, the limited homebrew firmware versions, and the non-homebrew firmware versions.
