With the most recent Sony PSP firmware versions, 2.0+, new provisions against end users running unauthorized UMD software (also known as "homebrew") have been introduced. Many new PSP owners give up when trying to get emulators of their old favorite Game Boy or NES games to run on their PSP with a new firmware versions. However, there are ways around this. The most frequently used one is to downgrade the firmware version of your PSP to 1.50 – the last official firmware version that does not place restrictions on unofficial UMDs. The catch is that downgrading does not work with all firmware versions. You can find out your firmware version like follows: boot up your PSP to the XMB (cross media bar, the home menu) and scroll all the way to the left to the "settings" column. From there, go to "System Settings" and "System Information". Your "System Software" is equivalent to your firmware.
Here's your basic course of action depending on the firmware you have in your PSP:
1.5 Celebrate! You're in luck! You're able to run homebrew right away.
1.51 Update to firmware 2.0, downgrade to 1.5
1.52 Update to firmware 2.0, downgrade to 1.5
2.0 Downgrade to 2.0
2.01 Update to 2.71, downgrade to 1.5
2.5 Update to 2.71, downgrade to 1.5
2.6 Update to 2.71, downgrade to 1.5
2.7 Update to 2.71, downgrade to 1.5
2.71 Use generic downgrader at [http://www.downgradepsp.org]
2.8 Out of luck for now
3.0 Out of luck for now
3.01 Out of luck for now, stay tuned! New downgraders may yet come.
One more thing to check is if you have a certain motherboard version (only about 1% of all PSPs) where the downgrading process renders the PSP inoperable. To check your motherboard, look at the top
of the circuit board for a small "IC1003" in gold letters. If you dont see it, you're good.
The basic procedure (for the 2.0 -> 1.5 downgrade) is as follows:
0) Disable anti-virus software on your PC.
1) Add several specially-formatted files in the Root and Photo folders of your PSP. Check out [http://www.downgradepsp.org] for the files and detailed instructions.
2) This leads to a buffer overflow in the image viewer, allowing access to PSP firmware.
3) Plug your PSP into the AC adapter. Start PSP up. Scroll to photo menu. Click X and try to scroll down. One of two things will happen: your PSP will hit a black screen with white letters and numbers, or your
PSP will freeze.
4) If the PSP freezes, just restart and try again. If you hit the black screen with white characters, perform a hard reset (hold power switch up 10 seconds) and restart.
5) With the AC Adapter plugged in, scroll to the right and access your memory stick under GAME
6) Run the 1.5 US Update
7) The update will run and inevitably fail at 99%
8) Restart the PSP, and you will hit the PSP's blue screen of death.
9) No problem- hit "O" and you are done!
If all went well, you should see the 1.50 firmware logo at the next reboot and be able to run any kind of homebrew now! This includes ROM emulators for other consoles such as Game Boy, NES, and many others,
movie and game backups, and custom-written programs. A good comparison of homebrew software sources for the PSP can be found at http://www.pspgoldmine.com .
A word of caution – tampering with your PSP as described above is risky and not authorized by Sony. If things go bad, you may end up with a messed-up PSP that will not run. To avoid that from happening, it is
essential that you know exactly what you do. From my experience, I can recommend the Insider's Guide on Downgrading a PSP at [http://www.downgradepsp.org]. It describes meticulously and with
audio / video comment what you need to do, and they also offer support if something goes wrong.