NOTICE: No virus in the downgrader!!
We have been receiving reports that Norton Antivirus reports the MPH Downgrader is a Trojan.PSPBrick. Here we clarify that this is a misreport of Norton Antivirus. The MPH Downgrader we are hosting here is safe for use. The downgrader works on almost every PSP (except PSP-1007 Taiwan model). And if the downgrader fails to work, the chance of bricking your PSP is still tiny.

NOTE: So that everyone gets a chance to see this piece of news, we will be keeping this article at the top and putting new news below it for a while.

Welcome to 1.50, PSP firmware 2.0 users! MPH has created a WORKING downgrader from PSP firmware 2.0 to firmware 1.50. This takes advantage of the toc2rta exploit and allows for the full downgrade of firmware 2.0 to firmware 1.50. I have tried this myself and have successfully downgraded from firmware 2.0 to firmware 1.50. Homebrew and UMD games WILL both work after the downgrade.

UPDATE by Jeff: You will be able to upgrade back to 2.00 after downgrading. I've tried this by myself. So feel free downgrading!

Although this has been tried and found working, this does not mean there is no risk involved so use at your own risk.

Steps to use the MPH downgrader:
- Create an UPDATE folder in the /PSP/GAME/ folder of your memory stick
- Copy EBOOT.PBP (update 1.50) in /PSP/GAME/UPDATE folder
- Unpack MPHDowngrader.zip
- Copy overflow.tif in your /PSP/PHOTO/ folder of your memory stick
- Copy h.bin to root of your memory stick (meaning in ms0:/)
- Copy index.dat in root of your memory stick (meaning in ms0:/ as well)
- Plug the AC adaptor

You memory stick filesystem should look like this (where X is your memory sticks directory):

X:/h.bin
X:/index.dat
X:/PSP/PHOTO/overflow.tif (with no other pictures in there)
X:/PSP/GAME/UPDATE/EBOOT.PBP (the 1.50 Firmware update eboot)

What you do next is go into the Photo Menu on the PSP and it will show some jumbled text, which is normal. Wait about 30 seconds and then restart your PSP.

From there you will now have a new file in your PSP?s root directory called ms0:/index.dat.bak. In the next step you will go to your Game Menu, Then Memory Stick, and then Launch ?PSP Update ver 1.50.?

It will then ask you if you really want to downgrade and then lead you along to the actual installing. Here is where I got scared. It installed to 99% then errored. This is OK. Restart your PSP and turn it back on. It will come up with another error which is OK as well. Restart it again and you will have PSP firmware version 1.50, and it will lead you through setting up language and time etc. Enjoy, and welcome to the world of legal homebrew, not piracy.

You can get the MPH Downgrader in our PSP Download section [here].
You can get the original Toc2rta exploit [here].
You can watch the video of the downgrader working [here].

You can get the 1.50 Update Eboot in our PSP Download section [here].

You can discuss it in our forums [here]. You can also talk about it on our IRC server (part of the toc2rta network) at irc.pspupdates.com #PSPUpdates.

Read the How To Downgrade Tutorial written by Garp [here].