The PSP 1.50 to 1.00 downgrader we mentioned the other day has been released. The usual precautions apply, since you can brick your PSP whenever you write to your PSP firmware.

1. Find someone with a 1.0 PSP and get them to install the downhelper program from the downdater download.
2. Copy the downhelper100 folder to /PSP/GAME/ and start the program.
3. It will dump your flash and your ipl to the memory stick. After finished, the program will exit.
4. Send the folder created at the root of your memory stick called "DOWNDATER" to someone with 1.50 to allow them to downgrade using the Easy downgrader app.

You probably shouldn't attempt this unless you know what you're doing and have a good reason for going down to 1.0. – Jason Chen

1.50 to 1.00 Easy Downgrader Released! [QJ.net]

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