Changing Idstorage and Downgrading always runs the risk something goes wrong and bricks your psp. Use of these files , requires that you accept those risk, and understand you do so at your own risk.
The files here were designed to downgrade a 2.71 ta-082, or ta-086. The included 1.5 Enabler is the latest as of 03/11/07. 1.5 enabler does NOT corrupt any keys other then necessary to run the 1.5 FW. It is also easily reversed if you choose not to run Custom Firmware any more. (This requires another file just to keep it safe for the newbies) The source files for 1.5 enabler are included.
Special thanks to Chilly Willy for taking the time to code this
Quote from the readme:
This tutorial is only for Ta-082 or Ta-086 2.71 downgrading to firmware 1.5.
Use this at your own risk. Its always possible
to break your psp.
To verify you have a Ta-082 or Ta-086 see the picture below.
PLEASE NOTE: YOU MUST HAVE YOUR PSP CHARGER IN AT ALL TIMES!
Donot power off During downgrade!
Donot use fake memory cards to downgrade or upgrade see link below to identify fakes.
Note: If at some point your screen goes black for more then a few seconds Hit the brightness key gently a few times. Be careful not to bump the power or other buttons. In some cases the brightness goes to off.
1. Before you start, format your memory stick and reset your default settings.
A. Format MS by going to System , Format Memory Stick. press X
B. Push down to restore Factory Settings
2.Create a USB connection between your PSP and computer.
3. Download the official Sony 1.50 eboot and rename it to UPDATE.PBP, and put it in the MSroot/PSP/GAME/UPDATE folder of this download with the name of UPDATE.PBP
official Sony 1.5 eboot ** http://www.psp-hacks.com/category/43
4.Copy the contents of the MS_root folder to your memory stick root, click yes to overwrite. Do not put the readme on the psp.
5. Run HEN-D if you are not already running it.
Simply goto photo and try to display rand. The psp should very briefly display a green screen. If it displays a red screen try again. Once you get a green screen proceed. (note rebooting your psp deactivates hend)
6. Execute the 1.5 enabler on the PSP. It needs 75% battery. It will verify/make your psp able to run 1.5 and enable downgrading the TA-082 or TA-086 PSP.
7. The program will exit to the XMB. Now run the generic downgrade, which will show in the XMB as “Update X.Yz” on the PSP.
8. The generic downgrader will also need 75% battery. IT will downgrade your PSP to 1.50.
9. At the end, it will ask you to press X to restart the PSP. Do it.
10. If all went fine, you’ll receive a blue screen telling you to press O. Do it, and re-enter your settings. Welcome to 1.50.
TA-082 downgrader by Dark_AleX/Mathieulh/Harleyg
1.5enabler by Chilly Willy
Original readme's adapted by XsavioR
photo thanks to Calo edited for content
proof of concept: Stapol, Vad