Looks like we once again have another HUGE development on the PSP Scene, it sure is making for one hell of a July! Dark_AleX, the amazing PSP Dev/Hacker and author of such programs as the PRX Decrypter, DAX zISO Loader, and of course the Downdaters has done it yet again. Today hes given us the very first custom firmware on the PSP. Though he considers it only a Proof-of-Concept, I personally think it still has very practical applications. Below is the information from the readme:

Custom Firmware – The proof of concept by Dark_AleX

There has been lately some discussion about if custom firmware in the psp are posible
(note: custom in the sense of writing our own executable code in the system, and not only data
like fonts, videos,…)

Even a lot of developers doubt that this is possible due to the protections in the psp.
Well, i\’m here with this simple proof of concept to show the contrary

Instructions:
(Note: this thing only works for 1.50)

- Copy the PSP folder to the root of your memstick.
- Execute the program "Custom Firmware – The proof of concept"
It will write to the flash some executable files.

Now you are done.

This program has ben tested on my psp. However, as all programs that write to the flash, there is
always some risk of bricking the psp. Use it at your own risk.
IMPORTANT (to avoid confussion): the program includes a file called vshmain.prx. This file is
NOT of Sony, it comes from me, the source of everything is released.

The features of this custom firmware – proof of concept are:

- Execution of normal pbp\’s (1.00 ones, no-kxploited)
- Posibility of hiding corrupt icons. (note: by default it\’s not enabled, look at the file
/PSP/SYSTEM/config.txt to see how to enable it)
- Posibility of skipping the SCE logo at the startup. (and in this way avoid the annoying auto-execution
of the UMD). Like the previous one, this is not enabled by default.
- "Recovery mode:". If you keep R pressed while starting the psp, it will enter in "Recovery mode".
Recovery mode is not more than a simple application that will let you to use the usb, and execute a
program under ms0:/PSP/GAME/UPDATE/EBOOT.PBP, that could be, for example, a sony updater or the
1.50 -> 1.00 downdater.

This would allow to recover potential bricks caused by the writing of bad fonts/videos/sounds… to
the flash.
(Note that this wouldn\’t allow to recover critical things like the overwriting of critical prx\’s)

- Autoexecution of a program at the startup. See the configuration file at /PSP/SYSTEM/config.txt
to see how to use it.