Epsilon BIOS is a custom flash "replacement" for the Sony PSP which unleashes the full potential of your handheld, allowing you to both use homebrew software and run UMD ISO games from your memory stick on the latest firmware releases while also enjoying the impressive features built into the operating system such as RSS feeds, WMA support etc. Currently the 2.71 firmware release is supported - thats right, this means we have cracked the new encryption methods and developed the operating system hacks necessary to allow unsigned code to run, even in kernel mode.
We have been developing Epsilon BIOS for quite some time, but due to the fact that it requires a dual-flash system (one flash is used to bootstrap our code, the other stores the normal PSP firmware) we have been unable to release it - until now, with the appearance of the Undiluted Platinum modchip. Previously we had been using our own custom hardware for development, however about a week ago we received Undiuluted Platinum prototypes and have since modified our code to work with their hardware - its working great, despite a few bugs which we need to iron out before the release. For those who are wondering, yes, you will need an Undiluted Platinum installed in your PSP to take advantage of this.
As mentioned above, using Epsilon BIOS its possible to launch homebrew software from the memory stick, kernel mode access is also available for software which requires this. Both 1.0 and 1.5 style EBOOTs are supported. UMD ISO loading is almost transparent, simply copy your ISO files into a directory on your memory stick and they will appear under "Game -> Memory Stick" in the operating system menu alongside your homebrew applications. Simply launch them from here, no need to use a seperate ISO loader application. Furthermore, since the games are actually running on 2.x firmware you dont need to worry about strange loading methods or patching the ISO files - they will simply work, in their original state. We have also developed our own compressed ISO format and will be distributing a packing tool.
We will be releasing a video over the next few days showing Epsilon BIOS in action - keep an eye out for this! As for the actual release, this depends on how soon we can resolve the remaining issues but we hope to have it out within 1-2 weeks.