Ps1 games and hacking the Vita: Why it won’t work

November 11, 2012

I once read a user post asking if it was possible to hack the vita using ps1 games. While the answer is simple and small: it’s possible but useless, I want to give people a more in-depth view of the pros and cons of doing so.

First, lets start with the pros:

- Back then the security measures in games were not even close to what they are now.
– Ps1 saves are not encrypted, so just hex edit the save and pop it back in.
– Making such hacks could be a lot simpler to perform (once you know how the system works)
– Such hacks will be compatible with all sony’s consoles out there: psx, ps2, ps3, psp and ps vita (partially), even xperia play.
– Ps1 is MIPS, so psp coders can easily make the jump.

So, with all this pros you might be saying: “hey this is nice, why won’t you do it? it will help get homebrews on the vita and the ps3″. The answer to is found by looking at the cons. For the cons I will go a bit more in-depth, which is the goal of this thread.

Cons

- Power:
This one is obvious, the ps1 is a 32mhz machine, so the amount of homebrews that can be ran will be a hell lot less than on psp. This of-course does not prevent pretty fun brews to appear, and it’s an unsolvable problem so we’ll just ignore it.

- Memory:
This is got to be the worst problem at attempting this hack. Where will you store the homebrews? ps1 didn’t have a usb and memory cards are way to small, you can create a lot of them and swap them when you need one or other homebrews, but 128kb of space is really small for any decent brew to appear. This two impediments kinda forces you to use the CD drive, which gets to my next con.

- No control over the CD drive:
Imagine the ps1 worked as a psp and it had user mode and kernel mode. Imagined you had a user plus kernel mode exploits and you can do whatever you want with them, that’s nice, right? wrong! As explained above, the only media with a reasonable amount of memory is the CD drive, but you can’t control something that is not even controlled by the system itself. For physical copies of the game it is you the one controlling whether to insert a disc or not, and the ps1 had sensors to detect if you changed the disc or not. These sensors can be overcomed and you can change discs without the ps1/2/3 knowing you had changed the disc, problem solved, right? wrong again! While this fixes the issue for physical formats, used by the ps1, ps2 and ps3, it does not solve it for digital copies, used by the ps3, psp and [b]ps vita[/b]. For digital copies it is the emulating system that takes care of swapping discs, and it will only swap a pre-defined amount of digital discs (i.e. it won’t let you choose what disc to swap it with). This is not much of a hassle since we need to modify the disc anyway so it doesn’t matter if we modify a pre-defined disc, so problem solved? wrong again, and again, and again! Running the modified the disc means we have to get the system to accept unsigned code, which would beat the entire purpose of hacking ps1 games.
This is an endless paradigm, to run ps1 homebrews you first need to have a modified disc where homebrews will be, to run that modified disc you have to hack the emulating system, beating the sole purpose of using ps1 hacks.

In conclusion:

Is it possible? yes, but it’s not of any use. The only homebrews we can run has to be ran on the memory card, which means the homebrew has to be 120kb at most, there is not much that can be done with that, specially when a decent 2d library already eats those 120kb.

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