> > With software, I can dump Flash0 which contains the actual firmware files. These
> > files are encrypted and sig-checked though.
> Right, and this is what Dullaron was alluding to. If MAME is going to emulate the PSP
> at all, we want to do it as low-level as possible.
> However, even the couple MAMEdevs who have probably shipped a PSP title would have
> only interacted with the hardware via Sony's development libraries and OS calls,
> never talking to the low-level hardware itself.
> As far as any of us are aware, all PSP "emulators", for their part, cut the system
> off at the knees and don't bother emulating it at a low level. Think of it like this
> - A MIPS R4000 chip always starts executing at a fixed address in memory: 0xBFC00000.
> There's always got to be something providing that initial startup code, either an
> internal ROM, or a microcontroller in the case of the N64, or whatever. By contrast -
> again, as far as any of us are aware - all PSP emulators just load the game
> executable directly into emulated memory, grovel into the Sony-documented executable
> header, and get the start address. Not exactly emulating the whole console, yeah?
> So what we're looking for is any sort of documentation or dumps that are sufficiently
> low-level that they could be used to emulate a PSP from "hard" power-on.
While not specifically talking about the PSP, I think the dev team do need to be flexible with such things to a point, emulating things at one level, then revisiting and improving on them later if more information comes to light.
I feel something like the Nuon would need such an approach as otherwise you're emulating an entire DVD Player just to get to the point where you can start to run software for a basically unrelated architecture that was bolted on.
Trying to aim for 'perfect from the start' doesn't always work. Look at all the MCU dumps we're adding in MAME right now, had we simply refused to do HLE of those back in the day MAME would not be the emulator it is right now and would have likely been surpassed by others who were willing to and we'd be talking about them right now instead of MAME.
The approach we took however left us in good stead for using the dumps now they're available, and making sure a lot of other things were correct in the meantime. If we were scrambling to write the entire drives for the first time it would have taken a lot longer to spot the bad dumps for example.