PSP News - Public Discussion - Emulation

[PSmonkey]

So DS has two processors. Oh no impossible.... No wait there is a huge problem. Comercial developers are not allowed to write custom code for the arm7 (unless nintendo is letting a few devs do something nobody else is allowed to).

Most of the arm7 functions could posibly be replaced with extensive HLE leaving only the arm9 to need emulation. Sure thats still a real beefy part to handle but still realistly could be done at an fps above 30fps.

The fact a not well optimised PC emu already plays a few games at 4fps on the psp is impressive to me. I remember back when all I got was a simple n64 fire demo running at 4-8fps.

Something i'm currious about this emu is few things
1) It's strange all games run at an almost equal fps. Second there is never an issue of screen teering. I think posibly SDL is causing vsyncs
2) Going with the above part, I wonder if some speed hacks might be posible (like stoping the cpu from emulating all the cycles caused by the code waiting on a vblank to trigger)
3) Should try modding the code to use the PSP to render the framebuffer and not using a off screen buffer (could see a performance boost).

I am not saying either would result in a marginal boost but I do find it odd a simple 2D game runs at the same FPS as a more complex 2D game.

-edit-
I forgot to note, I'm a geek. Even seeing the DS run on the PSP at 4FPS was great for me. I look forward to the day i see a saturn game boot on the PSP at 1-5fps. :P

[devmas]

Hmm... Here's what I think:

The DS would be extremely difficult to emulate at full speed on the PSP, because of the two processors.

Nintendo cretated an N64 emulator for their Gamecube, and it worked at fullspeed, yes... but even still, it had some frame rate issues in games (think Majora's Mask in Zelda Collector's Edition). The Gamecube's 485 MHz CPU with its 162 MHz GPU, compare it to the PSP's 333 MHz CPU and its 166 MHz GPU. But then again, it was running in 640x480 as opposed to the N64's 320x240...

The PSP could very well do N64 emulation at full speed, but the DS has two processors: the 67 MHz ARM9, and the ARM7, the same processor used in the Game Boy Advance (GBA's ARM7 is 16.8 MHz while DS's ARM7 is 33 MHz). So, essentially, you are talking about emulating a double-speed Game Boy Advance and an N64 at the same time, for the most part.

Another thing that the second poster pointed out is that the N64's processor and the PSP's processor are similar, so emulation could be made faster.

By the way, processor speed numbers, I got from Wikipedia, even PSP ones, just to confirm everything. It seems they say N64 speed is 92.5 MHz, compared to the original post's 62.5 MHz...

[Sektor]

The ARM7 is mostly used for sound, touch and wifi. Many games would be playable without those features. It's far more important to emulate the ARM9 efficiently. Emulating some DS games at 30 FPS on a PSP is entirely feasible. The hard part is finding someone with the time, motivation, desire and skills to make it happen.

[Axelius]

Hmm yeah, even if we got to a playable framerate, the thing that makes the ds worth the money is its cool feature: the touchscreen and the two screens.
With the PSP lacking these features I doubt that ds games would be fun on the psp...

[Sektor]

Some of the best selling DS games rarely use the touchscreen. The PSP resolution is only 32 pixels width off, if it displayed the screens side by side, so an emulator could cut off part of the less important screen, rescale one of the screens, only display one screen at a time or as is currently done, turn the screens sideways.

Without a touchscreen, it can never be a total replacement for a DS, which is a good thing, no matter how good the emulator gets, it shouldn't hurt Nintendo's sales in any significant way.

[odino]

N64 has 2 processor too:

Cpu: R4300 93 MHz
Coprocessor: Reality Immersion 62 MHz
Sound: Reality Signal processor

Anyway, i know that some games run at 33mhz on gba.

[yoshinatsu]

Exophase believes it can't be done
But why?? WHY??? We've seen THINGS and THINGS!
We SEE IT EVERYDAY!!! Things tagged "IMPOSSIBLE", YET HAVING THEM ON OUR PSPs RIGHT NOW!!!!!
Like gpSP, and Daedalus, and the custom firmwares!
I told it before, what I believe is that we NEED another genius to make this happen.
And some people pointed that there's no need to have a DS emulator cause it won't be fun. OH YEAH????
AND WHAT ABOUT PEOPLE THAT ENJOY THE DS' SINGLE SCREEN AND GAMES THAT DON'T USE THE SILLY TOUCH SCREEN??

I look forward to the day i see a saturn game boot on the PSP at 1-5fps. :P

Oooooooooooohhhhh. I'd give ANYTHING in this UNIVERSE to see Shining Force III booting on my PSP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! EVEN IF IT WAS AT 1 FPS!!!!

What if we ignore the sound and the second screen (the touch one)?
Will we gain any speed with that?

[Gold Line]

my opinion is, if u can make a ds emulator, great. BUT i will never use it because most ds games are crappy remakes of n64 games with weird controls.

i was refering to the touch pad being emulated, not when its on the acual ds.

Sorry bud but it has to be said theres only 3 or 4 n64 remakes and they all have great controls also your first post made you look like you where bashing the DS for no reason.

[firedragon_jing]

I think eventually it could be possible, especially if the N64 ever becomes full speed. It would work better, like every other homebrew, on the PSP Slim if it gets homebrew enabled because of the extra RAM, so that's the best bet of full-speed.

The only problem is the lack of a touch screen, which would make most games unplayable or extremely hard to play. Some could be handled with a mouse function with the analog stick, but it will never have the same feel. Also without the dual screens, it would be hard to play games that the uses both screens for gameplay, like Sonic Rush, but would still work for games that use it for maps and puzzles.

[Sektor]

A DS emulator doesn't need more RAM than what the PSP currently has. The PSP can read from the memory stick much faster than the DS reads from DS cards. There's no need to load the whole .nds file into RAM.