What Is Possible With The Gp2x?


Eolair

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idigital posted on Oct 18 2005 at 02:01 AM said:
BTW, nice mockup c64 gp2x skin in your sig there! Very cool  B)

Thanks. maybe I should make a real one some day ;)

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Alpha2

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no. it just has fewer special functions. The Genesis didn't have as high a color pallet, it didnt have Mode7 and it had a much simpler sound chip and those are just things I know as a NON-coder.
 

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Alpha2 posted on Oct 17 2005 at 10:38 PM said:
Wait, wait, wait....

If I recall, that Sega Genesis was always faster then the SNES....
And if genesis is 100% play-able, why isn't SNES?
Is Genesis more powerful?

Alpha2 posted on Oct 17 2005 at 10:38 PM said:
no. it just has fewer special functions. The Genesis didn't have as high a color pallet, it didnt have Mode7 and it had a much simpler sound chip and those are just things I know as a NON-coder.

No, that's not true, Alpha. (at any rate, why would having fewer 'special functions' make the console slower?) Here's the real situation between the MD and SNES.

The Genesis/MegaDrive is enormously faster than the SNES, and of course also more demanding to emulate (though not overly so). It uses a Motorola or Hitachi MC/HD68000 @ 7.67 MHz, and has a helper Zilog Z80 coprocessor (mostly used for sound operations) running at ~3.6 MHz. Its sound synthesis is performed by a Yamaha YM2612 chip (which is able to produce far superior FM audio on-the-fly than the SNES, while the SNES' processing of pre-recorded PCM samples is superior to that of the MD/Gen.), aided by a programmable sound generator like that in the SMS on top of all of it.

The SNES had a 16-bit hack (65c816) of an 8-bit chip (6502) running on a bottlenecked 8-bit bus. It relied primarily on a custom graphics chip to perform functions like hardware scaling/rotation to make up for the anemic processor. For the most part, MD/Gen games were much faster and relied more on reflex-testing gameplay, while SNES games relied more on prettier graphics and more recorded PCM audio instead of on-the-fly generated FM (I prefer the MD's approach and the sound of FM audio, but everyone has their own preference.) The SNES had a much larger color palette (32,768, 256 max onscreen at a time) compared to the MD's 512 colors and 64 max onscreen, however MD games made excellent use of creative dithering and sprite design to avoid being much limited by it-- also the SNES CPU's rather slow sprite arrangement made MD games able to use much larger sprites. The MD's native resolution is 320x224 (almost exactly that of the GP2x) while the SNES' was 256x224 (so it will need to be scaled up, a small detriment to emulation speed as well.) The SNES could run at higher resolutions but it took so long for the CPU to arrange the sprites each frame that the framerate plummeted and made games pitifully slow at this resolution, rather ruining its benefits.

The MD's hardware design, however, was no 'mess', it was elegant and efficient. The parts were selected well, and there were no awkward or peculiar bottlenecks or design flaws. The system even incorporated DMA allowing data to be fetched to RAM without the CPU's intervention-- the SNES had to drop its CPU clockrate from ~2.3 MHz to 1.79 MHz (the speed of the original NES) to read from the cartridge. Ever wonder why SNES games had such long intro credits or level-intro screens? That was actual load time. :p

If you still think the MD/Genesis was a mess, look at the NeoGeo arcade system, which is industry-renowned. It's almsot identical, with the exception of the CPU clock being higher, and the use of a chip a step up from the YM2612 audio synth chip, in the same generation. It even has a Z80 for the same functions, and uses the same video resolution. They're practically twins with different purposes.

As for emulation of the system, it can be done on an ARM9 @ 200 MHz, with efficient programming. There have been MD/Gen emulators for PocketPCs on XScale processors, one (incomplete) emulator called PicoDrive ran at 100% speed at all times (albeit without sound, that was never added, though not for speed reasons-- the emulator just isn't being maintained) -- on a 300 MHz XScale, with power to spare. Now, an XScale at 300 MHz is very significantly slower than 1 200 MHz ARM9-- XScale is well .. not a very good architecture. It just .. isn't. A rough approximation of XScale to ARM9 performance would be that a 300 MHz XScale is equivalent to a 75 MHz ARM9. Possibly slower. Emulation of the MD at full speed should be no problem, with effective programming, on the GP2x. And if I'm not mistaken, a full speed MD/Gen emulator with sound exists for the GP32 whose ARM9 runs at ~150 MHz-- and there is no forseeable reason why Z80 and YM2612/PSG emulation couldn't be done on the 2nd CPU, the 940T.

As for the Mega CD / Sega CD, the 2nd 68000 @ 12.5 MHz does not appear to be active most of the time, except when some specific functions are occurring (video decoding of Cinepack video like that on Ecco the Dolphin 1/2 (Sonic CD used sequenced tiles, not a video codec) so it's very likely the 2nd CPU would be doing nearly nothing most of the time, while the other helper chips in the Mega CD should not take any enormous speed toll (such as the VDP for functions like scaling/rotation which is almost never used by the games) or audio processing hardware which could probably be replaced by GP2x or SDL-specific code to play back Mp3 or OGG files where appropriate (it's not like you'll actually be playing from a CD, the drive would be emulated and the audio tracks virtual.)

I also see no real reason many of the helper chips could not be emulated on the 940T with some creative programming, or if synchronization of the CPUs across 2 threads is problematic, why at least audio decompression/playback couldn't occur there.

Whew, that was quite a rant. To anyone who read this far, you deserve a medal for putting up with my incessant rambling. :)
 
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idigital

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Epicenter posted on Oct 18 2005 at 08:47 PM said:
Whew, that was quite a rant. To anyone who read this far, you deserve a medal for putting up with my incessant rambling. :)

Hey, where's me medal!
 
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timthepig

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Now I've seen that list - why bother with a gp2x - keep the GP32 BLU. Yes the hardware is better etc - but really when you can get a psp for a bit more and keep your GP32 BLU.

Though the idea of having a media player in your pocket and plugging into a TV then watching divxs, is a feature which most desirable. Though the PSP can probably emulator all of this list and more(it already has snes\megadrive\atari 800\speccy etc), it also now has a device to plug into the TV.

Sorry I know I'm missing the point of this thread, but this really stupid that we are several years on from the gp32 and this is the potential emulator list? -
 

Skitzo

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I dunno..

The fact that the GP2X half the price of a PSP, that we are supporting an independant company rather than Sony (nothing against them.. much) by buying it, and that movies can be watched without converting to some PSP specific format, combined with the fact that the GP32's are no longer in production makes the choice of a GP2X pretty clear in my head.

Oh, and the whole open-source homebrew scene will be great, too. Being able to write a SDL app and port it with ease is pretty awesome for me as a developer.. not that I can say I've looked in to the PSP scene, but from what I've heard, I gather it's rather supressed.
 

Epicenter

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timthepig posted on Oct 18 2005 at 06:10 AM said:
Now I've seen that list - why bother with a gp2x - keep the GP32 BLU. Yes the hardware is better etc - but really when you can get a psp for a bit more and keep your GP32 BLU.

Though the idea of having a media player in your pocket and plugging into a TV then watching divxs, is a feature which most desirable. Though the PSP can probably emulator all of this list and more(it already has snes\megadrive\atari 800\speccy etc), it also now has a device to plug into the TV.

Sorry I know I'm missing the point of this thread, but this really stupid that we are several years on from the gp32 and this is the potential emulator list? -

The emulators available for the PSP have to be written mostly from scratch, there is no common API like SDL. SDL has been in use on PCs in Windows, Linux, BSD and other OS'es, on Macs and other platforms and has TONS of existing software that can be brought over in no time, some things have been ported in just hours like Squidge's Quake port test. Existing emulators can be brought over with ease (and some optimization) as can many many other applications. This also eases development from scratch as SDL is quite a simple API to get used to.

In addition, emulators for the PSP are still very primitive. Last I checked many run without sound and are terribly slow, even for lower-caliber systems like the SNES. Sony is actively trying to destroy the homebrew community, each firmware update wth various bug fixes (from what I've seen, it's fairly buggy firmware to begin with, and arguably buggy hardware as well) makes it more difficult to run homebrew applications, hence scrambling for a decreasing volume of Firmware 1.5 PSP units.

Combine that with the ~5 hour battery life at the stock speed of 222 MHz, then the fact that emulators require to be running at the rated speed of 333 MHz to try and squeeze more speed out of the machine, further decreasing battery life-- and you begin to see a compelling case against the PSP as the ultimate portable emulation platform in force.
 
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Hm, I hope this doesn't sound rude or anything, and it probably has been said thousands of times, but this kind of lists are purely stupid speculation.

First, even the easiest emulators have to be written/ported. The console can do lots of things, but only as long as someone writes the necessary programs, that's something everyone who has a gp32 knows.

Also speculation and Revolution-like hype is not good for anyone. Besides, I disagree about some systems. Why can't we have decent Neo·Geo emulation? "Even" a psp can do it :p. A 'less powerful' Dreamcast does it in an amazing way too. Chui and Fox68K (i hope you know why i mention them) together with Ron and the rest of DC scene are particularly interested in this emulator and they won't stop saying that it'll be possible.

So, instead of wasting time writing lists, why don't we all learn a bit of progamming? xD
 

Nuron_V

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I'm just glad most of the games i wanna run on the GP2X are available multiple platforms.
In some form Flashback or Another World should be feasable ( x86 VGA, Amiga, or SNES ).

I've been meaning to ask, I never owned a GP32 so i have no benchmark to think against, I know the GP2x isn't going to run modern MAME titles but what sort of thing is it LIKELY to be able to cope with, era wise:
Defender,
Rampage,
Starwars,
Super Puzzle Fighter?
 

Alpha2

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the GP32 runs games from around the mid to late 80s, I imagine the 2X could extend that by atleast 2 or 3 years. Maybe enough to get some early street fighter? But I'm thinking along the lines of speed and memory. The only one who'd know for sure is the person programing MAME and only after they get the hardware and start fiddling with it.

There's a port of Another World direct from the original computer version avalible for GP32 so I think a complete port could be made for the 2X, no emulator required, but a 2X version of DrMD is probably not to far off and it's near perfect on the GP32 so the Genesis version of Flashback should be availible in no time... (after the emlator is ported that is.)
 
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