Gp32 Memory Expansion


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Ages ago some clever chap whos name has escaped me set about boosting the amount of Ram inside his GP32! Now IIRC he had found some pin for pin memory replacement - which ran at the same voltage and rate - but it required some software jiggery pokery...

I'm very much a lurker here.. mainly pop along to check out the news - so can anyone fill me in on what has happened to this project, If its works, taken off - and how many folk have enhanced there GP32's?


Cheers,

Bobson
 
Well, that was me, and my site has all the details.

Status at the moment:
1) AFAIK, no-one else has done the mod, although I heard an unsubstantiated rumour about one person
2) The change does require a few wires
3) mr spiv and I did some bios changes to support the ram, it works perfectly.
4) gp32spain has a "32MB mod" entry in their "grand challenge" scheme, at the moment they've realised that spiv and I have done the work, but they haven't paid us out yet :D

So, with no installed base of 32MB GP32s, not surprisingly the emulator coders etc haven't been lining up to support it!
 
does the 32MB of ram upgrade increase the OC max speed? seeing as the limitation before was the ram. if it puts it higher i might look into finding soimeone to do the mod for me :)
 
divadsci: I don't personally believe that overclocking ability is related to RAM. I may be wrong, I usually am :D

Anyway, my site also has a section on overclocking, read it if you're interested.
 
Jr2swiss posted on Feb 8 2004 at 02:09 AM said:
Well if you can upgrade the ram would you be able to make a gba emulation since there is a larger amount of ram
c`mon, Not again.
You could have 1 gig of ram on the GP32, It still would not
make a GBA emulator run any faster.

Whats this with the GBA, Is it because the GP32 in some way resembles a GBA. If people want to play GBA games, Get a GBA. If people want to play GBA roms, Get a laptop. <_<

Enough already.

Excuse my American, I`m English ;)

Trooper
 
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trooper posted on Feb 7 2004 at 08:18 PM said:
Excuse my American, I`m English ;)
lol, nice one

we probably have GBA Emulation POSSIBLE for large roms on GP32, but at full speed... i say not

Technicalities are a good thing

and somtimes they bring more idiots asking stupid questions
 
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but, what if the GBA game you were wanting to play was only available in Japan (but you had a rom of it)?
 
I have done the mod. I am working on the OC mod now. I'm an ace @ soddering.... Take it easy. I haven't turned it on yet with the OC mods, cuz I'm afraid of f.ckin it up, so I'm letting my friend @ RS electronics take a look @ it.

-Matt (Robster ur a pretty good my friend, nice stuff)
 
Zero3K posted on Feb 7 2004 at 09:49 PM said:
but, what if the GBA game you were wanting to play was only available in Japan (but you had a rom of it)?
what does being a japanese rom have to do with anything? it's a GBA game through and through
 
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does the new ram remove that ugly ram bug that stops u from writing to memory at the full speed?
 
jlebrech posted on Feb 8 2004 at 08:25 AM said:
does the new ram remove that ugly ram bug that stops u from writing to memory at the full speed?
Its to do with quality not quantity. The GP32 has had many types of memory chp installed (Probably the cheapest Gamepark could get their hands on that could still manage 133mhz). So the 32meg expansion wll not necessary boost performance unless its really good quality ram. But then you have to start thinking about the quality of all the other components in the GP32.
Ahh well. ;)

Trooper
 
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maybe precaching all info into the ram can help but then u still have to blit image to the screen.
 
Gorillazero: you've done the 32MB mod? woohoo! You're the first, congratulations. :D Did you send me an e-mail about it? I've done a OS reinstall and lost lots of e-mail, sorry about that. But if you've done the 32MB mod, surely the OC mod is a walk in the park!?

jlebrech and trooper: woah back there boys! So much misinformation...

First off, RAM access bandwidth is a problem in every modern computer system, not just the GP32. That's why systems all have cache, to try and smooth out the load on the RAM bus. Believe me, if you try to do memory-to-memory copies on a 3GHz Pentium, even with the latest 500MHz DDR RAM, you'll get processor stalls while the memory catches up.

The GP32 doesn't run the memory at 133MHz, it runs at half (or quarter) of the CPU speed. So even at 166MHz, the RAM runs at 83MHz. That's not a problem for the RAM in any GP32, because even when the GP32 was a new product, 100MHz RAM was the standard (my GP32, and most I would imagine, had 133MHz RAM). The problem is with the CPU, and its buffers on the memory bus which aren't specified to run above 66MHz (you can read that in the data sheet). I won't go into the details, but this is the reason that doing my mod to increase the CPU core voltage allows better overclocking.

Finally, the "ugly bug" is also with the CPU. When the CPU write-back cache gets full, and it has to be cleared, the memory access can prevent other functions (such as sound DMA) from working. That's why you get choppy sound when doing screen blits etc. So Samsung is to blame for it, but don't be too hard on them- when you have lots of data going around various sources and destinations, it's a very difficult problem to make sure that all the priorities are correct. If you get into the details of it, the memory bus architecture on any modern processor system is extremely complex.

Right, end of rant :)
 
so, what advantages does a 32mb gp32 bring anyway? i mean it DOES sound tempting... :)
 
Well, basically, it means that large game files could be loaded at once, rather than being paged - this would be particularly useful if someone ever developed (the haven't yet, so not much point - yet) a Neo Geo emulator, since many of the games, if not all the games for that system are very very large, and the entire file must be loaded in order to play them (you could in theory page to the SMC, but that would be waaaaaay too slow).

So essentially, you'd be able to mod the SNES emu to let you play Tales of Phantasia, and possibly (although likely not) SFAlpha 2 and Star Ocean - the only SNES games that I know of that were larger than 4MB. Were someone to manage a perfectly otimised ASM GBA emu (which is unlikely on so many fronts as to be able to be said to be impossible), it would also let you use the 8MB, 16MB, and 24MB roms (the 32 ones would be a bit big, I think). This is, as already mentioned, extremely unlikely.

In addition, either you'd have to mod every program that came into the GP (the common view), or possibly write a software layer that effectively acted as a GP32 emulator on GP32 (effectively, you mod then as they're run, with instructions that wouldn't make sense to the new bios being replaced with standard ones - this is the first time I've heard this idea, but I'm probably forgetting some crucial thing that I never knew) in order to play anything at all. Overall, therefore, unless 32MB GPs start cropping up everywhere, methinks the mod prolly isn't worth it atm... Might be in the future though.
 
im still thinking about doing.. ok not myself. a friend of mine is very good at soldering... the mods :)
hmm, but until now only the OC mod seems to be useful, can i do this mod without the ram mod? is it hard to get the right chip for the ram mod?
about gba emulation, with more ram you can load the bigger games...
and if someone codes a good asm gba emu form scratch it would be also possible to play gba (withoutsound i think) at a playable speed... but no one really seems to be so intrested in gba emulation, i would be happy with perfect snes :D
 
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