Installing Extra Ram On The Gp2x

[God Ginrai]

interesting....

 

[Radek]

Probably all you need to do is find some larger-capacity RAM chips rated for 133 Mhz with the same pinout and you are basically set. It just won't be very easy to replace the old 32MB ones. May as well get RAM rated for 166 Mhz or higher to aid overclocking since 200 MHz CPU clock = 100 MHz RAM clock, 266 MHz CPU clock = 133 MHz RAM clock .. etc. Might help you break 300 Mhz easier.

Not from Eorex. My GP2x has em48am1684vta sdram chips. They are in 16Mx16 configuration so 256Mbits each. Eorex has some sdram chips at 512Mbits but in different packages and working at different voltages.

The MKII has Hynix sdram
And if you will look what Hynix has to offer then you should see that 256Mb are the biggest ones.

There is a question if there is enough lines in PCB exposed to adress more memory?

 

[Fishbong]

I seriously doubt it, but what about a memory mod for the second processor?
I don't know if it's possible, practical or even helpful, just an idea.

*sigh* THE GP2X HAS ONLY ONE PROCESSOR. This processor has two cores, that´s why its called a dualcore processor!
Actually the shared RAM is the only way both cores can communicate under linux, so giving them separate memory chips would be a very stupid idea.

 

[Vimacs]

no..

 

[Squidge]

Actually the shared RAM is the only way both cores can communicate under linux, so giving them separate memory chips would be a very stupid idea.

Actually, you can provide each processor with a mixture of it's own dedicated ram and shared ram. GPH decided to only use shared ram however. If you gave the 940 it's own dedicated ram, it would increase performance of that processor by a significant amount, as it's only held back due to the fact that both processors are fighting for the a/d bus at the same time.

Before someone asks how you upload code to the second processor when it has dedicated ram, you would upload it to the shared memory, and then the 940 would copy that code to it's own ram before execution (kinda how GBA games copy code from 16-bit rom to 32-bit wram for faster execution).

 

[Javacat]

I've manually altered the MMU tables, and can get full speed access to the whole 64MB. The emu I was playing with increased by about 3 fps too by doing so

*Intrigued*

Any chance of releasing a program to do this automatically? h34r:

 

[Aninhumer]

So is there any chance of that actually being practical squidge?

 

[Fishbong]

Actually the shared RAM is the only way both cores can communicate under linux, so giving them separate memory chips would be a very stupid idea.

Actually, you can provide each processor with a mixture of it's own dedicated ram and shared ram. GPH decided to only use shared ram however. If you gave the 940 it's own dedicated ram, it would increase performance of that processor by a significant amount, as it's only held back due to the fact that both processors are fighting for the a/d bus at the same time.

Before someone asks how you upload code to the second processor when it has dedicated ram, you would upload it to the shared memory, and then the 940 would copy that code to it's own ram before execution (kinda how GBA games copy code from 16-bit rom to 32-bit wram for faster execution).

I didn´t say it is impossible, but you´d need to transfer all the code from the shared section to the dedicated section of the memory. Wouldn´t that be rather slow ? Better to increase the whole memory....?

 

[Orkie]

I didn´t say it is impossible, but you´d need to transfer all the code from the shared section to the dedicated section of the memory. Wouldn´t that be rather slow ? Better to increase the whole memory....?

Once it is in the dedicated memory, it would run much faster though. On a PC video card, sending things to and from the card is quite slow, but the video card is so good at what it does, the time saved there makes up for it. Same idea here.

 

[Epicenter]

I seriously doubt it, but what about a memory mod for the second processor?
I don't know if it's possible, practical or even helpful, just an idea.

*sigh* THE GP2X HAS ONLY ONE PROCESSOR. This processor has two cores, that´s why its called a dualcore processor!
Actually the shared RAM is the only way both cores can communicate under linux, so giving them separate memory chips would be a very stupid idea.

Wrong. The MMSP2 is a System-on-a-Chip with 2 independent ARM9 processors, although the 940T's functionality is limited when not 'baby-sat' by the 920T.

 

[Radek]

I seriously doubt it, but what about a memory mod for the second processor?
I don't know if it's possible, practical or even helpful, just an idea.

*sigh* THE GP2X HAS ONLY ONE PROCESSOR. This processor has two cores, that´s why its called a dualcore processor!
Actually the shared RAM is the only way both cores can communicate under linux, so giving them separate memory chips would be a very stupid idea.

Wrong. The MMSP2 is a System-on-a-Chip with 2 independent ARM9 processors, although the 940T's functionality is limited when not 'baby-sat' by the 920T.

The MMSP2 is an asymmetrical dualcore machine. The 920T has more cache and MMU, the 940T has less cache and doesn't have a full MMU. But raw power of both is the same. It's an efficiency to utilize them well what is a problem.

 

[nubie]

I seriously doubt it, but what about a memory mod for the second processor?
I don't know if it's possible, practical or even helpful, just an idea.

It looks like that could gain us an appreciable speed boost for Dual-Core type things.

Possible/Practical, maybe not. The MMSP2 is on a BGA, Ball Grid Array, meaning all connections happen on the bottom like DDR2 Ram chips and the sides have no pins or legs, that means that pins without connectors "traced" out from under the Chip cannot be used.

The GP32 Ram upgrade depended on some extra wires going to the processor, I don't know if that is required here, but we would be SOL if that was the case.

I think Squidge's sweet MMU hack will help things to get better, I wonder if the PSX emulator is using it, or would benefit from it .

 

[Epicenter]

'MMU hack'? What is this?

 

[nubie]

'MMU hack'? What is this?

It is Squidge's way of re-ordering the Linux caches in the shared memory so that the main processor sees all 64MB and it makes it all the same speed to access (unlike the way it is now, with the upper 32MB being cached for the Co-Proc, and being slower to access because of it).

Here is a link to the thread, could only help to get more speed and ram to the main processor
http://www.gp32x.de/board/index.php?showtopic=29451

I meant that it might not be necessary to add more RAM because we aren't using what we got properly yet anyway.