Anyone know why the ps3 has 2 separate memory banks...

[ralexand]

when the cpu and gpu both have access to both. Why not just make it one source?

 

[EpicZero]

when the cpu and gpu both have access to both. Why not just make it one source?

I wasn't aware that they both have access to both... :?

 

[Carl B]

when the cpu and gpu both have access to both. Why not just make it one source?

I wasn't aware that they both have access to both... :?

Yup.

 

[Tim]

when the cpu and gpu both have access to both. Why not just make it one source?

I wasn't aware that they both have access to both... :?

They don't.

 

[Carl B]

They don't.

What are you saying here? It's fairly widely known that the RSX can access the XDR.

@Relazand: Anyway to partially address your original question, some theories are NVidia not being able to get their memory controller directly compatible with XDR, reduced cost of the GDDR modules, and the whole 'Cell limited to four devices' thing, which is untrue anyway, so...

But those are some of the ideas floating around for that.

 

[mckmas8808]

Tim everybody knows that they both have access, so just stop.
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[jvd]

Can the cell acess the gdr ? Never really heard anything about just assumed that it did . Though i don't see the need for cell to acess the gdr with its own pool of ram

 

[Carl B]

Can the cell acess the gdr ? Never really heard anything about just assumed that it did . Though i don't see the need for cell to acess the gdr with its own pool of ram

Yeah, on the Cell to the GDDR I don't know either, but like you said I never bothered to clear that aspect up for myself because why would it need to.

 

[Tim]

Tim everybody knows that they both have access, so just stop.

No Cell cannot access the GDDR - why are people spurring this kind of nonsense.

 

[jvd]

yea so i think its a bit much to claim that everyone knows they can both acess the other ones pool of ram.


But the one that will need to acess more ram more often can (rsx )

 

[mckmas8808]

So what is the VRAM then? :?
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[Carl B]

So what is the VRAM then? :?

Mckmas what? The RAM dedicated to the GPU is the 256 GDDR3.

 

[Teasy]

CELL can't address more then 256MB of ram, so Sony included another 256MB for the GPU. They gave the GPU access to CELL's ram as well so that if game code was less then 256MB the GPU could use that extra space.

 

[mckmas8808]

So what does this quote from Ken Kutaragi mean?

CELL and RSX have close relationship and both can access the main memory and the VRAM transparently. CELL can access the VRAM just like the main memory, and RSX can use the main memory as a frame buffer. They are just separated for the main usage, and do not really have distinction.

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[Carl B]

CELL can't address more then 256MB of ram, so Sony included another 256MB for the GPU. They gave the GPU access to CELL's ram as well so that if game code was less then 256MB the GPU could use that extra space.

Teasy that thing about Cell not being able to address more than four memory devices is a myth.

 

[Teasy]

Then why use 2 seperate banks of memory? What am I missing?

 

[Guden Oden]

No Cell cannot access the GDDR

Of course it can, don't be SILLY. The rambus interface to the GPU is bidirectional, of course it can address GPU memory.

CELL can't address more then 256MB of ram

Now that's just flat-out wrong, I don't know where you got that silly idea. Address registers are bound to be at least 32 bit wide even in the APUs and likely 64. The PPC core is a 64-bit chip throughout, it addresses way more than 256MB.

 

[Carl B]

Then why use 2 seperate banks of memory? What am I missing?

Refer to my comments above for that - unless someone has further clarification/hypothesis

 

[Teasy]

Now that's just flat-out wrong, I don't know where you got that silly idea. Address registers are bound to be at least 32 bit wide even in the APUs and likely 64. The PPC core is a 64-bit chip throughout, it addresses way more than 256MB

I got the idea from the few CELL threads I took a look at on this forum. I remember thinking at the time that since 360 had been confirmed to have 512MB of ram PS3 would have to as well. But if PS3's configuration of CELL only supported 256MB of ram then the only way to do that was to add another 256MB for the GPU. So when PS3's specs were announced and it did use two banks of 256MB that seemed to reafirm the claim so I assumed it was true, perhaps not then.

 

[Carl B]

The first page of *this* will clear it up for you.

(halfway down page)