Revolution out in mid-2006, uses MoSys Ram

[see colon]

Little birdies are actually telling me that Xenon's DRAM is the same. No clue if there is any significance to that.

not that i would ever question the validity of your sources, dave, but wouldn't mosys have mentioned the fact that their technology would be included in another console durring the conference call? unless xenon and revolution are the same thing. and i don't think i want to be barking up that tree so i'm going to shut up now.

 

[Acert93]

Little birdies are actually telling me that Xenon's DRAM is the same.

Yes.

No clue if there is any significance to that.

No.

Little birdies? Next thing you will be spouting is some nonesense how "teh Xbox 360 = teh Revolution!!!11" Why does everyone on the console forum pretend to be an insider? DaveBaumann, if you want to last a while on this forum I would stick to short answers like "Yes" and "No" and stop pretending to have insider info.









Just teasing Dave!

 

[GwymWeepa]

Okay, the gamecube's ram was touted as being incredible...why is that? Can someone explain to me the main benefits of the ram performance wise.

 

[PC-Engine]

Okay, the gamecube's ram was touted as being incredible...why is that? Can someone explain to me the main benefits of the ram performance wise.

Didn't you read my post? :?

 

[GwymWeepa]

The significance of 1T-SRAM is the fact "it's like having a huge L3 cache" as main RAM.

This one? Explain to me, why is it like having L3 cache? What are the performance specs compared to other, similar ram in other consoles?

 

[PC-Engine]

http://www.anandtech.com/printarticle.aspx?i=1566

"If cache is so fast, then why isn't everything made out of it?"
One of the most interesting things about the GameCube design is its focus on memory bandwidth efficiency. It attains this efficiency through the use of a special type of memory known as 1T-SRAM that offers lower latency operation and higher overall bus utilization than conventional DRAM. But before you understand exactly what that is, you have to look at the differences between conventional DRAM and SRAM.

The cache on the die of the Gekko CPU or any other CPU for that matter is a type of RAM known as Static RAM or SRAM. The prefix static comes from the fact that unlike DRAM (Dynamic Random Access Memory), SRAM cells do not have to be constantly "refreshed" in order to retain their data (since DRAM is capacitance based, it loses its charge after a while requiring a refresh of that charge in order to retain its data). One of the reasons DRAM is so much slower than SRAM is because of this constant refreshing process. It turns out that when reading the contents of a DRAM cell, the cell is actually refreshed making the most common way of refreshing DRAM cells to actually read the contents of the cell.

This is perfectly fine except for when the contents of the cells being refreshed are being read from or written to. SRAM avoids this by using a combination of usually 4 to 6 transistors to statically hold the data being stored in the memory. DRAM on the other hand only uses a single transistor in combination with a capacitor to hold data; the introduction of the capacitor greatly reduces the die size of DRAM cells thus making them cheaper to manufacturer but also introduces the problem of refreshing as we mentioned above.

Here you can see the problem with conventional SRAM being used in mass quantities since you can get multiple times the amount of SRAM out of DRAM at the same cost. The cost of SRAM prohibits it from being used as a main memory solution, but it makes perfect sense for use in small amounts such as in a cache.

A company by the name of Monolithic System Technology, Inc. (MoSys) came up with a clever design for DRAM that give it many of the performance benefits of SRAM without incurring a huge cost penalty.

The technology that has garnered all of the attention for MoSys is what they like to call 1T-SRAM. The name implies that they have been able to produce SRAM using only a single transistor (1T) instead of the 6 transistors that are much more common. The reality of the situation is that 1T-SRAM is much more like a special form of DRAM than it is like SRAM. The reason being that 1T-SRAM still requires its memory cells to be refreshed in order to retain their data, the only difference being in its very efficient method of refreshing those cells. According to MoSys, their 1T-SRAM design can hide the refresh process quite effectively to the point where they can claim latency and bandwidth figures that would rival those of conventional SRAM (although not surpass). Obviously it's very difficult to test since there have been very few cases where 1T-SRAM has been used in a testable platform, but it's clear that the technology does allow for lower latency accesses and higher memory bandwidth utilization. But at what cost?

MoSys claims that a 64Mbit 1T-SRAM has a die that is 10 - 15% larger than a 64Mbit SDRAM. While that may not seem like much, do keep in mind that a 64Mbit RDRAM device is 15 - 30% larger than the same 64Mbit SDRAM. This would put the additional cost in terms of die size of 1T-SRAM equal to anywhere between 1/3 and 1/1 of the added cost of RDRAM (production cost excluding license royalties) over SDRAM. However, 1T-SRAM is still cheaper than regular SRAM again because of the fact that it is manufactured using a single transistor vs. 6 for most SRAM designs.

The performance aspects of 1T-SRAM are very difficult to quantify because we've never seen it on a benchmarkable platform making the assessment of its value equally difficult. Needless to say that we didn't present you with this explanation for no reason, as Nintendo saw it fit to make heavy use of MoSys' 1T-SRAM in their GameCube design.

 

[cybamerc]

Little birdies are actually telling me that Xenon's DRAM is the same. No clue if there is any significance to that.

Wouldn't surprise me since GameCube is the major inspiration for Xbox 2. Imitation is the sincerest form of flattery but companies that can't come up with a single original idea really have no place in this business.

 

[GwymWeepa]

Interesting, so basically its DRAM with some nifty feature that makes it similar to SRAM in performance, we just don't know how much so. Didn't Capcom at one point credit the Gamecube's ram for the performance of RE4? (though I think they also cited the lack of it as a problem lol)

 

[GwymWeepa]

Little birdies are actually telling me that Xenon's DRAM is the same. No clue if there is any significance to that.

Wouldn't surprise me since GameCube is the major inspiration for Xbox 2. Imitation is the sincerest form of flattery but companies that can't come up with a single original idea really have no place in this business.

I see the X360 as the gamecube2, its amazing how many things MS is trying to take from Nintendo. I think its very smart though, Nintendo made a heck of a lot of profit this generation...and I think that MS recognizes that if there was no competition from themselves, if it was simply Sony and Nintendo in the market, Nintendo could have made a real killing (getting much more market share than they do now). So, I think they're trying to do everything in their power to essentially eliminate Nintendo by taking their place in the market and gobbling up any market share Nintendo could have taken...all the while making a profit.

 

[Shifty Geezer]

For all that lovely article, it still doesn't explain the performance bonuses of 1T-SRAM. Who cares how it works?! Why should people be excited about it's use? What tangible benefits doesn it actually bring to the console space? Whether it's built of 1 transitor, 6 transistors, carbon nano-tubes of pink elephants is neither here nor there

 

[PC-Engine]

The benefit is: "it's like having a very fast L3 cache for your main RAM" aka low latency.

 

[GwymWeepa]

The benefit is: "it's like having a very fast L3 cache for your main RAM" aka low latency.

Now...why isn't it used everywhere? Why is the only real big project I've heard about the gamecube...couldn't pc cards use this?

 

[Shifty Geezer]

The benefits in real life surely can't be anything like, otherwise why isn't it used everywhere? Are there real bandwidth/access figures for comparison with DDR and XDR? Or do we only have PR sound-bites to describe performance?

 

[GwymWeepa]

The benefits in real life surely can't be anything like, otherwise why isn't it used everywhere? Are there real bandwidth/access figures for comparison with DDR and XDR? Or do we only have PR sound-bites to describe performance?

Well, Nintendo choosing it again must speak for the benefits of the RAM, and Dave hinted at x360 also using the memory. Perhaps memory manufacturers do not want to invest in such different technology...I mean otherwise we'd be seeing MRAM by now (companies don't invest anywhere near as much money into new RAM solutions as they do to improve existing solutions).

 

[Bohdy]

The benefits (as I understand them) are 1.) Much lower transistor usage, which equals cheaper manufacturing, and 2.) predictably low latency, which means that code will run faster with less work.

The major drawbacks appears to be lower bandwidth compared to DDR equivalents, and probably higher initial technology licensing fees.

 

[PC-Engine]

Well we can easily ask why isn't everone using eDRAM?

 

[GwymWeepa]

I would love some developer comments on the use of the same sort of memory. Naturally the technology has progressed since 2000...could this memory compete with the XDR used in ps3?

 

[Megadrive1988]

nice find, PC-Engine.



Mosys press conference audio - zoom forward 9 min.
http://web.servicebureau.net/conf/meta?i=1112573237&c=2343&m=was&u=/w_ccbn.xsl

 

[Fox5]

The benefit is: "it's like having a very fast L3 cache for your main RAM" aka low latency.

Now...why isn't it used everywhere? Why is the only real big project I've heard about the gamecube...couldn't pc cards use this?

1. It is low latency, but also rather low bandwidth. I wouldn't be surprised if it had a tenth of the latency of xbox's ddr ram, but it was also 1/3rd the speed.

Video cards don't need it, high bandwidth tends to help more, cpus would need new memory controllers and drivers, and really it would have needed some kind of market push.

It also is more expensive to produce than DDR ram, and would have less of a market.

 

[PC-Engine]

The benefit is: "it's like having a very fast L3 cache for your main RAM" aka low latency.

Now...why isn't it used everywhere? Why is the only real big project I've heard about the gamecube...couldn't pc cards use this?

1. It is low latency, but also rather low bandwidth. I wouldn't be surprised if it had a tenth of the latency of xbox's ddr ram, but it was also 1/3rd the speed.

Video cards don't need it, high bandwidth tends to help more, cpus would need new memory controllers and drivers, and really it would have needed some kind of market push.

It also is more expensive to produce than DDR ram, and would have less of a market.

Are you talking about bandwidth per pin at the same clockspeed?