1T-SRAM vs. ZRAM vs. SRAM, etc.

[bk9]

So, I'm obviously a noob, but I've got some questions regarding the various memory technologies out there. I have searched the forum, used google, wiki, etc. so I've got a basic understanding of it, but wanted to hear your more seasoned opinions.

I pretty much get the differences between DRAM and SRAM, but why hasn't 1T-SRAM caught on? The technology has been around for years, but it seems as if 1T-SRAM hasn't really proliferated the market as much as I thought it would have. People like the Wei, but that doesn't seem to be enough.

- Some have told me that 1T-SRAM does work better than SRAM, yet it's more expensive and you really only get the benefit w/ gaming (ala the Wei)
- Others have said technology adoption is like a hockey-stick...and it's just taking a long time for people to adopt the 1T-SRAM
- Then, there's ZRAM, MagRam, and other SOI-based floating-body mem technologies...maybe people are waiting it out?

Anyone care to take a shot at walking through pro's/con's of 1T-SRAM vs. traditional SRAM & DRAM and the upcoming ZRAM? Do you know for what type of applications they each work best?

Sorry for the abundance of questions, I'm just trying to understand things and thought I could get some good assistance from the forum members.

Thanks for the help,
B

 

[Farhan]

It's unlikely IMO that 1T SRAM is more expensive than standard 6T SRAM. It's also slower and has to be refreshed, unlike 6T SRAM. In that sense it's closer to normal DRAM and ZRAM than 6T SRAM. You want to use it when density is more important than outright performance, if you need lots of onboard memory. 6T SRAM still wins if performance is your main concern.

 

[StefanS]

It's unlikely IMO that 1T SRAM is more expensive than standard 6T SRAM. It's also slower and has to be refreshed, unlike 6T SRAM. In that sense it's closer to normal DRAM and ZRAM than 6T SRAM. You want to use it when density is more important than outright performance, if you need lots of onboard memory. 6T SRAM still wins if performance is your main concern.

Yep, IIRC Moysy claims higher reliability than 6T-SRAM. It draws less power than 6T SRAM as well.

You might wanna check their HP for more info (LINK1, LINK2), bk9. They used to have some nice pdfs.

 

[crystall]

It's unlikely IMO that 1T SRAM is more expensive than standard 6T SRAM. It's also slower and has to be refreshed, unlike 6T SRAM.

Most 1T-SRAM implementation need refreshing but this is transparent as the currently refreshed bank is copied into a regular SRAM buffer. The real problem with 1T SRAM is that it doen't live well in a standard logic process since it uses DRAM cells for storage. ZRAM might be better from that POV but its speed is not exactly stellar either.

 

[Mat3]

How would 1T-SRAM as normal, external RAM compare to current, more traditional RAM? In the last generation of consoles, it was clearly better than RAMBUS in the PS2 or DDR RAM in the Xbox. Why didn't Nintendo use it instead of GDDR3 in the Wii? (I know it uses it as internal memory as part of the graphics processor, but I'm talking about main memory.) Has the performance gap closed, or was it simply a cost decision to use GDDR3?

 

[nonamer]

How would 1T-SRAM as normal, external RAM compare to current, more traditional RAM? In the last generation of consoles, it was clearly better than RAMBUS in the PS2 or DDR RAM in the Xbox. Why didn't Nintendo use it instead of GDDR3 in the Wii? (I know it uses it as internal memory as part of the graphics processor, but I'm talking about main memory.) Has the performance gap closed, or was it simply a cost decision to use GDDR3?

Overwhelming capacity per cost decision. GDDR3 is like 2.5-3 times more dense than 1T-SRAM.

 

[dodo3]

http://www.betanews.com/article/Rambus_DRAM_Royalties_to_be_Capped/1170694099

Could this mean Sony pays less royalties for XDR?

 

[Mat3]

http://www.betanews.com/article/Rambus_DRAM_Royalties_to_be_Capped/1170694099

Could this mean Sony pays less royalties for XDR?

No, the lawsuit deals with companies making SDRAM and DDR SDRAM, so they're not related at all. RAMBUS shouldn't be collecting a penny for any of it. They didn't do anything except sneak in their patents and then sue and demand royalties for what was supposed to be an open standard, while their own tech, RDRAM, was garbage.