What's the skinny on DDR-II?

[Sohcan]

Does anybody have any solid information (links?) on the technical details of DDR-II? A lot of people have been posting conflicting rumors:
- DDR or QDR?
- bandwidth?
- serial or parallel bus?
- SRAM row caches?

I went to Jedec's website, and the best I could find was this probably out-of-date PDF. Much of the design nature seems unresolved (at the time of writing), but it does imply that DDR-II will have a parallel bus (pg. 3: parallel control offers lowest inherent latency, DDR-I backwards compatibility).

Is there any more current information out there?

 

[PHATJACK]

This and this is all I could come up with.

 

[BurntKooshie]

Aha, here we go, found it:

"DDR2 and Low Latency Variants." Huh, I just noticed, one of the authors is a proff at my University...maybe I'll go look him up sometime 😉

Anyway, that's a 15 page paper discussing it, not that I've read through and understood it all. Anyway, a google search will bring a place to download it.

And of course, the bibliography is huge....happy hunting 😉

And, AFAIK, it's serial....

it can be found hre. For what it's worth, the place that is hosting it is a safehaven for all kinds of technical documents....

 

[Noriaki]

nevermind me, I just can't read today.
I think I'll just go have some more coffee.

 

[BurntKooshie]

Noriaki -- Sohcan aready linked to that one himself in the first post ;-)

 

[Noriaki]

lol I missed that 😉

Obviously it doesn't answer his questions...like I said I haen't read it very carefullly.

 

[Sohcan]

Eh, it's early (at least that's what I'm telling myself 🙂). That EE Times story that Phatjack linked seemed to imply that it's QDR (DDR signaling with four voltage levels), but it's 18 months old, and I haven't heard anything about it since then. The JEDEC PDF has been there for a while...I think I remember reading it about a year ago, so the specifications may have changed since then.

If PC3200 and PC4800 DDR-II is indeed 200MHz DDR and 266MHz DDR, respectively, it seems to be nothing more than higher-clocked DDR-I. I wonder what seperates DDR-I from DDR-II.

 

[Rand]

<<
it can be found hre. For what it's worth, the place that is hosting it is a safehaven for all kinds of technical documents.... >>



Thanks for that link, you were very right about it being a haven for many technical documents. Some great stuff in there 🙂

 

[Noriaki]

Actually PC4800 would be a 300Mhz DDR clock 😉

300Mhz * 2 * 8Bytes = 4800MB/s 😉
266Mhz * 2 * 8Bytes = 4256MB/s 😛

Maybe DDR-II is just DDR optimzed for high clock speeds like a GF2 over a GF-DDR.

.13um RAM maybe? 😉

 

[Sohcan]

<< it can be found hre. For what it's worth, the place that is hosting it is a safehaven for all kinds of technical documents.... >>

Aha! Thanks, that's exactly the kind of document I was looking for.



<< Actually PC4800 would be a 300Mhz DDR clock >>

Mental math didn't exactly quite cut it for me there. 🙂

 

[fkloster]

I thought this stuff was going serial. Not parrallel...