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I went to Jedec's website, and the best I could find was this probably out-of-date PDF.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...