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Rambus Takes Another Shot At High-End Memory
An anonymous reader writes "Tom's Hardware is running an article about Extreme Data Rate memory (XDR DRAM for short), which was developed by Rambus and now entered mass production in Samsung's fabs. Right now, Rambus says the memory is only for high-bandwidth multimedia applications such as Sony's Cell processor, but the company ultimately hopes to push XDR into PCs and graphics cards by 2006. Time will tell if Rambus has learned from the mistakes it made with RDRAM a few years ago."
I don't visit Tom's as a matter of principle - it's my feeling that Tom's reviews favor his biggest advertisers, not the best technology. ExtremeTech covers the same topic here: http://www.extremetech.com/article2/0,1558,1188770 ,00.asp
cuz it's 6-9x more transistors per bit so your gig o sram costs at least 6-9x more than your gig o sdram.
...SRAM is much more expensive to produce? It also takes more power and generates more heat.
That and the benefits of cache go DOWN as the size of the cache goes up. Past a MB or two the benefits would be lowered. Also as the # of address lines goes up the access gets slower. And finally a bigger bottle neck is that "external memory" is external.
So unless you want to pay for a cpu with a GB of onboard "memory" in the form of SRAM.... the benefits won't be that high.
Tom
Someday, I'll have a real sig.
Not necessarily. It depends on the application. In "streaming" applications (hint: 3D rendering like on a graphics card!) the latency doesn't matter nearly as much as bandwidth.
A deep unwavering belief is a sure sign you're missing something...
150million / 6 = 25 million...
25million bits / 8 = about 3MB.
Parent poster is correct.
Time will tell if Rambus has learned from the mistakes it made with RDRAM a few years ago.
Well, Rambus has expanded their latest lawsuit blitz to include DDR2 patent claims, so do you think they've learned?
"The introduction of XDR however is reminiscent of RDRAM around 2000/2001. The technology provided significantly more speed than DDR and was promoted by industry heavyweights such as Samsung and Intel."
Actually, RDRAM was introduced around 1995, and was used by industry heavyweights such as SGI and Nintendo.
3.06 GHz Pentium 4, 512KB cache, 533MHz FSB, RDRAM
3.00 GHz Pentium 4, 1MB cache, 800MHz FSB, DDR400 RAM
You're probably comparing a Prescott to a Northwood. They're fundamentally different processors -- way more than a remap from 130nm to 90nm, but share enough I guess for Intel to continue branding it Pentium 4. For example, Prescott has longer L1 latency than Northwood, twice as long L2 latency than Northwood, and longer mispredict penalty (11 more stages). All those latencies add up to not-as-good performance at the same frequency.
It's a tough act for Rambus to carry out; on the one hand, they have to deal with a small group of manufacturers who have (reportedly) been trying to defraud them and put them out of business, on the other hand, they have to rely on that same small group of manufacturers for all of their future revenue, so aggravating them too much is probably also a bad idea.
Of course, it's also possible that the judge was Just Plain Wrong, and Rambus was just trying to get submarine patents in place while they were a member of JEDEC. I don't have the expertise to make that judgement.
Whoever corrects a mocker invites insult;
whoever rebukes a wicked man incurs abuse.
--Proverbs 9:7
Why don't you use equivalent processors when doing this kind of comparison. Even though the second CPU has 1 MB of cache, it's a Prescott core and can often be slower than the older Northwood at same clock speed because of the much deeper pipeline.