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Rambus and DDR RAM writeup
jerkychew writes "Hannibal over at Ars Technica has written part 3 of his RAM guide,, this time focusing on the technical details of Rambus and DDR RAM. As always, a good (if compliacted)technical read. " If you're not scared of pin counts and parity, then this is a cool article.
DDr may be technically supperior to rambus but its dead out of the water. WHy then?
:-( ).
one word, PATENTS!
Rambus owns the intellectual property of virtually every syncronized ram chip in existance (including ddr)and also including a really scary patent on using a register to address memory!
I know you guys probably just read the previous story here about a guy who now claims that internet stock transactions are his own personal property and the last thing you want to hear are more greedy corporations and whining but they are a real problem.
The only reason sdram is still here is that rambus made it available cheaply now to show that there is competition to the fcc and also to highlight rambus as the next big thing. Rambus promissed no ddr ram chips in large qualitites would ever be introduced without big lawsuits.
I also read a news article on zdnet explaining that the p4 will be rambus only.
As the chip becomes standard expect ddr ram to slowly vanish and people will all forget about ddram since all the vendors like compusa and directwarehouse wont stock ddr because the demand will be too low (remember AMD hardly made a dent in intels armour. Many bussinesses only buy computers with intel chips).
As soon as the ddr is made in smaller and smaller quantities the price to manufacter will go up making it even more expensive then rambus (remember rambus will sue othe memory manufactors unless its priced much higher then rambus.
Company officals admitted they will try this tactic to wipe out ddr.
I believe sadly that amd's sledghammer will als be rambus only (correct if I am wrong guys. I would be happy if I was.). I thought I saw an article here on slashdot that amd finally gave in to rambus demands.
Its a shame supperior technology will be blocked again.
Remember to write to your politicians on patent abuse because its really hurting us.
you mean 'l337' don't you?
Pope
Freedom is Slavery! Ignorance is Strength! Monopolies offer Choice!
It doesn't mean much now, it's built for the future.
on ars (the ones at the bottom are broken and point to part III), so here they are :
part I
and
part II
these are really good, and very educational!
...dave
Think different? I'd be happy if most people would just think...
All the information I have read has pointed to the latency as a killing factor to RD-DRAM. While RD-RAM has faster access, it is only 16 bits at a time, which puts it with DDR-DRAM. If there is something that myself or others don't understand about RD-RAM which will make it better for future use could please allaberate more then just saying Rambus is actually a solid and viable memory technology? I have heard many techinical arguments against it. I am willing to hear arguments for it but I haven't heard any yet so if you have some please post them as I am more interested in the truth then in personal bias.
Molog
So Linus, what are we doing tonight?
So Linus, what are we going to do tonight?
The same thing we do every night Tux. Try to take over the world!
OK, this is obviously an uninformed post which is bordering on Trollness, but let me clear up some things for you.
;-)
1) Rambus is not a standard put out by Intel. Rambus is not even a standard at all. Rambus is a company which makes its money by licensing their intellectual property. Rambus Direct DRAM (RD-DRAM) is a standard put out by Rambus which outlines how to manufacture and communicate with their memory technology. Rambus licenses this to memory and chipset manufacturers such as Intel, NEC, and Samsung. FYI AMD also has a Rambus license, but they have done nothing with it.
2) While RD-DRAM does offer higher bandwidth than traditional SDRAM, its implementation brings about a whole bunch of other problems. Neither RAM standard is perfect, however DDR-SDRAM has better performance than RD-DRAM in almost all scenarios, and it's CHEAPER because A) no licensing fees and B) it's very very similar to SDRAM so fabrication plants can simply modify their existing production lines instead of creating whole seperate lines for RD-DRAM.
3) AMD has nothing to do with Rambus or DDR SDRAM. When you buy RAM you are not "buying Intel" or "Buying AMD." That's like saying you're "buying Honda" when you buy some Firestone tires that fit your Honda. [sarcasm]And of course we shouldn't buy Honda because they are an evil Japanese corporation, and Japan is where Pokémon came from, which is the spawn of Satan.[/sarcasm]
4) Intel is pushing the RD-DRAM standard because of an agreement with Rambus which, if they can make RDDRAM successful, they get enormous amounts of Rambus stock. Basically Rambus bribed Intel in order to get their superior product out there so they could make more licensing fee money.
5) Intel is NOT ALLOWED to market a DDR-SDRAM chipset for high-end desktop machines under the terms of this agreement. All this talk about Intel making a DDR-SDRAM chipset for regular PCs are foolish. They may try to produce a "server chipset" which supports DDR-SDRAM, but you will not see a high-end PC chipset from Intel which supports DDR-SDRAM. Note that the chipset must be made by Intel, that's not to say VIA or SiS can't make one.
6) Rambus is produced in the same fabrication facilities as SDRAM.
7) It's l337 or 1337, not l335.
"I want to get more into theory, because everything works in theory." -John Cash
RDRAM is technology that was good in the mid 90s but which has been surpassed by DDR SRAM. Making DDR SRAM scale is a far simpler problem than making RDRAM efficient. People tend to solve the simpler problems first.
--
It's a
-- Danny Vermin
I'm sure the engineers designing the Alpha EV7 are perfectly well aware of the limitations of Rambus technology. Probably more so than I am.
--
It's a
-- Danny Vermin
No you can't. Read the freaking spec sheets for a real RDRAM. Look at the CAS-to-CAS time for a single bank and do the sums yourself.
--
It's a
-- Danny Vermin
Glad we finally got there. Whew! ;)
--
It's a
-- Danny Vermin
Is that simple enough to understand, or is my crack-addled brain going too fast for you?
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It's a
-- Danny Vermin
I've been using Rambus parts for years (N64, now PS2) and the performance just isn't that great. Performance is what people like, not cool designs or easy board layout. The theoretical performance isn't even that important - it's the massive complexity of the RDRAM controller on the FSB which drags the actual numbers down. Add to that the fact that RDRAM bandwidth is only 1/3 of theoretical bandwidth even in the best case, unless you have multiple channels open simultaneously. Great for multiproc servers, perhaps, but lousy for singleproc desktop machines.
So, I'd be interested to know, why do you think future memory will be more like Rambus and less like SRAM?
--
It's a
-- Danny Vermin
I'll wait for independent benchmark tests on the P4, thanks. The only way you can saturate a 64-bit, 400MHz bus using RDRAM is to have 4 chips running pre-requested consecutive accesses, and even then the bus load will be more like 83% because of bank switches. This is *not* a real benchmark.
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It's a
-- Danny Vermin
Compliacted? Shoulda used the preview button.
So there I was. Naked. In a refrigerator. With a potroast on my knees. Smokin a cigar. That's when it got REALLY weird.
I've read enough... I'm just waiting for DDR SDRAM mobos to come out! Anyone have any ideas on how soon VIA and ASUS will be bringing something to market?
Vote Naked 2000
A feeling of having made the same mistake before: Deja Foobar
The slashdot crowd refuses to acknowledge that Rambus is actually a solid and viable memory technology (that's just a couple years ahead of its time). We'd rather just rant and rant about DDR is great and Intel sucks and Rambus is a fascist organization, yadda yadda yadda. Pack up your reality and go home.
I think the biggest problem with DDR SDRAM is the lawsuits. According to this article: http://www.tech-report.com/news_reply.x/882,
... I get very angry at what Rambus is trying to do.
... but basically these lawsuits need to be cleared before companies will invest in mass production of these chips.
June 16: Toshiba signed agreements with Rambus, Inc to pay Rambus royalties on SDRAM and DDR RAM based products. This development has the potential to seriously shake up the memory market. Toshiba has just set a precedent, and basically sold out the rest of the world's memory manufacturers.
Basically, Rambus is making Toshiba pay huge $$$ to make and market DDR SDRAM. In that article, it states that the royalty rate is even higher than RDRAM. (which we all know is way overpriced!)
Later on in the month, The Register ran this article: http://www.theregister.co.uk/content/3/11576.html
This one is by Hitachi which is counter suing Rambus stating they have an unfair monopoly on memory. Now I'm no lawyer, but reading these articles
Taken from the register piece:
Hitachi admits that the '804 Patent was issued to Rambus on September 21, 1999, and is entitled "Synchronous Memory Device Having An Internal Register."
There's more legal stuff in there
:P
My (quick) reading of the article indicated that RAMBUS does have a few problems:
1) More parts (thus, higher cost)
2) Only access 1/2 the banks of memory at a time.
3) RAMBUS claiming patents for SDRAM production doesn't make their case any better as well.
That being said, will RAMBUS (aside from the political issues) give better performance..say...5 years from now, when we all have 2Ghz machines running with an 800Mhz FSB motherboard? Some of what I've seen implies that the performance is really nasty right now, but in a few years when CPU and FSB speeds increase, it could pick up more performance.
-- Ever notice that fast-burning fuse looks exactly the same as slow-burning fuse? I didn't... (Edgar Montrose)
A follow up I found on The Register, so at least ALi and IWill are in the hunt, preview boards out early fall... sigh. Gonna be a long wait until Christmas, I guess.
Maybe I should just tighten the belt and go for the 1040MHz Alpha (w/DDR, AGPx2)
Vote Naked 2000
A feeling of having made the same mistake before: Deja Foobar
Here's the dirt:
Rambus is a member of the JEDEC, a committee of Semiconductor manufacturers which was created to help set standards for different types of chips. All the major manufacturers are JEDEC members, as well as other companies including Intel and Rambus.
One of the agreements to joining the JEDEC is that you must disclose all patents, finalized and pending, to the committee and you may not withhold such information, or use information gained in the JEDEC forums to file your own patents.
Rambus decided not to follow the agreement, and instead filed a patent during the SDRAM standard negotiations which would attempt to patent the exact implementation of SDRAM which was being written up. In the patent office, if your patent is not granted you can get extensions on it by modifying it. So what they did is continually string the patent along for several years, modifying it slightly so that as the SDRAM (and later DDR-SDRAM standard) was finalized, their patent looked exactly like what the standard was supposed to be.
Now the patent finally went through (god bless those morons in the patent office), and since everyone has implemented their RAM according to the standard, Rambus is suing them all for patent infringement.
However, there is very little chance they'll win. First, they violated the JEDEC agreement. Second, there is certainly prior art. Third, there was a decision back in '96 (I think) against Dell Computer when they patented something which was the result of "An Industry-wide Standardization effort" where the courts ruled that their patent was unenforceable. This is going to happen to Rambus, as well.
As for Hitachi and Toshiba backing down and paying license agreements there are specific reasons.
After the settlement, Hitachi sold their RAM division to NEC. They don't have to deal with the problem now, and since NEC is incorporating Hitachi's RAM infrastructure into their own, the licensing agreements probably mean jack now.
Toshiba, on the other hand, manufactures the RD-DRAM which is used in the PlayStation 2. They're making enormous amounts of money from this, and if they didn't agree to pay more licensing fees to Rambus, Rambus might pull their RD-DRAM license, thus forcing Sony to find someone else to manufacture the RAM.
Hope this has been informative...
"I want to get more into theory, because everything works in theory." -John Cash