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Yellowstone

post #1 of 13
Thread Starter 
Will Rambus rise like a Phoenix from the ashes?

Highly unlikely. There never has been a company so reviled by all parties, yet have such fantastic high performance technology. It's been in my dreams for a while for Apple to adopt Rambus technology, in particular as a super large high bandwidth backside cache, but Apple is so lethargic with the technology in its hardware that it will never happen.

Rambus has come up with a chip-to-chip and memory bus technology that has octo-data rate called <a href="http://www.rambus.com/technology/yellowstone_overview.shtml" target="_blank">Yellowstone</a> using differential Rambus signaling levels. It can have bandwidths from 16 to 32 Gbyte/s. Rambus. RDRAM would also be a very interesting choice for a prospective PPC 970 system, and is great for Apple's media and graphics markets. It's just too bad Apple, Motorola and IBM wouldn't make it work on PPC.
post #2 of 13
Is RDRAM still measurably more expensive than DDRRAM? One good reason for Apple not to adopt it.
post #3 of 13
Yes RDRAM is much more than DDRAM.
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post #4 of 13
Thread Starter 
One must also note that RDRAM also has higher performance than DDR SDRAM, and will continually do so as both technologies evolve. You aren't getting nothing for the higher prices.
post #5 of 13
[quote]Originally posted by THT:
<strong>One must also note that RDRAM also has higher performance than DDR SDRAM, and will continually do so as both technologies evolve. You aren't getting nothing for the higher prices.</strong><hr></blockquote>

Err...since when? Currently it has higher latencies and lower bandwidth. It's saving grace is it is dual channel but even Intel is replacing its Rambus solutions with Dual Channel DDR SDRAM solutions early next year for its performance motherboards.
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post #6 of 13
Thread Starter 
<strong>Originally posted by Telomar:
Err...since when? Currently it has higher latencies and lower bandwidth. It's saving grace is it is dual channel but even Intel is replacing its Rambus solutions with Dual Channel DDR SDRAM solutions early next year for its performance motherboards.</strong>

Ever since dual channel systems have been in use. Nearly every single i850 system will outbench a i845 system. Unless, you think I'm not allowed to include dual channel RDRAM in my statement. And currently, a dual channel PC1066 RDRAM system with a P4 is the highest performance memory system affordable to most of us.

And yes, Intel is moving to DDR memory solutions, thus my lament of highly unlikely. But for Apple's market, RDRAM would be a better choice for performance.
post #7 of 13
Doesn't intel own a big chunk of Rambus? Also Rambus is an evil hated company....dealing with them is asking for trouble...
post #8 of 13
Thread Starter 
<strong>Originally posted by Producer:
Doesn't intel own a big chunk of Rambus? Also Rambus is an evil hated company....dealing with them is asking for trouble...</strong>

This is an <a href="http://www6.tomshardware.com/business/01q4/011024/rdf2001-06.html" target="_blank">intriguing statement</a> from Tom's Hardware:

Maybe Rambus got a bad rap because, Intel didn't do them any favors. It's only just emerging that it was Intel's engineers who were the real conspiracy behind Rambus seeing the companies evolving roadmap as a safe harbor for their P4 and multi-GHz CPU ambitions.

I'm trying to find more info on this. But it just illustrates that the conception of good and evil for company behaviors in reality is at best flawed. To illustrate, our favorite company for which this site is dedicated to is guilty of a plethora of not nice things as well. The reality is that if Apple adopts Yellowstone and RDRAM for their next gen machines, they will have a legitimate and undisputed claim to having better memory performance. And especially for Apple's application mix (long streams of media data), RDRAM would be optimal.
post #9 of 13
I admit to hating RamBus both for their apparently business practices, and for their technology's high latencies. THT is right though -- from a purely technology point of view the 970 mated to a RamBus chipset would be a rocket and would immediately be able to fully utilize the 6.4 GB/sec bandwidth. The PowerPC w/ VMX is particuarly good at minimizing the impact of high latency memory due load/store architecture, the streaming instructions, and pipelined bus design.

RDRAM is still significantly more expensive, however, and that would be a serious issue if Apple adopted it. Apple's market isn't big enough to cause RDRAM prices to drop significantly and since the PC market has backed off it so much. Apple needs to be careful to no longer adopt standards which are Apple-specific, it ends up costing them too much and in too many ways. Some things they can take a leading position on, but if the rest of the industry does a 90o turn then they are left out in the cold.
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post #10 of 13
Thread Starter 
<strong>Originally posted by Programmer:
from a purely technology point of view the 970 mated to a RamBus chipset would be a rocket and would immediately be able to fully utilize the 6.4 GB/sec bandwidth.</strong>

Well, the PPC 970 bus is only 3.2 GB one way. Dual channel RDRAM solutions can hit its limits today. The PPC 970 plus a yellowstone bus and RIMM6400 or whatever at the time would be cool. A 64 bit PC800 RIMM can go 6.4 GB/s...

<strong>RDRAM is still significantly more expensive, however, and that would be a serious issue if Apple adopted it. Apple's market isn't big enough to cause RDRAM prices to drop significantly and since the PC market has backed off it so much.</strong>

It sort of depends whether the Playstation 3 and next gen Nintendo will use it or not. If they do, RDRAM won't be that expensive, at least not significantly. My idea was a quad channel single chip per channel RDRAM backside cache to feed a prospective PPC. So Apple would just be buying 4 RDRAM chips per CPU That's a very cheap 128 MB or 256 MB of backside cache at 8.4 to 12 GB/s bandwidth

<strong>Apple needs to be careful to no longer adopt standards which are Apple-specific, it ends up costing them too much and in too many ways. Some things they can take a leading position on, but if the rest of the industry does a 90o turn then they are left out in the cold.</strong>

Yes, of course. Thus, the lament. However, if they are trailing the pack in technology, they have no where to go but the status quo, or worse, down.
post #11 of 13
[quote]Originally posted by THT:
<strong>[qb]Originally posted by Programmer:
from a purely technology point of view the 970 mated to a RamBus chipset would be a rocket and would immediately be able to fully utilize the 6.4 GB/sec bandwidth.</strong>

Well, the PPC 970 bus is only 3.2 GB one way. Dual channel RDRAM solutions can hit its limits today. The PPC 970 plus a yellowstone bus and RIMM6400 or whatever at the time would be cool. A 64 bit PC800 RIMM can go 6.4 GB/s...

<strong>RDRAM is still significantly more expensive, however, and that would be a serious issue if Apple adopted it. Apple's market isn't big enough to cause RDRAM prices to drop significantly and since the PC market has backed off it so much.</strong>

It sort of depends whether the Playstation 3 and next gen Nintendo will use it or not. If they do, RDRAM won't be that expensive, at least not significantly. My idea was a quad channel single chip per channel RDRAM backside cache to feed a prospective PPC. So Apple would just be buying 4 RDRAM chips per CPU That's a very cheap 128 MB or 256 MB of backside cache at 8.4 to 12 GB/s bandwidth

<strong>Apple needs to be careful to no longer adopt standards which are Apple-specific, it ends up costing them too much and in too many ways. Some things they can take a leading position on, but if the rest of the industry does a 90o turn then they are left out in the cold.</strong>

Yes, of course. Thus, the lament. However, if they are trailing the pack in technology, they have no where to go but the status quo, or worse, down.[/QB]<hr></blockquote>

Apple has to choose their technology leads with care -- memory is one which is pretty much out of their hands since it needs lots of volume to make it work. They don't have to trail by as much as they have been, however.

The 970 doesn't have a backside cache. A single 970 can "only" consume 6.4 GB/sec of bandwidth, but a 2-way system + 8x AGP + dual ATA 133 could consume &gt;14 GB/sec. It'll be interesting to see if Apple is up to the task of building a chipset that can move this kind of bandwidth.
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post #12 of 13
Thread Starter 
<strong>Originally posted by Programmer:
Apple has to choose their technology leads with care -- memory is one which is pretty much out of their hands since it needs lots of volume to make it work.</strong>

Well, yes of course. But it's dependent on Sony using RDRAM for the PS3. They use dual channel PC800 RDRAM for the PS2. And Nintendo is thinking about it for their next gen machine. If both of them use RDRAM for their next gen systems, they'll provide enough volume to make RDRAM reasonable.

Rambus' main advantage is that RDRAM and Yellowstone provide a memory roadmap that can keep up with microprocessors, so is more suited for future needs. It depends on how things fall. It's not good for Rambus now, probably not good in the future either. It's just too bad.

<strong>They don't have to trail by as much as they have been, however.</strong>

Always trailing is the problem. Even with the PPC 970, they will continue to trail. Intel could easily move the Pentium 4 bus to 200 MHz quad data rate for an effective 6.4 GB/s bus by 2H 03 and it'll have more bandwidth than the PPC 970 bus because the 970 bus is only 3.2 GB/s one way.

<strong>The 970 doesn't have a backside cache.</strong>

I know. Where did I ever say it did? I said a prospective PPC. Since the idea of Apple adopting RDRAM is as far out as Apple designing its own chip, it wouldn't follow that I would specify any particular PPC chip.

<strong>A single 970 can "only" consume 6.4 GB/sec of bandwidth, but a 2-way system + 8x AGP + dual ATA 133 could consume &gt;14 GB/sec. It'll be interesting to see if Apple is up to the task of building a chipset that can move this kind of bandwidth.</strong>

The PPC 970 bus is only 3.6 GB/s one way for a 1.8 GHz 970. Only 3.2 GB/s is usable one way. A memory read can never be faster than 3.2 GB/s. A dual PPC 970 can be designed around a RIMM6400 system or a dual channel DDR400 so the memory tech isn't so far out. But building the chipset would be very difficult yes. Yellowstone could make it easy!
post #13 of 13
Unrelated but if you recall, Blue & White G3s were codenamed Yosemite, could Yellowstone one day become a Mac code name? How hella-cool would that be? Unrelated, but interesting. That's all.
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