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Technology Stocks : Rambus (RMBS) - Eagle or Penguin -- Ignore unavailable to you. Want to Upgrade?

To: Ali Chen who wrote (43972)	6/10/2000 6:20:00 PM
From: John Walliker	Read Replies (2) \| Respond to of 93625

Ali, You probably are not aware that to make a bus bi-directional, the point of connection must have both receiver and transmitter attached, and be enabled in alternative manner. It is hardly possible to provide the same impedance for active and inactive transmitter, therefore the bi-directional busses have inherent impedance mismatch at every connection point. The impedance also changes dynamically as the device transmits or receives data. It again introduces inhomogenuities and hence the unpredictable reflections. I think you may have missed the whole point of the Rambus interface. It does maintain an essentially constant (high) impedance regardless of whether the device is transmitting or receiving. That is one reason why it uses constant current bus drivers. (The other one is that multiple clock domains can then coexist on the bus.) However, what you wrote perfectly sums up the problems which DDR faces. John

To: Ali Chen who wrote (43972)	6/10/2000 9:24:00 PM
From: jim kelley	Read Replies (1) \| Respond to of 93625

You guys are too much.<G> RDRAM is already in volume manufacturing. You talk as though it can't be made. then you assert with no evidence to support you that the DDR and DDR-II busses will be vastly superior. This is goofy reasoning.<G> I have done lots of engineering for high volume PC board manufacturing in my past lives. Never got stopped by any of these problems which you seem to think are almost insurmountable. A lot of my boards were manufactured by Taiwan and Hong Kong. Go ahead and remove the pins and solder connections from your DDR chips if you can. I want to see this modern engineering wonder. Perhaps you can eliminate the discrete caps and resistors too. DDR is so great you can get rid of all your stubs too. <LOL> Simply put, my point is the criticisms made by BILOW of the RDRAM transmission line bus are also true also of the DDR-II bus. Thus if you can follow BILOWs logic to its natural conclusion DDR is a dead end memory technology. DDR-II is dead, dead , dead. <LOL> The 820 motherboard according to INTEL specs is 4 layers. This is not a big deal.