Hi Dan3; Re STBY and NAP modes in RDRAM. The nap mode is just a power down mode similar to what has been available for years in other memory types. Sure it can only stay there for a limited amount of time, but that is the case with any other power down mode. (DRAMs require refreshing, for instance.)
I believe that you are incorrect when you suggest that more than one RDRAM chip might need to be in the high power read or write states (in a particular RDRAM channel.) STBY would be the standard mode for the chips that are not being read or written. Keeping two chips in write mode, for instance, would suggest that you are writing the same data into both chips.
There is some tiny chance I could be wrong in the above statement, but it would probably have something to do with juggling memory banks in such a way as to remove bubbles from the data stream. I don't have my RDRAM data sheets with me, so I'll have to check back later.
In any case, I would like to give a balanced analysis of both the good and the bad things having to do with RDRAM, so I wanted to correct this before somebody else did.
Another EE-Times link:
"In cost-conscious Taiwan, the difference between a PC133 memory solution and a Rambus solution is the key sticking point here. We asked Intel to not give up on SDRAM yet," said Jeb Kuo of Acer Open Inc. "The higher cost of Rambus DRAM is still its major flaw. It's just too expensive."
An engineer working at First International Computer Co., who asked not to be named, agreed. "We are not in a hurry to develop Rambus DRAM boards. First, it's a matter of cost. A Direct RDRAM module could be about $200 more expensive. Also, we have no working samples of Camino," Intel's core logic that will support a 133-MHz front-side bus, the Pentium III processor and Direct Rambus.
McComas said "the total cost premium for a system using Rambus DRAM is almost $300. The premium for a raw D-RDRAM is about 35 percent higher than for a 133-MHz SDRAM. When packaging, testing, ECC compatibility and ramp-up costs are added, the premium is like 50 percent. Further, now that OEM orders for DRDRAM are plummeting, the price must rise to pay for production costs ,so the final price premium is around 70 percent."
techweb.com
-- Carl |
