RE: Transmission line busses
"I don't have anything against transmission lines, I use them all the time."
Carl, be truthful, you do not have time to work as an engineer when you full time employment is here on the thread. <G>
" Even transmission lines on PCBs aren't that much of a problem."
They are manufacturing millions of RIMMs so you correct there is no problem.
"Where RDRAM gets into trouble is with all the stuff attached to the transmission line."
You can't be referring to stuff like memory chips and memory controllers as well as the termination resistors and bypass caps. Really, Carl these are necessary. Which stuff do you think they ought loose? I really would like to know!
If they could have put the discretes on the chips I suppose they would have.
"I don't know what kind of transmission lines DDR-II is going to use, but I am certain that they are going to be a whole lot more robust than the RDRAM garbage."
Oops! You are showing your bias against RAMBUS. You admit that you have no idea how they are going to implement DDR-II transmission line busses or even what the problems will be.
"In addition to 32 RDRAM chips, there are a driver, a termination resistor, and up to six (was originally supposed to be eight) socket connections. This involves something like up to 39 solder joints, and up to 6 board/connector connections."
I think they need the solder to hold the components in place and make a good electrical connection. <G>
"Even then, they could get them to work, but in addition, they wanted them to be compatible between multiple manufacturers of the memory chips, up to 16 different numbers of RDRAM chips on each and therefore RIMM type, several different generations (i.e. 64Mb, 128Mb, etc.) of memory chips, and multiple different memory controllers."
What are you trying to do here mix Sony PS-II RDRAM with PC RDRAMS? This is a new product line no need to reach back into history for compatibility!
"Even that could be done, but in addition to all the above, they wanted to send data down the whole shebang at 800MHz, with 33 lines in parallel, and bidirectional, and using a standard CMOS process. No way."
You seem to be in denial Carl. They have done it! They are shipping millions of RIMMs and millions of RDRAM based computers. They are shipping 800 MHZ RDRAM PCs and Workstations.
"As an example of a reasonable use of transmission lines, take AMD's Lightening Data Transport. It has only two chips on a wire, it single directional, no connectors, and are at a much lower frequency. (And is therefore easily and cheaply manufacturable.)"
Carl, 820 motherboards are only 4 layer boards. Hardly, that expensive to make. The PS-II is way inexpensive to make. By the way bidirectional busses reduce the number of traces requirred on the MOBO.
"Quite frankly, RDRAM was an idea thought up by a bunch of impractical over-educated know nothings. We've all seen these kinds of people in action at technical companies. They show up with a big pile of credentials but no real understanding of the practical problems of the real world, and unless management is capable of recognizing engineering, they destroy whole projects and even companies."
Carl, there is nothing wrong with education. |
