To: MileHigh who wrote (7318 ) 9/21/1998 4:00:00 PM From: Mark Rosneck Read Replies (1) | Respond to of 93625
MileHigh, The ubiquitious-ness was a feeble attempt at humor on my part. To answer your question -- let's start with the benefits of embedded memory over external memory: 1) Size reduction (fewer chips in a design) 2) Weight (same as above) 3) Power consumption (no need to drive signals on the PC board with high power drivers) 4) Speed (you can use wide busses to move a great deal of data) 5) Cost (fewer chips to stuff onto the circuit board) Disadvantages are: 1) Cost. This is multifaceted -- Embedded dram processes are less well developed. Also, the testing process is more complicated since you have to test the logic, then the memory, laser repair bad memory locations, test again. Potentially, this means lower yields and a longer manufacturing time. 2) Speed. While you can do wider busses, you can't take advantage of new DRAM processes. You're limited to processes that also support logic. 3) Lack of design flexibility. It's hard to add a few extra megs of memory to a design when the memory is in the chip! Where are embedded DRAMs finding acceptance? Well, one place is portable devices (notably laptop computers) that benefit from reductions in size, weight, power, and can tolerate a higher price to get these benefits. How about set top boxes or things that connect to a computer such as a cable modem? Would the consumer be more willing to buy one of these at a premium price that was smaller, lower weight, and used less power? Probably not since it sits on a TV set or home computer and plugs into house power. Now if you can build one cheaper, then perhaps but that's not where the most powerful benefits of embedded memory reside. This is probably an oversimplification but: 1) If it's battery powered, the trend will likely be to embedded DRAM. 2) Otherwise, it will be off chip memory and we longs are betting that's Rambus starting next year. There's my $.02. Regards, Mark