Advanced systems designers have a dream. It is to put everything on a single die. Let's face it. It's not going to happen.
True, process technology advances provides smaller geometry's, thus higher densities, and faster performances. In many to most non demanding applications, today's level of technology is good enough to house enough ROM, RAM, processors, peripherals, and glue to achieve this dream.
But, anyone pushing the envelope will run out of resources, even with the millions of gate counts of available logic. It isn't a mere density limitation though. It has more to do with the fact that specific functions (like memory more so than others), are fabbed on a process that is optimized for that type of memory.
For example, a state of the art DRAM fab is not the same type of fab used on ASICs, FPGAs, or microprocessors/microcontrollers. The same is true with a Flash foundry process. The number of layers, the types of materials, the types of metals, etc, are all used for what advantages they bring to solve specific problems.
That's one reason I keep an eye out on Multi Chip and Stacking technologies. While not new or as ultimately inexpensive as a single die solution can be, they solve a lot of tomorrow's problems today.
Take for example, the joint release from Toshiba and Staktek. The announcement of the availability of the first 576Mb FCRAM. Based on Staktek's StakPak BGA stacking technology, it makes possible a seemingly single chip 16Mx36 Network FCRAM targeting the high-performance enterprise networking space.
For cutting edge designers the designated PDS-14100-00 means a doubling of the size of packet buffers in the same X-Y real estate. What's more, the Toshiba DRAM at the heart is fully compatible with Samsung's Network-DRAM, meaning they can live in this space. Maybe this will relieve some of the sole source worries when moving into new and uncharted territory.
Staktek's StakPak technology is 'unique' in that it provides controlled impedance interconnections and high-speed switching noise decoupling internal to the stack. These features are important as the industry continues on the path of higher and higher memory speeds
I foresee more application specific stacks and packs emerging. While a bit more costly than we would otherwise want, it gives us that much more, which could be the competitive edge.