fj> savings in terms of energy

in electrics you want to be really conservative about the trace distance bits have to go (q.v. capacitance and energy-per-bit).

it takes less than a femto-Joule of energy to move one bit worth of charge through the source to the drain of an MOS transistor in deep sub-micron CMOS technology, and about 10 fJ to move a bit through silicon TSV (a little bit less for SOI TSV).

additionally you need about one pico-Joule to move one bit across a 1cm die, 3 pJ to move a bit in a register, about 10 pJ to go to L1 cache, 20 pJ to L2 cache, and 40 pJ to L3 cache, along with a few nano-Joules to move data through wiring.

plus almost 100 pJ to move from one die to another (electrical SERDES), but only single-digit pJ for optical (like POET).

just wanted to put a yardstick of current real-world state-of-the-art numbers out there, so that once Geoff publishes datasheets, we'll have something to measure against.

GLAL,

R.