How about 1.8 volts +/- 10%. Yeah, I was reading a flyer about Atmel’s 32-bit AVR® UC3 chips with picoPower® technology. It points out selected devices will work off this low of a voltage. That means a couple of alkaline batteries that are almost dead at 0.9 volts will still power the chip. The flyer points out that the AVR UC3 will do 70 DSP functions, more proof that you don’t need those power-hogging DSP chips from our competitors to run your system. The UC3 chips also do peripheral DMA (direct memory access). This means you can hammer the SPI and USART at 33Mbit/s and the CPU will only be at a 15% load.