Methods and structure within a storage controller for using region locks to efficiently divert an IO request received from an attached host system to one of multiple processing stacks in the controller. The structure is comprised of a photodetector chip, having an isolated micromachined cavity on the chip surface, and a light emitter chip, stacked on the bottom surface inside that cavity, so that a stack-integrated embodiment of light detector and emitter capable of performing full duplex optical communication is resulted. The second logic circuit may be configured to detect and present a faster clock signal of the synchronized clock signals. A second memory block may be configured in a manner compatible with the first memory block format. In any event, the reference pressure or main pressure may be derived from a pump pressure which is being monitored. In addition, either a) 0\u2266x<2 and 0<y<1 or b) 0<x<2 and y is 0 or 1 with the proviso that if M is Ca2+ and x=1 then y is not 0.