The ongoing developments in nanotechnology promise extremely powerful computers, but they may require new designs. Heat dissipation will become a major issue at the high integration densities allowed by nanotechnology, and it is therefore unsurprising that techniques to reduce it, like asynchronous timing, have attracted growing interest in recent years. At the same time, some researchers have come to realize that the types of signal and circuit realizable by nanotechnology may be very different from those in solid-state electronics. Signals, for example, may be encoded by particles, giving them a token-like nature. Primitive operators in circuits will have to be designed with this in mind, and asynchronous circuits are no exception to this.