Reversible computing

In the present paper, we give a design methodology for reversible logic circuits. The implementation is based on complementary MOS (metal-oxide-semiconductor) transistor technology. Any Boolean function can be built from a 24-transistor building block. It follows that any combinatorial computer can thus be designed. The resulting digital computer is able to calculate in both directions, such that input and output are indistinguishable. Such reversible MOS circuits we call r-MOS systems. Because such systems have neither specific power lines nor clock lines, they are particularly suited for studying the fundamentals of digital computation. Endoreversible thermodynamics allow us to compare them to Carnot engines. (C) 1999 Elsevier Science Ltd. All rights reserved.