The properties of presently available components place special emphasis on two desiderata of logic design for use in a microwave digital computer: 1) Smallness of the number of active elements; 2) elimination of information-cycling paths having delay times comparable or short compared with the bit period, as in the conventional flip-flop. A logic design developed in response to these pressures is described in substantially complete detail. Property 1) is obtained by the use throughout of a multiplexing procedure such that the computer functionally (although not physically) resembles a number of nearly identical, and correspondingly slower, computers which are able to operate either independently or in concert.

A definition is provided for the term ``general purpose computer'' (gpc) which is compatible with usage and is analogous to, but distinct from, Turing's definition of a ``universal computer.'' A gpc is presented in functional and logical design which seems to approximate the minimum complexity consistent with this definition. No specific definition of complexity nor a bound on required complexity is presented.

The logical design described here is used in MINAC, partially constructed at the California Institute of Technology, and LGP-30, manufactured by Librascope Inc. These serial binary digital computers make use of magnetic drum bulk storage and use three circulating registers and fifteen flip-flops. The procedures used in performing the sixteen elementary operations are described. These descriptions indicate the circumstances in which each flip-flop or circulating register input is activated. The Boolean algebraic equations summarizing these circumstances constitute the logical design.