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Major problems encountered in the design of a micromodule digital computer (MICROPAC) for tactical operation within the Field Army are described and solutions presented. Such problems include module heat transfer, interconnection of modules and module assemblies and selection of module assembly size and configuration. The utilization of the circuitry booklet configuration for module mounting, interconnection and cooling is described. It is shown that reasonable air cooling will provide adequate heat transfer for several thousand modules dissipating an average of 120 milliwatts per module. The quantitative dependence of over-all circuitry packaging density upon connector pin per module requirements, type of booklet and harness wiring, booklet size and configuration, etc. is presented in analytical form. It is concluded that an over-all circuitry section (including connectors, backplane wiring, etc.) packaging density of 150,000 components per cubic foot is obtainable by the utilization of micromodules with an average packaging density of slightly less than 500,000 components per cubic foot. The extent to which the equipment designer and user will achieve their objectives by the application of micromodules to military digital equipment is discussed. It is indicated that more than 60,000 modules (each containing such logical elements as a flip-flop, two logic gates or equivalent) can be mounted, interconnected and adequately cooled within a volume occupied by a 6-foot rack. This dramatic reduction of volume (and weight) is accompanied by a corresponding decrease in the equipment support or overhead cost per module.