The present invention provides ink-jet writing engine modules for use with a compatible hard copy engine module, a hard copy apparatus based thereon, and methods of manufacturing, operation, and use. Fluidic and electronic partitioning for ink-jet hard copy apparatus is redefined. Modular separation of a hard copy engine from a writing engine allows a replaceable writing module containing all of the key elements of the ink-jet writing system based on writing system technology requirements, particularly for those most likely to age or fail as a result of time, frequency of use, or end-user actions. The writing engine subsystem includes: one or more printing modules having print head elements with concomitant ink manifold components and ink flow and pressure regulation mechanisms; one or more ink containers--either permanent, refillable, or replaceable; one or more ink formulations; one or more ink delivery means, such as tubes and valves fluidically coupling the ink containers to the ink manifolds; service station components; and a framework to retain the elements in a unitary module, insertable cassette-like manner. The present invention further provides a hard copy engine compatible with such a writing engine. The hard copy engine does not contain any components requiring direct contact with ink. Ink-wetted components are predisposed to ink-jet technological changes without affecting the electrical interface and the mechanical interface between the writing engine and the hard copy engine.