Computing hardware and software have advanced at extraordinary speed, yet system engineering often remains a document-heavy bottleneck. Volume One introduces Data Driven System Engineering (DDSE), an output-first method that organizes computing-system development around the data the system must produce. Every Data item is treated through two systematic attributes: Data Value and Data Timing. The book begins by distinguishing Computing Systems from conventional physical products and explaining why required Output Data-not documents, functions, or components-must become the center of engineering. It then develops the three Data roles of Input Data, Middle Data, and Output Data; the relationships and constraints that derive outputs; the System Operation Concept (SOC); Data Contracts; and the Executable Procedure Node notation used for recursive development. Chapters 6 through 12 turn these foundations into a complete method for development planning, requirements identification and refinement, system architecture, hardware and software allocation, verification, lifecycle management, and engineering traceability. The method is demonstrated continuously through door-open warning, cooling-fan control, and object-detection examples, with explicit signals, Value limits, Timing limits, data flow, interfaces, and verification evidence. Chapters 13 through 20 apply the same logic to automotive electronic control units, including sensors, control algorithms, communication, AUTOSAR integration, ISO 26262 functional safety, ISO/SAE 21434 cybersecurity, and Automotive SPICE. Rather than adding disconnected compliance artifacts, DDSE anchors engineering and assurance work to authoritative Data and relationship objects. Volume One is written for systems engineers, software and hardware engineers, ECU architects, safety and cybersecurity engineers, verification specialists, technical managers, researchers, instructors, and advanced students who need a clear and auditable path from engineering goal to verified computing-system behavior.