Digital-imaging based code symbol reading system employing a micro-computing platform supporting an event-driven multi-tier modular software architecture. The system includes: an image formation and detection subsystem; an illumination subsystem; an illumination control subsystem; an image processing subsystem; an input/output subsystem; and a system control subsystem. The image formation and detection subsystem has an area-type image sensing array for detecting digital images of objects formed thereon by image formation optics providing a field of view (FOV) for the system. Within the FOV of the image formation and detection subsystem, the illumination subsystem produces a field of illumination that illuminates the object during the image capture mode of operation, and one or more 2D digital images thereof are detected by an area-type image sensing array. A micro-computing platform is provided for implementing the digital image processing subsystem, the input/output subsystem and the system control subsystem. The micro-computing platform includes a microprocessor, a memory architecture, and a three-tier modular software architecture characterized by an operating system layer, a system core layer, and an application layer and responsive to the generation of a triggering event within the digital-imaging based code symbol reading system. Triggering events can be generated by an automatic object detector or a manually actuated trigger switch.