It is often cited that what differentiates an embedded microcontroller from other general purpose computing devices is its integration into a larger electrical or electro- mechanical system. While this is generally true, the fact remains that processors of widely differing capability and architecture are employed in this regard. Unfortunately, this broad explanation
defines nothing; we are still left to contend with everything from full-blown embedded PCs to the smallest self-contained single-chip microcontrollers. Within this expansive realm, conventional wisdom may lead to the conclusion that the smallest microcontrollers are only appropriate for driving smallscale applications with very limited processing
requirements. While this is unquestionabl y the case in many instances, a class of applications exists that mandates a relatively high level of program complexity within severely constrained space limitations. Faced with such a seeming paradox, engineers
often feel they have no choice but to adopt a less than optimal design strategy
using a larger microcontroller than originally intended.