A new breed of Computerized Monitoring and Control Systems (CMCS) and ever more powerful microprocessors performing “direct digital control” (DDC) are challenging traditional ways of doing HVAC controls. In spite of the fact that modern CMCS installations control complex mechanical processes, these systems are usually designed, built, and interfaced by computer types with little involvement of mechanical professionals. At this time microprocessors have solved some problems, especially in energy conservation, and created many new ones; however, in spite of difficulties, this new technology appears to be the “handwriting on the wall” announcing the demise of pneumatics.

The present article is based on the premise that if mechanical and com­puter professionals were to work together, the unavoidable transition to DDC can be achieved faster and more efficiently. One of the barriers to such collaboration is the confusing CMCS vocabulary; accordingly, this paper reviews some fundamentals of computers, microprocessors, field interfacing, software, and algorithms.