Think of variables (like objIE) as floating references or containers that refer to objects or numbers we want to manipulate. But before we get to use them, we have to declare, or Dim, them, which sets aside some memory for whatever kind of use we have in mind for them. To manipulate Internet Explorer as an object in VBA, we need to Dim the browser — either generically as an Object variable (an example of late binding objects), or more specifically as an InternetExplorer special object variable like we did here (an example of early binding objects).
Relay logic was introduced with factory electrification, which underwent rapid adaption from 1900 though the 1920s. Central electric power stations were also undergoing rapid growth and operation of new high pressure boilers, steam turbines and electrical substations created a large demand for instruments and controls. Central control rooms became common in the 1920s, but as late as the early 1930s, most process control was on-off. Operators typically monitored charts drawn by recorders that plotted data from instruments. To make corrections, operators manually opened or closed valves or turned switches on or off. Control rooms also used color coded lights to send signals to workers in the plant to manually make certain changes.
Engineers can now have numerical control over automated devices. The result has been a rapidly expanding range of applications and human activities. Computer-aided technologies (or CAx) now serve as the basis for mathematical and organizational tools used to create complex systems. Notable examples of CAx include Computer-aided design (CAD software) and Computer-aided manufacturing (CAM software). The improved design, analysis, and manufacture of products enabled by CAx has been beneficial for industry.