ABSTRACT
In control rooms built during the 1950s, information presented to operators was an analogue of plant functioning, for instance, movement of a needle on a dial represented a change in temperature or pressure. Each measured variable from the plant could be assigned its own indicator, which resulted in large panels of hard-wired displays. Many of the measured variables could be acted upon from within the control room through switches or levers. Panels were thus laid out so that controls and displays were correctly positioned, both in terms of physical proximity between a control and its associated display and in terms of the physical operation of a control.
