Abstract: A knob device includes a knob body, a graphic plate, and a light source. The knob body has a hollow space and has an end equipped with a screen. The graphic plate has multiple graphic windows including graphic symbols, respectively. The light source is configured to emit light through both at least one of the graphic windows and the hollow space to project at least one of the graphic symbols on the screen. The graphic plate is movable to switch the at least one of the graphic symbols to another of the graphic symbols.

Abstract: A Biorythms analog computer-calendar is provided to display without computations the level of the physical, the emotional, and the intellectual biorythms of a human body. The level of the three biorythms appears on display in analog and digital forms for any dialed calendar date, if the computer-calendar is set initially with the individual's birth date. The analog elements used to register the three biorythm levels are drums attached to gears with a number of teeth equal or proportional to 23, 28 and 33, or to the period of the three biorythms respectively. A calendar arrangement is introduced to create a correlation between the displayed biorythm levels and the calendar date associated with them.