Visual Displays in HCI
2006
With the invention of the light bulb, the first digital possibility to change electric power into a defined artificial light was created. Using this technology, it was possible to display two different stages with lamps, e.g. a conference room as “occupied” or as “free.” Also, the first freely programmable computer, Konrad Zuse’s Z3, used lamps as output to display four decimal digits with decimal point.