Computers and electronics play an enormous role in today's society, impacting everything from communication and medicine to science. Although computers are typically viewed as a modern invention involving electronics, computing predates the use of electrical devices. The ancient abacus was perhaps the first digital computing device. Analog computing dates back several millennia as primitive computing devices were used as early as the ancient Greeks and Romans, the most known complex of which being the Antikythera mechanism. Later devices such as the castle clock (1206), slide rule (c. 1624) and Babbage's Difference Engine (1822) are other examples of early mechanical analog computers.