The first true computing device was the ancient counting tablet called ABACUS.The word abacus (plural abaci)was derived from the greek term abax.That means table or board covered with dust.These counting tablets used the idea of pebbles for counting.Grooves were carved into the stone or clay table and pebbles were placed in these grooves.The pebbles could be slipped along the grooves from one side of the table to the other to represent numbers.This allowed for easier counting and steps with simple caculations,like addition or subtraction.