ROMAN ABACUS - Italy between 2nd and 5th centuries

The world abacus is used to describe one of the earliest calculating devices: digital, manually operated and with no automatic features, the abacus was the first computing device to provide five fixed decimal orders.
The Romans improved the primitive abaci. Counting beads (made of stone or ivory) were strung on a series of wire or rods, and calculations were performed by moving them back and forth according to a set of rules. (collection IBM Europe)