The Honeywell DDP 516 computer was part of Honeywell's Series 16 family of computers. In the 1960s, they were commonly used for data processing. DDP 516 computers were used as interface message processors (IMPs) in the early ARPANET network. ARPANET was the first computer network to use packet switching to share information between disparate computers. IMPs were the gateways that enabled packets of data to be transferred between machines.