NCP

NCP is short for Network Control Program, which was the very first network protocol on the ARPANET. The Network Control Program was developed and released in December 1970 by the Network Working Group (NWG), lead by Steve Crocker.
The kick-off for the development of this protocol was the first Request for Comment (RFC) written one year earlier, in April 1969 by Steve Crocker. NCP itself consisted of a set of programs for host-to-host connections.

Since the lower protocol layers were provided by IMPs, NCP basically provided a transport layer, which consisted of the ARPANET Host-to-Host Protocol (AHHP) and the Initial Connection Protocol (ICP). AHHP defined the method of transmitting a unidirectional data stream between two hosts. ICP defined the procedure of establishing bidirectional streams between multiple host-processes.
After more than twelve years or constant service for the ARPANET, the veteran Network Control Program was entirely replaced by the more flexible protocol composition of TCP/IP on January 1, 1983.