NCP
acronymnetworking
Network Control Program: the ARPANET host protocol that TCP/IP replaced.
NCP assumed the network beneath it was reliable, which the single ARPANET was, and that assumption is exactly what stopped it scaling to a network of networks. TCP's separation of a reliable conversation from an unreliable delivery service was the answer, and the cutover on 1 January 1983 is one of the few flag days in this history that actually happened. Anybody who has argued about where reliability belongs in a stack is repeating an argument NCP lost.
Also known as: network control program, network control protocol