Request for Comments: 689 May 1975 NIC #32656 TENEX NCP Finite State Machine for connections TENEX Memo Number 155 The attached figure describes the finite state machine used in TENEX version 1.33 to implement the ARPANET Host to Host protocol. This memo updates that of 27 August 1971, TENEX memo number 113, with regard to the finite state machine. Other parts of that memo have been incorporated into the JSYS manual and other documents. TENEX NCP Finite State Machine for Connections