X.28 (Paperback)

High Quality Content by WIKIPEDIA articles! X.28 is an ITU-T standard specifying the interface between asynchronous character-mode data terminal equipment (DTE), such as computer terminals, and a Packet Assembler/Disassembler (PAD) that connects the DTE to a packet switched network such as an X.25 network. Asynchronous serial communication describes an asynchronous, serial transmission protocol in which a start signal is sent prior to each byte, character or code word and a stop signal is sent after each code word. The start signal serves to prepare the receiving mechanism for the reception and registration of a symbol and the stop signal serves to bring the receiving mechanism to rest in preparation for the reception of the next symbol.