Digital Data Communications Message Protocol

{{Short description|Communications protocol}}

{{primary sources|date=October 2011}}

Digital Data Communications Message Protocol (DDCMP) is a byte-oriented communications protocol devised by Digital Equipment Corporation in 1974{{cite book|author1=Gurdeep S. Hura|author2=Mukesh Singhal|title=Data and Computer Communications: Networking and Internetworking|url=https://archive.org/details/datacomputercomm0000hura|url-access=registration|date=28 March 2001|publisher=CRC Press|isbn=978-0-8493-0928-1|page=[https://archive.org/details/datacomputercomm0000hura/page/483 483]|quote=Digital Equipment Corporation (DEC) developed a byte-oriented protocol known as digital data communications message protocol (DDCMP) in 1974.}} to allow communication over point-to-point network links for the company's DECnet Phase I network protocol suite. The protocol uses full or half duplex synchronous and asynchronous links and allowed errors introduced in transmission to be detected and corrected. It was retained and extended for later versions of the DECnet protocol suite. DDCMP has been described as the "most popular and pervasive of the commercial byte-count data link protocols".{{cite book|last=Barksdale|first=William J.|title=Practical Computer Data Communications|url=https://books.google.com/books?id=GTrrBwAAQBAJ&pg=PA185|date=13 March 2013|publisher=Springer Science & Business Media|isbn=978-1-4684-5164-1|page=185|quote=DEC Digital Data Communications Message Protocol (DDCMP)... is the most popular and pervasive of the commercial byte-count data link protocols.}}