Multics Relational Data Store
- RDBMS running under Unix's parent, Multics. Released June 1976, believed to be the first relational DBMS offered by a major vendor: Honeywell.
- http://www.mcjones.org/System_R/mrds.html

Business System 12
- An RDBMS designed to be strictly relational, unlike SQL. An important example of the model independence of a particular implementation such as SQL.
- http://www.mcjones.org/System_R/bs12.html