A history of system R and SQL/data system
Donald D. Chamberlin, A. M. Gilbert, Robert A. Yost · Very Large Data Bases · 1981
System R is an experimental database system constructed at IBM Research Laboratory in San Jose to demonstrate that the usability advantages of the relational data model can be realized in a system with the complete function and high performance required for everyday production usage. SQL/Data System is a relational database management system offered by IBM in the DOS/VSE operating system environment. SQL/DS interfaces with the CICS data communication subsystem, and can be used in conjunction with the DL/I data base product. This paper traces the development of System R as a research prototype and its evolution into the SQL/DS product.