Other relational systems

The 1995 SQL Reunion: People, Projects, and Politics discusses a number of the other early relational systems, including PRTV, Ingres, Oracle, Britton-Lee, Esvel, HP ALLBASE, Informix, Sybase, IBM DB2, Teradata, and Tandem NonStop SQL. Since the reunion, I've obtained some information about four other early systems:

Multics Relational Data Store
Business System 12
G-EXEC geological data handling system
Arnie Rhom's eXtractor

If you have additional information about these or other early systems, I invite you to contact me at <paul at mcjones dot org>.

System R home page; Paul McJones's home page
Internet address: paul at mcjones dot org