Unisys DMSII

The Unisys Data Management System II (DMSII) is a database system originally created by the Burroughs Corporation in 1972. It was available on the Burroughs (later Unisys) Small (B1000), Medium (4000, V Series) and Large System (5000, 6000, 7000) product lines. The later, A Series, Clearpath, Libra product lines support it and in recent releases of Unisys Clearpath software it has been renamed as the Enterprise Database Server for ClearPath MCP. The original DMS II used a network model.

It originally competed with IBM's IMS and CICS products and predated the popularity of relational databases.

History

DMSII provided an ISAM (indexed sequential access method) model for data access, transaction isolation and database-recovery capabilities. The database schema was written in the proprietary Data and Structure Definition Language (DASDL). The DASDL source code was compiled with a system utility into a file containing the metadata for the database (known as the description file). A database-utility program would use the database description file to create the remaining components of the database.