Phases in the development control system design software

Four phases of design software development in a control system research and development environment are described. The first phase consists of developing software to meet the needs of specific projects. The second phase is the formation of a common users library or federation of routines. The remaining two phases are developments of packages. One of these packages meets the need for simplicity in performing common design tasks The other package meets the need for performing experimental research tasks The role of three major factors that influence these developments is also discussed These factors are control technology computer technology, and convenience of usage.