A CASE (Computer Aided Software Engineering) tools mean any tool used to automate some activity associated with software development. Some of these CASE tools assist in phase-related tasks such as specification, structured analysis, design, coding, testing etc.
The classical Waterfall Model was the first Process Model. It is also known as a linear-sequential life cycle model. It is very simple to understand and use. Classical waterfall model is the earliest, best known and most commonly used methodology.
In Iterative waterfall model, the feedback paths are provided from every phase to its preceding phase. In practice, it is not possible to strictly follow the classical waterfall model for software development work. In this context, we can view the iterative waterfall model as making necessary changes to the classical waterfall model so that it becomes applicable to practical software development projects.
A software development life cycle (SDLC) is a series of identifiable stages that a software product undergoes during its lifetime. A software development life cycle model (also called process model) is a descriptive and diagrammatic representation of the software life cycle.
The spiral model is a software process model that couples the iterative nature of prototyping with the controlled and systematic aspects of the linear sequential model. Barry Boehm mentioned the Spiral model in this paper (1986).
COCOMO (Constructive Cost Estimation Model) model was proposed by Boehm (1981). According to Boehm, software cost estimation should be done through three stages: Basic COCOMO, Intermediate COCOMO, and Complete COCOMO.