XY-WINS is an integrated environment that supports design, prototyping, implementation, and debugging of graphical user interfaces. XY-WINS tools allow user interface designers to work at an abstract level, thus enabling non-experts in computer graphics to quickly prototype graphical interfaces. However, the tools also allow great flexibility in defining graphical features. XY-WINS supports the development of user interfaces consisting of two main modules: a Graphical Abstract Machine (GRAM), and a High-level Interaction Component (HIC). The GRAM encapsulates the lower levels of input and output, and provides the HIC with an abstract view of the user based on abstract representations of pictures and on input tokens incoming through input channels. The HIC implements the dialogue between this abstraction of the user and the back-end of the system.

An ongoing project concerned with the development of environments that support the specification and design of concurrent systems is reported. The project has two key aspects: an existing and working system, Clara, that supports Milner's CCS as a specification and design language; and the development of general techniques for computer-aided generation of Clara-like environments for other concurrent languages. The Clara environment is emphasized. It has two main components: support for the usage of formal techniques in the design process, and a rich and highly interactive simulation facility. A further distinguishing feature is the environment's graphical user interface which is based on a pictorial version of CCS. The semantics of CCS is defined nonprocedurally in two phases: an operational semantics given as a set of inference rules, and an algebraic semantics represented by a set of equational rules.>

In this paper we discuss our approach to a formal description of the UNIX operating system [Rit78a] [Rit78b] [Tho78], using Milner's Calculus of Communicating Systems (CCS) [Mil80].