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Structured analysis (SA) combines blueprint-like graphic language with the nouns and verbs of any other language to provide a hierarchic, top-down, gradual exposition of detail in the form of an SA model. The things and happenings of a subject are expressed in a data decomposition and an activity decomposition, both of which employ the same graphic building block, the SA box, to represent a part of a whole. SA arrows, representing input, output, control, and mechanism, express the relation of each part to the whole. The paper describes the rationalization behind some 40 features of the SA language, and shows how they enable rigorous communication which results frorn disciplined, recursive application of the SA maxim: "Everything worth saying about anything worth saying something about must be expressed in six or fewer pieces."

Requirements definition encompasses all aspects of system development prior to actual system design. We see the lack of an adequate approach to requirements definition as the source of major difficulties in current systems worlk This paper examines the needs for requirements definition, and proposes meeting those objectives with three interrelated subjects: context analysis, functional specification, and design constraints. Requirements definition replaces the widely used, but never well-defined, term "requirements analysis."

This paper describes a system for providing mixed graphical and verbal communications with a multi-access computer via a satellite computer with a display. We assume that such an arrangement is necessary to satisfy an on-line user's large-scale computation and storage requirements economically, and to provide graphical facilities at remote terminals. The general-purpose Display Interface System, parts of which reside in each machine, acts as an interface between the user's programs and the display terminal. It provides means for communication as well as system functions required in each machine. Since it is general purpose, and no user will require all the features it provides, the software exists in the form of system libraries from which a user may select an appropriate subset for his particular application. The user's interface with this system in each machine is intended to be hardware independent

At the previous SHARE Design Automation Workshop a general description of the then current activities of the MIT Computer-Aided Design Project was given. The principal activities which were outlined were: (1) The cooperative AED-1 Project in which visiting staff programmers from industry join with our MIT staff in the research and development of advanced compiler and language processing techniques to serve as the foundation for a total Computer-Aided Design System for man-machine problem solving, (2) Studies of mixed verbal and graphical language processing by the uniform techniques of the Algorithmic Theory of Language. Since that time extensive progress has been made in both of these areas.