Towards a Two-dimensional Programming Environment

167 The use of modern video display terminals for communication with a computer has a profound effect on the nature of the resulting dialogs. Screen-oriented interactive programs require a new set of tools, techniques and methods. We report on studies on these topics performed in a computing environment based on standard commercial hardware. The paper describes some of the tools which we have used and the ones we have designed ; it then discusses the methodological issues involved in designing two-dimensional dialogs, and shows the kind of program modularity which is required in this framework. Object-oriented programming appears to provide the right basis ; we have applied this methodology using the class concept of the Simula 67 language and the associated prefixing mechanism.