The Display Text Editor TED: A Case Study in the Design and Implementation of Display-Oriented Interactive Human Interfaces

We present the criteria used in designing the human interface of the display text editor TED and explain how the design tradeoffs were made. Although discussed in the context of a text editor, these criteria are applicable to the design of human interfaces in general. We present a critical evaluation of the TED human interface in hindsight, and suggest modifications to overcome the shortcomings thus uncovered. The new interface is judged to be less obtrusive and more flexible than its earlier version. This process of design-implementation-evaluation is essential to learning how to build good human interfaces in the future. We describe the software architecture of TED and point out how the use of sound software engineering principles has yielded a program that is easy to modify and interface to a variety of I/O devices, namely, screens, keyboards, cursor pointing devices, and voice recognition units.