This paper describes an interesting tool, developed by the authors, that helps designers create an on-screen prototype of a device. The authors use a bread toaster to illustrate the kind of design activity they support. Basically, their approach consists of providing a storyboard of the various actions a design may take, providing an easy way to specify the sequence of actions (put in the slices of bread, then pull down the toaster bar), and graphically displaying the output of each action on one or more output devices. These output devices might include a personal computer (PC) screen, a personal digital assistant (PDA) device, or a speaker (to which text-to-speech output may be directed).

The emphasis of the paper is on the flexibility with which the input to the model can be provided (via mouse click, keyboard, or voice input). The input may be a single input from one or more of these devices (a mouse click, a character from the keyboard, or a word input via a microphone), or an AND combination of inputs entered within one second of each other (a keyboard input of “d” and voice input of “down”). The tool contains many other capabilities, which I don’t have the space to mention.

The tool seems to be thought out and implemented fairly thoroughly. In fact, some of its capabilities may not be initially used by novice users. It appears to me that all of this multimodal, multidevice input and output may not be necessary to design the user interface of a toaster. It would be interesting if the authors had described other applications where these capabilities may indeed be justified. There may be many: the dashboard controls in a car, a complex audio/video set, and so on. The authors should have tried out their software on designers of these types of equipment to better understand their requirements. The software seems like a solution looking for a problem. Perhaps this is simply the technological exploration phase of a project, before a more disciplined software engineering approach is applied to understanding the requirements, which in turn may be met with available technology.