A graphical CAL author language

Abstract

Many CAL packages are implemented using an author language, which allows the developer of the package easily to create and alter lessons that are to be presented to the user. Typically, such a language must provide statements to send text to the screen, get input from the user, match this input against the expected answers and take the appropriate actions, etc., but it is suggested that recent advances in the development of both hardware technology and programming languages have meant that most author languages now have a severely outdated and ‘low-tech’ feel to them. Attempts to address this problem — and these appear to be few and far between — suffer other failings such as lack of generality or portability.

In this paper, we describe a new CAL author language that is aimed at exploiting the powerful graphical and other facilities offered by modern microcomputers and workstations. Thus, the language enables the author to specify the size and position of multiple windows; to direct text, diagrams and program output to any of these windows; to provide interaction via menus; and so on. Simple examples of use of the language in developing courseware are given. A highly portable interpreter for the language has been implemented, details of which are described in a subsequent section.