AdaTAD - a debugger for the Ada multi-task environment

In a society that is increasingly dependent upon computing machinery, the issues associated with the correct functioning of that machinery are of crucial interest. The consequences of erroneous behavior of computers are dire with the worst case scenario being, conceivably, global thermonuclear war. Therefore, development of procedures and tools which can be used to increase the confidence of the correctness of the software that controls the world's computers is of vital importance.

The Department of Defense (DoD) is in the process of adopting a standard computer language for the development of software. This language is called Ada¹. One of the major features of Ada is that it supports concurrent programming via its "task" compilation unit. There are not, however, any automated tools to aid in locating errors in the tasks.

The design for such a tool is presented. The tool is named AdaTAD and is a debugger for programs written in Ada. The features of AdaTAD are specific to the problems of concurrent programming.

The requirements of AdaTAD are derived from the literature. AdaTAD is, however, a unique tool designed using Ada as a program description language. When AdaTAD is implemented in Ada it becomes portable among all environments which support the Ada language. This offers the advantage that a single debugger is portable to many different machine architectures. Therefore, separate debuggers are not necessary for each implementation of Ada.

Moreover, since AdaTAD is designed to allow debugging of tasks, AdaTAD will also support debugging in a distributed environment. That means that, if the tasks of a user's program are running on different computers in a distributed environment, the user is still able to use AdaTAD to debug the tasks as a single program. This feature is unique among automated debuggers.

After the design is presented, several examples are offered to explain the operation of AdaTAD and to show that AdaTAD is useful in revealing the location of errors specific to concurrent programming.