Abstract This paper describes a new approach to dynamic link/unlink editing. The basis of this approach is a library of link editing functions that can add compiled object code to or remove such code from a process any time during its execution. Loading modules, searching libraries, resolving external references, and allocating storage for global and static data structures are all performed at run time. This approach provides the efficiency of native machine code execution along with the flexibility to modify a program during its execution, thereby making many new applications possible. This paper also describes three sample applications of these dynamic link editing functions: program customization, incremental program development, and support for debugging and testing. A prototype of this approach is implemented under UNIX as a library package called dld for the C programming language and is available for VAX, Sun 3 and SPARCstation machines.

Abstract This paper describes a novel approach to event‐based debugging. The approach is based on a (coarsegrained) dataflow view of events: a high‐level event is recognized when an appropriate combination of lower‐level events on which it depends has occurred. Event recognition is controlled using familiar programming language constructs. This approach is more flexible and powerful than current ones. It allows arbitrary debugger language commands to be executed when attempting to form higher‐level events. It also allows users to specify event recognition in much the same way that they write programs. This paper also describes a prototype, Dalek, that employs the dataflow approach for debugging sequential programs. Dalek demonstrates the feasibility and attractiveness of the dataflow approach. One important motivation for this work is that current sequential debugging tools are inadequate. Dalek contributes toward remedying such inadequacies by providing events and a powerful debugging language. Generalizing the dataflow approach so that it can aid in the debugging of concurrent programs is under investigation.

A token-ring local area network capable of operating in multiple parallel segments which are interconnected via a central switch (called a bridge) is the focus of this study. It is shown that while it is beneficial to operate the network as a single token ring at light loads, the single-ring mode also has a limited channel capacity, and that it is preferable to operate the ring in multiple partitions for heavier loads. In particular, it is found that if the switch processing delay is insignificant compared to the mean packet transmission time, it is preferable to operate the network either as a single large ring or as a star network. An approximate analytical model is used. The results are verified via simulation.>