The iPSC Interactive Parallel Debugger (IPD) is a symbolic debugger available for parallel C and FORTRAN programs on the iPSC/860. IPD has many of the features of sequential-program debuggers and also includes special functions for debugging parallel programs. For example, it is possible to set breakpoints for individual node processes, monitor message queues and display the process status table. More information on the IPD may be found in the iPSC manuals. On-line manual pages are also available for ipd.