Design of an interactive debugger for FORTRAN: MANTIS

MANTIS is a natural debugging facility for the FORTRAN language subsystem on the PDP-10. It was designed and implemented in an existing language subsystem in order to facilitate program preparation and debugging in the time sharing environment available on the PDP-10. Suitable debugging facilities should be included in the initial design of language subsystems. Language subsystems to run in time sharing operating systems should offer debugging facilities that exploit the interactive environment available to the user. This paper describes experience gained in designing and adding a useful interactive debugger to an existing FORTRAN subsystem. Objectives, implementation experience and system features are discussed and are related to the general problem of designing debuggers for language subsystems.