1. In a program debugging system for debugging a program, a debugger core unit comprising: a plurality of debugger memory areas, each exclusively associated with a corresponding one of a plurality of debuggers; means, responsive to an exception condition associated with the program, for selecting one debugger from the plurality of debuggers, wherein selection is made by determining which one of the plurality of debuggers is associated with the exception condition; means, coupled to the selecting means, for storing computer state information into a selected one of the plurality of debugger memory areas, the selected debugger memory area being exclusively associated with the selected debugger; means, coupled to the selecting means, for storing debugger state information into the selected debugger memory area; and means, coupled to the selecting means, for activating the selected debugger.