1. A real-time virtual machine method (RTVMM) for implementing real-time systems and activities, the RTVMM comprising the steps: implementing an O-OPL program that can run on computer systems of different designs, an O-OPL program being based on an object-oriented programming language (O-OPL) comprising object type declarations called classes, each class definition describing the variables that are associated with each object of the corresponding class and all of the operations called methods that can be applied to instantiated objects of the specified type, a "method" being a term of art describing the unit of procedural abstraction in an object-oriented programming system, an O-OPL program comprising one or more threads wherein the run-time stack for each thread is organized so as to allow accurate identification of type-tagged pointers contained on the stack without requiring type tag information to be updated each time the stack's content changes, the O-OPL being an extension of a high-level language (HLL) exemplified by Java, HLL being an extension of a low-level language (LLL) exemplified by C and C++, a thread being a term of art for an independently-executing task, an O-OPL program being represented at run time by either O-OPL byte codes or by native machine codes.