Abstract: According to the invention, an authoring tool comprises at least one nestable graphic state and transition machine, hereinafter referred to as a "state machine", each state machine comprising one or more states and zero or more transitions, each transition interconnecting a first state, known as the "from.sub.-- state", with a second state, known as the "to.sub.-- state". The first and second states can be the same state or different states. For each state in the plurality of states there can be any number of transitions, including zero, emanating therefrom and directed thereto. Each state machine has a state designated as its "current state" which changes in response to users actions or other events. Each state machine also has an initial state which is the state that is designated as the current state when the multimedia title is launched. The authoring tool allows an author to view a state machine simultaneously in several different formats, providing a full view and a map view.

Abstract: The invention provides a method and apparatus for switching between execution of a plurality of object code types having different conventions for invoking program procedures and performing stack manipulations. The invention may also be used to switch between different calling conventions within a single object code type. Briefly according to the invention, a computer system comprises a routine descriptor, a stack switch frame, a mode switching mechanism for switching from a first processor, code or calling convention type to a second processor, code or calling convention type and means for executing instructions in various code type codes. A routine descriptor describes a program or code segment and its code type and calling conventions. A routine descriptor contains, among other information, a "mixed mode" field which is set to a specific, predetermined value such as a value indicating an instruction which is not legal in the runtime environment of a first processor, code or calling convention type.