AVM1

AVM1, or ActionScript Virtual Machine 1, is the runtime environment used by Adobe Flash Player and related runtimes to execute ActionScript 1.0 and 2.0 code. It provides the ActionScript language execution context, the display and timeline model, and access to the Flash Player libraries.

AVM1 was introduced with the early generations of Flash and remained the primary VM for AS1/AS2 until the advent of AVM2 in Flash Player 9 and ActionScript 3. The architecture features a prototype-based object model and dynamic typing, with code compiled to AVM1 bytecode and executed by the VM within the SWF runtime. It supports runtime introspection and integrates with the Flash display list, event system, and built-in classes such as MovieClip and Sprite.

AVM1 is distinct from AVM2, which was designed for ActionScript 3 and employs a statically typed, class-based programming model and a different bytecode format. The two VMs are not compatible, requiring separate compilers for AS1/AS2 and AS3.

Following the end-of-life of Flash Player in 2020, AVM1 content has limited support in modern environments. Some projects and emulators, notably Ruffle, implement AVM1 interpretation to preserve legacy Flash content outside of Adobe's platform, but native support in current runtimes is not guaranteed.

As a legacy technology, AVM1 is primarily of historical and preservation interest. Its continued relevance today rests on preservation efforts and specialized emulation rather than active development within mainstream media runtimes.