Zmachine

The Z-machine is a virtual machine developed by Infocom to run their text adventure games. It executes Z-code, a portable bytecode representation of interactive fiction compiled from the Zork Implementation Language (ZIL). By isolating game logic from hardware specifics, the Z-machine enabled Infocom’s titles to run on many platforms with consistent behavior.

Introduced in the late 1970s, the Z-machine powered Infocom’s catalog of titles, including Zork I–III and The Hitchhiker’s Guide to the Galaxy. Its portability helped Infocom distribute sophisticated text adventures across personal computers, terminals, and game consoles of the era, contributing to the company’s catalog and reputation.

The architecture: Z-code files encapsulate the program’s data and executable bytecode. The Z-machine provides a memory space, input/output routines, a built-in dictionary for token-based parsing, and an object model used to represent rooms, objects, and puzzles. Opcodes drive game logic and interactions, with several versions of Z-code (commonly .z3, .z5, and .z8) indicating different feature sets.

Interpreters and toolchains: Modern readers can run Z-code with interpreters such as Frotz, Zoom, and Spatterlight. The Z-machine also influenced IF tooling; Inform, the popular authoring system, originally compiled to Z-code and later to Glulx, a more modern VM.

Legacy: The Z-machine remains a foundational technology in interactive fiction history. It enabled wide distribution of Infocom’s games and continues to be preserved and emulated today, while contemporary IF development often targets Glulx or other platforms.