Jon,

I figure I'll start by collecting some URLs in this post, which may be of use to you during development. Here's a few to start ...

Z-machine standards

Z-Machine Standards Document 1.0 (May 1997)
The web edition of the first standard.

Z-Machine Standards Document 1.1 (accepted September 2005)
Includes clarification on some interpretations of the 1.0 standard as well as some enhancements.

Quetzal (Version 1.4, 971103)
A standard for saved game files. Adherence to Quetzal is enormously helpful for players, as it allows games to be saved on one interpreter (say on a person's desktop machine) and resumed on another (say on a personal organiser on the train). Since there is no argument about what information needs to be saved, there is no real reason not to observe this standard.

Blorb - A standard package to hold resources needed by the story file in play (graphics, sound effects, etc.), one of which can be the story file itself, so that a multimedia work can be distributed as a single Blorb file. Even purely textual interpreters on platforms which could not manage graphics can benefit from supporting Blorb: the only absolute requirement is that an interpreter should be able to extract the Z-code part of a Blorb file and play it (ignoring all the other resources present if it chooses), and this is easily coded up.

Infocom Fact Sheet 4.95 - This file includes some information about Infocom's games and related subjects. It includes detailed info on the Datafiles and Game Statistics.

The Inform Designer's Manual, Fourth Edition by Graham Nelson, Chapter VII: The Z-Machine - This chapter of Graham's online book, has a good breakdown of the Z-Machine and the differences between the various versions, and how one can signify to a story file that a specific feature has not been implemented e.g. colours, sound or graphics.

How to Fit a Large Program Into a Small Machine by Marc S. Blank and S. W. Galley, describes the creation and design of the Z-machine.


Useful source code

Zoom, GPL Z-Machine Interpreter for Unix / Mac OS X

Frotz, Z-Machine Interpreter for Unix ported to loads of places.

Z-Machine Testers/Compliance Checkers, there's at least two here which may be of use for testing a Z-Machine interpreter.


Downloadable Z-Machine games

Zork I, II, III and Zork: The Undiscovered Underground, v3 versions - although I'm not sure they're legally redistributable.

Ireland Interactive Fiction Archive mirror - Z-Code games, in a variety of versions including Z-Machine v5 releases of ZDungeon, the more or less public domain game that evolved into the original Zork trilogy + Advent, the original 350-point Crowther & Woods Colossal Cave adventure + CtDoom, RtDoom & LDoDoom, Peter Killworth's epic Doomawangara trilogy that was converted from the BBC Micro originals in 2000 (though v5 games may not convert to a beeb).

The Hitchhiker's Guide To The Galaxy can be legally played online at Douglas Adams' homepage, and less-scrupulous people can craft a URL to download the v3 Z-code file from the website in order to play the game off-line, through a Z-Machine interpreter.


Sam.