The Å-machine

The Å-machine is a virtual machine for delivering interactive stories. It is designed for stories implemented in the Dialog programming language.

As the name suggests, the Å-machine is inspired by the Z-machine. The letter Å (pronounced [ɔː], like the English word “awe”) follows Z in the Swedish alphabet. In international contexts, å can be transcribed into aa, as in “The Aa-machine”.

The Dialog compiler can produce Å-machine story files starting with version 0g/01. The filename ending is .aastory. Support for the widely used and historically important Z-machine remains, and will not go away. But stories compiled for the Å-machine look better on the web, and are smaller and faster on vintage hardware.

In a sense, the Å-machine is to Dialog what Glulx is to Inform 7. It eliminates the tight restrictions on story size, and extends the basic functionality with a carefully balanced set of new features. But the Å-machine is designed to run the same stories on everything from 8-bit systems to modern web browsers. Data structures and encodings are economical, and the overall word size has not increased. Large stories are supported, but small stories still have a very compact binary representation.

Compared to the Z-machine and Glulx, the Å-machine operates at a higher level of abstraction. This improves performance on vintage hardware, both by making story files smaller, which improves loading times, and by allowing larger chunks of computation to be implemented as native machine code. The downside is that the virtual machine is more tightly coupled to the idiosyncracies of a particular high-level language, in this case Dialog.

Currently, two separate Å-machine interpreters exist. One is implemented in Javascript, and the other is implemented in 6502 assembler. Each must be combined with a frontend that handles input, output, and other platform-specific details. Available frontends include a web frontend based on jquery for the Javascript interpreter, and a Commodore 64 frontend for the 6502 interpreter.

Use the included tool, aambundle, to convert your .aastory file into a web-friendly directory structure, including story and interpreter, ready for deployment on a server. The same tool can create disk images for the Commodore 64.

Download

• aamachine-0.5.4.zip (Å-machine version 0.5.4, 904.0 kB)
• aamachine-0.5.3.zip (Å-machine version 0.5.3, 913.6 kB)
• aamachine-0.5.2.zip (Å-machine version 0.5.2, 911.9 kB)
• aamachine-0.5.1.zip (Å-machine version 0.5.1, 911.6 kB)
• aamachine-0.4.4.zip (Å-machine version 0.4.4, 880.7 kB)
• aamachine-0.4.3.zip (Å-machine version 0.4.3, 880.6 kB)
• aamachine-0.4.2.zip (Å-machine version 0.4.2, 870.6 kB)
• aamachine-0.4.1.zip (Å-machine version 0.4.1, 870.4 kB)
• aamachine-0.3.1.zip (Å-machine version 0.3.1, 832.9 kB)
• aamachine-0.2.2.zip (Å-machine version 0.2.2, 645.2 kB)
• aamachine-0.2.1.zip (Å-machine version 0.2.1, 646.1 kB)
• aamachine-0.2.zip (Å-machine version 0.2, 596.2 kB)
• aamachine-0.1.zip (Å-machine version 0.1, 592.2 kB)