virtual machine
In computing, a virtual machine (VM) is the virtualization/ emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized h ...
that was developed by Joel Berez and
Marc Blank
Marc Blank is an American game developer and software engineer. He is best known as part of the team that created one of the first commercially successful text adventure computer games, ''Zork''.
Career
Blank first encountered Don Woods and Will ...
in 1979 and used by Infocom for its text adventure games. Infocom compiled game code to files containing Z-machine instructions (called story files or Z-code files) and could therefore port its text adventures to a new platform simply by writing a Z-machine implementation for that platform. With the large number of incompatible home computer systems in use at the time, this was an important advantage over using native code or developing a compiler for each system.
History
The "Z" of Z-machine stands for
Zork
''Zork'' is a text-based adventure game first released in 1977 by developers Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling for the PDP-10 mainframe computer. The original developers and others, as the company Infocom, expanded a ...
, Infocom's first adventure game. Z-code files usually have names ending in .z1, .z2, .z3, .z4, .z5, .z6, .z7, or .z8, where the number is the version number of the Z-machine on which the file is intended to be run, as given by the first
byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
of the story file.
This is a modern convention, however. Infocom itself used extensions of .dat (Data) and .zip (ZIP = Z-machine Interpreter Program), but the latter clashed with the widespread use of .zip for PKZIP-compatible archive files starting in the 1990s, after
Activision
Activision Publishing, Inc. is an American video game publisher based in Santa Monica, California. It serves as the publishing business for its parent company, Activision Blizzard, and consists of several subsidiary studios. Activision is one ...
closed Infocom. Infocom produced six versions of the Z-machine. Files using versions 1 and 2 are very rare. Only two version 1 files are known to have been released by Infocom and only two of version 2. Version 3 covers the majority of Infocom's released games. Later versions had more capabilities, culminating in some graphic support in version 6.
The
compiler
In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs tha ...
(called Zilch) that Infocom used to produce its story files has never been released, although documentation of the
language
Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...
used (, a Lisp-family language similar to MDL) still exists, and an open-source replacement has been written. After
Mediagenic
Activision Publishing, Inc. is an American video game publisher based in Santa Monica, California. It serves as the publishing business for its parent company, Activision Blizzard, and consists of several subsidiary studios. Activision is one o ...
moved Infocom to California in 1989, '' Computer Gaming World'' stated that "ZIL ... is functionally dead", and reported rumors of a "completely new parser that may never be used". In May 1993,
Graham Nelson
Graham A. Nelson (born 1968) is a British mathematician, poet, and the creator of the Inform design system for creating interactive fiction (IF) games. He has authored several IF games, including ''Curses'' (1993) and '' Jigsaw'' (1995).
Educat ...
released the first version of his
Inform
Inform is a programming language and design system for interactive fiction originally created in 1993 by Graham Nelson. Inform can generate programs designed for the Z-code or Glulx virtual machines. Versions 1 through 5 were released betw ...
compiler, which also generates Z-machine story files as its output, even though the Inform source language is quite different from ZIL.
Inform has become popular in the interactive fiction community. A large proportion of interactive fiction is in the form of Z-machine story files. Demand for the ability to create larger game files led Nelson to specify versions 7 and 8 of the Z-machine, though version 7 is rarely used. Because of the way addresses are handled, a version 3 story file can be up to 128K in length, a version 5 story can be up to 256K in length, and a version 8 story can be up to 512k in length. Though these sizes may seem small by today's computing standards, for text-only adventures, these are large enough for elaborate games.
During the 1990s, Nelson drew up a Z-Machine Standard based on detailed studies of the existing Infocom files.
ZIL (Zork Implementation Language)
Here's what the definition of Zork I's brass lantern looks like:
Interpreters
Interpreters
Interpreting is a translational activity in which one produces a first and final target-language output on the basis of a one-time exposure to an expression in a source language.
The most common two modes of interpreting are simultaneous interp ...
for Z-code files are available on a wide variety of platforms. The Inform website lists links to freely available interpreters for 15 desktop operating systems (including 8-bit microcomputers from the 1980s such as the Apple II,
TRS-80
The TRS-80 Micro Computer System (TRS-80, later renamed the Model I to distinguish it from successors) is a desktop microcomputer launched in 1977 and sold by Tandy Corporation through their Radio Shack stores. The name is an abbreviation of '' ...
, and , and grouping "Unix" and "Windows" as one each), 10 mobile operating systems (including
Palm OS
Palm OS (also known as Garnet OS) was a mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. It is pro ...
and the
Game Boy
The is an 8-bit fourth generation handheld game console developed and manufactured by Nintendo. It was first released in Japan on April 21, 1989, in North America later the same year, and in Europe in late 1990. It was designed by the same t ...
), and four interpreter platforms (Emacs, Java, JavaScript, and Scratch). According to Nelson, it is "possibly the most portable virtual machine ever created".
Popular interpreters include Nitfol and Frotz. Nitfol makes use of the Glk
API
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...
, and supports versions 1 through 8 of the Z-machine, including the version 6 graphical Z-machine. Save files are stored in the standard Quetzal save format.
Binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that ta ...
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
systems,
DOS
DOS is shorthand for the MS-DOS and IBM PC DOS family of operating systems.
DOS may also refer to:
Computing
* Data over signalling (DoS), multiplexing data onto a signalling channel
* Denial-of-service attack (DoS), an attack on a communicat ...
, and
Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ser ...
.
Frotz was written in C by Stefan Jokisch in 1995 for DOS. Over time it was ported to other platforms, such as
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
systems,
RISC OS
RISC OS is a computer operating system originally designed by Acorn Computers Ltd in Cambridge, England. First released in 1987, it was designed to run on the ARM chipset, which Acorn had designed concurrently for use in its new line of Archi ...
, and
iOS
iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also include ...
. Sound effects and graphics were supported to varying degrees. By 2002, development stalled and the program was picked up by David Griffith. The code base was split between
virtual machine
In computing, a virtual machine (VM) is the virtualization/ emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized h ...
and
user interface
In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
portions in such a way that the virtual machine became independent from any user interface. This allowed more variety in porting Frotz. One of the stranger ports is also one of the simplest: an
instant messaging
Instant messaging (IM) technology is a type of online chat allowing real-time text transmission over the Internet or another computer network. Messages are typically transmitted between two or more parties, when each user inputs text and trigge ...
bot is wrapped around a version of Frotz with the minimum I/O functionality creating a bot with which one can play most Z-machine games using an instant messaging client.
Another popular client for
macOS
macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...
and other
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
systems is Zoom. It supports the same Quetzal save-format, but the packaging of the file-structure is different.
See also
*
Glulx
Glulx is a 32-bit portable virtual machine intended for writing and playing interactive fiction. It was designed by Andrew Plotkin to relieve some of the restrictions in the venerable Z-machine format. For example, the Z-machine provides native ...
– Similar to the Z-machine, but relieves several legacy limitations
*
Inform
Inform is a programming language and design system for interactive fiction originally created in 1993 by Graham Nelson. Inform can generate programs designed for the Z-code or Glulx virtual machines. Versions 1 through 5 were released betw ...
– A computer language that can produce Z-machine programs
* SCUMM – Script Creation Utility for Maniac Mansion by
LucasArts
Lucasfilm Games (known as LucasArts between 1990 and 2021) is an American video game licensor that is part of Lucasfilm. It was founded in May 1982 by George Lucas as a video game development group alongside his film company; as part of a large ...
, a graphical system similar to Z-machine
*
TADS
Text Adventure Development System (TADS) is a prototype-based domain-specific programming language and set of standard libraries for creating interactive fiction (IF) games.
History
The original TADS 1 was released by High Energy Software as ...
– Like Glulx, made to address some of its limitations
*
Motorola 68000 series
The Motorola 68000 series (also known as 680x0, m68000, m68k, or 68k) is a family of 32-bit complex instruction set computer (CISC) microprocessors. During the 1980s and early 1990s, they were popular in personal computers and workstations and ...
– The base architecture used for virtual machines in
Magnetic Scrolls
Magnetic Scrolls was a British video game developer active between 1984 and 1990. A pioneer of audiovisually elaborate text adventure games, it was one of the two largest and most acclaimed interactive fiction developers of the 1980s.
''Magnet ...