Nomenclature and conventions The "Z" of Z-machine stands for
Zork, Infocom's first adventure game. Infocom used file 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 had 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 modern convention for 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 of the story file. As previously noted, the Infocom games used the equivalent of .z1 through .z6; .z7 and .z8 were proposed and adopted after Infocom had shut down.
Before Z-machine The
MDL programming language was derived from
Lisp at the
Massachusetts Institute of Technology by the Dynamic Modeling group of the
Laboratory for Computer Science (LCS) in the 1970s; inspired by
Colossal Cave Adventure (1977), members of that group went on to write
Zork in MDL, completing the initial version two weeks later. Like
Adventure,
Zork was programmed for the
DEC PDP-10; the finished version occupies 1 MB of MDL code and requires 512 KB of RAM to run. Because contemporary home computers did not have these resources, considerable effort was needed to port the game. The compression required to run
Zork from
floppy disks with approximately 80 KB of storage seemed like an insurmountable barrier to Blank. Berez realized that
UCSD Pascal used a
virtual machine (VM) model to generate executable files that could be readily ported across platforms, and together with Blank, they devised requirements for a lightweight VM optimized for text adventure games, which would retrieve data and execute instructions as needed from storage to compensate for the relatively small RAM sizes in typical microcomputers.. Infocom's development tools compiled ZIL into Z-machine instructions in a two-stage process; this made text adventure development platform-independent and enabled porting to different systems simply by writing an appropriate Z-machine interpreter. Although ZILCH has never been released, documentation of ZIL still exists, and an open-source replacement called "ZILF" has been written. After
Mediagenic 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".
Graham Nelson and Inform In May 1993,
Graham Nelson released the first version of his
Inform 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, Graham Nelson drew up a Z-Machine Standard based on detailed studies of the existing Infocom files. The standard also includes extensions used by his newer versions, as well as links to the "
Blorb" resource format and the "
Quetzal" savefile format. In 2006, Nelson expanded Z-machine to the 32-bit
Glulx format for Inform 7. The
Interactive Fiction Technology Foundation, founded in 2016, manages all these standards. ==ZIL (Zork Implementation Language)==