This is an implementation of the Z-Machine, a virtual machine for interactive fiction games originally used by Infocom in the 1980s. It is written per the Z-Machine Standards Document v1.1 and supports story file versions 3, 4, 5, and 8. These are by far the most common versions, encompassing everything from Infocom's original Zork I to much more recent adventures.

Story files

• A list of games released by Infocom can be found on infocom-if.org, and the story files themselves are available from a variety of sources.
• Many newer games have been published by a range of authors: check out the IF Archive's zcode section and the IFDB.
• Graham Nelson's Inform programming language is a popular way to develop games for both Z-code and Glulx.

Usage

Take a .z3, .z4, .z5, or .z8 story file (or .dat for old Infocom games) and pass it to the storyfile_conv.py script, which will convert the binary representation to assembly code. (Note that .zblorb format is not supported, although the story file it contains could be extracted.) Save the output of this script to a file, and change the @include directive in zmach5/zmach5.asm to point to it. Assemble the interpreter, and puzzle away! (The interpreter must be assembled for ram-only mode, not combined flash/ram, because the story file constitutes the read-write memory image of the interpreter in addition to static data. Use the prototype kernel to load the assembler output into ram.)

Notes

• Full color is supported, although few games use it. Bold, italic, and reverse video styles are implemented via red text, grey text, and black-on-white text respectively.

Quirks

• Saving the game state is not properly supported, however, the save opcode puts the interpreter into a state where its memory image can be stored and later restarted from address 0, where the game will resume.
• Timed input reads are not supported -- some games (like Vicious Cycles by Mark Simon) use them to add a thematic delay; for these games, the player will need to press a key on the keyboard to complete the timed read.
• The random number generator is functional but not stellar, and it always uses the same seed.
• The encode_text, erase_line, and print_table opcodes are not implemented
• Only a plain-text font is available, and custom alphabet tables are not implemented.
• The header extension table is not implemented.
• Printing signed numbers is not implemented.
• Sound output is not implemented.

Endnotes

Thanks to Czech and other test story files for helping me write and debug this interpreter.