FROTZ(6)

NAME
frotz - interpreter for Infocom and other Z-Machine games

SYNOPSIS
frotz [options] file

DESCRIPTION
Frotz is a Z-Machine interpreter. The Z-machine is a virtual machine designed by Infocom to run all of their text adventures. It went through multiple revisions during the lifetime of the company, and two further revisions (V7 and V8) were created by Graham Nelson after the company's demise. The specification is now quite well documented; this version of Frotz supports version 1.0.

This version of Frotz fully supports all these versions of the Z-Machine except for version 6. Version 6 is semi-supported by displaying the outlines of V6 graphics with the picture number in the bottom-right corner.

OPTIONS

-a  Watch attribute setting. Setting and clearing of attributes on objects will be noted in debugging messages.

-A  Watch attribute testing. Every time the z-machine tests an attribute value, the test and the result will be reported.

-b <colorname>
    Sets the default background color. <colorname> corresponds to one of the Z-machine colors, which are as follows:
    black red green yellow blue magenta cyan white
    If color support is disabled or not available on your terminal, this option does nothing.

-c N
    Sets the number of context lines used. By default, after a ``[MORE]'' prompt, and assuming there is enough output pending, Frotz will allow all the currently visible lines to scroll off the screen before prompting again. This switch specifies how many lines of text Frotz will hold over and display at the top of the next screen.

-d  Disable color.

-e  Enable sound. If you've disabled sound in a config file and want to hear sound effects, use this.

-f <colorname>
    Sets the default foreground color. <colorname> corresponds to one of the Z-machine colors, which are as follows
    black red green yellow blue magenta cyan white
    If color support is disabled or is not available on your terminal, this option does nothing.

-F  Force color mode. If you've disabled color in a config file and want to Frotz to display colors, use this.

-h N
    Manually sets the screen height. Though most curses libraries are intelligent enough to determine the current width from the terminal, it may sometimes be necessary to use this option to override the default.

-i  Ignore fatal errors. If a Z-Machine interpreter encounters a zcode error such as division-by-zero or addressing an illegal object, the proper response is to abort execution. This is done because the zcode program doesn't have a clear idea of what is going on. There are some games out there that cause fatal errors because the authors were careless and used an interpreter that didn't properly check for errors. This option is intended to get around such bugs, but be warned that Strange Things may happen if fatal errors are not caught.

-l N
    Sets the left margin, for those who might have specific formatting needs.

-o  Watch object movement. This option enables debugging messages from the interpreter which describe the moving of objects in the object tree.

-O  Watch object location. These debugging messages detail the locations of objects in the object tree.

-p  Plain ASCII output only. This inhibits the output of accented letters and other characters from the Latin-1 character set, replacing them with reasonable alternatives. This may be necessary on devices lacking these characters.

-P  Alter the piracy opcode. The piracy opcode was never used by Infocom. This switch is really only useful for those who like to toy around with Z-code.

-q  Quiet. Turns off sound effects. Useful when running Frotz on a remote machine and you don't want to bother whoever's near the console with weird noises.

-r N
    Sets the right margin.

-s N
    Set the random number seed value. The given seed value is used as the initial seed value on every restart. This is helpful for testing games like Curses which make random decisions before the first input (such that the hot key Alt-S does not really help).

-S N
    Set the transcript width. By default your transscript files are formatted to a width of 80 columns per line, regardless of the current screen width. This switch allows you to change this setting. In particular, use -S 0 to deactivate automatic line splitting in transscript files.

-t  Sets the z-machine's Tandy bit, which may affect the behavior of certain Infocom games. For example, Zork I pretends not to have sequels, and Witness has its language toned down.

-u N
    Sets the number of slots available for Frotz's multiple undo hotkey (see below). This defaults to twenty, which should be sufficient for most purposes. Setting too high a number here may be dangerous on machines with limited memory.

-w N
    Manually sets the screen width. Again, this should not be necessary except in special circumstances.

-x  Expand the abbreviations "g", "x", and "z" to "again", "examine", and "wait". This switch is for use with old Infocom games that lack these common abbreviations which were introduced in later games. Use it with caution: A few games might use "g", "x" or "z" for different purposes.

-Z N
    Error checking mode.
    0 = don't report errors.
    1 = report first instance of an error.
    2 = report all errors.
    3 = exit after any error.
    Default is 1 (report first instance of an error).

CONFIGURATION FILES
On startup, frotz will first check the system's frotz.conf then $HOME/.frotzrc for configuration information. The configuration file uses a simple syntax of
<variable> <whitespace> <value>

Color names may be any of the following:
black | red | green | blue | magenta | cyan | white

ascii on | off
Use plain ASCII only. Default is "off".

background <colorname>
Set background color. Default is terminal's default background color.

color yes | no
Use color text. Default is "yes" if supported.

errormode never | once | always | fatal
Set error reporting mode.
never Don't report any errors except for fatal ones.
once Report only the first instance of an error.
always Report every instance of an error.
fatal Abort on any error, even non-fatal ones.
Default is "once".

expand_abb on | off
Expand abbreviations. Default is off. Expand the abbreviations "g", "x", and "z" to "again", "examine", and "wait". This switch is for use with old Infocom games that lack these common abbreviations which were introduced in later games. Use it with caution. A few games might use the "g", "x", or "z" for different purposes.

foreground <colorname>
Set foreground color. Default is terminal's default forground color.

ignore_fatal on | off
Ignore fatal errors. If a Z-Machine interpreter encounters a zcode error such as division-by-zero or addressing an illegal object, the proper response is to abort execution. This is done because the zcode program doesn't have a clear idea of what is going on. There are some games out there that cause fatal errors because the authors were careless and used an interpreter that didn't properly check for errors. This option is intended to get around such bugs, but be warned that Strange Things may happen if fatal errors are not caught.
Default is "off"

piracy on | off
Alter the piracy opcode. Default is off. The piracy opcode was never used by Infocom. This option is only useful for those who like to toy around with Z-code.

randseed <integer>
Set random number seed. Default comes from the Unix epoch.

sound on | off
Turn sound effects on or off. Default is "on".

tandy on | off
Set the machine's Tandy bit. This may affect the behavior of certain Infocom games. For example, Zork I pretends not to have sequels, and Witness has its language toned down. Default is "off".

undo_slots <integer>
Set number of undo slots. Default is 500.

zcode_path /path/to/zcode/files:/another/path
Set path to search for zcode game files. This is just like the $PATH environmental variable except that you can't put environmental variables in the path or use other shortcuts. For example, "$HOME/games/zcode" is illegal because the shell can't interpret that $HOME variable.

The following options are really only useful for weird terminals, weird curses libraries or if you want to force a certain look (like play in 40-column mode).

context_lines <integer>
Set the number of context lines used. By default, after a ``[MORE]'' prompt, and assuming there is enough output pending, frotz will allow all the currently visible lines to scroll off the screen before prompting again. This switch specifies how many lines of text frotz will hold over and display at the top of the next screen. Default is "0".

left_margin <integer>
Set the left margin. This is for those who might have special formatting needs.

right_margin <integer>
Set the right margin. This is for those who might have special formatting needs.

screen_height <integer>
Manually set screen height. Most curses libraries are intelligent enough to determine the current width of the terminal. You may need to use this option to override the default.

screen_width <integer>
Manually set screen width. Again, this should not be necessary except in special circumstances.

script_width <integer>
Set the transcript width. Default is 80 columns per line, regardless of the current screen width. This switch allows you to change this setting. You may set this to "0" to deactivate automatic line-splitting in transcript files.

The following options are mainly useful for debugging or cheating.

attrib_set on | off
Watch attribute setting. Setting and clearing of attributes on objects will be noted in debugging messages. Default is "off"

attrib_test on | off
Watch attribute testing. Every time the z-machine tests an attribute value, the test and the result will be reported. Default is "off".

obj_loc on | off
Watch object location. These debugging messages detail the locations of objects in the object tree. Default is "off".

obj_move on | off
Watch object movement. This option enables debugging messages from the interpreter which describe the movement of objects in the object tree. Default is "off".

ENVIRONMENT
If the ZCODE_PATH environmental variable is defined, frotz will search that path for game files. If that doesn't exist, INFOCOM_PATH will be searched.

FURTHER INFORMATION

A git(1) repository of all versions of Unix Frotz back to 2.32 is available for public perusal here:
https://github.com/DavidGriffith/frotz/.

The bleeding edge of Frotz development may be followed there. A wiki summarising Frotz is also there at this URL:
https://github.com/DavidGriffith/frotz/wiki/

The Interactive Fiction Archive is a good place to find games to play with Frotz. Various ports and builds for Frotz may also be found here. Here is its URL:
http://www.ifarchive.org/

Most distributions of Linux and BSD include Frotz in their package repositories.

CAVEATS

The Z Machine itself has trouble with the concept of resizing a terminal. It assumes that once the screen height and width are set, they will never change; even across saves. This made sense when 24x80 terminals were the norm and graphical user interfaces were mostly unknown. I'm fairly sure there's a way around this problem, but for now, don't resize an xterm in which frotz is running. Also, you should try to make sure the terminal on which you restore a saved game has the same dimensions as the one on which you saved the game.

You can use a path like "/usr/local/games/zcode:$HOME/zcode" with $ZCODE_PATH or $INFOCOM_PATH because the shell will digest that $HOME variable for you before setting $ZCODE_PATH. While processing frotz.conf and $HOME/.frotzrc, a shell is not used. Therefore you cannot use environmental variables in the "zcodepath" option within the config files.

This manpage is not intended to tell users HOW to play interactive fiction. Refer to the file HOW_TO_PLAY included in the Unix Frotz documentation or visit one of the following sites:
http://www.microheaven.com/ifguide/
http://www.brasslantern.org/beginners/
http://www.musicwords.net/if/how_to_play.htm
http://ifarchive.org/

If you prefer a PDF file of how to play, here is one:
http://inform-fiction.org/I7Downloads/Examples/dm/IntroductionToIF.pdf

BUGS
This program has no bugs. no bugs. no bugs. no *WHAP* thank you. If you find one, please report it to the Github site referenced above in FURTHER INFORMATION.

AUTHORS
Frotz was written by Stefan Jokisch for MSDOS in 1995-7.
The Unix port was done by Galen Hazelwood.
The Unix port is currently maintained by David Griffith <dave@661.org>.

SEE ALSO
dfrotz(6) nitfol(6) rezrov(6) jzip(6) xzip(6) inform(1)