Provided by: sdlfrotz_2.55+dfsg-2_amd64 
NAME
sfrotz - interpreter for Infocom and other Z-Machine games (SDL interface)
SYNOPSIS
sfrotz [options] file [blorb_file]
At least one file must be specified on the command line. This can be either a plain Z-code file or a
Blorb file. A Z-code file is a compiled executable for the Z-Machine. A Blorb file contains audio,
graphics, and other things in addition to the game wrapped up into a single file. It can also optionally
contain the Z-Machine executable. If a plain Z-code file is supplied, then Frotz will check for a Blorb
file with the same base name but an extension of .blb, .blorb, or .zblorb and load it if found.
If the file supplied on the command line is a Blorb file, then Frotz will check to see if a Z-code file
is contained within. If not found, then Frotz will complain and exit.
An alternatively-named Blorb file can be supplied as the optional second parameter to the command line
invocation.
If you want to play any of the games from Infocom that use sound or graphics, you will need to get a
corresponding Blorb file from the Interactive Fiction Archive. See FURTHER INFORMATION below.
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 1.1. See Z-MACHINE
STANDARDS below..P This version of Frotz fully supports all these versions of the Z-Machine including the
graphical version 6. Graphics and sound are created through the use of the SDL libraries. AIFF sound
effects and music in MOD and OGG formats are supported when packaged in Blorb container files or
optionally from individual files.
STANDARD 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.
-C <filename>
Load this configuration file instead of $HOME/.sfrotzrc.
-d Disable color.
-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.
-h N Manually sets the text height.
-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.
-I N Set the interpreter number. Infocom designed the Z-machine such that a game could tell on what
kind of machine the interpreter was running. See INTERPRETER NUMBER below.
-l N Sets the left margin, for those who might have specific formatting needs.
-L <filename>
When the game starts, load this saved game file.
-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 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.
-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. By default, the random number generator is initialized based on the system clock; this
allows you to make the random number generator predictable, for use in recorded scripts or
debugging. For instance, Curses makes 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 transcript files are formatted to a width of 80 columns
per line, regardless of the current text width. This switch allows you to change this setting. In
particular, use -S 0 to deactivate automatic line splitting in transcript 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
25, 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 text width.
-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).
EXTENDED OPTIONS
-@ <listfile>
Use resource files listed in <listfile> (see NON BLORB RESOURCES).
-% Use local resource files.
-F Run in fullscreen mode (see NOTES).
-m <msecs>
Set the timer interrupt cycle to <msecs> milliseconds, instead of the default 100 (1/10 sec).
-N <mode>
Set the mode (date or name) for creating default file names for save/script etc. For date, a
timestamp is prepended to the filename extension. For name, a four-digit number beginning with
0000 is prepended to the filename extension.
-T Use traditional in-game requests for file names, instead of on-screen dialogs.
-v Show version information and exit. This will display the version of Frotz, some information about
what's enabled and what's not, the commit date of the source code, and a git(1) hash of that
commit.
-V Force the use of default monospaced VGA font.
HOT KEYS
Sfrotz supports the same hot keys as standard Frotz, plus the Ctl-Alt-X combination for immediate exit,
which may be used in case of emergency. Note that these hot keys are enabled only when the Z-machine is
waiting for line input (for Z-machine experts: @read opcode), with the exception of Ctl-Alt-X which also
works in single character input mode (@read_char opcode).
Alt-D Set debugging options.
Alt-H Help (print the list of hot keys).
Alt-N New game (restart).
Alt-P Playback on.
Alt-R Recording on/off.
Alt-S Set random number seed.
Alt-U Undo one turn.
Alt-X Exit game (after confirmation).
Ctl-Alt-X
Exit game immediately (no confirmation).
WINDOW
Sfrotz has a hardwired default screen size of 640x400. The screen size can be changed by the values in
this section, by the values found in the Reso chunk of a Blorb file, and finally by the -w and -h command
line options (in that order). Note however that Sfrotz shall refuse to set a screen width less than 640
and/or a height less than 400. NOTE: for normal (windowed) usage, the screen size should obviously be
less than the physical screen resolution (taking into account also window decorations, taskbars etc.) For
fullscreen usage, the size should preferably be one of those supported by the PC video driver; otherwise,
SDL shall try to use the next higher available resolution, with black borders around the Z-machine
screen. In fullscreen mode, however, it may happen that for some strange resolutions SDL accepts the
request, but the screen goes blank... In such a case, you may shut down the program by pressing Ctrl-Alt-
X.
INTERPRETER NUMBER
The interpreter number is a setting in the Z-machine header which is used to tell the game on what sort
of machine the interpreter is running. Sfrotz will automatically choose the most appropriate number for
a given Infocom-produced game. Should you want to override the number, the -I option is available.
An interpreter should choose the interpreter number most suitable for the machine it will run on. In
Versions up to 5, the main consideration is that the behaviour of 'Beyond Zork' depends on the
interpreter number (in terms of its usage of the character graphics font). In Version 6, the decision is
more serious, as existing Infocom story files depend on interpreter number in many ways: moreover, some
story files expect to be run only on the interpreters for a particular machine. There are, for instance,
specifically Amiga versions. The DECSystem-20 was Infocom's own in-house mainframe.
For Infocom's four V6 games, the interpreter number will be automatically chosen based on the title and
release number. Of course, this can be overridden at the command line.
Infocom used the following interpreter numbers:
1 DECSystem 20
2 Apple IIe
3 Macintosh
4 Amiga
5 Atari ST
6 IBM PC
7 Commodore 128
8 Commodore 64
9 Apple IIc
10 Apple IIgs
11 Tandy Color
NON BLORB RESOURCES
Besides Blorb-packaged resources, Sfrotz can also render graphics and sound from individual files,
provided the latter are either suitably named (e.g a common root with a numeric field specifying the
resource number), or listed in a suitably formatted text file.
Note that this feature is not automatic, but must be enabled by the -% or -@ command line options. When
the feature is enabled, resources found this way override those in the Blorb file, if present.
This feature can be useful to game designers, as it eases changing and adding resources without having to
re-compile the Blorb file each time. The format of the list file used with the -@
option (see EXAMPLE BLC FILE) is identical to that of the BLC control file used by L. Ross Raszewski's
iblorb package, so one can use the same list for compiling the final Blorb file for distribution.
TRUETYPE FONTS
Sfrotz can display text with Truetype or Type1 fonts, using the FreeType2 rendering library. The location
of the necessary font files must be specified in the setup file. Also, antialiased rendering of Truetype
fonts can be specified. Please note that this feature in sfrotz is still experimental, so don't expect
too much (e.g., kerning is not supported).
DEFAULT FONTS
Sfrotz does not need Truetype fonts to work; in fact it has a default monospaced font, based on an 8x16
VGA font, which can be used for both the TEXT_FONT and the FIXED_FONT of the z-machine, with suitable
(though not very nice) modifications for the various styles. Even if Truetype fonts are specified in the
setup file, Sfrotz can be forced to use the VGA font by the -V command line switch.
UNICODE
Sfrotz supports Unicode glyphs by way of UTF-8 as long as the fonts loaded contain the glyphs you need.
The default font provided by SDL does not contain much beyond the Latin alphabet and some diacritical
marks. Inverted punctuation marks as used in Spanish are missing. Two monospaced fonts known to work
well with most commonly-encountered alphabetic languages are Leggie and FreeMono. They can be found at
https://memleek.org/leggie/ (X11 BDF fonts) and https://www.gnu.org/software/freefont/ (Truetype fonts).
Logographic glyphs (Kanji and Chinese are not currently supported.
Z-MACHINE STANDARDS
Sfrotz complies with the Z-Machine Standard 1.1 of May 2006, revised February 2014. The authoritative
version is found here:
http://inform-fiction.org/zmachine/standards/z1point1/index.html
As of 1.1, an additional optional prompt parameter is allowed on Version 5 extended save/restore. This
parameter allows a game to read or write an auxiliary (aux) file without prompting the player. See
section 15 of the Standard for details. Frotz restricts such files to having an ".aux" filename
extension.
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. Any additional files required, such as graphics files,
sounds directory, auxilary, or blorb files must be in the same directory as sfrotz finds the story file.
SETUP FILE
On startup, sfrotz will check $HOME/.sfrotzrc for setup information. The setup file has four sections:
Interpreter, Display, Fonts, and Resources.
The Interpreter section deals with options having to do with how the Frotz core works.
The Window section deals with screen display. Sfrotz has a hardwired default screen size of 640x400. The
screen size can be changed by the values in this section, by the values found in the Reso chunk of a
Blorb file, and finally by the -w and -h command line options (in that order). Note however that sfrotz
shall refuse to set a screen width less than 640 and/or a height less than 400.
NOTE: for normal (windowed) usage, the screen size should obviously be less than the PC screen resolution
(taking into account also window decorations, taskbars etc.) For fullscreen usage, the size should
preferably be one of those supported by the PC video driver; otherwise, SDL shall try to use the next
higher available resolution, with black borders around the z-machine screen. In fullscreen mode, however,
it may happen that for some strange resolutions SDL accepts the request, but the screen goes blank... In
such a case, you may shut down the program by pressing Ctrl-Alt-X.
The Display section is reserved for future developments.
The Fonts section is for defining the font directory, font files, and if antialiasing is enabled (which
is currently not supported).
The following eight statements: textroman, textbold, textitalic, textbolditalic, fixedroman, fixedbold,
fixeditalic, and fixedbolditalic; specify the eight font faces used by the z-machine (not counting the
so-called graphics font used in Beyond Zork, which is hardwired in the program), that is the normal
TEXT_FONT and the monospaced FIXED_FONT, each in four styles (roman, bold, italic and bold+italic). A
single face is specified by the file name (with its suffix!), optionally followed by an @ sign and a
number, indicating the font size in pixels (default is 14). Multiple face files can be specified,
separated by pipe (|) characters; Sfrotz shall use the first one it finds (see the example in EXAMPLE
SETUP FILE). This feature allows e.g. to use the same setup file on different systems.
The Resources section is for configuring graphics and sound resources. Each template must contain
exactly one C-style decimal format specifier (e.g. Pict%d) to be substituted by the resource number.
SETUP FILE GRAMMAR
[Interpreter]
Number = number
Set the interpreter number (default is 4, i.e. Amiga Interpreter)
Error Reporting = level
Set the error reporting level (same as the -Z option)
Ignore Errors = 0/1
Ignore (1) or not (0) non-fatal runtime errors.
Expand Abbreviations = 0/1
Set/reset expansion of g/x/z abbreviations. Expansion is useful for old v1 games which do not
understand such abbreviations. Default: 0 (the -xoption can set this switch.)
Tandy Bit = 0/1
Set/reset the Tandy bit. Default: 0 (the -t option can set this switch.)
Wrap Script Lines = nc
Set the width (number of columns) of the transcript to nc. Same as -S option.
SaveNames = date/name
Set the mode (date or name) for creating default file names for save/script etc. For date, a timestamp
is prepended to the filename extension. For name, a four-digit number beginning with 0000 is prepended
to the filename extension.
[Window]
AcWidth = width
Set the screen width in pixels (default: 640)
AcHeight = height
Set the screen height in pixels (default: 400)
[Display]
(This section reserved for future developments)
[Fonts]
antialias = 0/1
Set antialiased rendering of Truetype fonts off (0) or on (nonzero). Note that this option cannot be
overridden by a command line switch.
fontdir = folder
Specify the directory containing the Truetype fonts. If this does not begin with a slash, then the
directory is assumed to be relative to the user's home directory.
textroman = fontspec
Set the font file for TEXT_FONT, roman style.
textbold = fontspec
Set the font file for TEXT_FONT, bold style.
textitalic = fontspec
Set the font file for TEXT_FONT, italic style.
textbolditalic = fontspec
fixedroman = fontspec
Set the font file for FIXED_FONT, roman style.
fixedbold = fontspec
Set the font file for FIXED_FONT, bold style.
fixeditalic = fontspec
Set the font file for FIXED_FONT, italic style.
fixedbolditalic = fontspec
Set the font file for FIXED_FONT, bold and italic style
[Resources]
Dir = folder
Specify the folder for individual graphics/sound resource files.
Pict = template
Template for picture resource files.
Snd = template
Template for sound resource files.
EXAMPLE SETUP FILE
# The # denotes the start of a comment
# Everything after the # is ignored, up to the end of the line
[Interpreter]
SaveNames=date
[Window]
# The following entries are commented out
# but they are the same as the hardwired defaults, anyway
#AcWidth = 640
#AcHeight = 400
[Display]
[Fonts]
antialias=1
fontdir=/usr/share/fonts/truetype/freefont
textroman=arial.ttf@16|FreeSans.ttf@16
textbold=arialbd.ttf@16|FreeSansBold.ttf@16
textitalic=ariali.ttf@16|FreeSansOblique.ttf@16
textbolditalic=arialbi.ttf@16|FreeSansBoldOblique.ttf@16
fixedroman=cour.ttf@16|FreeMono.ttf@16
fixedbold=courbd.ttf@16|FreeMonoBold.ttf@16
fixeditalic=couri.ttf@16|FreeMonoOblique.ttf@16
fixedbolditalic=courbi.ttf@16|FreeMonoBoldOblique.ttf@16
[Resources]
Dir=./ # the current dir
Pict=PIC%d # i.e. PIC1, PIC2, ...
Snd=SND%d # i.e. SND3, SND4, ...
EXAMPLE BLC FILE
Exec 0 ZCOD ani.z6
Snd 13 FORM busyalone.au.aiff
Snd 12 FORM s0020.au.aiff
Snd 11 FORM s0154.au.aiff
Snd 10 FORM s1484.au.aiff
Pict 10 PNG edleft.png0.png
Pict 11 PNG edleft.png1.png
Pict 12 PNG edleft.png2.png
Pict 13 PNG edleft.png3.png
Pict 14 PNG edleft.png4.png
Pict 15 PNG edleft.png5.png
Pict 16 PNG lauhoh.png0.png
Pict 17 PNG lauhoh.png1.png
Pict 18 PNG lauhoh.png2.png
Pict 19 PNG edfront.png0.png
Pict 20 PNG edfront.png1.png
Pict 21 PNG edfront.png2.png
Pict 22 PNG edfront.png3.png
Pict 23 PNG edfront.png4.png
Pict 24 PNG edfront.png5.png
Pict 25 PNG hoagie.png0.png
Pict 26 PNG hoagie.png1.png
Pict 30 PNG dott0.png
FURTHER INFORMATION
The Frotz homepage is at https://661.org/proj/if/frotz/.
A git(1) repository of all versions of Unix Frotz from 2.32 to the bleeding edge is available for public
perusal at
https://gitlab.com/DavidGriffith/frotz/.
The Interactive Fiction Archive, at https://www.ifarchive.org/, is a good place to find games to play
with Frotz. To play Infocom's games that use graphics or sound, you'll need to get corresponding Blorb
files from there. Various ports and builds for Frotz may also be found at the IF Archive.
Most distributions of Linux and BSD include Frotz in their package repositories.
It is distributed under the GNU General Public License version 2 or (at your option) any later version.
https://www.gnu.org/licenses/gpl-2.0.en.html
This software is offered as-is with no warranty or liability. If you find a bug or would like Frotz to
do something it doesn't currently do, please visit the above Gitlab website and report your concerns.
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.
Audio latency might be unreasonably long depending on the settings of your operating system. Linux
generally has things right. The BSDs may need some sysctl(8) settings adjusted. See the sound(4) or
audio(4) manpages for more information.
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/
BUGS
This program has no bugs. no bugs. no bugs. no *WHAP* thank you. If you find one, please report it to
the Gitlab site referenced above in FURTHER INFORMATION.
AUTHORS
Frotz was written by Stefan Jokisch for MSDOS in 1995-7.
The SDL port was done in 2009 by Aldo Cumani and is currently maintained by David Griffith
<dave@661.org>.
SEE ALSO
frotz(6) dfrotz(6) nitfol(6) rezrov(6) jzip(6) xzip(6) inform(1)
SDL Frotz v2.55 2025-02-01 SFROTZ(6)