FROTZ V2.01 - an interpreter for all Infocom games. Complies with standard
0.2 for all games except V6 (graphic) games. Written by Stefan Jokisch in
1995-96.

    This program evolved from Mark Howell's Zip. Although the source
    code is completely re-written, one can still find traces of Zip.

    Many thanks to Paul D. Doherty for his continuing support of this
    project. Thanks to Alan Sherrod for testing the performance; to
    John Kennedy and Ambat Sasi Nair for helpful hints on PC video
    boards; to Thomas Biskup, Ian Carpenter, Graeme Cree, Jason Dyer,
    Bernhard Fuchs, Joe Hachem, Kirk Klobe, Marnix Klooster and John
    Mackin for their bug reports; to David Kinder for his Amiga port.

    Frotz is freeware: It may be used and distributed freely provided
    no commercial profit is involved. (c) 1995, 1996 Stefan Jokisch.

    Please report bugs to jokisch@ls7.informatik.uni-dortmund.de.

Features:

    - support for V1 to V8 games
    - various text and graphic modes
    - timed input ('Border Zone')
    - built-in graphic font ('Beyond Zork')
    - mouse support ('Beyond Zork' and all V6 games)
    - function key support including number pad keys ('Beyond Zork')
    - command line editing and history
    - small save files (Zip 2.0 format is still understood)
    - switch for setting the Tandy bit
    - sound effects ('Lurking Horror' and 'Sherlock')
    - cheat functions
    - multiple UNDO (via hot key, even for old V1 to V4 games)
    - input line recording and playback (via hot key)
    - support for European characters ('Zork I German')
    - underlined, reverse and boldface text
    - fast performance without virtual memory

Special keys:

    Alt-N             - new game (restart)
    Alt-P             - turn on input line playback
    Alt-R             - toggle input line recording on/off
    Alt-S             - set the random seed
    Alt-U             - multiple UNDO (even for old V1 to V4 games)
    Alt-X             - exit game (quit)

Command line options:

    -l #     set the left margin
    -r #     set the right margin
    -c #     set the number of context lines to keep when scrolling

    -u #     set the number of undo slots for multiple undo

    -o       monitor object movement
    -O       monitor object locating
    -a       monitor attribute assignment
    -A       monitor attribute testing

    -t       set the Tandy bit (see below)

Questions and answers:

    Q: What is Frotz?
    A: Frotz runs text adventures which come in so-called story files:
       ZORK1.DAT, TRINITY.DAT, CURSES.Z5, JIGSAW.Z8, ARTHUR.ZIP etc.

    Q: Where can I find story files to use with Frotz?
    A: First, you can use the files from your original Infocom games. It
       is possible to play PC, Atari ST, Amiga or Macintosh games once
       you manage to transfer the story files. Some people even extracted
       story files from old Atari 800, Apple II and C-64 disks! Second,
       there is also an increasing number of new games available on the
       Internet. Check the if-archive at ftp.gmd.de.

    Q: Why does Frotz stop with an error message?
    A: Your story file may be corrupt. Be sure to download story files in
       binary mode.

    Q: When exactly should I hear sound?
    A: Here are two examples: In 'Lurking Horror', you can hear chanting
       during your dream in the terminal pool. In 'Sherlock', you should
       play the violin.

    Q: Why doesn't the sound work?
    A: Be sure to use the correct story files: 'Sherlock' release 26 (not
       release 21) or 'Lurking Horror' release 221 (not release 203). The
       release number is shown at the start of the game.

    Q: How can I send transscription to the printer?
    A: Type PRT: as file name.

    Q: Why doesn't multiple undo work as often as it should?
    A: The number of undo slots is limited by your free memory.

    Q: What is this Tandy bit?
    A: Some old Infocom games were sold by the Tandy Corporation. These
       games behave slightly different when this bit is set. For example,
       'The Witness' gets censored: bastards turn into idiots, private
       dicks into private eyes and so on.

List of fatal errors:

    - "Byte swapped story file"
    - "Call to illegal address"
    - "Call to non-routine" [1]
    - "Cannot open story file"
    - "Division by zero"
    - "Error reading save file"
    - "Illegal attribute number"
    - "Illegal object number" [2]
    - "Jump to illegal address"
    - "No such property"
    - "Out of memory"
    - "Print at illegal address"
    - "Stack overflow" [3]
    - "Store out of dynamic memory"
    - "Story file read error"
    - "Text buffer overflow"
    - "Unknown opcode"
    - "Unsupported Z-code version"

    [1] The first byte of a routine must be less than 16.
    [2] In V4 and above, object numbers > 2000 are considered illegal.
    [3] This condition is only checked on every call instruction.