GnuChessMac 4.0 is a free chess game for the Macintosh derived from GNU Chess 4.0 available on other platforms. It is distributed under a GNU Public License and may be given away, but not sold. See the file “Copying” for details of the GNU Public LIcense.
Version 4.0 was ported by Dan Oetting (oetting@gldfs.cr.usgs.gov) assisted by Tom Gerardy (tomg@whacked.com) and Erich Oetting (erich_oetting@stortek.com). Dan started with GNU Chess 4.0 but made many changes to the search routines, openings and transposition table. The Mac interface is based on the version 3.0 Mac port done by Airy Andre.
The version released by Dan Oetting was identified as 4.0b5. This release (4.0) is by Rolf Exner (r.exner@trl.oz.au) and adds Apple Event support, move output in standard algebraic notation, and minor tweaks to the window sizes and positions and the command keys. The Apple Event support allows GnuChessMac to be used as a chess engine by programs such as ExaChess and ExaChess Lite.
Please let us know if you find any bugs in this release. Suggestions for future enhancements are also welcome.
Starting GnuChessMac
GnuChessMac should run on any Mac with System 7.0 or better and a megabyte of free RAM. If more RAM is available for the transposition table, the program will play a stronger game. Change the preferred size to 4000K or more if desired.
GnuChessMac starts in Human vs Human mode, allowing you to play both sides of the game until you have set up the desired opening. To then play White, choose Human vs Mac from the Players menu; to play Black, choose Mac vs Human.
Playing a Game
Moves are made by dragging a piece and dropping it on the desired position. Castle by moving the King two squares in the desired direction. If you attempt to make an illegal move, GnuChessMac will return the piece to its proper place.
Once White’s first move is played, it is entered in the move list. Then the Black clock in the information window is started. When Black’s move is played, the Black clock is stopped and the White clock starts.
The game will continue till a checkmate or stalemate is reached or you resign.
The Menus
File Menu
New Game - Reset the board and get ready for a new game in Human vs Human mode. The opening book is loaded at this time.
Open - Load a saved game to resume play.
Save - Save the current game. Games are saved as text files in the "PGN" standard chess format.
Quit - Exits GnuChessMac.
Edit Menu
The edit functions work as expected.
The UNDO function will take back the last move by a human player.
Players Menu
The first four items in this menu select who plays what side.
Human vs. Mac - You play first as white and the computer plays black. The clocks will start when you make the first move.
Mac vs. Human - The computer plays white, you play black. This also starts the clock.
Mac vs. Mac - Turns GnuChessMac into a spectator sport.
Human vs. Human - Play a game with another human. GnuChessMac keeps track of moves and the clock. The white clock is started when this is selected. This option is set whenever a new game is started.
The last two items control the clock setting for each side.
White Level - Set white clock.
Black Level - Set black clock.
The default clock settings are for a fairly quick game. GnuChessMac (and humans) play better if given more time. The game is not stopped if one side runs out of time.
Options Menu
Easy - If selected GnuChessMac only thinks during its turn. When not selected, GnuChessMac will look ahead while its opponent is thinking.
Reverse Display - Normally white plays from the bottom side of the display, select this to show the board with black at the bottom.
Animation - If selected, GnuChessMac moves are done slowly to make them more obvious.
Randomize - If selected, GnuChessMac will randomly pick its move from among the top candidates instead of always using the “best” move. Opening book moves are always chosen randomly regardless of how this is set.
Show Thinking - Not Implemented yet.
Show Score - Not implemented yet.
Hint - Not implemented yet.
Play Now - Force GnuChessMac to stop thinking and make its move immediately.
Windows Menu
Chess Board - Brings the chess board window to the front.
Information - Brings the information window containing the clock to the front. When a game is in progress the white or black clock will be running.
Game List - Brings the game list to the front. Moves are listed in algebraic notation.
Message - Brings the message window to the front. This is a command line interface used in testing. See the source code for how these commands work.
Console - Shows testing and play details, only present if the mouse button is held down when the program is started.
Chess Openings
A file named “openings.pgn” should be in the same folder as GnuChessMac. When a new game is started, GnuChessMac reads this file and decides how opening moves and responses should be played. A larger version is also included, but takes too long to load on a low end Mac. To use the big openings file, just rename “openings.big” to “openings.pgn”.
Both openings files are lists of opening moves in a standard chess notation. GnuChessMac will follow the recommended moves while it can, choosing one randomly. When no listed move is found, it will do its own evaluation. The openings files can be modified with any text editor.
Source Code
The regular GNU Chess release can be found on GNU archive sites such as prep.ai.mit.edu. Source code for this Mac version is available from Rolf Exner (r.exner@trl.oz.au).
Scripting
GnuChessMac is scriptable using Apple’s scripting system. Here is a small script to demonstrate GnuChessMac's scripting capabilities:
tell application "GnuChessMac"
new game
move "1 e4 e5 2 Nf3 Nc6 3 Bb5 a6"
move "2… Nf6"
search ""
end tell
Version History
4.0 - Added scripting support, which allows GnuChessMac to respond to events from the
CHES event suite. Changed position and size of initial windows to line up better.
Added support for standard algebraic notation on output
Added Close Cmd-W to File menu (changed White time control shortcut to Cmd-F).
Changed Confirm Close dialog to new style.
4.0b5 - Added Open, Save and Undo. 68k and PPC versions combined in fat binary.
4.0b4 - Fixed crashes caused by last bug fix. Developers can no longer beat the program
