GNU Chess Mac 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 has 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.
Please let us know if you find any bugs in this release. Suggestions for future enhancements are also welcome.
Starting GNU chess
GNU Chess should run on any Mac with System 6.0.7 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.
Playing a game
When a new game is started, GNU Chess assumes you are playing white and waits for your first move. 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, GNU Chess will return the piece to it’s 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 GNU chess plays black’s move, the black clock is stopped and the white clock starts.
The game will continue till a checkmate or stalemate is reached or you resign.
File Menu
New Game - Reset the board and get ready for a new game with the user playing white. 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 GNU Chess.
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. This option is set whenever a new game is started. 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 GNU chess into a spectator sport.
Human vs. Human - Play a game with another human. GNU Chess keeps track of moves and the clock. The white clock is started when this is selected.
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. GNU chess (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 GNU chess only thinks during it’s turn. When not selected, GNU chess will look ahead while it’s 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, GNU chess moves are done slowly to make them more obvious.
Randomize - If selected, GNU chess will randomly pick it’s 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 GNU Chess to stop thinking and make it’s 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 the GNU Chess application. When a new game is started, GNU Chess 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. GNU Chess will follow the recommended moves while it can, choosing one randomly. When no listed move is found, it will do it’s 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 Dan Oetting (oetting@gldfs.cr.usgs.gov).
Version History
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
