Due to the limitations of its Spartan user interface, it is recommended that CHEOPS be run in a text mode supporting at least fifty lines. In MS-DOS, this may be accomplished by typing mode con lines=50. If launching the program from a Windows 95/98 shortcut, activate the shortcut properties window and select an appropriate screen size from Initial size drop-down list box under the Screen tab.
To start the program, simply type cheops at the command line. There are no command-line parameters. Once CHEOPS is invoked, the program displays a title screen and prompts the user for who controls each player. If a computer opponent is chosen, a list of default static evaluation function weights is displayed. (See Figure 1.) To accept the default values, type done; otherwise, enter the number of the weight to change. The program will then prompt for the new value. The program will allow the user to adjust the weights until done is entered.
Following player setup, the board is displayed and the game begins. The board is represented by a simple ASCII diagram using the standard one-character piece abbreviations; white pieces are represented by small letters and black pieces by capitals. Each player makes his move in turn; human players are prompted for their move, and computer players move automatically. To make a move, enter the source and destination coordinates in standard algebraic notation--for example, g1f3 moves the knight at g1 to f3. (See Figure 2.) For pawn promotions, the promotion piece must be appended--for instance, e7e8n promotes to a knight. For castling, the user may either enter the source and destination coordinates of the king, or he may simply type o-o or o-o-o for kingside or queenside castling, respectively. The players may continue entering moves in this manner until a checkmate or draw state is reached. As in regular chess, a draw occurs upon stalemate, triple observance of the same board configuration with the same side to move, or observance of fifty moves without a capture or pawn advance.
In addition to legal moves, the following commands are also available as responses for human players. At the end of a game, no further moves are possible, and one of these commands must be entered.