sw/chekmo/CHEKMO.WU

   1
   2
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   5
   6         ABSTRACT
   7         --------
   8
   9         CHEKMO-II is a chess playing program which will run on any PDP-8
  10         computer.  The program will play either the White pieces or the Black
  11         pieces and will play and accept all classes of legal moves, including,
  12         castling both short and long, en-passant pawn captures, and pawn pro-
  13         moting moves to any legal promotion piece.  The program prints out its
  14         moves in Algebraic Notation, and accepts moves using this Notation.
  15
  16         Included in the command structure of the program are commands which
  17         allow you to input board positions using Forsyth Notation, and get a
  18         printout of the board at your terminal.
  19
  20         EQUIPMENT
  21         ---------
  22
  23         CHEKMO-II will run on any PDP-8 family computer with a minimum of 4K
  24         of memory and an ASR33 Teletype (1), or equivalent terminal.
  25
  26         EXECUTION TIME
  27         --------------
  28
  29         The time that CHEKMO-II takes to calculate a move is highly dependent
  30         upon the position of the pieces, but it is generally within the range
  31         of 20 seconds to 2 minutes per move.  In "blitz mode"  (see the "BM"
  32         command), CHEKMO-II makes its moves much more quickly, but at the cost
  33         of reduced playing strength.
  34
  35         Note:  All times quoted are assuming that CHEKMO-II is being run on
  36         a PDP-8/e (1.2 us cycle time).
  37
  38         LOADING AND STARTING CHEKMO-II
  39         ------- --- -------- ---------
  40
  41         The CHEKMO-II binary tape is a standard binary tape and can be loaded
  42         using the BIN Loader program (DEC-08-LBAA-PM), or the OS/8 "ABSLDR"
  43         program.  The starting address for CHEKMO-II is 0200.  CHEKMO-II can
  44         be halted and restarted at location 0200 at any time.
  45
  46
  47         (Note for OS/8 users:  A short patch to the input routine is available
  48         which allows CHEKMO-II to respond to CTRL/C (^C) by returning to the
  49         monitor system.  Play may be resumed simply by typing ".ST" followed
  50         by a carriage return.  Specify '/S' to ABSLDR to include this patch.)
  51
  52
  53
  54
  55         (1) Teletype is a registered trademark of the Teletype Corporation.
  56 \f
  57
  58         CHEKMO-II  Chess Program for the PDP-8               Page 2
  59
  60
  61
  62
  63         ON LINE OPERATION
  64         -- ---- ---------
  65
  66         Before continuing please note that all lines of input to CHEKMO-II
  67         must be terminated with a carriage return.  Typing a CTRL/U character.
  68         echos "^U" and erases anything typed so far on a line.  Typing a RUBOUT
  69         character deletes the last character typed and prints a "\" character
  70         to indicate the deletion.  CHEKMO-II has an input buffer with room for
  71         24 characters.  If more than 24 characters are typed on a line (exclud-
  72         ing rubouts and the "rubbed out" characters), a "^U" is printed and the
  73         entire line is deleted.
  74
  75         When CHEKMO-II is started at location 0200 it will print. . .
  76
  77         CHEKMO-II
  78
  79         To identify itself and setup the pieces on its internal board to their
  80         original squares.  Then it will ask. . .
  81
  82         W.  YOUR MOVE?
  83
  84         The "W. " at the beginning of the line is to indicate that it is whites
  85         move.  The "YOUR MOVE?" indicates that CHEKMO-II is waiting for you to
  86         input a move for white, using modified Algebraic Notation (described on
  87         P. 6).  If the move that you type in is illegal or impossible CHEKMO-II
  88         responds with. . .
  89
  90         ?
  91         W.  YOUR MOVE?
  92
  93         asking again for you to type in a legal move.  If a legal move is typed
  94         CHEKMO-II will make the move on its internal board, then ask. . .
  95
  96         B.  YOUR MOVE?
  97
  98         CHEKMO-II is now waiting for you to type in a move for black (note the
  99         "B.").  As before, typing in an impossible move causes CHEKMO-II to...
 100
 101         ?
 102         B.  YOUR MOVE?
 103
 104         ask again for a legal move.  A legal move causes CHEKMO-II to make that
 105         move on its internal board, then ask for a move for white.
 106 \f
 107
 108         CHEKMO-II  Chess Program for the PDP-8               Page 3
 109
 110
 111
 112         Play continues in this manner until a move is made that checkmates or
 113         stalemates.  At that time CHEKMO-II will print. . .
 114
 115
 116         CHECKMATE
 117
 118         or
 119
 120         STALEMATE
 121
 122
 123         In either case the final position is then printed
 124
 125                     -- ** -- BK -- ** -- **
 126                     ** -- ** WQ ** -- ** --
 127                     -- ** -- ** WK ** -- **
 128                     ** -- ** -- ** -- ** --
 129                     -- ** -- ** -- ** -- **
 130                     ** -- ** -- ** -- ** --
 131                     -- ** -- ** -- ** -- **
 132                     ** -- ** -- ** -- ** --
 133
 134         CHEKMO-II now restarts itself at location 0200 and is ready to play
 135         another game.
 136
 137
 138
 139         Codes:    B-  BLACK
 140                   W-  WHITE
 141                   P-  PAWN
 142                   B-  BISHOP
 143                   R-  ROOK
 144                   Q-  QUEEN
 145                   K-  KING
 146                   N-  KNIGHT
 147                   S-  ALSO A KNIGHT
 148 \f
 149
 150         CHEKMO-II      Chess Program for the PDP-8            Page 4
 151
 152         SPECIAL COMMANDS
 153         ------- --------
 154
 155         Whenever CHEKMO-II is waiting for you to type in a move, you may
 156         instead type in one of the 10 special commands currently implemented.
 157         Each special command consists of 2 characters and is described below:
 158
 159         PW -- CHEKMO-II is instructed to play the white peices.  Whenever it
 160               is whites turn to move CHEKMO-II will printout and make a move
 161               for white instead of asking "YOUR MOVE?"
 162
 163         PB -- Same as "PW" except that CHEKMO-II makes a move for the black
 164               pieces every time it is blacks turn to move.
 165
 166         PN -- CHECKMO-II plays neither white nor black.  This cancels previous
 167               "PW" and "PB" commands.
 168
 169         BD -- CHEKMO-II will print out the current board position.
 170
 171         MV -- Causes CHEKMO-II to printout and make the next move for the side
 172               whose turn it is.
 173
 174         SK -- Skip the move that CHEKMO-II is asking for, and make it the other
 175               sides move.
 176
 177               Note:  According to the laws of chess, "The 2 players must alter-
 178               nate in making 1 move at a time".  The SK command is included be-
 179               cause it can sometimes be fun to use in "non-serious" games.
 180
 181         RE -- Stands for "Reset" (or "Resign").  It resets CHEKMO-II's internal
 182               board to the initial starting position and begins a new game.
 183
 184         BM -- Puts CHEKMO-II into "Blitz mode".  In Blitz mode, CHEKMO-II does
 185               not think very deeply about its moves, but instead, makes them in
 186               3 seconds each on the average.
 187
 188         TM -- Resets CHEKMO-II to its regular "thoughtful" mode of play.
 189
 190         IP -- Instructs CHEKMO-II to accept the input of a position using For-
 191               syth notation (described on Pg. 6)  CHEKMO-II prints a ">" to in-
 192               dicate that it is ready for you to enter a line.  If you violate
 193               the rules of Forsyth notation, an error message is printed, and
 194               CHEKMO-II waits for you to enter the error line again. If you en-
 195               ter in a good line, CHEKMO-II prints a ">" and waits for the next
 196               line.  When all 8 ranks are entered successfully, the board posi-
 197               tion just input gets printed out.  Possible error messages and
 198               their causes are described below:
 199
 200               Message               Cause
 201
 202                  1?        More than 8 squares specified
 203                  2?        Less than 8 squares specified
 204                  3?        Piece color not "W" or "B"
 205                  4?        Unknown piece letter
 206 \f
 207
 208         CHEKMO-II     Chess Program for the PDP-8          Page 5
 209
 210         ALGEBRAIC NOTATION
 211         ---------- -------
 212
 213         Algebraic Notation is the system recommended by the International
 214         Chess Federation (F.I.D.E), for the recording of chess moves.  Since
 215         in regular Algebraic Notation, both upper and lower case letters are
 216         used, and since most teleprinters output only upper case letters,
 217         CHEKMO-II uses a modified form of algebraic notation to accept moves,
 218         and to print out its own moves.  This modified Algebraic Notation is
 219         described here.
 220
 221         The ranks (horizontal rows of squares) are numbered from 1 to 8 start-
 222         ing from whites side of the board. The files (vertical rows of squares)
 223         are numbered from A to H starting at the left (blacks right) hand side
 224         of the board.  The intersection of the file letter and rank number
 225         gives each square a unique name, for example, in the initial position,
 226         whites king occupies square E1, blacks king occupies square E8, and
 227         the pawn in front of blacks queen occupies square D7.  Whites Knight
 228         is on square B1 and can move to squares A3 and C3.
 229
 230             A8 B8 C8 D8 E8 F8 G8 H8    BR BN BB BQ BK BB BN BR
 231             A7 B7 C7 D7 E7 F7 G7 H7    BP BP BP BP BP BP BP BP
 232             A6 B6 C6 D6 E6 F6 G6 H6    -- ** -- ** -- ** -- **
 233             A5 B5 C5 D5 E5 F5 G5 H5    ** -- ** -- ** -- ** --
 234             A4 B4 C4 D4 E4 F4 G4 H4    -- ** -- ** -- ** -- **
 235             A3 B3 C3 D3 E3 F3 G3 H3    ** -- ** -- ** -- ** --
 236             A2 B2 C2 D2 E2 F2 G2 H2    WP WP WP WP WP WP WP WP
 237             A1 B1 C1 D1 E1 F1 G1 H1    WR WN WB WQ WK WB WN WR
 238
 239         A move is specified by the square number of the piece that is moving,
 240         an optional "-" or ":", and the square number that the piece is moving
 241         to.  Using this notation, the 2 possible moves for Whites Knight on
 242         square B1 would be: B1-C3 and B1-A3.  The symbol "O-O" is used to spec-
 243         ify king side castling and the symbol "O-O-O" is used to specify queens
 244         side castling.  Pawn promotion moves are printed out in the same manner
 245         as any other pawn move, except that they are followed by a "=" and
 246         the initial of the piece the pawn is promoting to.  For example, on
 247         an empty board, a pawn on A7 would have 4 possible moves:
 248
 249             A7-A8=N    A7-A8=B    A7-A8=R    A7-A8=Q
 250
 251         On input, if no equal sign and initial are specified, the promotion
 252         is assumed to be to a queen.
 253
 254
 255
 256         (Note: CHEKMO-II uses the ':' symbol to indicate that a piece was taken
 257         by that move.  You may wish to type your moves in the same way.)
 258
 259 \f
 260
 261         CHEKMO-II      Chess Program for the PDP-8          Page 6
 262
 263
 264         FORSYTHE NOTATION
 265         -------- --------
 266
 267         Forsythe Notation uses the 2-letter codes shown on page 3 (and used
 268         throughout this discussion) to specify the pieces and numbers to in-
 269         dicate how many spaces occur between pieces.  When entering a board
 270         configuration each position in every row must be accounted for -
 271         see the error message summary on page 4.
 272
 273         Example:  BR4BK2 looks like:  BR ** -- ** -- BK -- **
 274
 275
 276         ERROR HALTS
 277         ----- -----
 278
 279         There are 2 legitimate error halts possible with CHEKMO-II
 280
 281         Address               Explanation
 282
 283         5004    An unexplained interrupt has occurred.  Press the CLEAR
 284                 and CONTINUE keys (START on a non-PDP-8/e).  If the error
 285                 persists, try to find its cause and eliminate it.  A likely
 286                 cause is a DF32 Disk Unit set to the OFF position.
 287
 288         1761    The position has gotten too complex and CHEKMO-II's push
 289                 down list has overflowed.  You Win!!  Just before halting,
 290                 CHEKMO-II will print out. . .
 291
 292                 I RESIGN
 293
 294
 295                 This error can probably only occur if one or both sides has
 296                 queened several pawns.
 297
 298         Halting at any other address is extremely unlikely, and is caused
 299         either by a hardware failure, or an as yet unknown program bug.
 300
 301         KNOWN BUGS
 302         ----- ----
 303
 304         There are no known "bugs" in CHEKMO-II Rev #62.
 305
 306         KNOWN DEFICIENCIES
 307         ----- ------------
 308
 309         CHEKMO-II as of Rev. #62 does not recognize the value of passed pawns
 310         until they reach the 6th or 7th rank.
 311
 312         CHEKMO-II has been programmed to use the same strategy throughout
 313         the game.  This strategy has been optimized for good play in the
 314         Middlegame and Opening.  As a result, CHEKMO-II plays poor moves
 315         in some Endgame positions.
 316 \f