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• In the Help menu, I replaced the old option for copying the Chenard web page URL with a new option that directly opens that page with the default browser.
• Now it is possible to directly open a PGN file using Windows Explorer: Right-click on the PGN file, say Open With..., and choose winchen.exe as the program to open it with. This causes the filename to be passed to Chenard, which now knows to look for it and open it. The game will be loaded. If Chenard created the PGN file, it will show the initial dialog box for creating the players as White/Black being human/computer the same way they were when the PGN file was saved. Otherwise, the old behavior of suggesting the player sides randomly will remain in effect.

• Corrected a problem when the user edits the board position and the side to move is Black afterward: the ply counter would be off by one, causing XChenard to be wrong about how many moves were left in a timed period. This could cause XChenard to run out of time and lose.
• When the WinBoard/xboard client supports debug output, XChenard will log whether it is a 32-bit or 64-bit build.

• XChenard was occasionally profoundly confused about how many moves remained in the current time period because it was using a chess board object that was still in the middle of a line of analysis, and therefore it could randomly think either White or Black had the move.
• It was not resetting the move counter when it received the "new" command from WinBoard/xboard.
• It was calculating the number of remaining moves when WinBoard/xboard sent the "time" command, not when the opponent's move had been received. This affects whose turn it is, and therefore the number of remaining moves. Now XChenard records the time when the "time" command arrives, but waits until it is just about to start thinking before doing the math to calculate how much time to think.

• XChenard was occasionally profoundly confused about how many moves remained in the current time period because it was using a chess board object that was still in the middle of a line of analysis, and therefore it could randomly think either White or Black had the move.
• It was not resetting the move counter when it received the "new" command from WinBoard/xboard.
• It was calculating the number of remaining moves when WinBoard/xboard sent the "time" command, not when the opponent's move had been received. This affects whose turn it is, and therefore the number of remaining moves. Now XChenard records the time when the "time" command arrives, but waits until it is just about to start thinking before doing the math to calculate how much time to think.

• Fixed compiler warnings in the Linux text-only version of Chenard. There were no algorithm changes, just minor tweaks in the file uistdio.cpp that make the warnings go away.

• Fixed a bug in XChenard that happened when WinBoard, xboard, or a compatible host was configured to supply moves from an external opening book. The problem was that XChenard did not properly follow the protocol for tracking how many moves were left in a given time period when some of those moves were fed in from the hosting software, instead of being computed by XChenard. See this forum discussion about this common timing bug for WinBoard and xboard chess engines for an in-depth technical explanation.

• Implemented the WinBoard 4.4.0 "option" command in XChenard. XChenard uses this command to provide a check box in WinBoard 4.4.0 (and above) to enable/disable XChenard's built-in opening book and training file chenard.trx.
• If you are using XChenard with WinBoard or xboard that does not support the "option" command, you can still disable XChenard's built-in opening book by creating a text file called xchenard.ini and putting the following exact line of text in it (note that this is case sensitive):

  Use opening book=0

  Use your favorite text editor to change the 0 to 1 if you want to enable the opening book instead, or just delete the file xchenard.ini, since enabling the opening book is the default. The file xchenard.ini must be placed in the same directory as the chess engine executable xchenard.exe.

• Implemented the WinBoard/xboard "memory" command. By default, XChenard uses about 800K (0.8MB) of hash table memory. However, using this option it can be increased to any number of megabytes from 1 to 1024. Any value larger than 1024MB (1GB) will cause Chenard to use 1024MB.

• Made WinChen.exe pondering algorithm work more like XChenard's: favor moving faster over thinking longer when it correctly predicts the opponent's move.
• Fixed a bug where Chenard would report a draw by repetition when the position had repeated only 2 times, not the required 3.

• Thanks to Jim Ablett, I learned about using Profile-Guided Optimization in Microsoft Visual C++ 9.0, and was able to use it to speed up Chenard by about 22%. See this conversation on the WinBoard forum. Jim is using similar features in the Intel C++ compiler.

• Made minor tweaks in the source code so that people using Microsoft Visual C++ Express Edition (the free download version of Microsoft's C++ compiler) to compile the Windows GUI version of Chenard (winchen.exe) will no longer get compiler errors about missing header files in winchen.rc. It turns out the free version of the compiler doesn't ship with the header file afxres.h like the professional version does. This change has no effect on the behavior of the engine. If you are not a computer programmer who is trying to compile my source code, you can safely ignore this change!
• Fixed a minor bug in the WinBoard/xboard version of Chenard (xchenard.exe) that could theoretically cause it to let its flag drop in a timed game, when there was less than 2 seconds left on the clock. I say "theoretically" because I have not experienced this bug myself, nor have I had any reports of it. I discovered the issue while reviewing the source code.

• Fixed a bug in the chess engine that could cause the program to crash in extremely rare circumstances. Most people would never encounter this, but it is a good idea to upgrade to this version, just in case.

• WinBoard/xboard version of Chenard now supports pondering, which means the option of thinking while it is the opponent's turn.
• WinBoard/xboard version of Chenard now has a better understanding of time controls for tournament games. It will move faster as its clock runs lower. Before, it would keep spending the same amount of time thinking about each move, often causing it to run out of time and lose.

• Bug fix (problem in new WinBoard/xboard code only): Whenever the opponent played Black and tried to promote a pawn, the move would always be rejected as an illegal move.
• Support display of thinking to WinBoard/xboard via the commands post and nopost.

• Under the Edit menu, there is now a command for setting the board position using Forsyth Edwards Notation (FEN).
• The URL listed in the Help/About box was wrong! Fixed it.
• Because computers are so much faster these days than when I started Chenard, the first time someone runs winchen.exe, the default think time will be 3 seconds instead of 10 seconds. As always, the program will remember whatever settings were used the last time, so people upgrading will not see any difference.

• The WinBoard version of Chenard (wxchenard.zip) now supports the Move Now command for interrupting the search and making a move immediately. (This was already correctly working for the Linux/xboard version of Chenard.)
• Added a new endgame database (optional download) for King and Queen versus King and Bishop. To use this new endgame database, you must download this version of the software, and download the file endgame.zip, and extract the zip file to the same directory where you run the software.

• Improved the endgame databases: corrected some inaccurate estimates on how many moves away from forced mate a given endgame position is. This also fixed issues with sometimes playing less than optimal moves, meaning moves that minimize how long the opponent can postpone checkmate.
• Chenard now writes a game result token to the end of a PGN file, as is required by the PGN spec.
• Fixed bug that would erroneously report syntax errors in PGN files that were created by other software. Specifically, Chenard did not know about "*" at the end of a listing for an incomplete game, and did not understand braces or semicolons as comments.
• Chenard can now load/save PGN files for edited board positions.
• Fixed a bug that prevented the Move Undo and Move Redo commands in WinChen.exe from working after loading a game from a PGN file.

• When View|Analysis was enabled, the eval/sec numbers on very lengthy searches could jump to a faulty value. This was due to overflowing a 32-bit integer. This calculation is now done internally using floating point math, which eliminates the problem.
• When thinking on opponent's time was enabled (called pondering), and the opponent resigned, the pondering would continue even though the game was over. Now pondering is stopped as soon as the opponent resigns.

• Updated Windows code to use QueryPerformanceCounter instead of GetTickCount for internal timing. This postpones a theoretical problem with integer overflow after 49 days to instead happen after 248 days of continuous run time. The 248-day limit is inherent in Chenard's use of 32-bit signed integers to represent time to centisecond (0.01 second) precision. If this becomes a problem (someone running the program continuously for a good fraction of a year) I will have to convert to using 64-bit integers for timing.
• My build process was not packaging the Linux files build and sourcefiles. This has been corrected.
• Windows was causing uppercase and lowercase versions of the same directory to appear as separate directories in the zip files, when unzipped in Linux. Fixed the build process to rename important files and directories to all lower case before zipping them up.
• Automatically correct Linux script files for Linux text format: remove extraneous '\r' characters.

• Text-only, portable versions of the chess engine now support PGN and longmove notation (e.g. e2e4 or e7e8q). Nonstandard formats that I made up are no longer supported.
• Note that from now on, I am changing my version numbers to be the same as the calendar date of publication, in yyyy.mm.dd format. This will be applied consistently across all Windows builds. If you build the code yourself, most of the executables will contain the date and time that you built the code. However, the Windows GUI program winchen.exe will say "unofficial build".

There was a bug that caused Move Undo to not work right after a game file was opened. Before, you would have to make a move before Undo started to work again. This has been fixed.

Fixed a bug that caused Move Undo to not work when the game was over.

Now you can press F1 as a keyboard shortcut for Suggest Move.

Improved the search by making it pretend that any position which is repeated at all during the search is a forced draw. This will make Chenard avoid wasting time when it should be avoiding a draw, and will increase the likelihood of finding a forced draw when that would be in its favor.

Added new evaluation heuristics for attacking squares in front of the enemy king that are not protected by an enemy pawn.

Improved search efficiency by using transposition tables.

More minor additions to evaluation heuristic: refined bishop pin detector, and added a rook pin detector. Also added a queen position table to try to keep computer's queen out of corners.

New option "automatic singular move" allows Chenard to make your move for you when you have only one legal move anyway.

Minor enhancement to evaluation function: computer looks for veiled bishop attacks and pins.

"Copy game listing" command now uses a 64K buffer instead of a 4K buffer.

Added a program icon (finally!).

When the computer is considering its move, "< thinking >" is displayed below the board.

Now the user may enter a non-integer number of seconds for the computer's think time. The minimum think time has been decreased from 1 second to 0.1 seconds.

The default piece style is now "Skak" instead of "Tilburg".