versionreleasedtechnical notesrating1
0.5.8c2014.06.30Bugfix: identified and fixed some overflows causing crashes.2224
0.5.8c2014.06.12Bugfix: EP flag wrongly updated in making/unmaking null moves, causing bad play in ignoring opponents' EP recaptures.
0.5.8b2014.06.06Bugfix: UCI mode wasn't working in some GUI's. Stop (move now) command has been implemented.
0.5.8a2014.06.02Bugfix: book was disabled and hash used was wrongly displayed.
0.5.82014.06.01Bugs in evaluation and in quiescence search found and fixed. Hash size is now adjustable from 16 to 512 MB, default 256. Statistical piece/square move table removed. Wrong "mate in" value was displayed in XBoard mode. Tuned most parameters.
0.5.72010.01.18Added UCI mode. Hash size is now adjustable from 1 to 256 MB, default 128. Emergency book removed. For debugging and tuning purposes, evaluation suite command added. Move order improved, also using a statistical piece/square move table.1974
0.5.6a2007.02.20Hash 64 MB fixed. Eval fixed. This version works only when the book is available.1933
0.5.5cct2007.02.17New deep eval. New book format, 4 times more compact. This version works only when the book is available.1766
0.5.4a2007.02.05Bugfix: on some GUIs, the engine failed to play as Black; WinBoard I/O management completely rewritten. WinBoard crushed if the book wasn't found. PV move numbers displayed were wrong. A forced move wasn't played immediately.1722
0.5.42007.02.03Two bugs fixed: castling was displayed with the wrong symbol (0-0 instead of O-O), with Arena GUI not recognizing the move; reported by Tony Mokonen, Carlos Pagador and Hans Eriksson. Black's kingside castling wrongly altered the vertical rotated bitboard, causing mistakes in generation of moves where a1 is the destination square; discovered by myself after thousands of tests. Many code optimizations. Time management: now the engine tries to optimize the allotted time for the whole game. Quiescence search now ignores losing captures, thanks to a fast SEE implementation. Move generator has been highly optimized, with distinct check evasions, captures/queen promotions and normal moves generation; fast Perft and Divide commands added. Piece-square evaluation improved. Aspiration search, zero window and basic search extensions and reductions. A compact opening book is now included (2.6 MB zipped); embedded emergency opening book, automatically selected if no book is found. Syntax and legality check for Setboard command. SAN moves representation with better PV display. SAN input accepted and checked. Detailed search statistics. Console mode with color display and many debugging commands. Testsuite command with detailed results. Engine logo has been slightly changed.-
0.5.32006.06.147-ply alpha-beta search and null moves (R=3).1242
0.5.22006.06.13Added 5-ply alpha-beta full search.1221
0.5.1b2006.06.11The bug has been found and removed: now all modules work properly.1035
0.5.12006.06.11Added a 2-ply full search to test piece-square table and makemove/unmakemove routines. Unmakemove still has a mysterious bug, occurring in one game out of 200.-
0.5.02006.06.10The engine has been completely rewritten, in Delphi and ASM, and now is based on rotated bitboards. This first release just plays a random move (captures and castling first) to test movegen, makemove and WinBoard communication routines.not tested
0.4.42004.07.233-ply alphabeta search plus 3-ply quiescent search.1228
0.4.32004.07.19Replaced 3-ply minimax search with 4-ply alphabeta search.not tested
0.4.22004.07.13Added piece-square evaluation.1169
0.4.12004.07.11Added 3-ply minimax search, with material only evaluation.1073
0.3.22004.07.05Bugfix: always the best move was played from the book; thinking wasn't displayed in WinBoard.826
0.3.12004.07.05Added an opening book, with about 3 millions positions. Size: 23 MB, disk space needed: 130 MB. Without the book, this version is identical to 0.2.2. The book is no longer available.-
0.2.22004.07.03Bugfix: taking a Rook on its original square didn't clear the castle-allowed flag; the WinBoard command "computer" wasn't recognized.839
0.2.12004.07.02Sorts the legal moves and plays a gaussian-random one. Released to test the move ordering.-
0.1.12004.06.30Plays a random move. Released to test the move generator.710
1 According to GSEI 1'+1" tournaments