Clarabit Chess Engine 

Technical Info

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Technical Info

            Minimun Hardware Recomended:

  • Intel Pentium 100Mhz
  • 128MB RAM

            O.S. Supported:

  • 32bits and 64bits Windows  98/2000/XP/2003/Vista
  • 32bits and 64bits Linux


  • UCI Protocol
  • Winboard 2 Protocol

            Data Structure:

  • Bitboard based
  • Rotated Bitboard
  •  Magic Bitboard   


  • Principal Variation Search
  •  Limited Quiescent Search
  • Static Exchange Evaluation and MVV/LVA
  • Null Move Prunning (R=2/3)
  • Single Transposition Table and Pawns Hash Table
  • History Heuristic
  • Killers , Mate Killers
  • Check Extension
  • Late Move Reduction
  • Pondering


  • Basically pieces evaluation is based on Material, Mobility(attack bitboards),  Piece/Square tables, Piece type own positional knowledge.
  • Pawns Evaluation considers Doubled, Backward, Isolated, Passer and Candidate Passer. Passers have a more complex evaluation.
  • King Safety is very important  and ponderated in evaluation function.
  • Specific Endgame Knowledge.

            Opening Book:

  • ProDeo´s  Opensource Opening Book code slightly modified. Thanks to Ed Schröder.
  •  Book  GM2001PD.  Thanks to Olivier Deville and Fonzy. 

                Endgame Bitbases

        •  Scorpio  Endgame Bitbases Access. Thanks to  Daniel Shawul.


Last update 28/01/2008