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Release V1.40

V1.40 was released on 2020-Apr-05. You can download the release ZIP file (5 MB):

Changes from V1.34

  • More aggressive pruning in search.
  • Increased value of rook vs. minor and pawns if both sides have pawns.
  • Improved handling of KQ:KR.
  • Simplified code for KNB:K.
  • Compressed the bitbase for KP:K from 32 kB to 24 kB.
  • The mate searching mode is about 30% faster, and opponent mate search has been removed.
  • More opening book knowledge.
  • Improved protection against false opening book hits.
  • Added option for aggregate castling rights in the position editor.


  • The Android build chain has been updated from NDK r18b to r21.

Raspberry Pi

  • The GCC build chain has been updated from 4.6.3 (Wheezy) to 8.3.0 (Buster).

Known issues

All versions

  • The PV may contain an illegal move in the rare case that a PV position allows pawn takes queen with queening, but this is not the best move. However, the root move is not affected so that no illegal move will be played.

Embedded target

  • When entering a new position after undoing or redoing moves, the move list in the main screen is not cleared.

UCI versions

  • The “en passant” square given via FEN position string is discarded erroneously.

Note: issues are fixed with new releases only – there are no backports. However, if an issue is found, it will be listed for the previous releases where applicable.