Skip to content

Ninth Release V1.33

V1.33, released 08-Jan-2019, is the ninth stable version. You can download the ZIP file (5 MB):

Download V1.33

Changes from V1.32

  • Improved move sorting for quiet moves with regard to depth killers.
  • Improved move sorting resulting from internal iterative deepening.
  • When a best move is retrieved from the hash table, the move generation is deferred until the hash move has been tried without cut-off.
  • Quiescence detects stalemate against lone king.
  • Improved pawn evaluation: more penalty for isolated double pawns.
  • Improved king handling in endgames like KRPP:KR.
  • Added draw with KNP:K for rim pawns on 7th/2nd rank with defending king in the edge.
  • Improved KBP:KP with attacker rim pawn and wrong bishop.
  • The hash tables use a compressed move format which gains 16 kB of free RAM.
  • The PV lines also use the compressed move format which saves 1 kB of stack.
  • Entering moves has auto correction for swapped move squares if that converts an illegal entry into a legal one.
  • The position editor catches double entries of the same piece type.
  • In time per move mode, going into the menu and back displays the same thinking time as before instead of rounding up.
  • Refactored and improved the driver layer. The clocking allows for possible future addition of USB, and energy consumption in standby has been reduced.
  • Starting a software update may fail when the CT800 is running idle, see the troubleshooting section in the manual.


  • The Android build chain has been updated from Android NDK r17b to r18b.


  • A build script using Clang is supplied for generating a macOS 64 bit binary.

Known issues

  • When the supply voltage exceeds 5.4 V, the firmware erroneously displays a “low battery” warning and shuts down the device.

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.