An alternative efficient chessboard representation based on 4-bit piece coding

This paper describes theoretical and practical aspects of an alternative efficient chessboard representation based on 4-bit piece coding technique. There are two main approaches used by the majority of computer chess programs: arrays and bitboards. However, after the years of researching and experimenting in chess engine Axon and its parallel version Achilles, we would like to introduce an alternative chessboard representation C. C. R. (Compact Chessboard Representation) based on a new coding technique that performs very well both on 32-bit and 64-bit hardware platforms.