Devel Chess Engine

Devel is a free UCI engine (32-bit application) for Windows, written by Per Skjerpe. The program works well with Graphical User Interface (GUI) programs such as Arena and Chessbase.
All source code is original, but many ideas have been taken from other programs. Most useful was the source code of the following programs:
Fruit 2.1 by Fabien Letouzey.
Stockfish by Tord Romstad, Marco Costalba, and Joona Kiiski.
Crafty by Robert Hyatt.
The static evaluation function in Devel resembles that of classical Chess 4.5, the ancestor of all modern chess programs. This old program was described in detail by David J. Slate and Lawrence R. Atkin: Chess 4.5-The Northwestern University chess program in the book "Chess Skill in Man and Machine", by Peter W. Frey (ed.), Springer-Verlag, 1983.

The program is written in C++. The internal data structure is quite straight-forward, the chess board is embedded within a convenient 16x16 integer array, in the reverse direction there are arrays giving the placement of pieces on the board. This data structure is in fact quite similar to that of Fruit. In Devel, evaluation of king safety is quite similar to that of Fruit and Stockfish. Evaluation of passed pawns is nearly the same as in Stockfish. The search is standard recursive with an expectation window (alpha-beta pruning) and quiescence search for nodes beyond nominal depth. The most common pruning techniques are used, including razoring, futility pruning (at parent and child node), null move pruning. Default hash table is 256 MB, configurable up to 2048 MB. Principal variation search (PVS) with multi-PV option. Supports all common time controls, but never use pondering (thinking on opponent's time).

Devel 3.0.0a

Devel 3.0.0b

Devel 2.0

Devel 1.8090