- Meet the Authors -




CHESSMASTER   (also known as "The King")

The King, Version 3.12c (January 29, 2001)

In 1987, Johan de Koning (de Koning is Dutch for “The King”) started writing chess programs. The first version of “The King” was running on a 68000 processor, which had been introduced in microcomputers shortly before. Always trying to improve performance, The King was rewritten for the ARM-family of RISC-processors and finally for the Intel 80X86-family.

From the start, The King was given an attractive and enterprising playing style. Unlike many other computer programs, The King actively seeks attacking possibilities and is ready to sacrifice material not only on tactical, but also on positional grounds. Results and playing strength of the program steadily increased, and it has been among the world’s strongest ever since 1990.

ChessMaster pages...

CHESS SYSTEM TAL   Chris Whittington

Chess System Tal II is a knowledge based program. It packs many chess ideas into its evaluation function. It helps to give it some time to work up its ideas. The longer the time control the better.

CSTal II is not designed to play fast chess against other programs. It is designed to play chess against other chess players (eg humans). You can watch CSTal play, see its ideas, observe the positional and sacrifical algorithms and learn new concepts from it. Playing endless automated games against other materialistic programs is not recommended for the sake of your own sanity and the development of your own brain. Please get a tank of fish instead.

The opening book is on the original release CD. If you don't want to copy 520 Mbytes onto your hard drive, then please make sure the CD is in the drive, and the opening book dialog is set up to point at it (this is done by default, but is worth checking on start-up). If the CD is not in place, CSTal will then use a much smaller gambit book, but this is less desirable.

End game table bases are automatically installed if you chose the 'full install' option. All the 4-man bases are supplied, and you can download any or all of the 5-man table bases from the Internet. If you are short of space or download time, then we recommend KRPKR and KQPKQ as the two most useful 5-man table bases.

CSTAL Home...


Christophe Théron author of CHESS-TIGER started chess programming at the age of 17 in 1982. Like Ed Schröder (Rebel) Christophe started with his chess program on the good old TRS-80 1.77 Mhz because in these days this was the only available Personal Computer.

Nowadays the current version is 13.0 and 14.0 is going to be released soon.

Totally new is Gambit Tiger which plays a whole different game of Chess using a new king safety concept. Gambit Tiger is able to play all kind of gambits much better than the Classic Tiger. Gambit Tiger is part of REBEL 11.0 distributed by Schroder BV.

Gambit Tiger won the Dutch Open, the French Computer Chess Title, winner of Halloween 2000, winner of Jeroen's Christmas 2000 tournament, winner of Jeroen's Christmas 2000 BLITZ tournament, winner of NGT 2001. The list is found on the Rebel pages.


COMET   Dr. Ulrich Türke

Design and implementation in 1991 originally guided by GNU chess 3.0. search algorithm based on alpha-beta search, triggered by a home-made modification of the MTD driver.

Uses 3 hash tables (transpositions, evaluation & table-base-cache). (recursive) Null-Move-Heuristic with reduction=2 and 1. 2 knowledge based cuts a depth 1, positional learning function, compatible to Ch. Donningers Auto232 and Chess232, reads and writes standard formats (EPD and PGN), supports Nalimov's 5-man endgame table bases.

Available as freeware (DOS & winboard) as well as a native Chessbase analysis engine.



Robert Hyatt, Associate Professor. Available via for questions nearly 24 hours daily, on ICC and/or (or other servers) when you see "hyatt" logged on.

Research Interests, Computer Chess (Crafty). This research is developing the computer chess program "Crafty", which is a direct descendent of Cray Blitz, the World Computer Champion from 1983 to 1989. This program is a "freeware" package available from

Crafty is based on the classic BITMAP approach to representing the chess board, but uses a unique methodology called "rotated bitmaps" to significantly improve the performance of the chess engine. This program is currently searching around 800,000 nodes per second on a quad xeon processor, and is playing on ICC and regularly. Its current peak ICC ratings are 3108 (bullet), 3249 (blitz) and 2785 (standard). Crafty is portable, and uses xboard/winboard as a GUI under the appropriate operating systems.


EUGEN   Eugenio Jimenez

Eugen was born in 1994 like a personal free time project, initially writen in Pascal and assembler, in 1995 it was changed to C language.

Eugen is partially inspirated in freeware programs like TChess, Gnu, and Crafty. It uses 16 bit attacktables who are setup in every make and unmake move, the search uses iterative deepening, a short recursive nullmove (R=2).

In quiescence  a selective move generator is activated.

Actually node speed evaluations are improved specially for endgame.

FRITZ   Frans Morsch, Matthias Feist

Fritz is build around a selective search technique known as the null-move search. As part of its search, Fritz allows one side to move twice (the other side does a null-move). This allows the program to detect weak moves before they are searched to their full depth. Move generators, evaluation functions and data structures have been designed to maximize the effectiveness of the null-move search.

Fritz is the winner of the previous computerchess world championship in Hong Kong 1995. 1993 Fritz tied for 1st place in a Blitz tournament in Munich with the complete world elite. It scored the best computer result in the 1996 man-computer Aegon tournament. In 1998 Fritz was leading the prestigious Swedish rating list. It won an active chess tournament Frankfurt 1998 with a full point ahead of 36 grandmasters.

Fritz pages...

GANDALF   Steen Suurballe and Dan Wulff (picture)

Gandalf was started around 1985 by Steen Suurballe. The program was a rule-based selective program, which was very slow, but did surprisingly well. In 1993 Dan Wulff joined in the work, and has been doing the opening library ever since.

In 1995 Steen decided to skip the selective search, and concentrate on the evaluation function. The program got much stronger after this change, and although it has become a lot faster than the prior version, it is still rater slow, when compared with other programmes.

The search was changed to a standard alpha/beta search, with null-move reductions, and a lot of extensions. The latest version of Gandalf is a WinBoard-compatible engine.


GENIUS   Richard Lang

Richard Lang's ChessGenius series of programs have a long history of being the strongest in the world - since the early 1980's he has won Computer Chess World Championships not less than 10 times.

Perhaps ChessGenius's greatest achievment came in August 1994 when it shocked the Chess World and became the first program ever to beat a World Champion (Gary Kasparov) at a non-blitz time level! Genius also knocked GM Nikolic out of the same tournament, achieving an astounding 2795 ELO rating for its performance in that tournament - all on a mere 100 Mhz Pentium PC!

This, and other impressive performances demonstrate Genius's real strength - a sound & powerful playing style that can beat Human (and not just other computer) competitors.

The fundamental power of Genius's basic playing algorithms are demonstrated by the fact that it outperforms all others at "blitz" levels - ie, even on a shallow search the algorithms play sound chess. This is particularly important on platforms such as the Palm with limited processing power. For these reasons, Genius remains a "classic" favourite with Masters and Correspondence chess players alike - with its own unique and distinctive style of play.

Other Chess programmers have long looked to ChessGenius as the "standard" program - indeed it was told that even the Deep Blue team sparred with ChessGenius before their famous victory against Gary Kasparov in 1997.

Richard Lang has worked full time on Chess programs since the early 1980's. He has written programs for the Sinclair Spectrum, Tandy Colour Computer, Atari ST, Apple Mac, Sinclair QL, Psion Series 3 Organiser, many 'Mephisto' dedicated chess computers and recently for IBM Compatible PC's.

Genius pages...

GOLIATH   Michael Borgstädt

Little Goliath is a tactical monster due to its search speed and therefore well suited for analysis. The strongest free winboard engine after Crafty.

The 2000a and 2000 v.2.0 versions is capable of searching 1.000.000 NPS on fast systems (eg. AMD K6-3 450). A book generator is available at the homepage of Michael Borgstädt. It converts .CBF files (only old chessbase format) to bookformat. A pgn2cb can found in the conversion utilities directory at the archives of the Pittsburgh University chess club (link page).


GROMIT   Frank Schneider & Kai Skibbe

GromitChess is a C++-program, developed in a Linux-environment (Emacs, gcc). It searches about 25000 to 50000 nodes per second on a K6/200 and tries to be intelligent rather than fast.

Attacktables are the primary datastructure (16 bit for every square and player; bit n is set if piece n attacks the square). The search uses iterative deepening, PVS, transpositiontables, killer- and historyheuristic, nullmove (R=2), about 10 chess-specific extensions and some pruning heuristics.

The quiescence uses a static exchange evaluator and includes some checks and other threatening moves. Parts of the evaluation are initialized at the root but most of the work is done at the leafnodes.

Gromit pages...

HIARCS   Marc Uniacke

HIARCS is written entirely in 'C' on a very spare time basis.

HIARCS searches around an order of magnitude less positions per second (av. 18,000) than most of its competitors. However, it makes up for this apparent slow speed by clever searching and accurate evaluation.

HIARCS uses many selective search extension heuristics to guide the search and incorporates a sophisticated tapered search to resolve tactical uncertainties while finding positionally beneficial lines.

HIARCS won the title of World Microcomputer Chess Software Champion in 1993 in Munich, Germany and has won numerous other computer and human tournaments. HIARCS 7.0 is currently the top rated chess program on the SSDF and Selective Search rating lists.

In April 1997, HIARCS 6.0 became the first PC chess program to win a match played at tournament time controls over a FIDE International Master. This great achievement was further built on when HIARCS won the Godesberg Open ahead of Grandmasters and International Masters.


JUNIOR   Amir Ban

Junior6 is the improved version of the computer chess champion of 1997.

It gave impressive proof of it´s playing strength at the Tel Aviv chess festival in 1999 when it played against the Olympic team of Israel, scoring 2:2, and beat the top-ten player Boris Gelfand in two game match with a score of 1.5:0.5.

In January 2000 it was the first program to cross the 2700 Elo barrier on the SSDF world ranking list. In February 2000 it won the prestigious Cadaqués tournament ahead of all other strongest programs. Available in the following languages: English and German.


MCHESS   Marty Hirsch

M-CHESS belongs to the strongest chess programs. The former NASA programmer Marty Hirsch living in Novato, CA, has been in chess a long time. Legend has it that he decided to create a world champ chess program at the age of seven! And then in 1995 it happened: M-CHESS PRO 5 became world champion in chess software.

M-CHESS has, of course, all the necessary features. But Marty's main interest has always been playing strength. The style of his program is more positional. More than 600 000 opening positions are included. They were prepared by the Italian expert Sandro Necchi.

The new version 8 cannot be called revolutionary. It looks and feels the same as the last version. All will depend if it plays any stronger than that.

This is the latest version of M-Chess Professional which has many computer chess achievements including First Place in the 1995 World Micro-computer Championship and beating three grandmasters in one event at Aegon, 1995. This program uses comprehensive evaluations, and unique algorithms to detect long-range tactics. It has a dynamic playing style and is known for its exciting play and excellent results against strong human opponents.

M-Chess Pro. 8.0 is a DOS program written by Marty Hirsch in Assembler and C language. It includes a lot of chess knowledge and it has been developped to simulate the human style of play as much as possible. I mean that the program will take more risks trying to win all games rather than just playing on the opponents mistakes.

The opening book is also simulating the humans chess players as much as possible with deep knowledge on selected variations. The available moves choise selection is quite wide to alternate the play. It includes a unique book learning feature that allows the program to increase and modify it's opening book. All this makes M-Chess Pro. program quite strong and fun to play.


NIMZO   Chrilly Donninger

Nimzo is one of the leading professional chess programms. It combines sound positional play with extremly strong tactics.

The 32Bit-Programm Nimzo 2000 is a development from Dr. Christian Donninger from Vienna, Austria. He is well known as the inventor of the Autoplayer 232.

Nimzo 2000 is one of the strongest chess programms on the market and has won a lot of computer chess tournaments in the past. Nimzo 2000 is a part of the Wm-Package 2000.

It is also equipped with an own Chess-Advice-Language (Che++) which allows strong human players to formulate chess-knowledge. The programm can also access in its search endgame databases. It therefore searches regularly from the middlegame into won endgames.


PATZER   Roland Pfister

Patzer uses the standard alpha-beta PVS search, enhanced by hashtables (4 retries replacement scheme), recursive nullmove (R=2) with verification if only one piece present, special pruning heuristic for ALL-nodes, various extensions.

Patzer's playing style: Patzer understands something about king safety and piece mobility, which sometimes leads to interesting attack games. It also sacrifices pawns to get positional boni. Sometimes that even leads to success (e.g. versus Nimzo Leiden 1998), but I am still skeptical, because it happens that the initiative vanishes and the pawn is away.

In closed positions Patzer manoeuvres sometimes not so bad (e.g. against Diep Leiden 1998). Patzer knows the "wrong colored bishop" even without tablebases in the evaluation, has a perpetual check heuristic, that saved a half point against Gandalf at IPCCC 2000. It also understands the "crazy rook" (e.g. Rh5 in the game Nimzo vs. King Munich 1993).

Patzer is the first program to solve the famous Behting study (1.Kc6 draw) because it knows that it cannot win with a lonely queen.



Ed Schröder creator of REBEL and founder of the Schröder BV was born in The Hague, the Netherlands. Ed learned chess from his father at the age of 6 and was able to defeat his father one year later. In high school Ed showed a great passion for chess but lost interest after his marriage to Lies his wife. Ed has 4 kids.

In 1980 Ed again showed an interest for chess when the first `personal computers' entered the market. Being an experienced senior programmer and system analyst Ed felt the challenge to write a chess program just for a hobby. The first performance of his chess program REBEL in the Dutch Computer Championship of 1982 was the sensation of the tournament, a third place.

A few years later (as REBEL was constantly improved) Ed received an attractive offer from the world's biggest Computer Chess Manufacturer at that time Hegener & Glaser. Ed accepted and since 1984 Ed's time has been fully devoted to chess programming.

Technical, REBEL is written in optimized fast assembler code, uses the traditional aspiration search with a default window of 0.50, 6-split hash tables, an own developed algorithm for selective search based on chess knowledge (no null-move), large pieces of chess knowledge coding, no table bases yet. For playing strong humans (grandmasters) REBEL uses a special piece of knowledge known as "anti-GM".

Hobbies, music (pop and classic), chess, history, astronomy, football, psychology and his granddaughter of 1½ year.

REBEL pages...

SHREDDER   Stefan Meyer-Kahlen

Winner of the 9th WMCCC and the 9th IPCCC 2000 in Paderborn! Shredder has started in 1995 as a project at university. Good tournament and test results encouraged me to spend more work in it and lead to the winning of the 1996 WMCCC in Jakarta.

Shredder has been commercially available since then and continued to perform very well in computer chess championships. It was 3rd in Paris 1997 and managed to finish as the runner up in the blitz championship there.

Shredder is written in ANSI-C and therefore it can easily compiled on various hardware platforms.

Shredder pages...

SOCRATES   Don Dailey

Socrates by D.Dailey, C.Joerg, B.Kuszmaul, C.Leiserson, R. Blumofe, M.Frigo, L.Kaufman (IM), K.Randall, Rolf Riesen and Yuli Zhou (USA).

The Star Socrates 2.0 chess program developed at the MIT Laboratory for Computer Science, will be running on the 1824 node Intel Paragon parallel supercomputer located at Sandia National Laboratories. The lead programmers are Don Bailey and Christopher F.Joerg and the project team is lead by Prof. Leiserson.

Heuristic Software provided the original Socrates program on which StarSocrates was originally based. The Paragon is about 50 feet long and weighs about 30,000 pounds. Each node consists of two 50MHz I860 processors with either 16 or 32MB of memory. The program currently runs on both the Connection Machine CM-5 and the Intel Paragon.


SOS   Rudolf Huber

SOS is an amateur program which was started in 1993 and has since then competed in a number of tournaments. The newest version runs on multiprocessor systems with a parallelized version of mtd(f) as its minimax search algorithm.

SOS used to be a relatively fast searcher and relied on outsearching the opponent. This has changed now and more knowledge and special cases have been implemented which slow it down.

Little effort is spent on the opening book. It plays a very broad range of openings. However it learns to avoid unsuccessful lines and tries not to repeat lost games. It uses publicly available endgame databases.


VIRTUAL CHESS   Marc-Francois Baudot

Virtual Chess is the commercial version of the Ecume and Cumulus 2 chess programs. It holds the title of World Professional Computer Chess Program '97. Its most recent result : a 1.5/2 match win against GMI Etienne Bacrot at the Cap d'Agde tournament. It finished first (tied with Vaisser and Chernin) of the 1996 rapid Aubervilliers tournament.

The chess engine is written in C and 32 bits assembly. It is based on PVS, uses null move pruning and includes dynamic evaluation of king safety and pawn structure. The evaluation function attempts to build plans whenever it recognizes important features in a position.

It runs on a PC with Windows (95, 98 or NT), with a splendid graphical interface written by the French firm Titus Interactive.


WCHESS   Dave Kittinger

WCHESS is written by Dave Kittinger known from the famous Constellation table top computer. The Constellation was the first program that was able to understand the Bh7+ sacrifice and solve the KBNK mate.

WChess received world-wide attention after it scored 5 out of 6 against some of the strongest American grandmasters in the Intel Harvard Cup Man v Machine tournament held in October 1994. The program consolidated its position as one of the top micro-computer chess programs by winning the 1994 Uniform Platform Computer Chess Tournament held in London.

WChess uses an iterative, depth first alpha-beta search with forward pruning and a tactical swap-off evaluation to limit the growth of the search tree. The evaluator is somewhat primitive and is not currently as dynamic as the author would like. Positional information is communicated to the search mainly by piece value tables. The current version of the program only implements end game databases for KPK although the author is looking into adding more databases.

Wchess is also available as Power Chess distributed by Sierra.

NOVAG the home of Kittinger's table top computers.

YACE   Dieter Buerssner

Yace (Yet Another Chess Engine) is developing into a very strong computer chess program. Probably somewhere between 2325-2375 ELO in strength and maybe even higher, especially at blitz.

Yace is a splendid addition to the growing number of strong WinBoard programs that I have the pleasure of testing. The number of features are increasing at the speed of light due to a fast, attentive and communicative programmer.

All in all it's a very recommendable program to anyone, who likes to fiddle with chess program settings. Furthermore, if you have any ideas about features worthy of implementation, please contact the author, or post them at the WinBoard Forum.


ZARKOV   John Stanback

I began writing Zarkov in 1988 after finishing version 2.0 of Gnu Chess. The first version was similar to Gnu Chess in search and evaluation, but I changed the data structures to make move generation and attack table generation more efficient. I also spent a lot of time playing it against my Fidelity Excellence and trying to fix the search or evaluation function when I encountered strange behavior or got into tactical trouble. Playing lots of games by hand is a really valuable method for finding and fixing problems. I don't do much of that anymore, but I should. I considered the hardware I was using at the time to be pretty state-of-the-art: an 8 Mhz 286 PC with two 1.2M floppies and no hard drive. The A drive contained the most useful MSDOS commands, a simple editor that I wrote, and the Borland C compiler. The B drive contained the source and executables for Zarkov. I don't think compiles took any longer than they do now on a computer that's about 200 times faster! In between making changes to the chess engine I created a graphical interface for Zarkov. I had to learn sort of esoteric stuff like using mouse interrupts and writing to DOS video memory.

Zarkov's best result is a second place finish to Deep Thought in the ACM '94 tournament. It also did quite well in the Aegon tournaments held from 1994-1997, finishing with four points in six games each time.

Zarkov usually maintains a blitz rating of about 2900 on the Internet Chess Club.


ZCHESS   Franck Zibi

The first chess program I wrote was HpChess for the Hp48 calculator. It is an assembler program released in 1995 and I am still receiving postcards and e-mail about it.

Due to the low speed of the Hp48, HpChess can look at a depth of only 3 plies: not enough to play decently against a strong player or to avoid even easy traps. The best achievement of HpChess was to draw a blitz game in 1996 against a PC Chess program running on a P75.

In late 1996, I was very interested by the 'Object Oriented stuff', I decided to convert all the C source of ZChess in C++. It was a big re-write and this new version played its first game in April 1997.

ZChess is an object oriented program written in Visual C++ / MFC, WinBoard Compatible, Fritz UI Compatible, it is massively BITBOARD oriented (using rotated and attack BITBOARD [for all pieces of the board]), Hash Tables (using multiple probe scheme) Pawn Tables, and King Safety Tables Iterative deepening, SEE (both for move ordering and cutoff), NULL Moves (R=2), heavy pruning.

When Zchess makes a big mistake, it stores the position where it blundered in the file z_learn.epd to avoid playing it again. When Zchess is out of book in a bad position, it will store the bad book line in the file : z_style.txt Tactical extensions to detect some common combinations. ZChess will offer a draw to a human opponent if he has made a mistake in a clearly better position.

ZCHESS Home...


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