RDChess

Auf Viren überprüftes RDChess herabladen von Heise.de

2010-01-17T16:39:00.003+01:00

Neben dem direkten Download von RDChess besteht die Möglichkeit, RDChess auch vom
Softwareverzeichnis auf heise.de
herabzuladen.

Bored losing day after day against chess computers?

2010-01-16T22:40:00.002+01:00

Play the number puzzle Sudoku with Sudoku Rax!

RDChess Bedienungsanleitung in deutsch

2010-01-16T17:17:00.001+01:00

Informationen, neue Features, Fehlerbehebungshinweise und die jeweils
neueste Programmversion zum Download finden Sie auf http://rdchess.com.

RDChess ist ein Freeware Schachprogramm für Personal Computer unter MS Windows.
RDChess kann auf 2 Arten benutzt werden

- im Winboard Modus
- im Windows (non-WinBoard) Modus

RDChess hat eine WinBoard-Schnittstelle (SS), welche RDChess das Spielen von Partien gegen eine große Zahl anderer Schachprogramme bzw. als Client auf Internet Schach Servern (ICS) ermöglicht. Aber RDChess besitzt im Gegensatz zu den meisten nur WinBoard-fähigen Schachprogrammen auch eine eigene grafische Windows-Benutzeroberfläche. Die RDCHESS Fenster werden im Winboard-Spiel zusätzlich zum Fenster des Programmes Winboard angezeigt.

Im Winboard-Modus wird RDChess durch das Programm WinBoard oder dazu kompatible Programme (z.B. Arena, WBTM,..) gestartet.
Wenn RDChess vom Betriebsystem gestartet wird und die Kommandozeile enthält "xboard" (ohne Anführungszeichen) bzw. /xb oder /wb, geht es in den WinBoard-Modus und tauscht Kommandos und Züge über die Winboard-SS aus. Die Züge des Gegners werden in das WinBoardfenster eingegeben bzw. über WinBoard von anderen Schachprogrammen empfangen. RDChess sendet seine berechneten Züge an WinBoard (aber aktualisiert auch das Brett und alle anderen Daten in den RDCHess-Fenstern).
Die RDChess Fenster dienen im WinBoard-Modus nur zur Information, nur einige wenige RDChess-Parameter und Funktionen bleiben verfügbar (Partie speichern, ...).

Im "non-WinBoard" Modus wird RDChess ausschließlich über seine grafische Benutzeroberfläche gesteuert.

Die RDChess-Benutzeroberfläche besteht aus einem Hauptfenster mit Menü, dem Schachbrett zur Anzeige der Position und der Eingabe von Zügen. Weitere Fenster dienen zur Anzeige bzw. zum Editieren von Schachpartiedaten, der Zug-Historie, Konfigurationsparametern, Schachuhren, programmtechnischen Daten etc. Viele Fenster besitzen Kontext - Menüs, die durch Drücken der rechten Maustaste auf einem sensitiven Objekt aufgeklappt werden können.

1. Hauptfenster

Das Hauptfenster besteht aus dem Schachbrett sowie
* Einem Hauptmenü oben,
* Einer Symbolleiste für häufig benötigte Befehle,
* Einer Statuszeile unten, die Hilfe u.a. nützliche Informationen über den aktuellen Status anzeigt..

Partie Menü

Die Befehle des Partiemenüs dienen zum Setzen der Ausgangsstellung, dem Laden und Speichern von Schachpartien, dem Wiederabspielen der aktuellen Partie, dem Ausführen von Testläufen (Benchmarks) sowie dem manuellen Aufstellen von spezifischen Stellungen.
Im WinBoard-Modus kann über Menüeinträge für die aktuelle Partie ein Remis angeboten werden, ein (zukünftiges) Remisangebot des Gegners angenommen werden bzw. die Ratie aufgegeben werden.
Schachpartien werden im Format "portable game notation" (.pgn) (mit FEN-Position und tlw. EPD Erweiterungen) gespeichert und geladen. Figurensymbole in der .pgn-Datei sind aus Kompatibilitätsgründen in englisch (P=pawn, Q= queen, B = Bishop, R = rook, K = king, N = knight).
Enthält beim Laden eine .pgn Datei mehr als 1 Schachpartie, öffnet sich ein Fenster mit einer Listanzeige aller enthaltenen Partien. Durch Selektion bzw. Doppelklick einer Partie wird diese geladen. Im automatischen Spiel (über WinBoard, Auto232, kontinuierlich) werden die Matchpartien selbstätig in eine pgn-Datei ins RDChess Programmverzeichnis geschrieben.
Partiedaten, wie z.B. der Ort, das Datum der Partie, die Namen der beiden Spieler etc. werden gemeinsam mit den Zügen in der .pgn Datei gespeichert, werden jedoch im Programm RDChess in einem eigenen Fenster (Partiedaten) verwaltet.

Modus Menü

RDChess ermöglicht 3 Modi

- Spieler gegen Computer (Standard Modus),
- Spieler gegen Spieler (Spieler spielt beide Seiten),
- Computer gegen Computer (Computer spielt beide Seiten).

RDChess befindet sich jeweils in einem von 2 Zuständen: in einem "kontinuierlichem Spiel" bzw. im "1 Zug Modus". Im kontinuierlichem Spiel antwortet RDChess jeweils automatisch auf einen eingegebenen Spielerzug bzw. denkt ("Permanent brain") in der Zeit, in der ein Spieler seine Zugeingabe überlegt.
Im 1-Zug-Modus geht RDChess nach jedem Zug (Spieler- oder Computerzug) in den "Untätig"- Zustand.

Einige Funktionen des Schachprogramms können nur im Untätig-Zustand angewählt und ausgeführt werden!

Zugeingabe
Züge werden mittels "Drag and Drop" (anklicken der Ziehfigur und verschieben aufs Zielfeld mit gedrückt gehaltener linker Maustaste) oder
mittels Clicken mit der linken Maustaste ins "von" - Feld und anschließendem Clicken in das "nach" - Feld eingegeben.
Eine gültig zum Zug ausgewählte Schachfigur wird auf einem mittels farbiger Schraffur ausgezeichnetem Feld dargestellt. Dies zeigt an, das Programm auf die Eingabe des Zielfeldes des Zuges wartet.
Als weitere Hinweise wird das Zielfeld des letzten ausgeführten Zuges blau umrandet bzw. ein im Schach befindlicher König auf einem rot umrandeten Feld dargestellt (letzteres mittels Kontextmenü abschaltbar).

Abbrechen einer Zugeingabe bzw. eines Computerzuges
Ein Zug kann durch Drücken der Escape-Taste (Esc) jederzeit abgebrochen werden. Das Programm geht damit in den Untätig-Zustand.
Während der Zugeingabe bewirkt das Klicken mit der Maus auf ein ungültiges Feld ebenfalls den Abbruch.
Ein laufender Computerzug (bzw. eine Zugeingabe mit Permanent Brain) kann durch Anklicken des Symbols "Zug abbrechen" auf der Symbolleiste beendet werden.

Zugrücknahme/ Wiederausführung

Mit den entsprechenden Kommandos im Zug-Menü, Short Cuts (horizontale Links/ Rechtspfeile oberhalb des Schachbrettes) bzw. mit Hilfe des Journalfensters (s.u.) können bereits gespielte Züge wiederholt zurückgenommen bzw. wieder ausgeführt werden.
Es ist möglich, durch die gesamte gespielte bzw. geladene Partie (bis zum Beginn bzw. zum Ende der Partie) zu navigieren.

Wechseln der Seite
RDChess merkt sich im Verlauf einer Partie, ob der Spieler (Mensch) bzw. das Programm am Zug ist.
Im Untätig-Zustand kann mit Hilfe des Symbols "1 Computerzug" bzw. des Menüpunktes "Zug -> 1 Computer Zug" jederzeit der Computer zur Ausführung eines Zuges gezwungen werden. .
Andererseits kann im Ruhezustand durch Mausklick auf eine gültige Ziehfigur, durch Mausklick auf das Symbol "1Spielerzug" bzw. mit dem Menüpunkt "Zug-> Spiele 1 Zug" ein Spielerzug gestartet werden

Spielende
RDChess zeigt im Journal (durch die Annotation ...Mxx Matt in xx Zügen) bzw. auf Wunsch in einer Dialogbox an, wenn es mattsetzt bzw. mattgesetzt wird.
RDChess kennt alle Regeln über Unentschieden (Patt, zu wenig Material, 50 Zug-Regel, 3x Positionswiederholung) und sendet das Resultat auch an einen Winboard-Gegner. RDChess bietet in bestimmten anderen Stellungen ebenfalls ein Remis an. Abhängig von einer Checkbox gibt RDChess auf, wenn es um eine gewisse Materialdifferenz hinten ist.
Im Winboard-Modus kann ein Operator mit einem Kontextmenü (rechter Mausclick auf das Brett) ein Remisangebot des Gegners "bedingungslos" akzeptieren,auf Operatorwunsch selbst Remis bzw. im Namen von RDChess aufgeben. anbieten.
Die zuletzt gespielte Partie wird im RDChess-Verzeichnis automatisch unter dem Namen LastGame.pgn gespeichert und beim Programmstart wieder geladen.

Optionen Menü

Mittels der Optionen -Menüpunkte kann das Brett gedreht werden, die Farbe der Figuren bzw. der weißen und schwarzen Felder geändert werden, die Bediensprache (deutsch <-> englisch) geändert werden sowie ein Konfigurationsdialog aufgerufen werden.
Der Konfigurationsdialog ermöglicht auf mehreren Tafeln diverse Einstellungen, wie die Computerspielstärke, Suchparameter (Permanent Brain, Mattsuche, Verwendung von Hashtabellen, ...) u.a.
Die Größe der Positions-Hashtabelle kann auf 0, 1, 2 bzw. 4 Mill. Einträge gesetzt werden.
Die Computerspielstärke kann folgendermaßen eingestellt werden

- Computer sucht unabhängig von der Zeit bis zu einer fixen Tiefe n
- Tournament Zeitkontrolle (m Minuten für n Züge, z.B. 120 Minuten für 40 Züge). Verbraucht ein Spieler seine gesamte Zeit, verliert er durch Timeout. Nach n Zügen (z.B. 40) wird die Zeitkontrolle für die nächsten n (z.B. 40) Züge neu auf m Minuten gesetzt
- Incrementeller Modus (verwendet am ICS Schach Server): Jeder Spieler bekommt für das gesamte Spiel eine Basiszeit (m Minuten) und ein Zeitinkrement von n Sekunden nach jedem ausgeführtem Zug zugewiesen. Ist sein Zeitguthaben verbraucht, verliert er ebenfalls durch Zeitablauf.
- N Sekunden für einen Computerzug
- Zeitkontrolle, in der die Computerbedenkzeit an die Bedenkzeit des Spielers angepasst ist ("in Summe gleich viel kumulierte Zeiten)
- Unbegrenzte Suche (z.B. zum Lösen von Matt-Suchaufgaben
___________________________________________________

2. Zusätzliche Fenster

Mit dem Fenster-Menü können 5 zusätzliche Fenster für Standardbenutzer geöffnet werden.
Weitere 7 Fenster zeigen programmtechnische Hintergrundinformationen wie z.B. Hash -Tabellen-Nutzung, Zugsortierung und andere statistische Daten, welche eventuell für Benutzer aufschlussreich sind, die sich für Schachprogrammierung interessieren.
Die Daten in allen Fenstern werden in verschiedener Detaillierung angezeigt, die von den Einstellungen der Optionsfelder "Test Level 1" und "Test Level 2" im Konfigurationsdialog abhängen.

Das Journalfenster

Zeigt die Zug-Historie (Züge mit ev. Zuganmerkungen) an. Zusätzlich zu den bereits erwähnten Navigationsmechanismen kann im Journalfenster mittels den Cursortasten (auf/ ab, Seite auf/ ab, Pos1, End) navigiert werden bzw. durch Doppelklick auf eine selektierte Zeile / Kontextmenü zu einer bestimmten Stellung in der Partie gesprungen werden.
Für jeden Halbzug wird angezeigt
- die Zugnummer,
- Zugnotation, z. B. Ng1f3 (Springer von Feld g1 nach Feld f3) im .pgn Format (mittels Konfigurationsschalter zwischen langer/ kurzer Notation umschaltbar),
- System- oder Benutzerzug-Anmerkungen innerhalb geschwungener Klammern {}
Abhängig von den Konfigurationsschaltern "Test Level 1,2" beinhaltet eine Systemzuganmerkung folgende Daten
{C 1.48/ 218.888/MxViT:14/NSWh:15/NM#:6667/NM-ßCut:5732/HTU:6/Ha-ßCut:6550}
C= Computerzug (/ P = Spielerzug / O= Zug aus Eröffnungsbibliothek)
1.48 Bewertung der aktuellen Position (Bauernwert = 1.00, + ist gut für weiß, Minus ist gut für schwarz. Mxx bedeutet Matt in xx Halbzügen.
218.888 Anzahl der besuchten Knoten in der Suche für diesen Zug
MxViT: 14 Maximal erreichte Suchtiefe (inkl. Ruhesuche) = 14
... und weitere programmtechnische Daten (NegaScout Wiederholungen, Null Move Zähler, Anzahl Null Move Beta-Cut-Offs, Hashtabellen - Benutzungszähler, Cut-Offs durch Hashtabellennutzung, etc.

Durch Klick mit der rechten Maustaste auf eine Zeile im Zugjournal kann im Kontextmenü der Menüpunkt "Zuganmerkungen" angewählt werden.
Es erscheint ein Editierfenster, in dem Zuganmerkungen editiert bzw. neu erstellt werden können.

Das Status - Informationsfenster

Zeigt Daten über die aktuelle Position (Rochaderechte, 50-Zugregel-Zähler, Spielstatus etc. an.

Das Partiedaten-Fenster

Dient zur Anzeige und zum Editieren von (.pgn-) Daten der aktuellen Schachpartie (Event, Ort, Datum, Resultat, Name der Spieler, ..)

Das Eröffnungsbibliotheksfenster

Zeigt den Status und Informationen über die verwendete Eröffnungsbibliothek an.
Die RDChess- Eröffnungsbibliothek (RDCH_op.lib) hat ein proprietäres Format und befindet sich im Standard - RDChess - Verzeichnis. Wird beim Programmstart kein Verzeichnis gefunden, wird ein neues, leeres angelegt.
Das Programm ist normalerweise beim Start aus der Grundstellung heraus "innerhalb" der Eröffnungsbibliothek, verwendet für Computerzüge nur Züge aus der Bibliothek und wird durch Züge des Gegners, die sich ebenfalls in der Bibliothek befinden, weitergeschaltet.
Ein Eintrag in der E.-Bibliothek kann 0 bis 6 Züge für die aktuelle Stellung beinhalten. Der Computer am Zug wählt einen dieser Züge zufällig aus. Ein Zug in der E.-Bibliothek kann "aktiv" bzw. "passiv" markiert sein. Passive Züge werden vom Computer nur dann verwendet, wenn der Gegner eine solche Variante ansteuert.
Durch Doppelklick mit der Maus auf einen Zug im Eröffnungsbibliothekfenster wird dieser ausgeführt. Damit kann z.B. eine bestimmte Eröffnungs-Zugfolge durchlaufen werden.
Die Eröffnungsbibliothek kann benutzerspezifisch mittels eines "Vorspielmodus" (Lernmodus) erweitert werden. Dazu muss man innerhalb der Eröffnungsbibliothek zu der gewünschten Stellung gehen und dann mittels des "Start Lernen" Schaltknopfes in den Lernmodus wechseln. Die eingegebenen Züge werden in der Eröffnungsbibliothek gespeichert und die Stellung weitergeschaltet. Das Programm erlaubt dabei die Angabe einer Anmerkung zur jeweiligen Stellung. Mittels des ""Lernen beenden" Knopfes wird der Lernmodus beendet. Mittels einer Checkbox kann geählt werden, ob die gelernten Züge als "aktive" bzw. "passive" Züge (s.o) in die Eröffnungsbibliothek eingetragen werden.

Das Schachuhren-Fenster

Zeigt 2 digitale Uhren mit den bisher von den beiden Spielern verbrauchten (aufkumulierten) Zeiten. In den Einstellungen "Tournament" (n Züge in m Minuten) bzw. ICS (inkrementeller Level mit m Basisminuten und n Sekunden Inkrement pro Zug)wird die verbleibende Zeit bis zur nächsten Zeitkontrolle bzw. bis zum Spielende angezeigt.
Eine Checkbox erlaubt die Synchronisation der RDChess Uhren mit der WinBoard Uhr im Winboardmodus.
Die Uhren können mittels eines "Reset" Knopfes auf Null zurückgesetzt werden.

Das Watch Dog Fenster (Computersuche-Überwachung)

Ist ein kleines Fenster, normalerweise oberhalb des Hauptfensters.
Während einer Computersuche zeigt es die Anzahl der besuchten Knoten, die aktuell favorisierte Hauptvariante (beste Zugfolge), die Bewertung dieser Variante (in Bauerneinheiten * 100) und anderen Daten (aktuelle Suchtiefe, ..).

Debug Fenster

Derzeit gibt es 7 "Debug" Fenster, welche nur für Benutzer interessant sind, die sich für Schachprogrammierung interessieren.
Das Positions- Hash-Tabellenfenster und das King + Pawn Hash-Tabellenfenster zeigen Daten über den Status und die Ausnutzung der beiden Hashtabellen.
Das Fenster "Iterative Computersuche-Infos" (Search Statistics) zeigt im Detail den iterativen Vertiefungsprozess bei der Suche mit Knotenzähler, Suchzeit und Hauptvariante für jede Suchtiefe.
Das Bewertungsfenster zeigt Bewertungsfunktions-Daten der aktuellen Stellung sowie Daten über die Bauernstruktur.

3. Systemanforderungen

Windows. 95, 98, ME, NT, 2000 or XP
- Windows Desktop Auflösung mindestens 800 x 600. 1024 x756 oder mehr empfohlen.
- PC mit 64 Mbytes Hauptspeicher.

4. Programm - Installation

Zum Installieren unzippen sie die RDCHESSVx.zip Datei in ein temporäres Verzeichnis und starten das Programm setup.exe. Setup installiert alle RDChess - Programmdateien in ein Standardverzeichnis (c:\RDChess), oder in ein anderes Verzeichnis ihrer Wahl.
Das Programm besteht aus der RDChess.exe Programmdatei, einer readme.txt Datei mit Lizenzhinweisen, einer Eröffnungsbibliotheksdatei (RDCH_op.lib), einer englischen und deutschen Bedienungsanleitung (im .txt Format) sowie einigen .pgn Beispielpartien.
Von der RDCHESS Download-Seite im Internet können sie auch den Delphi Quellcode von RDCHESS downloaden und in ein Unterverzeichnis von RDCHESS (RDCHESS/Source) installieren.

5. Hinweise und bekannte Probleme

Die Standard - RDChess - Fensterpositionen am Desktop sind optimal auf eine Bildschirmauflösung von 1152 x 864 oder höher eingestellt. Auf Bildschirmen mit kleinerer Auflösung müssen Sie eventuell die Fenster manuell in eine günstigere Position verschieben (sorry, ich habe bisher noch keine RDChess-Desktop Save/ Restore Funktion implementiert).

Auf PC's mit weniger als 64 Mbytes Hauptspeicher treten eventuell Probleme bei der Verwendung der Hashtabellen auf (die Standard - Hashtabellen benötigen ca. 26 Mbytes Platz).
Falls ihr Computer während einer Computersuche häufig auf die Auslagerungsdatei auf Festplatte zugreift bzw. langsam läuft, schalten sie im Konfigurationsdialog (Menu Optionen-> Konfiguration... -> Computer Search -> Use Hash Table aus.

Nicht alle Oberflächenelemente der RDChess Benutzeroberfläche werden richtig zweisprachig angezeigt.
Die "Partie laden" - Dateiauswahlbox sowie einige andere Systemschaltknöpfe werden fix in der Installationssprache von Windows (sprachabhängige .dll) angezeigt und bleiben von der Sprachumschaltung im RDChess-Optionen-Menü unberührt.
Alle Debug - Fenster sowie einige andere Fensterinhalte sind überwiegend nur mit englischen Bezeichnern implementiert.

RDChess versteht dzt. nur das WinBoard Setup Komando "setboard" und nicht die älteren "edit"-Kommandos zum Aufstellen einer Schachposition.

RDChess macht manchmal (relativ selten) schwerwiegende Fehlzüge (z.B. opfert sinnlos Material). Trotz intensivster Suche konnt ich diesen schwierig zu reproduzierenden Fehler bisher nicht finden :-(

Details zur Programm-Installation RDChess (Deutsch)

2010-01-16T16:50:00.004+01:00

RDChess: Copyright (c) 2010 Rudolf Posch 2630 Ternitz, Österreich
Kommentare, Vorschläge, Fehlermeldungen willkommen als e-Mail

Zum Installieren unzippen sie die RDCHESSV3xx.zip Datei
in ein temporäres Verzeichnis und starten das Programm setup.exe.
Setup installiert alle RDChess-Programmdateien in ein
Standardverzeichnis (c:\RDChess), oder in ein anderes
Verzeichnis ihrer Wahl.
Das Programm besteht aus der RDChess.exe Programmdatei,
der vorliegenden readme.txt Datei mit Lizenzhinweisen,
einer Eröffnungsbibliotheksdatei (RDCH_op.lib),
einer englischen und deutschen Bedienungsanleitung
im .txt Format. sowie einigen .pgn - Beispielpartien.
Einige Konfigurationsparameter von RDChess (Farben, Bedien-
sprache, ... ) werden permanent in der Windows Registry
gespeichert und beim Programmstart gelesen.

Auf der RDChess Internetseite befindet sich auch ein Link auf
eine Datei RDCHESSSrcVxxx.zip mit den RDChess-Quelldateien.
Durch Aufruf von Setup.exe werden die Quellprogramme
in ein Unterverzeichnis \Source des
Installationsverzeichnisses kopiert.

Setup WinBoard.exe für RDChess:
-------------------------------
RDChess muß mit dem Parameter "xboard" (oder /xb oder /wb)
in der Kommanozeile aufgerufen werden, um im WinBoard-Modus
zu starten.

D.h. Erzeugen sie eine Verknüpfung am Desktop zum Aufruf von
winboard.exe mit RDChess als "erstes Schachprogramm (fcp)"
mit folgendem Kommandozeileninhalt:

"C:\Program Files\WinBoard\winboard.exe"
/cp /fcp="d:\rdchess\rdchess.exe xboard" /fd="d:\rdchess"
(in einer Zeile ohne Zeilenumbruch; verwenden sie die Pfade
von winboard und rdchess, wie sie auf ihrem PC installiert sind!)

Detailled program installation RDChess (English)

2010-01-16T16:43:00.001+01:00

Freeware program RDChess Copyright (c) 2010 by Rudolf Posch 2630 Ternitz, Austria Europe
Comments/ suggestions / error reports welcome!

To install the program unzip the RDChessV3xx.zip file
into a temporary directory and start the setup program setup.exe.
Setup installs all RDChess program files into a
default directory (c:\RDChess) or into a directory
that may be chosen at the installation process.
The program consists of the RDChess.exe program file,
the actual readme.txt file with licence agreement,
an opening library file (RDCH_op.lib),
an English and German help-file in .txt format
and a few example chess games in .pgn format.
A few configuration parameters of RDChess (colors, language
of User interface, ... ) are stored permanently by RDChess
in the registry and read at the program start.

A second Zip file RDChessSrcV3xx.zip is available free on the
RDChess download site with the source code.
The source files are installed into a subdirectory \Source
of the install directory.

Setup WinBoard.exe for RDChess:
-------------------------------
RDChess must be called with the parameter "xboard" (or /xb or /wb)
in the command line in order to run in Winboard mode.

E.g. create a shortcut on the desktop calling the program
winboard.exe with RDChess as the
"first computer program (fcp)" with the following content:

"C:\Program Files\WinBoard\winboard.exe" /cp
/fcp="d:\rdchess\rdchess.exe xboard" /fd="d:\rdchess"
(enter as a full line; use the path specifiers for winboard
and rdchess as installed on your machine!)

Features of RDChess

2010-01-16T12:44:00.004+01:00

Medium strength state of the art chess engine
Graphical User Interface in English and German (Main window with chess board and other info and dialog windows)
Play gainst the RDChess program, choose the strength of RDChess
Watch playing RDChess as it plays against itself
Load and save chess games in the Portable Game Notation Format (.pgn)
Setup board positions, get a hint move for a position
Replay or navigate back and forward through the moves of a chess game
Display and edit game and move annotations
Opening book with learning mode and navigation
Display of technical data for computer chess experts (search statistics, hash table usage, evaluation data, move sort order, ...)
RDChess runs also under WinBoard , allowing to play with RDChess against other WinBoard compatible chess engines or on ICS chess servers
Delphi Source code available

Licence Agreement for RDChess

2010-01-15T23:24:00.003+01:00

RDChess version V3.23 is freeware and may be copied unlimited for personal use.
It must be copied as a full package (file RDCHESSV323.zip), containing all the files therein.
The program must not be changed. The program must not be sold or a fee collected for its use.
The program may be used on his/ her own risk.
The author doesn't guarantee that the program functions properly and takes no responsibility for a possible damage caused by its use.

Copyright for source code parts included in RDChess

Bitmaps for the chess pieces Copyright(c) by Free Software Foundation GNU GENERAL PUBLIC LICENSE
RDChess Version 2.98 and greater uses a subset of the Winboard Chess Engine Communication Protocol Version 2 (c) Tim Mann
RDChess Logo created by Wilhelm Hudetz

Some chess programming/ chess playing URL's

2010-01-14T17:10:00.000+01:00

The following table contains a small collection of links to chess papers, chess home pages, chess servers, companies etc., which I saved as bookmarks because they were seemingly more or less important for me;

Books and Literature:
Bitboard Infrastructure (Heinz)
Computer Chess Books
Computer Chess programming (Verhelst)
Chess GML (Andreas Saremba)
Chess Programming Topics (Bruce Moreland)
14.3 Computer Chess
DelphiMax chess program from Bauer &Schweitzer
Game Programming Eppstein
GameDev.net--Chess Programming Part I Getting Started
GameDev.net--Chess Programming Part II Data StructuresGameDev.net--Chess Programming Part III Move Generation
GameDev.net -- Chess Programming Part IV Basic Search
GameDev.net -- Chess Programming Part V Advanced Search
Guide to Endgames Table BasePGN XML Proposal

Academics:
Int. Comp. Games Association (ICGA)
WWW Pages of DarkThought (Dr. E.Heinz)Home Page of Jonathan Schaeffer
Ph.D.Thesis Dennis Breuker'sDownloads:
FTP Directory _ftp.cis.uab.edu_pub_hyatt_

Chess servers for playing chess:
PlayChess.com
Free Internet Chess server (FICS)
Internet Chess Club
Kaiserslautern Chess Server
MSN Gaming Zone Chess
Diverse:
ChessBase
Computerschach u.Spiele(german periodical)
FIDE
Franks Chess Page
Rebel (Schroeder BV NL)
The Week in Chess (London Chess center)
Tim Mann's Chess Pages
Chess engines Tournaments Ridderkerk (Leo Dijksman)

WinBoard Forum
news:rec.games.chess.computer

RDChess User Manual

2010-01-13T18:05:00.005+01:00

RDChess is a chess playing program for personal computers running under MS Windows. RDChess has a graphical user interface by its own, but interfaces also to Winboard, which allows RDChess to play by itself against a great number of other chess engines.
In Winboard mode RDChess is started from the program WinBoard or compatible programs (e.g. Arena,..).
When RDChess is started with the command line parameter "xboard" (without quotation marks), it assumes Winboard play and exchanges commands and moves over the Winboard interface. Opposite player moves are entered into the WinBoard window or received from other chess engines. The RDChess windows are for information only. Only a limited number of data may be entered or changed into the RDChess windows (Save, some config params, etc.). RDChess sends its calculated move to WinBoard (and updates the board and position in the RDChess windows).
In the standard (non-WinBoard) mode RDChess is controlled solely by its Graphical User interface (GUI).
The User Interface consists of a main window with menus and the chess board for entering and displaying moves.
Various other windows are for displaying and editing chess game data, move history, configuration parameters, chess watches, technical data etc.
Some windows have context menus, which pop up by clicking with the right mouse button on a sensitive object.

1. Main Window

The main window displays the chess board and controls the program with

a menu bar at the top,
a tool bar with shortcuts for often used commands,
the names of the white and black player and arrows for scrolling backwards and forward through the positions of the actual chess game,
a status bar at the bottom, displaying help and other useful information about the current game state.

Game Menu

With the “Game” menu items you

start a new game from the initial position,
load or save a game,
replay the current game,
set up a specific board position manually or
make test runs with pgn libraries like the Bratko-Kopec test suite and
end the RDChess program.

Chess games are stored and loaded in the"portable game notation format" (.pgn). Piece symbols are in English (K = king, Q = queen, R = Rook, B = Bishop, N = Knight, P = pawn).
The start position of the chess game is stored in FEN-Format. A few "Extended position description" (EPD) tags are also stored (best move(s), principal variation, position id).

If a stored .pgn file contains more than one chess game, a dialog window opens and allows selecting a single game out from a list box for loading.

Game related data like the event, site, date and result of the game, the white and black player names etc. are displayed and may be edited in an extra “Game Data” window (see below), but are stored together with the move journal in the .pgn file.

Playing a game
There are 3 playing modes

Player against computer (standard mode),

Player against player (player enters moves for both sides),

Computer against computer (computer plays both sides in an automatic mode)

which may be selected with the “Mode” menu items.
There are further a “continuous” and a “single step” mode. In the continuous mode the computer makes repeatedly a move if it is its turn or waits for the player to enter a move (thinking on “permanent brain”).
In single step mode the computer is idle after each move (of which side whatsoever).
Some functions (controls) of the chess program are available only in the program idle state!

Entering a move
A move is entered by drag and drop (clicking with the left mouse button into the "from" square and moving the mouse with still pressed left button to the move destination square and releasing it there), or by 2 clicks, clicking into the "from" square and afterwards into the "to"-square. A valid selected piece to move is highlighted with a hatched brush on the “from” square, indicating that the program is waiting for enter of the “to” square.
For information purposes the target square of the last made move has a blue rectangle around it.
A king in check has a red rectangle around the square he is sitting on (this feature may be deactivated with the board context menu). Interrupting the move entering or a computer move search
You may interrupt a move with the "Escape" key. Click on an invalid board square to abort move entering and return to the idle state.
By clicking the “Abort move” icon on the tool bar a running computer move (“computer is thinking”) is interrupted.
Undo / Redo a move (ply)
With the appropriate move commands moves may repeatedly be undone or replayed.
You may navigate through a whole chess game (going to the begin or to the end position, ...) with help of the horizontal left and right arrow icons above of the board or with help of the Journal window.
Changing the side to play
In the idle state you can force the computer to play one ply with the menu command “Move->Computer 1 ply” (or shortcut Icon).
In the idle state you can start a players move by clicking into the board (on a square with a valid to move chess piece) or with the menu command “Move->Play 1 ply” (or shortcut).
Options Menu
The “Options” Menu items allow turning around the board, switch the user language (English <--> German) and choose the colour of the black and white board squares and pieces.
A tabbed control Configuration allows setting diverse parameters for the playing strength (level), kind of computer play (“Permanent brain”, “Mate search”, …) and debug data.
The Transposition Hash Table size may be set to 24 MByte (standard), 48 MByte or 96 MByte
The check box “Use hash table” may be switched off in case of to less available main memory.

The playing strength of the program may be set to different levels

Tournament time control (m minutes for the n moves; e.g. 120 minutes for 40 moves). If one player uses up his time, he looses by timeout. After n (e.g. 40) moves of both sides the time control is set new to m minutes for the next n (e.g. 40) moves
Incremental mode (lie used on the ICS Server): Each player is allocated a base time (e.g. 2 minutes) and an increment of n seconds after each move
N seconds search time allocated for each computer move
Computer searches independently of time until the maximum search depth n
Time control giving the computer and player equal time spans
Unlimited search time (e.g. for solving mate puzzles).

2. Additional windows and controls

Windows of RDChess (User language German above, English below)

The 2 screen shots above show a Windows Vista desktop with most of the RDChess program windows open in German resp. Englsh user language. To the left above is the Main window, on top of it a search watchdog and below the chess watches and Opening Library.
On the right above is the Journal (move history), below right the Info Windw and further below "Game Data" window.

The “Windows” Menu items allow to open 6 additional windows for standard chess playing users.
Even 7 more windows are for technical background /debug purposes and show program data like e.g. the usage of the hash tables, search statistics and other data.
Data in all (13) windows are shown in different detail, depending on the configuration checkboxes “Test level 1” and “Test level2” in the tabbed configuration dialog box.

The Journal Window

Displays the game history (moves with system or user entered annotations).You may scroll through the chess game positions in the move list with the cursor movement keys (up, down, page up/down, Pos1, End, ..) or by clicking to the line where you want to go in the journal.
For each move is displayed the move number, move notation e.g. Bg1f3 (Bishop from square g1 to f3) in pgn format (there exists a configuration switch for long or short notation) and system or user move annotations inside the { } brackets.

Move annotation: Depending on the “Test level 1" and "Test level 2” configuration switches in the Configuration menu a move annotation looks like
{C 1.48/ 218.888/MxViT:14/NSWh:15/NM#:6667/NM-ßCut:5732/HTU:6/Ha-ßCut:6550}
and means

C = computer move ( P = player move , B = book move from opening library , 1 = One move flag, D = Direct move from permanent brain)
1.48 evaluation of current position (pawn value = 1.00, + is good for white; minus is good for black. Mxx means mate in xx.
218.888 Number of nodes searched for the calculation of this ply
MxViT: 14 maximal visited search depth = 14
... and further program technical data (NegaScout repetitions NSWH, Null move count NM#, Null move beta cut-offs NM-ßCut, Hash table use count (HTU), Beta cut-offs through hash table use, etc.
By clicking with the right mouse button into a line with a move a popup menu appears and offers a move annotation, which may be edited in an edit control

The Status Information Window

Displays (read only) information about the actual current position like game state, position value, castling rights, 50-move repetition count, position repition count, computer search level of play, last move, opening type etc

The Game Data Window

The game data window displays and allows editing data related with the actual loaded chess game.

The window has 3 parts

standard pgn data fields (event, site, date, name of white and black player, ...) ,

EPD data fields (best move, ..) and

a large edit field for a comment to the chess game.

The Opening Library Window

Displays the status and information about the current opening library in use. The RDChess opening library (RDCH_op.lib) has a proprietary format and has to reside in the default RDChess directory. If there is no opening library file found in the current chess directory, a new (empty) opening library is inserted.The program is usually “inside” the library when starting a new chess game from the initial base position and progresses the opening library state as long as the opponent makes moves which are stored for the actual position in the opening library. An entry in the opening library may contain 0 - 6 moves out of the actual chess position. The computer chooses arbitrarily an opening move out of these 1-6 when it is to move. A move may be marked “active”/ or “passive”.” Passive moves will be used from the computer only if there are no active moves in the current opening library entry for the position. One of the 1-6 stored opening book moves may be selected from the move list by double clicking the line with the wished move in the opening library window.The opening library may be extended by a user through going to a stored position in the opening library and then starting the “learning mode”. Playing a move on the board enters it automatically in the opening library. The program asks for an annotation for each newly entered position. Clicking the “Stop learning” button stops extending the opening library.

The Chess Watches Window

Displays 2 digital watches for the times used so far by the black and white player. In the Tournament and the "ICS" mode the watches display the remaining time until the next time control/ end of game.

The watches may be reset to zero with the "Reset" push button.
When playing in WinBoard mode with use of the "tim/ otim WinBoard protocol commands" the time difference between the remaining times of RDChess and the opponent is displayed additionally.

The Search Watchdog Window

Is a small window, usually sitting just above the main window. During a computer search it displays the number of visited nodes, the currently favored “best move” (mean continuation, “principal variation”), the evaluation (in centi pawn units) of this variation and some other data (current search depth, progress bar, ..).

Debug windows

There are currently 7 “debug” windows, which are not important for a user just playing chess with the program.
The data may be interesting for users programming chess computers, although I am too lazy to describe here the meaning of all the displayed data.
The “position hash table” window (see below) and the “king + pawn hash table” info window (not shown here) display information about the actual status of the hash tables and its usage within the last search.

The iterative search overview window shows in detail the iterative search deepening process of the computer search with search depth, evaluation values measured in centi pawn units (Alfa, Best, Beta), search time, node counts and principal variation for every searched depth.

The Evaluation data debug window (not shown here) displays various data about the evaluation function values of the current position and the pawn structure.
A Winboard connection debug window shows online all moves and data traffic sent and received over the Winboard interface pipes and logs the data into a Winboard log text file.

Help

The Help menu offers 2 entries

Clicking "General help" opens a short user manual in English or German language (depending on the language setting in the Options Dialog box),
Clicking "About" shows a Dialog box with the current RDChess program version and the Copyright notice of the author.

3. System requirements

Windows 95, 98, ME, NT, 2000, XP, Vista
Windows desktop resolution at least 800 x 600. 1024 x756 or more are recommended.
Intel x86 or compatible AMD PC with MMX instruction set.
When using the hash tables at least 128 MBytes main system memory recommended

4. Program Installation and execution
The program downloads freely from http://rdchess.com
To install the program unzip the RDCHESSVx.zip file into a temporary directory and start the set up program setup.exe. Setup installs all RDChess program files into a default directory (c:\RDCHESS) or into a directory, which may be chosen at the installation process.
The program consists of the rdchess.exe program file, a readme.txt file with a licence agreement, an opening library file (RDCH_op.lib), an English and German help-file in .txt format and a few example chess games in .pgn format.
RDChess is executed with the command line ... path\rdchess.exe [xxxxx.pgn] [xboard]
The optional parameter "xxxxx.pgn" loads the chess game xxxxx at startup. When RDChess is known to MS Windows as program for executing .pgn files, a double click on a .pgn file loads automatically RDChess.
The optional parameter "xboard" starts RDChess in WinBoard mode (see next paragraph). This parameter makes no sense when RDChess is called stand alone with its own GUI.

The RDChess Delphi source code can be downloaded separately and freely from http://www.rdchess.com and installed with Installshield to a subdirectory ...\Source.

Installing RDChess for use by WinBoard
To install a chess engine to be called from Winboard see the WinBoard Homepage of Tim Mann .

RDCHESS.EXE must be called with the parameter "xboard" (or /xb or /wb) in the "DOS" command line in order to run in Winboard mode.
E.g. create a shortcut on the desktop calling the program winboard.exe with RDChess as the "first computer program (fcp)" with the following content:
"C:\Program Files\WinBoard\winboard.exe" /cp /fcp="d:\rdchess\rdchess.exe xboard" /fd="d:\rdchess"
c:\Program Files\WinBoard .... is the directory where winboard.exe resides,
d:\rdchess .... is the directory where rdchess.exe resides
Another example for playing Gromit Chess V3.82 as first engine against RDChess as second computer chess engine a match of 10 games :
"C:\Program Files\WinBoard\winboard.exe" /cp /matchGames 5
/fcp "c:\Program Files\gromit382\gromit382.exe xboard" /fd "c:\Program Files\Gromit382"
/scp="d:\rdchess\rdchess.exe xboard" /sd="d:\rdchess" (input as a single line !)

5. Known problems and hints

E1) The RDChess windows positions on the desktop are optimally arranged for a screen resolution of 1152 x 864 or higher. On screens with smaller resolutions you may have to move the windows to a better position manually. (Sorry, I have not yet implemented a “Save/ restore RDChess desktop to disk”).
E2) If your PC has less than 64 Mbytes main memory, there may be problems with using the hash tables (full standard hash tables use approximately 26 Mbytes).
If your computer accesses at a computer move (search) frequently the hard disk and the program runs slowly, uncheck the “Use hash table” check box in the configuration control (Menu Option/->Configuration… ->Computer Search).
E3) Not all user interface items are properly displayed in English or German language.
The File Dialog Menu as well as buttons in dialog boxes use the language of the installed windows (.dll) and are not switched with the RDChess language configuration check box.
The debug windows are mainly in English only.
E4) RDChess (all versions) has a bug, playing sporadically a blunder move (e.g. giving away material for nothing). Despite eager long search I was not able to find this bug.

RDChess Technical Program Description

2010-01-13T16:38:00.005+01:00

1. Architecture and Data structures

The following description is meant for computer programmers, who are already acquainted with the basic principles of chess programming like search algorithms, evaluation functions etc. The text describes the actual implementation in RDChess and highlights on specific features implemented in RDChess, probably not found (in this form) in other chess programs.

Programming environment

RDChess runs under 32 bit MS Windows on Personal computers.
RDChess is written with the Borland Object Pascal language. Performance critical functions (e.g. the whole move generator, some evaluation functions like pawn evaluation etc.) are written in (Pentium II optimized / MMX) Intel assembler code.
The program uses the Borland’s DELPHI Visual Component Library for the Graphical User Interface (GUI) and to some extent (in not performance critical sections) self written classes.
Because of the use of some DELPHI 5 specific compiler extensions (e.g. 64-bit integers int64) the program compiles only with the DELPHI 5 or later compiler. RDChess consists of about 27 Delphi user interface forms (.frm) and 34 Delphi units ( .pas). The source code contains about 25.000 lines of code.

The following text describes the chess engine only. The User interface program parts are not included here, some information about it you find in the RDCHESS User manual. Information about the WinBoard interface built into RDCHESS you can read here.

Architecture

RDChess is based on the broadly used template of "Shannon type A brute force searchers" , described in detail for the Northwestern University chess program CHESS 4.5 (/1/).
RDChess makes a "nominal" full width Alfa-Beta (NegaScout) search (/2/, /4/) until a predefined search depth, followed by a "quiescent search". The leaf positions in the search tree are scored with a static evaluation function, taking into account the material situation (number and type of black and white pieces) and -to a far less extent- the positional terms.
I have developed the program mainly with information contained in the following 5 books. I recommend /1/ and /2/ as classical standard books, reading these is a must for every serious chess programmer:
Peter Frey (editor)
/1/ Chess Skill in Man and Machine
Springer-Verlag, 1982 ISBN 0-387-90790-4, 3-540-90790-4
Tony Marsland, Jonathan Schaeffer (editors)
/2/ Computers, Chess, and Cognition
Springer-Verlag, 1990 ISBN 0-387-97415-6, 3-540-97415-6
Bartel, Kraas, Schrüfer
/3/ Das grosse Computerschachbuch
Data Becker 1985 ISBN 3-89011-117-3
Alexander Reinefeld
/4/ Spielbaumsuchverfahren (Informatik-Fachberichte 200)
Springerverlag, 1987 ISBN 3-540-50742-6
Ernst A.Heinz
/5/ Scalable Search in Computer Chess
Vieweg 2000 ISBN 3-528-05732-7

Data Structures

The data items described in the following are used in the chess engine. Additional data structures used for the representations on the graphical user interface are not described here.Chess board representation (TBoard)
RDChess doesn’t use the today very popular “bit boards” (64 bit fields for diverse chess board representations, like e.g. a bit board with bits set for all pieces standing on the squares addressed by the bit number of the bit board).This has historical reasons, I started the program development with a board array and never changed to bit boards. Anyway, with the soon coming availability of Intel 64 bit micro proccesors I should revise my decision. Instead of, RDChess uses an older scheme, a 12 x 12 byte array as board, linearly addressed (Board: array[0..143] of TPieces). 2 rows and 2 files are added on both sides of the 8 x 8 chess board for easier move generation purposes.
Each field of the array contains a set value for the piece standing on the square (e.g. white king, black rook, etc.), or the value for a “free square” (only on the inner 8 x 8 chess board) or the value for an “outside square”.A second 144 byte (12 x 12) array contains for each square an index into the Piece List (to identify an actual piece standing on the square, discriminating e.g. between 2 rooks). Piece Lists (TPList)
RDChess keeps one list for all white and one list for all black pieces which are still on the board (max. 16 pieces per side), containing the set-value for the piece and the square index where it sits on the board (index into the 144 byte Board array).
The chess board and piece lists (and some more data in the following position context) are updated incrementally during a search, that means at deepening and restoring a chess position when executing/ taking back a move only the data items changed with the move are updated. This is faster than calculating e.g. the whole piece list every time from the scratch in a new position.
Move Structure (TMove)
The 32 bit TMove structure consists of four 1 bytes fields

the "from" and "to" squares (indices in the TBoard array),
the move type (normal move, capturing move, castling move, en passant pawn capturing move, pawn promotion move),
the set value of the piece which is moved (wKing, bRook etc.) or the promotion piece (white or black queen, rook, bishop, knight) in case of a pawn promotion move.

Moves are stored in Move Lists, which are described below within the Move Generator.
Position context (TPosCtxt)
There is one large important data structure, which is used throughout the program. It contains all chunks of data which describe one chess position (additionally to the TBoard and TPL list).

TPosCtxt contains for a specific position

the actual castling rights,

the "Fifty move rule" count,

the en passsant pawn status (to - square of an eventual double advance pawn move of the opponent, which resulted to the actual position),

the previous move (which resulted to the actual position),

the full width search depth of the current search

the number of the white and black officers, white and black pawns (for null move and "pawn endgame" discrimination and other purposes)

Material sums for the white and black pieces,

144 bytes (12x12) Attack Tables (TAttack, see below) for white and black,

64 bit hash value of the actual position for the position hash table (incrementally updated),

32 bit hash value of the actual King-Pawn formation for the King - pawn - hash table (incrementally updated),

Game/ Opening library state information,

a list of pinned pieces (for the "Pinned pieces evaluation term" and the "really legal" move generators),

and more.

Attack Tables
RDChess calculates for each position (just before calling the move generator) two 12x12 byte attack table arrays for the black and white attacks to each square on the board. The RDChess attack table routines were implemented in assembler code with only one byte reserved for attacks to 1 square and have therefore severe shortcomings.

One square on a chess board may be attacked by

0 - 1 king (1 k-bit),
0 - 8 (!) queens, implemented is only 1 q-bit ( 0-1 queens),
0 - 4 rooks, implemented are only 2 rr-bits (0-3),
0 - 4 bishops and
0 - 8 knights. Implemented are only 2 bb bits (0-3) for bishops and knights together!
0 -2 pawns ( 2pp-bits).

The 8 attack bits are arranged in the attack byte from bit 0 - 7 as "k-q-rr-bb-pp", so an attack with a higher attack byte content is more threadening.
There are no extra X ray attack tables. But in the attack tables an X ray attack of a less valued piece through a more valued piece (like a rook behind a queen) is counted in the above described attack byte. X ray attacks of sliding pieces (queen, rooks, bishops) through the king are also counted on the squares behind the king.
Because of the above described shortcomings, the attack tables may not be used for a full fledged static exchange evaluator. But the attack tables suffice to support the "really plausible" move generator (see below) and for the purpose of better move ordering, where a wrong ordering because of missing attack data (e.g. not counting a second queen) may only result in a performance penalty and not in e.g. fully missing a good move.

An evaluation term for field control is calculated in the position evaluation routine, using the attack tables.
Pinned pieces array
The position context includes a "Pin" record array for a maximum of 8 pieces (from the side to move), which are pinned by opponent sliding pieces against the own king. A Pin record contains the direction of the pin, the pinned piece and the pinning piece, together with the squares where both pieces sit on.
This data is used during "really plausible" move generation and for an evaluation term, punishing pins which may be bad for the side on move.
Main Variation array
The principal variation array keeps for every searched depth the best move continuation (sequence of alternating best moves for both sides).
There are kept several main variation arrays, one for the search, one for the root position (permanent brain search) and others.
Killer move array

For each search depth 2 "killer" moves (best and "second best" move of all positions searched in this depth) are stored with attached killer move use counts.
New (different) killer moves overwrite the killer move with the less use count.
The killer move with the higher use count is searched first.

2. Move Generation
RDChess implements a Move List Class (TMovLst), containing all legal moves out of a position and the member functions for move generation etc.
RDChess is outstanding in this respect, most of the move generators of other current chess programs generate "pseudo legal" moves, containing also moves which may leave the own king in check (e.g. moving a piece which is pinned to the own king). Generating only the "really legal" moves needs a high programming effort (much code), which I think is the main reason for its rare use.
The additional code consumes time at move generation, which is lost in cases where the move is not even searched later (because of Alfa-Beta pruning) .
But RDChess uses efficient Pentium inline assembler code nearly throughout the whole move generators and a very efficient 32 bit TMove structure (which fits into the 32 bit registers of the Intel processor architecture).
Overall the "really legal" move generation seems advantageously.
Moves ( 32 bit TMove items) are generated and stored in 2 different move lists,

one for capture (+ en passant, + pawn promotion ) moves,

one for normal (non capture, including castling) moves.

There exist 4 move generation routines. At positions, where the own king is not in check

a Full Move Generator, which generates all possible moves (capture and non capture) and
a Capture Move Generator, which generates only capture moves.

In positions, where the own king is in check, there are

a "Capture Checking Piece" Move Generator, which generates all possible captures of checking pieces and
an "Escape Check" Move Generator, which generates non capture moves, leading out of check (king moves to unchecked squares and moves from pieces to block the ray from the checking piece to the own king).

Besides the above mentioned 4 move generation routines there exist no "incremental" move generation routines, creating only few moves at a time, in the hope an early cutoff saves partly move generation effort.
For better Alf-Beta efficiency the moves are preordered at generation time to some extent. The move generators generate moves in direction "forward" and in direction to the opponents king before generating moves backward and away from the opponents king. For this purpose black and white"direction tables" with one of 8 entries per "from"- square (North, East, South, West, NW, NO, SW, SO) are precalculated. The opponents kings square from the root position is used for choosing the proper direction table at the root level of the search.
Capture moves from less valuable pieces are normally generated first as well as some other rules are followed (e.g. double rank advance pawn moves before single rank advance move are in the average presumably more valuable) .
During the search moves are selected from the preordered move lists applying special rules (see below), but the pre-order is coming into effect if no other rules override.
2 debug windows of RDChess show the moves in generation order and in the order, in which they are searched.

3. Search Engine

The Search is called for a computer move, returning a "main variation" (best move sequence) out of the current position and an evaluation value for this best move. The search is also called during the opponents time to think for his move ("permanent brain"). Assuming the opponents most favorable move done, a computer reply move for that position is searched . If the opponent doesn't choose the expected move, the search result move is discarded and the search for the computer answer move must be started again from the position reached by the unexpected move.
The search routine runs not in an extra MS Windows thread (I had no opportunity yet to implement this). Instead of the search suspends at regular intervals (with an "Application.ProcessMessages" call) to the Windows message loop, allowing the processing of user interaction (e.g. press of the Escape key) during the computer search.
The search engine uses an depth first Alfa- Beta search routine in NegaMax formulation and consists of 3 routines.
At the root level (depth 0) a search function with an aspiration window (preset Alfa and Beta value guesses) deepens the search iteratively until the allocated time has expired or the maximum assigned search depth is reached. If the search result is outside the Alfa-Beta aspiration window values, the search is repeated.
The root search returns a best move out from the Principal Variation, an evaluation value for the move and additional data (search statistic data, ...).

Until the maximum full width search depth, the search calls recursively a full width NegaMax search routine.

The full width search routine features

Use of Position hash tables
Null window search ("Nega Scout" search algorithm with an narrow window after the first ("best") move of each position has been searched ),
Null move heuristic,
Search extensions, increasing the full width depth for 1 ply under certain conditions (when the own king is in check and in a few other positions, e.g. after moving a pawn from the six to the seventh rank),
Recognize position repetitions (inside the search as well as in the move history of previous moves) and evaluate them to "near draw values",
Forward Pruning techniques like razoring at horizon depth -3, extended futility pruning at horizon depth - 2 and normal futility pruning at frontier nodes (horizon depth -1) (see /5/).

Search order of moves:

First a stored move from the position hash table is tried,
Secondly a null move (only under certain conditions like "own king not in chess" and others ) is searched;
Moves which capture pieces, which have captured an own piece at the previous move,
Moves from the killer move list (there are two killer moves stored for each search depth),
Capture moves with an expected positive static exchange value, sorted falling with expected win value,
Normal moves (= non capture) from "strongly" attacked squares to "not attacked" or defended squares,
Remaining normal moves from any squares to "not attacked" or defended squares,
Remaining normal pawn moves (from any squares to any squares),
Capture moves with an expected negative static exchange (e.g. queen captures a pawn, which is defended by a pawn),
All remaining normal moves.

Move generation is postponed after a hash table respectively null move has been tried.
After the full width search a quiescent search tries eventual capturing moves in order to reach a "quiescent" position for static evaluation.
The quiescent search routine features

Use of position hash tables (reading hash values; but storing only at the nominal full width search depth),
Forward pruning of non-checking moves if the static position evaluation value plus an estimate of a capture gain value is below the current Alfa boundary (assuming that the capture move doesn't lead inside the Alfa-beta window),
estimation of a position value without calling the evaluation function , if the material score plus/ minus a reasonable maximum value for positional evaluation parts of the position are below/ above Alfa/ Beta,
estimation of a position value without calling the evaluation function for positions beyond the maximum full width search depth

The quiescent search terminates when a capture move leads to a Beta cutoff or after the best of the capture moves searched raised the static position evaluation value.
Is not such a capture move found, it will be assumed that at least one "non capture" move leads to an evaluation as good as the static position evaluation and the search is terminated also. This is only true if the own king is not in check. If the own king is in check, after the "Capture checking piece" moves there are generated all "Escape Chess" moves and tried one by one. If the score of one of these moves reaches the static position evaluation value, the quiescent search terminates, assuming that the remaining "non capturing" moves don't lead to scores greater than the static evaluation.
Position (Transposition) Hash Table
The current implementation of RDChess stores during a full width search for each position which increases the Alfa value a hash record in the transposition hash table.
The hash record contains

a 64 bit hash key (for collision detection),
the best move (32 bit TMove) for this position,
a set value for the type of the hash entry (value is exact, upper bound or lower bound),
the value of the position (exact value or value of upper bound or value of lower bound),
a "draft" (search depth which was used for acquiring the position value).

These stored values are used if the same position is reached again in the search later on,

because the same position was reached over another path (transposition),
or in a search repetition because of a null window fail high < Beta,
within iterative deepening
or in searching a follow up root position.

In full width search, only hash entries are used with a draft greater/ equal then the current remaining search depth. In quiescent search, a successfully read hash entry is used independently of the draft.
Depending on both the bounds in effect when the hash value was stored and the current Alfa-Beta values, the hash value may be used immediately (e.g. with an exact value), or leads to a cutoff (lower bound hash value greater/equal to current Beta value; higher bound hash value lower/ equal to current Alfa value) or raise the current Alfa value (lower bound value greater than current Alfa value) or lowers the current Beta value (upper bound lower the current Beta value).
For calculating the position hash key a constant table with 64 (square index) x 13 (piece set values) random 64 bit integers is used (Zobrist scheme).
The hash key is calculated by adding for each piece on the board a 64 bit integer out from the table, indexed by the piece value and the square the piece sits on. In order to discriminate fully a board position, additional random numbers are folded in, depending on the side to move (black or white), on the castling rights and the Enpas square.
The 50 move rule count is not counted for. Positions devaluated because of "position repetition" are therefore not stored in the hash table.
The hash table is not cleared after executing a move in the root position. Instead of, the hash table is used and expanded for several moves on the board. Entries from previous searches are flagged and will be earlier overwritten in case of low memory.
A "hash table use count" is incremented (at normal moves by one, capture and pawn moves by 2) until a preset "maximum hash table use count" is reached. The maximum use count is set higher in the endgame as in the early/ middle game.

4. Evaluation Function

Position Evaluation

RDChess's position evaluation is like in most other chess programs dominated by material. The possession of a pawn is worth 100 units. Stronger pieces are valued similar to figures documented in the chess literature (a queen with about 900 units, a rook with about 510 units, bishops and knights with about 325 units).
Positional scores for diverse positional advantages (e.g. a rook on a free file) are much less weighted as material advantage. They rarely exceed the value of one pawn (e.g. at bonuses for passed pawn near the 8th rank).
A chess mate position is valued -VMATT or +VMATT (generic value about +/- 18000 for loosing respectively winning), although such a position is detected in the search, and not in the evaluation function.
The RDChess evaluation is called in game states outside the opening library and discriminates between

standard positions in the early and middle game,
standard positions in (early) endgames states,
Pawn end games (with only both kings and some pawns on the board),
Near mating positions (the opponent being more than one rook value behind and having no pawns left). In such positions an abbreviated evaluation function is applied, driving the opponents king into a corner to mate;
drawn positions because lack of material, positions with 50 Move Rule counts > 100 etc. A value for "Drawn position" is returned;
Game theoretical special positions like KBB against K or KBN against K end games. A specifically adapted evaluation function is called for these positions.

RDChess doesn't use Endgame databases.

RDChess keeps diverse global game state variables like the side to which (white and black) has castled, "White in the Endgame" etc.
Depending on that Game State variables, some position evaluation parameters are switched before searching at the root level.
E.g. the pawn advancement bonuses are increased at falling material sums or on the opposite side where we have castled, or the king changes his strategy from hiding in a corner in the early middle games to strive for the center, if the opponent material decreases.
For standard positions the evaluation function calculates the sum of

the material balance (material difference between the sum of the material values of the white and black pieces),
an additional material function value with a trade down bonus, raising the score for the side in advantage, if there are less pieces and less pawns on the board (this term is described in articles about the Northwestern university chess program CHESS 4.5),
a field control term (difference between the number of from black and white attacked squares, weighted with quality factors),
and positional score terms for pawns, the king and all the other pieces.

The detailed evaluation features and exact values of the many evaluation parameters are not described here because of lacking space. Interested may look at the source code, freely available.
Pawn evaluation
The calculation of the pawn score term is the most elaborated part of the evaluation function and certainly one of the most important procedures.
Various positional characteristics like isolated pawns, doubled pawns, backward pawns, pawn advancement and passed pawns are scored.
For pawn advancement 12 x12 board advance tables are pre calculated at each root position, containing a value which is scored for a pawn standing on this square. The king castling status at the root position is taken into account. E.g. pawns on the opposite side of the board where the own king has castled get a higher advance bonus. Has the opponent king castled to this side, the advance bonus is even more raised.
Passed pawns are scored higher if they are supported by adjacent, connected own pawns. The attack status or blocks on squares before a passed pawn (in direction to the promotion square) is taken into account.
King evaluation
The king evaluation is strongly divided into a standard evaluation where king safety is of importance and an Endgame evaluation, where the king actively takes part in the game.
The standard evaluation punishes facts which hinder castling and rewards a king which has already castled. The punishment decreases for an not castled or "lone standing" king proportionally with a falling material strength of the opponent.
In the endgame there is a bonus for center tropism (small distance of king to the center of the board)..
The king evaluation is strongly interconnected with the positions of the pawns.
In standard evaluation the pawn shelter around the king is rewarded.
In the Endgame the distance of the king to pawns, especially to passed pawns and to "backward" pawns (pawns which cannot advance because of threads or hang behind) is of advantage and positively scored.

In a Pawn Endgame the distances of the kings to the promotion squares are considered ("square of king"- promotion rule) and in unmistakable favorable positions for queening very high bonuses are scored .
King-Pawn Hash Table
RDChess doesn't use like most other chess programs a pawn formation hash table and eventually a king hash table..
Instead of, because of the many evaluation terms both depending on the places of the kings and pawns, a single hash table, holding evaluation values for positions with identical king and pawn squares is kept.
This unique scheme proved to be quite advantageous, the read hit rate in the King-Pawn-Hash-Table is quite high, which I believe is because of seldom advantageously made king moves during a search.
Evaluation of Officers
All officers are punished for standing on the first rank in the early middle game, in order to favor early piece development (but queens are punished for moving too early over the third rank).
All officers get bonuses for controlling more centrally located squares and squares around near the opponents king.
Hung pieces (of the side on move) are punished. Against the king pinned own pieces are punished (see Pinned Pieces).
Rooks get a bonus for being on the seventh rank, for doubled rooks, for being on a file with passed or backward pawns. Standing behind a passed pawn in the Endgame is even more advantageously.
"Bishop pairs" (possession of more than one bishops of opposite colors) get a bonus.
In the endgame an proprietary RDChess bishop positional term is added. At endgames with different colored bishops or where the opponent has only a bishop of one color the own pawns get bonuses for standing on fields with the same color as the own bishop and punishments on fields with opposite color as the opponents (lone) bishop. For the opponents pawns there counts the opposite.
This term makes it easier to defend own pawns and attack the opponents pawns with bishops and should be advantageously in endgames, where is more room on the board. On the other side putting
There are some other scores not mentioned.
5. Performance
RDChess is a medium strength program, comparable with other free/ shareware chess programs like GNUCHESS or Waxman.
It is clearly inferior to commercial programs like Fritz etc. and other good academic programs like Crafty.
Anyway, it's strong enough to win nearly always against its creator (me) and 95% of all chess players on the world with a setting of 3 seconds/ move.
RDChess searches about 30.000 nodes/second in the opening, about 60.000 in the middle game and more than 90.000 nodes/s in end games (with few pieces left) on an Intel Pentium III 450 MHz processor.
On a newer PC with Intel Core 2 Q6600 Quad CPU with 2,4 GHz RDChess searches in the middle game around 500.000 nodes per seconds (which is quite few compared to other chess engines).
I observed a strong dependence of the search velocity on the alignment of critical data structures and (supposedly) the distribution of dynamical data in memory (L2 cache). Inserting a few bytes of code and rebuilding the program causes an unpredictable variation in the search velocity of up to 20 %, supposedly depending on the alignment (byte, word, .. paragraph/32 byte boundary) of often used data structures !
I have no data about the quality of code (relating to speed) generated by the Delphi 5 compiler (with compiler option “optimization” checked) compared to C++ Builder V4 or MS Visual C++ V6 generated code.
I assume that C++ code with compiler optimization is faster than Object Pascal code, but that is only a guess of mine.
I tried compiling the Delphi 5 code with C++ Builder V4, in order to port later the code to C++. This failed because of some incompatibilities between both compilers relating to register use in inline assembler code.

RDChess WinBoard Interface implementation

2010-01-13T16:20:00.000+01:00

The following description is meant for computer programmers, who are interested in how and what of the WinBoard protocol is implemented in RDChess.

If you want to know how to install RDChess into Winboard please go to the User Manual Part 3 Installation

The WinBoard Communication protocol has been the most common link for playing chess games between chess engines. Recently even the commercial chess programs support this interface. The best known program is WinBoard by Tim Mann.
A newer interface is the UCI (Universal Chess Interface) protocol, which has more functions than WinBoard. UCI is supported e.g. by Arena.

Implementation of the WinBoard interface in RDChess:

RDChess is a Delphi program written in Object Pascal. The main program is a single process (thread) and uses heavily the Borland Visual Component Library (VCL).
Winboard.exe (or an equivilant program) starts RDChess and creates 2 pipes for standard input and standard output. My interface code is based on an example by Tony Werten

RDChess writes to the output pipe with an output handle (created by gHandleout:=getstdhandle(std_output_handle) ) by calling _lwrite(gHandleout,PCHAR (string),length).
RDChess reads from the standard input in an own thread WBReadThread, derived from the VCL TThread class.
In the thread function ( procedure TWBReadThread.Execute ) the commands received from WinBoard are read and analysed. It is critical and Borland does not recommend to use VCL functions in this extra thread, because many are not thread safe. So I use at some points the Delphi supplied method Synchronize. Larger work is postponed to the main thread by posting messages to the RDChess main thread with PostMessage(MainForm.Handle, ...) .
A few calls to VCL functions and global variables are still used directly in the thread execute method, but I also use frequent calls to Application.ProcessMessage, which should decrease the risk of a collision.

WBReadThread is set to a lower priority than the main thread in order that the main thread ends his work on a received command faster before it takes actions for a newer command. (e.g. all the work at receiving a "result" winboard command (for instance saving the chess game) must be done before a received "new" winboard command sets all data to a new game). I had problems with synchronizing the both tasks at the beginning of using the thread (and even program crashes!) until RDChess V3.07, but in V3.08 it seems there are no problems.

RDChess "uses" currently the following Winboard commands

Receiving (WinBoard-> RDChess):

xboard, new, random, protversion 2
hard, easy, post, nopost, computer, name, ics hostname
rating (in ICS mode)
level, st (all 3 styles conventional, ICS-style, nr of seconds per move)
sd (set maximum search depth)
time, otim (used optionally for synchronizing of RDChess internal timining routines with WinBoard timing)
force, go, white, black
hint, "?" (move now)
moves in standard notation (not SAN format !)
remove
setboard FEN (for setup of positions and at loading games)
analyze, undo , "." , bk (bk only partially implemented)
result
draw
quit

Sending (RDChess -> WinBoard):

answers to protversion 2:
name=1      // request the name from the opponent!!!
time=1       // send time and otim cmds
  setboard=1 // FEN-cmd instead of edit-cmd
ics=1        // inform about ICS data
  analyze=1    // implemented
move xxxx (computermove calculated by RDChess)
0-1 (or 1-0, 1/2-1/2) {xxxxxx} xxxxxx = result/ resigns

"offer draw" (when RDChess is behind 12 pawn units and at certain types of endgames (RK-RK; QK-QK) and the opponent is not in time troubles)

Error (xxxxxxxxxxx) : yyyyy // error messages from RDChess to the opponent

Thinking output ( ply score time nodes pv) (when state is "post command received")

Status update (stat01: time nodes ply mvleft mvtot mvname) in response to a received "." cmd. mvleft and mvtot are not supported and set to a default value 1.

RDChess understands only the newer (protversion 2) position setup command "setboard" and not the older "edit" commands for seting up positions. This means that currently chess games may be loaded from .pgn files with the program Winboard.exe only and not with the program Arena.exe.

RDChess playing strength

2010-01-13T16:05:00.004+01:00

The strength of RDChess has been evaluated by

playing against humans. RDChess usually wins, except you are a very professional chess player.
playing at Leo Dijksman's chess computer test site WBEC Ridderkerk Tournaments
playing against other computer chess programs in Olivier Deville's Chesswar Tournaments
playing at Guenther Simon's Regensburger WinBoard Cicuit RWBC
and many other chess test sites. Look at and search for rdchess in WinBoard Forum.
RDChess played as computer at the American Free Internet Chess Server FICS. After playing 531 games RDChess had a Blitz score of 2175 and a computer rank of 73.
with RDChess playing against test suites (see below).

If anybody runs test games against RDChess, I would be pleased to receive any kind of feedback as posting to this site or to my e-Mail adress.

RDChess test suites
There are a few test suites (Bratko-Kopec, Fine, Louguet II, WinAtChess, etc ; annotated with EPD best move tags ) stored for download here on this site.
RDChess has a built in automatic test procedure, which is started with the menu Game-> Run Test suite ...
In the file dialog you select a game library in .pgn format. In the PGN FEN setup string of each game in the library there has to be set an Extended Position Description (EPD) tag "bm" (best moves out from the start position). RDChess plays one move for each position and compares the calculated (searched) move with the stored best move from the "bm" - tag.
If the moves are identical, a hit counter is incremented. At the end of the test run a statistic with the number of test games, number of hits, used time, accumulated total node count etc. is displayed and may be printed:

Click on the screen shot to enlarge

RDChess.exe File only Download

2010-01-13T14:30:00.000+01:00

If you have already a full version of RDChess installed before on your computer you may

download the RDChess V3.23 patch only:

RDChessV323Patch.zip (Dec 22, 2003, 486 kB).

Installation:

Unzip RDChessV323Patch.zip (contains rdchess.exe) into the RDChess program directory (usually C:\RDChess ) on your Windows computer and overwrite the old rdchess.exe file

RDChess Download

2010-01-13T14:09:00.001+01:00

This link downloads the file RDChessV323.zip (Dec, 22 th, 2003; Size approx. 1,2 MB).

Installation

Unzip the downloaded file and run setup.exe to install RDChess on your Windows computer (all Windows versions).
Installshield copies the rdchess.exe file, a small openig book, help files, a few chess games and a license agreement info file to a RDChess directory and makes RDChess Windows registry entries.
Please read and adhere to the Licence agreement!
If you have already a full version of RDChess installed before on your computer you may download RDChessV323Patch.zip (Dec 22, 2003, 486 kB) only.
Installation
Unzip the downloaded file (contains rdchess.exe) into the RDChess program directory (usually C:\RDChess ) on your Windows computer and overwrite the old rdchess.exe file.

Transfer of RDChess web pages

2010-01-13T12:13:00.000+01:00

The RDChess web pages were moved today from http://rdchess1.multiply.com/ to the RDChess-Blog at Blogger.com http://rdchess.blogspot.com/

The link

http://www.rdchess.com

is still valid and redirects to http://rdchess.blogspot.com/

Some chess links

2010-01-01T15:11:00.000+01:00

The following table contains a small collection of ("old") links to chess papers, chess home pages, chess servers, companies etc., which I saved as bookmarks because they were seemingly more or less important for me.
Chess Programming Wiki
Tim Mann's Chess Pages
Bitboard Infrastructure (Heinz)
Computer Chess programming (Verhelst)
Chess GML (Andreas Saremba)
DelphiMax chess program from Bauer &Schweitzer
Game Programming Eppstein
GameDev.net -- Chess Programming Part I Getting Started
GameDev.net -- Chess Programming Part II Data Structures
GameDev.net--Chess Programming Part III Move Generation
GameDev.net -- Chess Programming Part IV Basic Search
GameDev.net -- Chess Programming Part V Advanced Search
Guide to Endgames Table Base
PGN XML Proposal
Int. Comp. Games Association (ICGA)
WWW Pages of DarkThought (Dr. E.Heinz)Home Page of Jonathan Schaeffer
Ph.D.Thesis Dennis Breuker's
FTP Directory _ftp.cis.uab.edu_pub_hyatt_
CSS-Forum
WinBoard Forum
news:rec.games.chess.computer

Game Data Base Chess Games.com
ChessBase
Computerschach und Spiele (german periodical)
FIDE
The Week in Chess (London Chess center)

PlayChess.com

Free Internet Chess server (FICS)

Internet Chess Club

Kaiserslautern Chess Server (german language)MSN Gaming Zone Chess

WBEC Ridderkerk (Leo Dijksman)