Configuration File

You can also view this list of commands by typing “help” at Chiron’s prompt.

absscore <on|off> : shows the score from white point of view (on) or from Chiron’s one (off). This only works when you are using Chiron with the Winboard protocol.

blockage <mode>: disable (0) pawn blockage detections, use it only in analysis mode (1) or use it always (2)

book <off|name>: turns off the opening book or sets its file name. Chiron supports Polyglot (.bin), CTG and Arena opening books.

book2 <off|name>: turns off the second opening book or sets its file name.

bookautolimit <on|off>: if set to on Chiron will automatically limit its opening book knowledge (depth and width) according to the Elo set with the command limitstrength. The purpose of this option is to avoid that Chiron plays too many moves from the opening book even at a low Elo, which would be unrealistic.

bookdepth <depth>: if you set a value different from 0, Chiron will limit the depth in full moves of its opening book to the value set. This option overrides the limit imposed by the Auto Limit Book option.

contempt <value>: sets Chiron’s draw contempt in centipawns. If you want Chiron to avoid draws set a positive value otherwise negative. The default value is 0.

createini: creates “chiron.ini” initialization file with default settings.

drawaccept <on|off>: sets on/off draw offers accepting.

drawoffer <off|count>: disables draw offering or sets the number of moves for which the score must not change so that Chiron should offer a draw.

egbb <on|off>: enables/disables the use of Scorpio endgame bitbases.

egbbcache <size>: sets the size of the Scorpio bitbases cache in MB. It contains the results of positions for which the Scorpio bitbases have been already probed.

egbbloadtype <type>: sets the type of bitbases loading in RAM at program startup. It can be LOAD_NONE if you don’t want to load bitbases in RAM at all, LOAD_4MEN to load all the 4 pieces bitbases, SMART_LOAD to load the most used and LOAD_5MEN to load all the 5 pieces bitbases (about 225MB)

egbbpath <path>: sets the path of Scorpio endgame bitbases.

gtbcache <size>: sets the size of the Gaviota EGTB cache in MB. It contains the results of positions for which the Gaviota tablebases have been already probed.

gtbpath <path>: sets the path of the Gaviota endgame tablebases. Chiron will automatically detect the compression scheme.

hash <size>: sets the search hash table size in MB. The maximum size is 2GB in the 32 bit version and 1TB in the 64 bit version. Don’t use more than the available physical memory otherwise also virtual memory (ie the hard disk) will be used and Chiron will run slower.

kibitz <a> <b>: 0->never 1->only with computer 2->always
1->score, depth 2->also pv 3->after every iter

largepages <on|off>: sets on/off memory allocation using large pages for hash table

limitstrength <elo>: sets the Elo to which Chiron must limit its playing strength. Set it to 0 to restore full strength.

log <on|off>: enables/disables logging. A log file is created in the subfolder “logs”.

nalimovcache <size>: sets the size of the Nalimov EGTB cache in MB. It contains the results of positions for which the Nalimov tablebases have been already probed.

nalimovpath <path>: sets the path of the Nalimov endgame tablebases.

numa <on|off>: enables/disables NUMA awareness. It should be enabled if Chiron is running on a NUMA system (typically one with multiple sockets) to improve speed.

resign <off|threshold> <count>: disables the resigning or sets the threshold and move count for it. If Chiron’s score is below the threshold for n moves, Chiron will resign. Resigning only works with the Winboard protocol.

syzygyfifty <on|off>: set to off to ignore the 50 moves rule or to on to respect it.

syzygypath <path>: sets the path of the Syzygybases.

tb <type>: selects the endgame tablebases to use. It can be 1(Nalimov), 2(Gaviota) or 3(Syzygy). Set it to 0 if you don’t want to use tablebases at all.

tbprobedepth <depth>: sets the minimum depth for tablebases probing. It’s set to 6 by default. Lower it if you have a SSD.

tbusage <mode>: mode can be 0 (tablebases never probed), 1 (tablebases probed only at the root when on the board there are 6 or less pieces) or 2 (tablebases probed also in the search).

threads <auto|n>: sets the number of threads for parallel search. Set it to auto to automatically detect the number of cores to use.

tourbook <on|off>: if set to on Chiron will always play the best move according to its opening book (ie the one with the highest weight). If two or more moves have the same weight, the choice will be random among them.