Contents

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FAQ - Frequently Asked Questions

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Problems

Sigma Chess crashes under OS X 10.5
On some OS X 10.5 Intel Macs, Sigma Chess 6.1 crashes randomly. We are currently investigating this problem. There is a known incompatibility between QuickTime 7.2 and all Carbon applications (such as Sigma). Also, certain non- standard alert sounds (in System Preferences) can cause crashes.

Sigma Chess crashes at startup under OS 8.6/9.x
Sigma Chess 6.1 requires the "CarbonLib" extension (version 1.4 or later) because it has now been ported to run natively under OS X as well. You can download the latest version here. After download you should copy the CarbonLib extension to your "Extensions" folder inside your "System" folder, and then restart your Mac.

Sigma Chess performed an illegal pawn capture!
Most likely it has played the so-called en passant move, which is a perfectly legal (but admittedly rather strange) move in reply to a double pawn move. For example: If Black has a pawn on d4, and White moves a pawn from e2 to e4, then Black may capture this e4 pawn en passant by playing d4xe3, just as if White had only moved his pawn to e3. En passant moves are suffixed with the letters "EP" in the move list.

How do I force Sigma to play with the White pieces?
Simply start a new game and select the Go command from the Analyze menu. Sigma Chess then makes the first move, and from now on you then play the Black pieces (you might also want to turn the board so the Black pieces are at the bottom of the display).

Does Sigma Chess support "human vs. human" mode?
Yes. Select the Manual mode from the Playing Mode & Level dialog. When you perform a move in this mode, Sigma Chess won't start thinking automatically. This is useful for entering games manually - hence the name.

How do I perform a castling move?
Simply move the king two squares to the side (e.g. from e1 to g1). The rook is then moved automatically for you (e.g. from h1 to f1).

Why can't Sigma Chess open previously saved games?
When opening a previously saved game, Sigma Chess per default shows the final position. This can be changed in the Preferences dialog so it instead shows the initial position. However, in this case it might appear that Sigma Chess doesn't open the game properly. But you can still replay the game move by move using the Redo Move command from the Game menu.

Why is my 400 MHz PowerBook/iBook not fast enough for the 2400 ELO setting?
For maximum performance on a PowerBook/iBook, you need to turn off Processor Cycling in the Energy Saver control panel.

I have problems installing with StuffIt Expander. What's wrong?
You will need StuffIt Expander 5 or later to unpack the downloaded ".sit" file. However, there have been reports of problems with StuffIt Expander version 6.0.1.

Playing Strength

How strong is Sigma Chess?
I don't have a precise ELO rating because Sigma isn't on any rating lists. Based on various test suites and games against other Mac programs, Sigma seems to have a rating of about 2500 ELO on a 1 GHz G4.

Is Sigma Chess 6.1 Pro stronger than Sigma Chess 6.1 Lite?
Yes, there is a relatively minor difference in strength because Sigma Chess 6.1 Pro supports much larger transposition tables (up to 320 MB). The Lite version is restricted to max 10 MB transposition tables.

What's the strongest Macintosh chess engine?
HIARCS, Shredder and Fruit are the three strongest engines. Other very strong engines are ChessMaster 9000, Ruffian, and Deep Sjeng.

New Features

Can Sigma Chess read ChessBase files?
No, not currently. I may add support for this in a later version. Currently you will need to export to PGN from ChessBase and then import into Sigma Chess. The Macintosh program ExaChess can read the older ChessBase format (.cbf) files, and save them as PGN files Sigma Chess can read. The free version of ExaChess is limited to 128 files games per file. ExaChess can not read the current Chessbase format (.cbh) files

Other Platforms

Does a PC version of Sigma Chess exist?
No. Although I would like to port it to Windows too, it's not realistic at the moment. Chess programming is just a hobby and my spare time is rather limited.

Where can I find some good freeware PC chess programs then?
Steve Pribut has a very comprehensive list of freeware Windows chess programs here.

What about other platforms - Linux, BeOS, Palm OS etc?
As for a Windows version: I would like to port Sigma Chess to other platforms, but my time is too limited, so it's not likely to happen.