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FAQ - Frequently Asked Questions
Will a native Intel version of Sigma be available?
Sigma Chess is a legacy PowerPC application using the Carbon APIs, and the
built-in engine is written mainly in PowerPC assembler. Therefore producing
an Intel version (and switching to the Cocoa APIs) will more or less require
a complete rewrite. Chess programming is just a hobby, and my spare time
is limited, so I alas won't have time to move away from the legacy PowerPC/Carbon
Will Sigma run on Mac OS X 10.7?
No. According to rumors, Mac OS X 10.7 will no longer support PowerPC applications
running under Rosetta emulation.
Sigma Chess crashes under OS X 10.5 and 10.6
On some OS X 10.5 Intel Macs, Sigma Chess crashes randomly. We are
currently investigating this problem, but so far it has alas been very difficult to trace and
reproduce. 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.
Update 24 May 2009:There seems to be a general problem with Rosetta
on some OS X 10.5 Intel Macs. Creating a new Mac OS X user account and running Sigma
from there seems to cure the problem.
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).
The right side of the display has disappeared!
You can get it back using the Toggle Info Pane command from the Display menu,
or by clicking the green widget button in the top left corner of the window title bar.
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.
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.
What's the strongest Macintosh chess engine?
HIARCS, Shredder and Fruit are the three strongest engines. Other very strong engines are ChessMaster 9000, Glaurung, Ruffian,
and Deep Sjeng.
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
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
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.
Copyright (C) 2011, Ole K. Christensen
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