Treating castling and e.p. rights seriously

One of the most important changes betwen WinBoard 3.4 and predecessors is that it is fully aware of the game state. That is, it keeps track of castling rights and e.p. status, and takes that knowledge into account in legality checking of the moves and mate testing. As a result it can do 100% reliable adjudications: forfeit engines that do illegal moves, or make false result claims, and terminate the game on 3-fold repetition of due to the 50-move rule.

Supporting fairy pieces

WinBoard F does not only support the six piece types of orthodox chess, but expanded the number to 22. Most of these have well-specified moves known to WinBoard, such as the Archbishop (a B+N compound) and the Chancellor (R+N) of Capablanca Chess. Others are wild cards just supplied as graphics, and can only be used with legality testing off.

In board sizes middling (49) and bulky (72) a bitmap for each of these 22 pieces is supplied, while size petite (33) supports most. In the intermediate sizes, only Archbishop and Chancellor are available, while for sizes below 33 and above 72, none are. Some of the more common piece types, such as those for Chinese or Capablanca Chess, were added to the piece menu in Edit Position mode, while others can be made by 'promoting' or 'demoting' the more common ones.

Configurable and non-square board formats

WinBoard F allows the use of other boards than 8x8. In particular, the number of ranks does not have to be equal to the number of files. Options -boardWidth and -boardHeight can be used to specify exactly the board you want, but a value -1 for these options means WinBoard will use the default size for the variant you are playing (so 8x8 for normal chess or suicide).

Piece-ID letters in SAN and FEN

Unfortunately the names of fairy pieces are not as standardized as they are in orthodox chess: a piece that moves in the same way can be called Marshall in one variant, Chancellor in another, and Champion in a third. This affects the single-letter abbreviation one would use for writing SAN moves in notations for these variants. WinBoard accounts for this through the -pieceToCharTable option, where you can define for each of the 44 colored piece types what letter should be used for them. This can also used to disable pieces, by setting their character to a period. For each of the predefined variants, WinBoard has a default table, and uses that as soon as you select the variant.

Predefined variants

With the unorthodox piece types and board formats WinBoard F can support a large number of chess variants. Some of these variants are pre-defined: they can be selected through a New Variant item in the File menu, which brings you to a dialog where you can pick one, and optionally change its board size from the default.

For these predefined variants, WinBoard usually knows the rules exactly, meaning that it can do legality checking, reliably detect checkmate, etc. Some variants are only partially supported, however, and need to be played with legality testing off. The predefined new variants are:

• Xiangqi (Chinese chess)
• Shogi (Japanese chess)
• Capablanca, Gothic and Capa-random Chess (on 10x8 board)
• Courier chess (a medieval precursor of modern chess)
• Shatranj (ancient Arabic chess)
• Knightmate (King moves as Knight, and vice versa)
• Cylinder chess (the board wraps around at the edge files)
• Berolina chess (Pawns capture straight and move diagonally)

The latter two can only be played with legality testing off. The ICS variants that were already supported in 4.2.7 (Fischerandom, Suicide, Losers, Giveaway, Atomic, Twokings, Threechecks) are all fully supported in local mode, and WinBoard is aware of their rules for victory, so it can adjudicate.

Normally all these variants would be played with the piece symbols shown above. But the almost infinite configurability of the WinBoard look through board textures and font-based rendering does allow you to perfectly mimic traditional representation of Asian variants, for example. On the screenshot above, you see how suppressing the grid that normally separates the squares, and using a drawing of a Xiangqi board and the XIANGQI font for piece rendering, can give a very good looking Xiangqi interface.

Dragging and dropping from displayed holdings in Bughouse

Drop variants like Bughouse and Crazyhouse used to keep track of the holdings as text in the title bar, and required a drop menu to select dropped pieces from. This only worked in ICS mode, as the holdings were not updated in local play. In WinBoard F, the holdings are displayed beside the board, and you can grab and drag the piece to drop from there. They are also fully updated in local Crazyhouse play. (Bughouse still can only be played on an ICS, being a 4-player game where WinBoard is only a 2-player GUI.)

Shogi is also a drop game, and uses the same mechanism. In fact WinBoard F allows you to play any variant as a Crazyhouse-style drop game, by configuring holdings for it through the options -holdingsSize, where you can specify the number of piece types for which space should be reserved in the holdings. (Beware: for practical reasons this cannot be larger than the number of board ranks!) Piece types for which no space is reserved will revert to Pawn oon capture.

Promoted Pawn or primordial piece?

In Bughouse promoted Pawns revert to Pawn on capture, and are thus in principle different pieces than the primordial pieces of the same type. WinBoard F shows this difference by using alternate representations for pieces obtained through promotions. In sizes where these are available, fairy pieces are used; in other sizes a slightly smaller representation of the normal chess piece.

Displaying engine logos

WinBoard F offers the possibility to display logos of the playing engines next to the clock. The options -firstLogo, -secondLogo allow you to explicitly specify bitmap files for those. The logos will be scaled to 2x1 aspect ratio, so results are better if they already have this to begin with.

There also is a persistent boolean option -autoLogo, which makes WinBoard look automatically in the engine directory for a file called logo.bmp, and display that if it finds it (and this is not overruled by an explicitly given file). In ICS mode this option makes WinBoard look for a logo of the ICS in the logos folder, e.g. freechess.org.bmp for FICS.

Modernizing WinBoard protocol

WinBoard protocol lacked commands to control the engine's hash-table size and number of CPUs it could use. This was of course because such things did not exist at the time when it was devised. This situation was corrected in WinBoard 4.3, by adding the 'memory' and 'cores' commands. These commands allow the GUI to specify the hash size and CPU number through the protocol interface, with as a result they can now be set through the GUI, rather than requiring editing of obscure ini files.

Of course this only works on engines that actually support these features. But (through Polyglot) all UCI engines do, so the dialogs to set these options were useful from the beginning.

Bitmaps for traditional Japanese Shogi pieces

As an extra service to Japanese users, board size 'moderate' (58) uses a complete set of traditional Shogi pieces in variant shogi. To properly use them, the options -allWhite and -flipBlack were added, and have to be set to true. Other board sizes (i.e. middling and bulky) use the normal chess-style bitmaps, except that special forms of the Gold are used to indicate some promoted pieces.