The Viewer makes possible to connect two PCs through Internet if you know the IP address of both computers. Furthermore, it allows working with just one PC (local mode). If you use this mode the toolbar will be visible permitting to setup any position over the board, to draw arrows, frames, to exchange files, which is especially useful for public presentations either local or remotely.
When two PCs are connected, the actions over one board will be reflected on the other PC. Even though the PC to PC mode has a “chat” allowing exchanging text between both PCs, it is highly recommended to use, at the same time, another application that allows voice communication between both PCs like Messenger, or Skype , both free and with a great quality.
When the button is pressed, from the Viewer toolbar, a new window pops up:
One of the PCs acts as a server and the other as a client. From the operating system point of view, it is indifferent to be client or server, because the functions are exactly the same. The difference is in the way the connection is established. The PC acting as a server has to be the first one in trying the connection. The Internet and Server radio buttons should be checked before clicking on the OK button. In this moment the window is closed and in the toolbar you can read “waiting for the client”. Now, the PC that will act as a client checks on the Internet and Client radio buttons, enabling the remote IP textbox, where you have to enter the IP address of the server PC. Usually, it will be the same IP showed in the server PC window (in the image above: 192.168.1.34). However, as we will see in a while, it is not always the same. When the OK button is pressed the connection will be made between both PCs and the toolbar will be visible:
By default, the composer tool is selected (
), which allows moving with the mouse the pieces currently over the board. In the lower right side line, the toolbar shows the selected tool in every moment, for example: in the image above, the composer tool.
Some of the actions included in the toolbar are not a real tool so when you select one of them the active tool is not affected, for example: to setup the initial position, to show the clock, etc. These options make a specific work. The real tools are selected to perform repetitive operations: to draw lines, to put a piece, to remove a piece, etc, and that’s why these tools are “active” until a different tool is selected.
The buttonfrom the main toolbar of the application closes the PC to PC connection.
Remote IP. The PC acting as a server PC shows a value for its own IP that could be the real IP address of the PC in Internet, or a local IP address that is different from the IP address the PC shows in Internet. Usually, the real IP is shown on connections through a modem connected to the telephone line. The local IP is shown when the PC has access to Internet from a local network or router, which is the case of ADSL connections. The PC acting as a client needs to write in the “remote IP” field the real IP address of the server PC. Therefore, when the server shows a local IP it is necessary to obtain the real IP address by using another procedure. A simple procedure is to connect the server PC to the online playing room so as to get the IP that is showed when you connect, for example:
S: Connection accepted. S: 213.97.182.213 Identifying... S: Welcome to the playing room of InterAjedrez.
In this case, the server PC real IP es 213.97.182.213, the one you have to enter in the remote IP field.
Another important aspect is the necessity of the server PC to accept incoming connections in the Port specified in the Port field (it is the same in both PCs). If the server is connected through modem to the telephone line it is unlikely that problems might occur. However, on other type of connections, such as ADSL, it is expected that they will not accept incoming connections. In this case you have to change the router configuration. Most routers require a different configuration, but the general procedure could be as follows:
Connect to the router configuration page through the internet navigator, like Internet Explorer, for example, connecting to http://192.168.1.1/
Look for the NAT option which will lead you to a series of options from which usually, the only one activated by default is the "SUA Only".
Edit the SUA only details by opening the port, for example: 4141 for the local IP showed in the server PC (192.168.1.34)
Integrity of communication: To make sure that the communication between both PCs is running correctly, The Viewer uses the “eco” strategy. Any time that a command is run in one PC like drawing arrows, moving a piece, etc, the command is transmitted to the other PC. When the second PC receives the command, it sends a copy to the original PC. When the original PC receives the copy, in this moment and not before, executes the command.
Therefore, if we run a command to draw an arrow and it is executed in our PC we have the certainty that the second PC did receive the order. If the actions we attempt to execute do not have any effect, it is possible that we have problems in the communication between the PCs. If the speed of the connection between the PCs is low we will observe that there is a time between the command given and the execution of it. This is the time the command needs to go to the other PC and return.
Resources. While the connection PC to PC is active, it is still possible to use the button (
) to load a PGN file or to open an HTML web page (located in our PC). If we load a game it will be visible and we will be able to reproduce it as usual. If we wish that any change occurred in the game when we reproduce it be transmitted to the other PC (the new position and the correspondent move), we will need to have the automatic send activated. The automatic send mode can be activated or desactivated with the button
. By default, when the connection is initiated, it is activated.
If we load an HTML web page we can send it to the other PC through the button
We have to take into account that only the web page and not the referenced elements, like images, will be sent. That is why it is necessary that the images be located in some server and the web page have to make reference to them through it’s absolute URL.
If what we want is that both PCs show a web page, the button to be used is which opens a window where you can enter the web direction (URL) to be shown.
This mode allows to transfer any kind of file such as text, images, games, etc, from one PC to the other through the buttonThe maximum file capacity is 250k approximately.
Games. One of the possibilities of the PC to PC connection is to play games, for which there is a clock and an annotation sheet available. It is important to note that the PC to PC environment simulates a board and a clock with some difference regarding the games being played in the online playing room. In the online zone, to castle it is enough to move the King and the system completes the castling automatically by moving the rook. However, in the PC to PC environment, after moving the King, you have to move the rook. In the same way when you realize an “unpassant” capture, in the online room the system removes the captured pawn automatically. In PC to PC mode we have to remove it manually by using the tool “remove piece”
In the same way when a pawn is promoted we have to replace it manually for the piece to be converted by selecting the tool of the piece. After these operations that needed to change the tools we cannot forget to select the compose tool again.
Regarding the clock, something similar happens. In the online room, immediately after the move is completed, the clock switch sides automatically. In PC to PC mode is like in real word, we have to press manually the clock.
The system will not check the validity of any move.
3D View. The 3D Viewer can be opened and it will reflect any change over the board. However, it will not show any auxiliary elements like arrows, marks, pointers, etc. The 3D board can show a maximum of 32 pieces. The 2D board can show a maximum of 64 pieces even though it makes no sense to have more than 32 pieces over the board. In case the 32 pieces limit is overstepped, the 2D board will show them, but not the 3D board.
In the 3D board you cannot drag the pieces with the mouse to make a move. You have to click (with the mouse) over the square in which the piece currently is. Then you have to do another click over the square in which you want that piece to be moved.
Recording a session. The recording of a session is similar to the creation of a multimedia content,
you will not need to activate the audio recording and video.
To replay a previously recorded session, you have to use the button You have to specify the file that contains the recorded session and it will be reproduced, respecting the exact time between the different actions during the recording. The replay can be canceled by pressing this same button that once in replay mode will show as
PC to PC communication. 
), which allows moving with the mouse the pieces currently over the board. In the lower right side line, the toolbar shows the selected tool in every moment, for example: in the image above, the composer tool. 
from the main toolbar of the application closes the PC to PC connection. 
) to load a PGN file or to open an HTML web page (located in our PC). If we load a game it will be visible and we will be able to reproduce it as usual. If we wish that any change occurred in the game when we reproduce it be transmitted to the other PC (the new position and the correspondent move), we will need to have the automatic send activated. The automatic send mode can be activated or desactivated with the button 
. By default, when the connection is initiated, it is activated.
We have to take into account that only the web page and not the referenced elements, like images, will be sent. That is why it is necessary that the images be located in some server and the web page have to make reference to them through it’s absolute URL.
which opens a window where you can enter the web direction (URL) to be shown.
The maximum file capacity is 250k approximately.
In the same way when a pawn is promoted we have to replace it manually for the piece to be converted by selecting the tool of the piece. After these operations that needed to change the tools we cannot forget to select the compose 
and it will reflect any change over the board. However, it will not show any auxiliary elements like arrows, marks, pointers, etc. The 3D board can show a maximum of 32 pieces. The 2D board can show a maximum of 64 pieces even though it makes no sense to have more than 32 pieces over the board. In case the 32 pieces limit is overstepped, the 2D board will show them, but not the 3D board.