Excerpt from the TacOps4 User Guide.
16. Play By Mail And Modem
TacOps can be played on two non-networked computers by exchanging orders files using floppy disks, or by using directly connected modems, or by using electronic mail to exchange orders files. The same basic procedure is used to exchange orders files by each method. For simplicity, all four methods are referred to as "Play-By-Mail".
In a play-by-mail game, when both players have finished giving orders to their units during the Orders Phase, they each save a special "orders file" to a disk and then they exchange those files by mail, by personal meeting, or electronically by direct connection or by email. Each player then loads the orders of his opponent and executes a Combat Phase. The orders exchange and combat execution cycle is then repeated.
The orders exchange process is simpler for you in practice than the description below suggests. The program will guide you to the next correct step in the orders exchange process. All you have to do is to look at the Combat/Begin Combat menu item, the File/Receive Orders menu item, and the File/Send Orders menu item. Only one of these menu items will be active at any given point, the other two will be dimmed. The one undimmed menu item indicates the next step in the process. To further aid you in identifying what file to load, the titles of the File/Receive Orders and the File/Send Orders menu items include the turn number of the orders file that needs to be loaded next. - example, "Send Orders #2".
Caution: When playing by mail or email, it is important that you coordinate in advance with your opponent to insure that you both have the same preference settings when you begin a game. If the preference settings of the two computers do not agree when the program loads an enemy orders files, you will be shown an alert dialog telling you what the differences are. If you are the Blue player the program will then change the incoming Red orders to match your preferences settings. If you are the Red player the program will then change your game preferences to the settings of the Blue player.
16.1 Play-by-Mail Procedure
Start the TacOps program in the usual way. When the Startup Window appears, select the Two Players Play-By-Mail item and also select whether you will command the Blue or the Red forces. Finally, select the appropriate item for playing either a standard scenario or a saved game. Click the OK button.
Setup your units in the usual way.
When you have finished giving orders to your units, select the File/PBM Send Orders menu item. You will be shown a standard file saving window. Accept the suggested file name or change it and then click the OK button to save your orders to disk (this file will be sent to your opponent - you will not need your own orders file again). Once you have written your orders to a disk file, the program will not allow you to give any more orders to your units, or to change the game preference or option parameters in any way. Do not try to defeat this. To do so would likely cause the subsequent Combat Phase to produce different results on the separate computers and thus ruin your game in progress. You may only save orders once per orders phase from within the program. Immediately after your orders are written to disk you will be presented with another file save window - this time it will be to save your game in progress to disk. If the game session must be interrupted while awaiting receipt of your opponent's orders (i.e. you want to turn off your computer - the usual case), you should generally go ahead and accept this save opportunity and then refuse any subsequent offers to save the game as you quit the program. Following this suggestion guarantees that you will not inadvertently do something later that disrupts the consistency of the game on the two separate computers. You must preserve this saved game file. You will need it to restart the next game session if you quit TacOps.
Send just the orders file to your opponent. Do not send him your saved game file.
When you receive your opponent's orders file [if necessary, restart the TacOps program using your saved game file] use the File/PBM Receive Orders menu item to load your opponent's orders into the TacOps program. Be careful not to load your own orders, or a previous set of your opponent's orders. Preferences will be automatically checked. If critical preference settings do not agree on both computers corrective action will be taken or an error message will be displayed. The program will also confirm that both players are using the same version of TacOps and the same versions of the appropriate scenario and map files.
Execute the Combat Phase then repeat the orders phase, save orders, save game, orders exchange, and combat phase cycle until game completion.
This procedure will work for exchanging orders via mail, by personal meeting, or by using email.
To exchange orders by email you simply use your own communications program to transfer your orders file to some intermediate computer system - using Internet, or a local area network, or a local or national bulletin board system (BBS) - and to obtain your opponent's orders file from same. If you wish to use email on a BBS to exchange orders, the BBS must be one that allows you to send non-text (sometimes called binary) files to other BBS users. The usual procedure is to "attach" the non-text file to a normal text post.
16.2 Play-by-Modem Procedure
[Section text snipped as this mode of play (phone modem to phone modem) has become practically extinct.]