Having a sense of how the combat program works internally can help you use the system more effectively, so a brief explanation is given here.

Combat is handled by a single, rather large program (asys-combat) that works in conjunction with the event manager (asys-eventmgr) to handle and 'event loop' or 'combat loop', as follows:

    Preprocessor  -?->  Combat   -->  Processor 
                         Loop   <--

The preprocessor interprets commands and sets props that indicate your actions and modes. If the command declares an offensive action, and you are not yet engaged in combat, the preprocessor then initiates a combat loop, a portion of the program that executes repeatedly, once each turn. With each iteration of the loop, the program pauses for one turn, then checks props to determine your current activities. When an activity is determined, execution jumps to the Processor, where the results of the activity are calculated and applied. Execution then jumps back to the loop and pauses for another turn. This cycle (enter loop --> pause --> determine action --> process action --> reenter loop --> pause --> determine action... etc.) will continue until you or combat events interrupt it.

You can only have one combat sequence running at a time, but you can issue additional combat commands at any time. If you have a combat sequence running, additional commands you enter will usually just change the props that indicate what you are doing and how, and leave the loop unaffected. On the next iteration of the loop, these new activities will be executed instead of whatever you were doing before.

The fact that new offensive commands modify what happens in the current combat process rather than starting a new one is significant: once you are in a combat sequence, offensive commands you enter may take effect faster than the initial action that started the sequence. When you start a combat sequence, your first offensive action will occur one turn after you enter the command (30 seconds, say). When you are already in combat, and enter another offensive command, the results of the command will be executed on the next iteration of the loop, which might be coming up in one or two seconds, rather than thirty. You don't get extra turns by entering new commands, and your turns don't go faster, but the results of your commands might be applied more quickly. The moral is: start a combat sequence as immediately if it looks like you may soon be engaged in combat. If you are uncertain of your best offensive action or target, or if you do not want to be the aggressor but nonetheless want to be able to respond quickly, you can initiate a combat sequence with either of the two readiness manuevers, +wait or +target. If you do not have a readied weapon, you should probably do a +ready quite soon as well, although readying a weapon does emit a notice to the room, which might be construed as a threatening gesture. Readying a weapon is treated as an offensive action by the program: it too may be completed more quickly when you are already in a combat sequence rather than starting a new one.

Defensive actions or mode changes are applied immediately, whether you are in a combat sequence or not, and do not emit a notice. So, if you switch from Dodge to Parry and are attacked three seconds later, the roll will be calculated against your Parry result, even if you haven't had a turn since you switched to Parry.

You can only have one event loop running at a time, and only one designated action. So, sometimes you need to pay attention to what is happening and change actions as soon as possible. For example, readying a weapon and attacking are both actions... You need to wait until your weapon is readied before doing +attack, unless you want the attack to be figured as unarmed combat.