If you get WinISD and want the box dimensions, you need the beta (older).. and the box will be square.. if you get the Alpha (pro, newer) it doesn't do box calcs (not the build I have anyway)..
but, that's moot.. you know the shape you want.. that's all that matters.. Now, you can put in the specs on the sub (might be in the existing database).. then you adjust the box volume and tuning freq until you get a curve you like (on the transfer function graph)..
Then you can look at the port tab and set the dimensions (diameter or if 'square' the sides) and number, it tells you the length... look at the 'rear port air velocity' graph while you do that.. try to stay under (I believe) 20 m/s..
All you have to do is decide what sizes you need for sides etc to make the volume you put in.. keep in mind that the ports, if inside, have to be ADDED as volume to your final box size.. though, it seems that the ports can be external.. then you make the box the 'size' you put in the prog.. and have the ports out of the box..
Hope that helps.. OH.. and set the 'watts' on the signal tab too, and watch the 'cone excursion' graph to make sure you won't bottom out the sub.. I have a 500 rms sub (in sealed recomended box).. at the ported box I want, I can only run 350 watts to it.. but, at 30 Hz, it's better than the 500 in a sealed..
(1) Alpine CDA 7892 HU ($214)
(2) 12" Pioneer Premier 1241DVCs in sealed MDF box (gonna glass them eventually) ($69 each)
->removing.. ->(2) 10" Pioneer Premier 1041DVC's in sealed MDF box (gonna glass them eventually) ($59 each)
(2) Lanzar Vibe248 1200 watt 2 chnl amps ($119 each)
It's bump'n GOOD!
You can lead a horse to water but you can't make a moron understand...