Brian Carpenter's Texas Instruments calculator program. This program will work on the TI-83/84. It calculates port length, frequency, volume, slot displacement, and port displacement. It has been compared to another popular online calculator, and the results were identical.

TIP: When selecting the slot displacement feature, the program assumes you're using 0.75 inch MDF, and the port uses the top, one side, and bottom of the box for your port walls. It also assumes the port is entirely in the box.