If you have ever wondered why today's fireworks extravaganzas are so much better today than they were years ago, it's all due to computers.

Those of us who are over 40 (ahem—50?) may remember watching fireworks as a kid, but it was a totally different experience from today.

I recall sitting on a rooftop with a view of Long Island Sound watching a barge out in the water. We sat and waited, and waited, and waited, and I thought I would literally explode from the anxiety and, eventually, frustration. Then finally, one rocket would launch and, yes, it was good! A single shower of white starlets floating down toward the water. Then we would go back to waiting—staring at the barge, wondering if the guy lighting them dropped his lighter in the water and there would only be but one "firework."

Today's fireworks are a marvel of computerization. Computers have revolutionized modern fireworks shows. Special computer programs coordinate the synchronized firing of thousands of fireworks from ground stations. They do it fast, and they do it precisely.

How does it all work? For ground displays, a computer sends a signal and opens an electrical current along a wire that reaches a metal match head that ignites a spark. This lights a fuse, which lights the rocket. In less than a millisecond, the computer transmits another electrical current to the next fuse. The computer is so fast and precise that it allows technicians to match fireworks explosions to notes of a song.

Aerial displays are launched when an electric signal ignites two fuses attached to a shell—one quick and one time-delayed. The quick-match fuse and lift charge send a jet of fire to black powder inside a shell. The shell hurtles into the air while the time-delayed fuse ignites chemical-packed pellets, called stars, that are buried inside. The stars blow open the shell and wow! That's how it used to be done until a couple of years ago.

Today, there is actually fireworks software that is used to design everything and special chips to ignite the shells. One leading design program is called Visual Show Director 4D (there may be others). Using the software, you can design any color, height, size, speed, and combination of fireworks effect. The software combines the laws of gravity and meteorological conditions, such as wind, to give a virtual fireworks display on screen. It even puts together a list of the chemicals that must be packed in each shell to deliver the colors displayed on the monitor. It also produces the required ignition timing schedule to go with the rhythm of the show and music.

For the perfect show, the secret sauce nowadays is a special computer chip located inside the firework shell itself called the Magic Fire electronic time chip. Use of the chip assures pyrotechnicians that the shell will burst at exactly the same time as it did on the computer monitor.

Now when your kid asks you this July 4, "Daddy (Mommy), how do fireworks work?" you can say, "It's all just a matter of computers. You know, son, your daddy (mommy) works on computers just like the ones that produced those fireworks!"

Editor's Note: A version of this column appeared in the July 3, 2007, issue of Showcase magazine.