Technological signposts change every day

When cassette tapes loaded with music from classical to pop first hit the market, only a few savvy marketers realized the days of the phonograph and record albums were numbered.

Then came compact discs.

Now digital video discs are pushing videocassette tapes off the shelves.

The space devoted to DVDs at video-rental outlets continues to grow, even though 95 percent of American homes have videocassette recorders while 30 percent -- and growing -- have DVD players.

One major retailer -- Circuit City Stores Inc. -- has opted for DVDs and will stop selling videocassette tapes. The decision reflects the preferences of consumers who, in the end, are responsible for all retail decisions.

In this technological age, the switch to DVDs is yet another signpost along an ever-changing road.