Grass or clay, asphalt, cement, Sporteze, Laykold, Supreme-Court, Grasstex—for us hackers it doesn't much matter what tennis-court surface we use, whether we are playing on the immaculately manicured lawns of Wimbledon or on hard-packed sand in Khartoum—although it must be admitted that grass is absolutely the best for throwing down a racket in disgust. The bounce is most satisfying and any serious damage to the racket is minimal.

According to a 1974 survey by the A. C. Nielsen Company, more than 33 million people play tennis "from time to time." In the U.S., unhappily, "from time to time" often means whenever they can find an empty court. Most American players do their double-faulting in public parks, where lines can be longer than queues at Disney World.

Enter a gentleman named Morrie Hodes, a tennis hacker who is in the parking-lot business in Los Angeles. He figures that he has the answer for people who want to get out and hit a few balls and don't care if it's on Centre Court grass or Siberian salt as long as the bounce is reasonably true. Hodes has invented Port-A-Court, a carry-around tennis court that two people can put up in less than 30 minutes on a parking lot, a rooftop, a playground—anyplace that is hard, flat and big enough. The cost of the equipment: $1,500.

A Port-A-Court consists of two weatherproofed backdrop nets held up by eight galvanized-steel posts and a center net supported by either a free-standing aluminum device or more galvanized-steel posts. If holes have to be made for posts, the equipment includes safety caps to cover them. The court lines can be painted or taped in a contrasting color. Hodes says the equipment can be stored in an area of 40 cubic feet.

Hodes has installed three Port-A-Courts so far, one in the parking lot of a Los Angeles bank. Another is in the playground parking lot of a Catholic school, where the monsignor finds it "a good use of space" and wishes it were as easy to find putter-uppers and taker-downers as it is to find players. The third is in the parking lot of the Hyatt House Hotel in City of Commerce, adjacent to L.A., where the ambience includes whizzing cars close by on the Santa Ana Freeway. Still, the hotel manager says the court gets plenty of use by businessmen, and so far no tennis ball has been stained too badly by oil dripped from cars. Port-A-Court's address: P.O. Box 35161, Los Angeles, Calif. 90035.