Made-for-cable movies, quite good and getting better, are blossoming on basic cable television. From none in 1988, the number on USA, TNT, Lifetime and The Family Channel reached 40 last year, and 68 are scheduled for 1990. That's almost six new movies every month on basic channels. The average number could reach two a week by late 1991.

The quality, while hardly uniformly great, can be rated as vastly improved, and the money these networks are willing to pour into movies is plentiful. TNT's executive president Scott Sassa notes that films must cost less than $2 million each and the network must control international sales to break even. Yet TNT is spending $3- to $6 million on movies, often without control of future sales and syndication.

By airing their own movies, these cable networks are sending out the message that they are doing business on the same level as the traditional broadcast networks and that they don't mind spending a few bucks to get viewers to switch to basic cable. Latest figures show The Family Channel averaging $2.25 million per movie; USA and Lifetime, $2.5 million, and TNT, $4.5 million.

HBO, Disney and Showtime have long depended on made-for-cable movies to lure subscribers to their pay-TV fold. The very first effort was HBO's "The Terry Fox Story" in 1983.

Early this year, USA posted an 8.4 Nielsen rating for the premiere of "The China Lake Murders." making it the highest-rated movie ever on a basic cable network. (It should be noted that the three major broadcast networks were airing an address by President Bush that evening.)

TNT's "Cold Sassy Tree" (late 1989), easily the service's most criticially praised effort, starred Faye Dunaway, who was also the film's executive producer. Close behind was "Treasure Island" starring Charlton Heaton,directed and produced by his son, Fraser. This hit is now out on video and is being scheduled into movie houses. (Remember when it was movie houses first and cable TV last?)

Other stars who recently appeared in basic cable movies include Julie Harris, Ed Asner, Vanessa Redgrave, John Lithgow, Corbin Bernsen, Meredith Baxter Birney and Jason Robards, Among those due up are Cicely Tyson and James Earl Jones in "Heat Wave" and Diana Ross in "The Josephine Baker Story," both for TNT; and Nancy Allen in "Memories of Murder" and Lori Singer in "Story and Sorrow," both for Lifetime.

Sunday on The Learning Channel at 8 p.m. The new series "Distant Lives" features director Jonathan Demme's gripping documentaries on the Western hemisphere's poorest nation "Haiti: Dreams of Democrac" and "Knobit."

Saturday on TBS at 7:05 p.m. Larry ("My first love has always been baseball") King will announce the Atlanta Braves games at Philadelphia. King, an analyst for Miami Dolphins games on radio from 1969 to 1977, had made guest appearanceds in the Baltimore Orioles' booth. King will also anchor the 17-day Goodwill Gaames on TBS from Seattle, July 20.