and a fine actor to boot -- so tonight's "American Playhouse" production of "Overdrawn at the Memory Bank" (Channel 26 at 9) becomes a science fiction spoof of more than trivial note, even though it is not especially original in either concept or execution. Nevertheless, this fable about a future fellow who swims against the computerized tide and is sent off for "doppling" therapy is certainly inoffensive, occasionally funny and altogether watchable.

Julia plays the role of Aram Fingal, a bored-to-death computer programmer who taps into a secret section of the world's computer, which regulates everything from weather to wildlife. Fingal finds old movies and gets hooked on them. This is a big no-no, for some unexplained reason, and when he gets caught watching "Casablanca" he is sent off for doppling. To be doppled -- which many of these future citizens do voluntarily as a kind of R&R -- means to have one's identity temporarily transferred into an animal on a wildlife refuge known as Nirvana Village.

In Fingal's case, two things go wrong:

First, a snooty kid on a school tour switches the tag on Fingal's body, now emptied of identity, and the body is misplaced.

Second, some sort of naturally fermented fruit is ripe on the wildlife preserve and Fingal, in the body of a drunken baboon, is trapped in a tree under attack by a drunken elephant.

With only eight hours to prevent Fingal's identity from disappearing altogether, the computech on duty for his doppling -- Apollonia, played by Linda Griffiths -- persuades the president of the huge computer to store Fingal temporarily inside the computer itself until his body can be found. (The interim cube, she says, is made of "low-quality synfab.")

Fingal is "tracked" by computech Apollonia as he turns his new world into a compu-Casablanca. At the same time, the president of the computer company (Donald C. Moore), in the guise of a latter-day Sydney Greenstreet, is after Fingal's scalp because, in his boredom, he has broken the code . . .

You've heard it all before, but, what the heck, that world is getting closer all the time. Corinne Jacker wrote the screenplay, based on a story by John Varley. The play is a joint production of WNET in New York and RSL Films of Canada.