Two decades ago, at an off-Broadway theater in New York City, two one-act plays shared American premieres in what was to prove an important moment in the history of theater of the absurd.

"The Zoo Story," by the young American playwright Edward Albee, was paired with "Krapp's Last Tape," the work of Samuel Beckett, the Irish playwright whose earlier ventures into absurdism had included "Waiting for Godot" and "Endgame."

Round House Theatre, in Silver Spring, has taken on the challenge of staging these difficult plays in its repertory series, for a limited run ending Sunday. And, with certain reservations, it turns out to be a creditable undertaking.

"Krapp's Last Tape" seems to tell a simple enough story -- an old man relives moments in his life as he listens to tapes that the recorded in earlier years. Crotchety as he may be, Krapp is a likable old man. Yet underneath lies Beckett's vision of a lonely man isolated from human contact.

Jeffrey Posson, a guest actor from Memphis State University, gives a believable at times touching, performance as Krapp. As he listens to a tape recounting the sensual pleasures of a long-ago love affair, the unkempt old man sitting at the batterd desk is transported back in time to savor those moments once again. The voice on the recording is the strong and assured voice of a 39-year-old man. For the old Krapp, Possen modulates his voice beautifully into a rough rasp.

Posson fills the stage in the demading role. Director Douglas A. Cummings, who directed both plays, is in control of his material, orchestrating pace and intensity from the first scene, which introduces Krapp as the eccentric hermit with his banana peels, tapes and memories. For the Round House production, the tone is one of bittersweet sadness rather than bitter alienation.

In Ablee's "The Zoo Story," David DiGiannantonio and Iliff McMahan play the two strangers who meet by chance in Central Park and begin what seems a casual conversation. They are Jerry, who opens the dialogue and keeps promising to tell what happened at the zoo, and Peter, who has been quietly reading a book on a park bench.

DiGiannantonio brings a friendly heartiness to the role of Jerry in the beginning. He is a brash young man in sweat jacket and jogging shoes. Deftly he builds the feeling of menace and alienation. As Peter, McMahan's role makes him a listener for a good part of the play until the explosive last scene. He plays Peter as a rather stuffy, ineffectual young man. This works to the detriment of Albee's play, where the sinister impact is heightened if Peter is seen as an average man stripped bare of his civilized veneer.

The two plays will be performed at the Round House Theatre, 12210 Bushey Dr., off Connecticut Avenue, in Silver Spring, through this Sunday. Performances are at 8 tonight and Saturday with 2 p.m. matinees on Saturday and Sunday.