NEW YORK (AP) _ Gilbert P. Williamson, chief executive of NCR Corp., has been elected to the board of American Telephone & Telegraph Co., which completed its purchase of the computer maker last week, AT&T said Tuesday.

Williamson, 54, joins AT&T Chairman Robert E. Allen and Vice Chairman Randall L. Tobias as members of management who sit on AT&T's 17-member board.

Williamson also is chairman of an internal, three-member NCR board of directors. The other members are NCR President R. Elton White and Richard S. Bodman, an AT&T senior vice president.

The external NCR board of directors was abolished following the completion of the $7.4 billion merger.