Lester M. Alberthal Jr., president and chief executive of Electronic Data Systems Inc., has been named chairman. The EDS chairmanship had been vacant since the company's founder, H. Ross Perot, sold his interest in EDS to General Motors Corp. in December, 1986. Alberthal has served as president and CEO since then. Alberthal began his career with EDS as a systems engineer trainee in 1968. EDS, a wholly owned subsidiary of General Motors, is a Dallas-based computer and communications company.