PALO ALTO, Calif. (AP) - Software company VMware Inc. said Tuesday that its executive vice president of research and development, Richard Sarwal, has resigned.

Sarwal is returning to Oracle Corp., which he left in December to join VMware.

VMware said it expects to announce "organizational changes" to replace Sarwal. In the meantime, Stephen Herrod, its chief technology officer and senior vice president of research and design, will assume day-to-day responsibilities for VMware's research and development organization.

VMware's "virtualization" software allows a single computer to act like many.