This paper addresses the change from batch mode to online mode in offices and workplaces in the 1970s and 1980s. Particular focus is on the role of IBM and the 3270 display terminal. The change had profound implications for users and system developers. The paper is based on oral history interviews with former employees of the two large Danish service bureaus, Datacentralen and Kommunedata, and addresses a number of themes: driving forces, technology, education and training, skills and knowledge, and systems development practice.