ABS at the SPS and LEP

LEP and SPS are large circular accelerators equiped with more than 100 orbit monitors and corrector dipoles in each plane. At the SPS orbit control is mainly used to minimize beam losses, while for LEP the orbit is a crucial parameter for lumonisity performance. Various algorithms and strategies have been developped for LEP to find "Golden Orbits" that optimize the dispersion and the beam emittances. Despite those differences, the two machines share a large amount of control software for beam steering. The experience and problems related to beam steering at such large machines will be presented. The limitations of the orbit control system sharing between the two machines will be reviewed.