Out of the four VLT Unit Telescopes, three have had first light and of those, one is in full scientific operation. So the VLT style Telescope Control Software is in regular operation on three out of four originally foreseen telescopes, and is being installed and tested on the fourth. In fact, it is actually installed and successfully operating on a whole family of ESO telescopes: the NTT, the 3.6m Lit Silla, the Seeing monitor telescopes on Paranal and La Silla. That means that this software is installed and running on a total of eight telescopes of different kinds, for the moment. The three Auxiliary telescopes of the VLT interferometer and the VLT Survey Telescope, now in the development phase, will join the family. Another member of the family is the Simulation Telescope, called "Control Model", at ESO headquarters in Garching. Although it cannot look at the sky tit is pure electronics and software: no mechanics and no optics) it has been, and still is, of great value. It can he reconfigured to emulate any of the actual telescopes and it is used for off-line testing of new software releases and to analyse and fix problem reports and change requests submitted from observation sites, without disturbing operation. It is also used to test instrumentation software and its interfaces with the TCS before the actual integration at the telescope. This paper presents the actual status of the Telescope Control Software on the VLTs and on the other telescopes. The main focus is in the characteristics that make the TCS architecture portable on very different mechanical and optical configurations. Then the paper concentrates on the strategy used throughout the projects for integration and testing of the modular components. Particular attention is given to the installation and commissioning phases for the VLT telescopes.
