The paper describes the basic design methodology and the technological aspects involved in the integration of a high performance Prolog machine on silicon. The need of an efficient Prolog engine arises from the A.I. applications requiring great symbolic computation power. Currently available Prolog machines are implemented using a large number of boards. As a consequence they are expensive, cumbersome and have not yet achieved industrial standards. The described processor, PROXIMA, is a VLSI Prolog engine prototype suited to be added on a commercial workstation. The project has been carried out as a cooperative effort of SGS-Thomson Microelectronics and the Politecnico di Torino.