McCarthy proposed the key hardware modifications to an MIT IBM 709 computer which would allow apparently simultaneous, or time-shared, use of a computer by multiple users. It was his early advocacy of timesharing that inspired much of the interest in developing multi-user timesharing systems such as the MIT CTSS timesharing system. In 1958, Russian computer scientist Andrei Ershov attended the Teddington Conference on the Mechanisation of Thought Processes where he met and befriended McCarthy. McCarthy reciprocated with a visit to Ershov in Novosibirsk in 1965, making him the first Westerner allowed to visit a Soviet computing research center. Ershov and McCarthy would remain lifelong colleagues. Working with Alan Kotok at MIT, McCarthy developed a program which played a four-game match in 1966-1967 against a Soviet program developed by George Adelson-Velskiy, Vladimir Arlazarov, A. Ushkov, A. Bitman, and A. Zhivatovsky. The Soviet program won two and drew two. In 1968, McCarthy spent two months in Novosibirsk teaching and interacting with students and faculty. McCarthy was the director of SAIL, the Stanford Artificial Intelligence Laboratory, from 1965 to 1980, where research was conducted in machine intelligence, graphical interactive computing, and autonomous vehicles. McCarthy continued to teach at Stanford until his retirement in 2000.