The Rice Institute Computer, also known as the Rice Computer or R1, was a 54-bit tagged architecture digital computer built during 1958–1961 (partially operational beginning in 1959) on the campus of Rice University, Houston, Texas, United States. Operating as Rice's primary computer until the middle 1960s, the Rice Institute Computer was decommissioned in 1971. The system initially used vacuum tubes and semiconductor diodes for its logic circuits; some later peripherals were built in solid-state emitter-coupled logic. It was designed by Martin H. Graham.