 These included the Bell Laboratories TRADIC, completed in January 1954, which incorporated a single high-power output vacuum-tube amplifier to supply its 1-MHz clock power.The first fully transistorized computer was either the Harwell CADET, which first operated in February 1955, although the price paid for this was that it only operated at the slow speed of 58 kHz, or the prototype IBM 604 transistor calculator.The Burroughs Corporation claimed the SM-65 Atlas ICBM / THOR ABLE guidance computer (MOD 1) that it delivered to the US Air Force at the Cape Canaveral missile range in June 1957 was "the world's first operational transistorized computer".