In 1953 Dr. Norikazu Sawazaki developed a prototype helical scan video tape recorder. Another solution was transverse-scan technology, developed by Ampex around 1954, in which the recording heads are mounted on a spinning drum and record tracks in the transverse direction, across the tape. By recording on the full width of the tape rather than just a narrow track down the center, this technique achieved a much higher density of data per linear centimeter of tape, allowing a lower tape speed of 15 inches per second to be used. The Ampex VRX-1000 became the world's first commercially successful videotape recorder in 1956. It uses the 2″ quadruplex format, using two-inch (5.1 cm) tape. Because of its price, the Ampex VRX-1000 could be afforded only by the television networks and the largest individual stations.