CDC 6400

The CDC 6400 was a mainframe computer from Control Data Corporation and a member of the CDC 6000 series, the family of large solid-state, general-purpose digital computers that also included the 6200, 6300, 6500, 6600 and 6700. It was delivered in April 1966, after the flagship CDC 6600 of 1964. The 6400 has a single central processor with the same instruction set as the 6600, but its single unified arithmetic function unit can only carry out one instruction at a time, which makes it a slower and less expensive serial implementation than the 6600's ten parallel functional units. All other aspects of the machine were identical to the 6600, including the ten peripheral processors that handle input and output and the 60-bit central memory word. Like the rest of the series it ran under the SCOPE operating system, and by 1970 also the time-sharing oriented KRONOS. The CDC 6500 combined two 6400 central processors, and the 6700 paired a 6400-style processor with a 6600-style one.