“The IBM 1401”. IBM 1401 Restoration Project. Computer History Museum. 2012年7月15日閲覧。 “The 1401’s clock frequency is 86,957 cycles per second, or about 87 kiloHertz! This corresponds to an 11.5 micro-second system clock cycle time. ... The 1401 CPU does everything in a character-serial manner. In order to add say two N-digit numbers, the CPU takes several cycles to fetch the instruction itself and then one cycle for every character of the instruction’s two operands or arguments, or 2N cycles total.”
IBM Corporation (1961年). “IBM 1401 Principles of Programming, Section 7” (PDF). IBM Personal Study Program. IBM Corporation. p. 19. 2012年7月15日閲覧。 “The timing of the IBM 1401 is described in terms of the time required for one complete core storage cycle, which is 11.5 microseconds ... The time required for any internal processing instruction is always a multiple of this interval of time.”
