The computers developed between 1959 and 1960, including OPC-1 and OKITAC5080, were not implemented with software such as an operating system or a monitor for controlling the computer itself. Conversion programs that enabled programs written in machine languages to be input and executed from punch cards or paper tapes were among the few available software programs.
With the completion of OKITAC5090 in 1961, language-processing programs such as assembler languages, FORTRAN and ALGOL were developed for business use, allowing a written source program to be input on a punch card or a paper tape, and output to a paper tape as an object program. This object program was re-input and executed together with other sub-routines for such functions. From model OKITAC5090 C, it became possible to connect a magnetic tape to the computer, and magnetic tape monitors were developed, enabling these executions to be controlled automatically.
The architecture of OKITAC5090H, developed in 1963, was substantially different from those of models A through D and M of the previous OKITAC5090 series, and realized a time-sharing system.
In due course, Oki Electric Industry formed a partnership with Sperry Rand Corporation, which held the second largest market share in the United States, and in 1963 they established the joint venture company Oki-Univac Co., Ltd. As a result of this alliance, Oki Electric Industry withdrew from the development of general-purpose, large-scale computers and became committed to developing small-scale computers, peripherals and terminal units.