IBM System/360
A family of compatible computers announced in April 1964 that let customers upgrade without rewriting their programs.
IBM announced System/360 on April 7, 1964. It was a family of six computers and some 40 peripheral devices that all ran the same instruction set. A customer could start with a small model and move to a larger one without rewriting software.
The project was enormous and risky. Many accounts put the development cost at about five billion dollars, and the operating system, OS/360, ran late. Fred Brooks, who managed OS/360, drew on the experience for his 1975 book The Mythical Man-Month. The 8-bit byte and the 32-bit word became industry standards through System/360.
Why it matters
System/360 established compatibility across a product line as the way computers are sold. It made IBM dominant in mainframes for decades, and its architecture still shapes IBM Z mainframes today.
Key facts
- Announced April 7, 1964.
- Six initial models and about 40 peripherals.
- Standardized the 8-bit byte.
- Fred Brooks led OS/360 development and wrote The Mythical Man-Month.
- Built with SLT circuit modules.
Sources
- Campbell-Kelly, Martin, and William Aspray, et al. Computer: A History of the Information Machine. 3rd ed. Westview Press, 2013.
- Pugh, Emerson W., Lyle R. Johnson, and John H. Palmer. IBM's 360 and Early 370 Systems. MIT Press, 1991.
- Brooks, Frederick P. The Mythical Man-Month. Addison-Wesley, 1975.