IBM System/360 Model 67

The IBM System/360 Model 67 (S/360-67) was an important IBM mainframe model in the late 1960s. Unlike the rest of the S/360 series, it included features to facilitate time-sharing applications, notably a Dynamic Address Translation unit, the "DAT box", to support virtual memory, 32-bit addressing and the 2846 Channel Controller to allow sharing channels between processors. The S/360-67 was otherwise compatible with the rest of the S/360 series.

Origins

The S/360-67 was intended to satisfy the needs of key time-sharing customers, notably MIT (where Project MAC had become a notorious IBM sales failure), the University of Michigan, General Motors, Bell Labs, Princeton University, the Carnegie Institute of Technology (later Carnegie Mellon University), and the Naval Postgraduate School.

In the mid-1960s a number of organizations were interested in offering interactive computing services using time-sharing. At that time the work that computers could perform was limited by their lack of real memory storage capacity. When IBM introduced its System/360 family of computers in the mid-1960s, it did not provide a solution for this limitation and within IBM there were conflicting views about the importance of time-sharing and the need to support it.

A paper titled Program and Addressing Structure in a Time-Sharing Environment by Bruce Arden, Bernard Galler, Frank Westervelt (all associate directors at the University of Michigan's academic Computing Center), and Tom O'Brian building upon some basic ideas developed at the Massachusetts Institute of Technology (MIT) was published in January 1966. The paper outlined a virtual memory architecture using dynamic address translation (DAT) that could be used to implement time-sharing.

After a year of negotiations and design studies, IBM agreed to make a one-of-a-kind version of its S/360-65 mainframe computer for the University of Michigan.