History of the CAL Timesharing System

The CAL Timesharing System (CAL TSS) was developed at the University of California at Berkeley between 1968 and 1971 to provide interactive computing for research and instruction. It ran on a mainframe computer, the Control Data Corporation 6400, and was one of the earliest systems to use capabilities for protection. Using our memories, archival records, and files preserved by McJones that are part of a donation to the Computer History Museum, we discuss the origin of the project, development of the software, and the brief experience using the system before it was shut down in May 1972.