Recent Developments in Operating Systems

tem point of view, was 1950. On the earliest digital computers, each user’s job ran separately and had exclusive use of the computer for the duration of the program. The program communicated with I/O devices and managed other resources without assistance. When the program completed, an operator halted the computer and manually prepared the next job. The mid1950s saw the dawn of batch processing and early operating systems which did little more than load programs and manage I/O devices. More generalpurpose systems did not emerge until the mid-1960~.“~ Many of these were multimode systems. They not only provided batch processing, but also included modes for time sharing and some real-time processing. These behemoths tried, within a single system, to provide every functionality to all users.4