A Discipline of Multiprogramming

The main software challenge in developing application programs during the 1960s and the 1970s was that the programs had to operate within limited resources, i.e., slow processors, small memories, and limited disk capacities. Application programming became far more widespread during the 1980s because of the falling prices of hardware (which meant that more processing power and storage were available for the same cost) and a better understanding of the application programming process. However, most applications still ran on mainframes or over a cluster of machines in a local-area network; truly distributed applications that ran over wide-area networks were few because of the latency and bandwidth limitations of long-haul communication. The 1990s saw great strides in broad-band communication, and the World Wide Web provides a giant repository of information. This combination promises development of a new generation of distributed applications, ranging from mundane office tasks —e.g., planning a meeting by reading the calendars of the participants— to real-time distributed control and coordination of hundreds of machines —e.g., as would be required in a recovery effort from an earthquake.