Personal, Distributed and Client/Server Computing

In 1977, Apple Computer popularized personal computing. Computers became so eco- nomical that people could buy them for their own personal or business use. In 1981, IBM, the world’s largest computer vendor, introduced the IBM Personal Computer. This quick- ly legitimized personal computing in business, industry and government organizations, where IBM mainframes were heavily used.

These computers were for the most part “stand-alone” units—people transported disks back and forth between them to share information (this was often called “sneak- ernet”). Although early personal computers were not powerful enough to timeshare several users, these machines could be linked together in computer networks, sometimes over telephone lines and sometimes in local area networks (LANs) within an organization. This led to the phenomenon of distributed computing, in which an organization’s computing, instead of being performed only at some central computer installation, is distributed over networks to the sites where the organization’s work is performed. Personal computers were powerful enough to handle the computing requirements of individual users as well as the basic communications tasks of passing information between computers electronically.

Today’s personal computers are as powerful as the million-dollar machines of just a few decades ago. The most powerful desktop machines—called workstations—provide individual users with enormous capabilities. Information is shared easily across computer networks, where computers called servers (file servers, database servers, web servers, etc.) offer data storage and other capabilities that may be used by client computers distributed throughout the network, hence the term client/server computing. Today’s popular oper- ating systems, such as UNIX, Linux, Mac OS X and Microsoft’s Windows-based systems, provide the kinds of capabilities discussed in this section.