A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe. The distinction between small mainframes and minicomputers is vague, depending really on how the manufacturer wants to market its machines.
IBM System/390 site This IBM site offers news, products and services, marketing and network information, and developer solutions for the System/390.
Mainframe Service Providers home page MainFrame Service Providers offers IBM S/390 hardware and support services. Their home page provides links to a company profile, technology information and news, and service offerings.
