Mainframe computers are used in large organizations such as insurance companies and banks, where many people frequently need to use the same data.
In a traditional mainframe computer environment, each
user accesses the mainframe's resources
through a device called a terminal (see Fig. 1
Fig. 1: Mainframe Computer.
Large organizations use mainframes for highly critical applications such as bulk
data processing and ERP. Most of the mainframe computers have capacities to host multiple operating
systems and operate as a number of virtual machines. They can substitute for several small servers.
There are two kinds of terminals in mainframe computers
A dumb terminal
does not process or store data; it is simply an input/output (I/O ) device that functions as a window
into a computer located somewhere else.
An intelligent terminal
can perform some
processing operations, but it usually does
not have any storage. In some mainframe computer
environments, however, workers can use a
standard personal computer to access the
Fig. 2: Mainframe computers are housed alone in special rooms, away from their user.
Mainframe computers are large, powerful systems (sec Fig. 2
). The largest mainframe computer can handle the processing needs of thousands of users at any given moment. But what these systems offer in power, they lack in flexibility. Most
mainframe computer systems are designed to handle only a specific set of tasks. In your
state's Department of Motor Vehicles, for example, a mainframe computer system is probably devoted to storing information about drivers, vehicles, and driver's licenses, but little or nothing else. By limiting the number of tasks the system must perform, administrators preserve as much power as possible for
You may have interacted with a mainframe computer system without even knowing it. For example, if you have ever visited an airline's Web site to reserve a
seat on a flight, you probably have
conducted a transaction with a mainframe computer.