EMainframe computers:
§Are large-sized, powerful multi-user computers that can support
concurrent programs.
§That means, they can perform different
actions or ‘processes’ at the same time.
§Mainframe computers can be used by as many as
hundreds or thousands of users at the same time.
§Large organizations may use a mainframe
computer to execute large-scale processes such as processing the organization's
payroll.
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| Mainframe computers |
§Examples:
IBM’s ES000, VAX 8000 and CDC 6600.
E Mini-Computers:
§Are mid-sized multi-processing computers.
§Again, they can perform several actions at the same time and
can support from 4 to 200 users simultaneously.
§In recent years the distinction between mini-computers and
small mainframes has become blurred.
§Often the distinction depends upon how the manufacturer wants
to market its machines.
§ Organizations may use a mini-computer for
such tasks as managing the information in a small financial system or
maintaining a small database of information about registrations or
applications.
§ Examples: PDP 11, VAX 7500, IBM(8000 series).
EWorkstation:
§Are powerful, single-user computers.
§They have the capacity to store and process
large quantities of data, but they are only used by one person at a time.
§However, workstations are typically linked
together to form a computer network
§called a local area network, which means that
several people, such as staff in an office, can communicate with each other and
share electronic files and data.
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| workstation |
§A workstation is similar to a personal
computer but is more powerful and often comes with a higher-quality monitor.
§In terms of computing power, workstations lie
in between personal computers and mini-computers.
§Workstations commonly support applications
that require relatively high-quality graphics capabilities and a lot of memory,
such as desktop publishing, software development and engineering applications.
Personal
computers:
•(PCs), also called microcomputers, are the
most popular type of computer in use today.
•The PC is a small-sized, relatively
inexpensive computer designed for an individual user.
•Today, the world of PCs is basically divided
between IBM-compatible and Macintosh-compatible machines, named after the two
computer manufacturers.
•Computers may be called ‘desktop’ computers,
which stay on the desk, or ‘laptop’ computers, which are lightweight and
portable.
 |
| Personal computer |
•Organizations and individuals use PCs for a
wide range of tasks, including word processing, accounting, desktop publishing,
preparation and delivery of presentations, organization of spreadsheets and
database management.
§Supercomputers are fast because they are
really many computers working together.
§Supercomputers were introduced in the 1960's
as the world's most advanced computer.
§These computers were used for complex
calculations such as forecasting weather and quantum physics.
§Today, supercomputers are one of a kind; they
are fast and very advanced.
 |
| SuperComputer |
§The term supercomputer is always evolving as
tomorrow's normal computers are today's supercomputer
§Examples:
CRAY-3, Cyber 205 and PARAM.
Microcontroller:
§Microcontrollers are mini computers that
enable the user to store data, do simple commands and tasks, with little or no
user interaction with the processor.
§These single circuit devices have minimal
memory and program length but can be integrated with other processors for more
complex functionality.
§Many such systems are known as Embedded
Systems. Examples of embedded systems include Smart phones or car safety
systems.
§Microcontrollers are important, they are used
everyday in devices such as appliances and automobiles.
Server:
§Similar to mainframes in that they serve many
uses with the main difference that the users (called clients) do their own
processing usually.
§The server processes are devoted to sharing
files and managing log on rights.
§A server is a central computer that contains
collections of data and programs. Also called a network server, this system
allows all connected users to share and store electronic data and applications.
§Two important types of servers are file
servers and application servers.
