Classification of computers
Computers may be compared on
the basis of cost, capacity (memory size, data word length, size of secondary
storage) and performance (speed).
They may be classed broadly as
are very large, often filling an entire room. They can
store enormous amount of information, can perform many tasks at the same time,
can communicate with many users at the same time, and are very expensive. The
price of a mainframe computer frequently runs into the millions of dollars.
Mainframe computers usually have many terminals connected to them. These
terminals look like small computers but they are only devices used to send and
receive information from the actual computer using wires. Terminals can be
located in the same room with the mainframe computer, but they can also be in
different rooms, buildings, or cities. Large businesses, government agencies,
and universities usually use this type of computer.
Point to be remember: -
Large number crunches
Multi-user e.g. transaction processing for a whole company
E.g. IBM, Fujitsu
are much smaller than mainframe computers and they are also
much less expensive. The cost of these computers can vary from a few thousand
dollars to several hundred thousand dollars. They possess most of the features
found on mainframe computers, but on a more limited scale. They can still have
many terminals, but not as many as the mainframes. They can store a tremendous
amount of information, but again usually not as much as the mainframe.
and small businesses typically use these computers.
Point to be remember :-
Small multi-user host
Used by several people in a department e.g. VAX
the types of computers, which are generally used in colle.g.es and institute
for teaching purpose. These computers are usually divided into desktop models
and laptop models. They are terribly limited in what they can do when compared
to the larger models discussed above because they can only be used by one
person at a time, they are much slower than the larger computers, and they can
not store nearly as much information, but they are excellent when used in small
businesses, homes, and school classrooms. These computers are inexpensive and
easy to use.
They have become an indispensable part of modern life.
Points to remember :-
General purpose computers
Used by only one person
Desktop size e.g. IBM PC, Mac.
Points to remember
E.g. Sun, Silicon
solve very complex calculations
processors operating simultaneously
e.g. Cray, Fujitsu