A computer is one of the most brilliant inventions of mankind. Thanks to computer technology, we were
able to achieve storage and processing of huge amounts of data; we could rest our brains by employing
computer memory capacities for storage of information. Owing to computers, we have been able speed up
daily work, carry out critical transactions and achieve accuracy and precision at work. Computers of the
earlier times were of the size of a large room and were required to consume huge amounts of electric
power. However, with the advancing technology, computers have shrunk to the size of a small watch.
Depending on the processing power and size of computers, they have been classified under various types.
Let us look at the classification of computers.
Based on the operational principle of computers, they are categorized as analog
: These are almost extinct today. These are different from a digital computer because an analog computer can perform several mathematical operations simultaneously. It uses continuous variables
for mathematical operations and utilizes mechanical or electrical energy.
: They use digital circuits and are designed to operate on two states, namely bits 0 and
1. They are analogous to states ON and OFF. Data on these computers is represented as a series of 0s and
1s. Digital computers are suitable for complex computation and have higher processing speeds. They are
programmable. Digital computers are either general purpose computers or special purpose ones. General
purpose computers, as their name suggests, are designed for specific types of data processing while general
purpose computers are meant for general use.
: These computers are a combination of both digital and analog computers. In this type
of computers, the digital segments perform process control by conversion of analog signals to digital ones.
Based on Sizes and Processing Powers
This was the classification of computers based on their style of functioning. Following is a classification of
the different types of computers based on their sizes and processing powers.
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.
A computer with a microprocessor and its central processing unit is known as a
microcomputer. They do not occupy space as much as mainframes do. When supplemented with a
keyboard and a mouse, microcomputers can be called personal computers. A monitor, a keyboard and
other similar input-output devices, computer memory in the form of RAM and a power supply unit come
packaged in a microcomputer. These computers can fit on desks or tables and prove to be the best choice
for single-user tasks.
Personal computers come in different forms such as desktops
and personal digital assistants
. Let us look at each of these types of computers.
: A desktop is intended to be used on a single location. The spare parts of a desktop computer are readily available at relatively lower costs. Power consumption is not as critical as that in laptops. Desktops
are widely popular for daily use in the workplace and households.
: Similar in operation to desktops, laptop computers are miniaturized and optimized for mobile
use. Laptops run on a single battery or an external adapter that charges the computer batteries. They are
enabled with an inbuilt keyboard, touch pad acting as a mouse and a liquid crystal display. Their
portability and capacity to operate on battery power have proven to be of great help to mobile users.
: They fall in the category of laptops, but are inexpensive and relatively smaller in size. They
had a smaller feature set and lesser capacities in comparison to regular laptops, at the time they came into
the market. But with passing time, netbooks too began featuring almost everything that notebooks had. By
the end of 2008, netbooks had begun to overtake notebooks in terms of market share and sales.
Personal Digital Assistants (PDAs)
: It is a handheld computer and popularly known as a palmtop. It has a
touch screen and a memory card for storage of data. PDAs can also be used as portable audio players, web
browsers and smartphones. Most of them can access the Internet by means of Bluetooth or Wi-Fi
: In terms of size and processing capacity, minicomputers lie in between mainframes and
microcomputers. Minicomputers are also called mid-range systems or workstations. The term began to be
popularly used in the 1960s to refer to relatively smaller third generation computers. They took up the
space that would be needed for a refrigerator or two and used transistor and core memory technologies.
The 12-bit PDP-8 minicomputer of the Digital Equipment Corporation was the first successful
: They are computers designed to provide services to client machines in a computer network. They
have larger storage capacities and powerful processors. Running on them are programs that serve client
requests and allocate resources like memory and time to client machines. Usually they are very large in
size, as they have large processors and many hard drives. They are designed to be fail-safe and resistant to
: The highly calculation-intensive tasks can be effectively performed by means of
supercomputers. Quantum physics, mechanics, weather forecasting, molecular theory are best studied by
means of supercomputers. Their ability of parallel processing and their well-designed memory hierarchy
give the supercomputers, large transaction processing powers.
: A record-setting step in the evolution of computers was the creation of wearable
computers. These computers can be worn on the body and are often used in the study of behaviour
modelling and human health. Military and health professionals have incorporated wearable computers into
their daily routine, as a part of such studies. When the users' hands and sensory organs are engaged in other
activities, wearable computers are of great help in tracking human actions. Wearable computers do not
have to be turned on and off and remain in operation without user intervention.
: Tablets are mobile computers that are very handy to use. They use the touch screen
technology. Tablets come with an onscreen keyboard or use a stylus or a digital pen. Apple‘s iPod
redefined the class of tablet computers.