A computer is an electronic device that processes and stores data. There are several types of computers including microcomputers like personal computers and portable computers like laptops and tablets. Other types are workstations, minicomputers, mainframe computers, supercomputers, and wearable computers. Microcomputers are the most commonly used type and include personal computers designed for individual use and portable computers that can be easily moved.

1. WHAT IS
COMPUTER?

2. DEFINITIONS OF COMPUTER:
• A computer is an electronic device that
helps people perform different task.
• An electronic device for the storage and
processing of information.
• A programmable machine that inputs,
processes and outputs data.
• An electronic device that stores, retrieves,
and processes data, and can be
programmed with instructions.
• In general, a device that uses digital
technology to process and manipulate
information.

3. TYPES OF COMPUTERS
• 1. Microcomputers
• 2. Workstation
• 3. Minicomputers
• 4. Mainframe Computers
• 5. Supercomputers
• 6. Wearable Computers

4. 1. Microcomputers
• The term microcomputer is
generally synonymous with
personal computer (PC), or
a computer that depends on
a microprocessor.
• Two classifications of microcomputer
a) Personal computer or PC
b) Portable computer

5. Personal computer or PC
• A small, relatively inexpensive computer
designed for an individual user. In price,
personal computers range anywhere from
a few hundred dollars to thousands of
dollars. All are based on the
microprocessor technology that enables
manufacturers to put an entire CPU on
one chip. Businesses use personal
computers for word processing,
accounting, desktop publishing, and for
running spreadsheet and database
management applications. At home, the
most popular use for personal computers
is for playing games

6. Portable computer
• A portable computer is a computer
that is designed to be moved from
one place to another (in other
words, it is a computer that is
portable). Portable computers, by
their nature, are microcomputers.
These includes laptops or
notebook, sub-notebooks, tablet
computer and personal digital
assistant.

7. Types of Portable Computer
 i. Laptop/Notebook Computer. Laptop
computers have similar computing power to
personal computers, but are much lighter and
portable. Laptops have a removeable,
chargeable battery pack so that the user
does not always require a mains electricity
supply for its` use.

8.  ii. Sub-notebook Computer. A
portable computer that is slightly
lighter and smaller than a full-
sized notebook computer.
Typically, subnotebook computers
have a smaller keyboard and
screen, but are otherwise
equivalent to notebook computers.

9.  iii. PDA or Personal Digital Assistant. Personal data
assistants (PDAs) are handheld computers that were
originally designed as personal organizers, but became much
more versatile over the years. PDAs are also known as
pocket computers or palmtop computers. PDAs have
many uses: calculation, use as a clock and calendar, playing
computer games, accessing the Internet, sending and
receiving E-mails, video recording, typewriting and word
processing, use as an address book, making and writing on
spreadsheets, use as a radio or stereo, recording survey
responses, and Global Positioning System (GPS). Newer
PDAs also have both color screens and audio capabilities,
enabling them to be used as mobile phones (smartphones),
web browsers, or portable media players. Many PDAs can
access the Internet, intranets or extranets via Wi-Fi, or
Wireless Wide-Area Networks (WWANs). One of the most
significant PDA characteristics is the presence of a touch
screen.

10. iv. Tablet PC. A Tablet PC is a notebook- or slate-
shaped mobile computer. Its touch screen or
digitizing tablet technology allows the user to
operate the computer with a stylus or digital pen, or
a fingertip, instead of a keyboard or mouse. The
computer is linked to a network using a wireless or
wired link. The form factor offers a more mobile way
to interact with a computer. Tablet PCs are often
used where normal notebooks are impractical or
unwieldy, or do not provide the needed functionality.

11. 2. Workstation
• A desktop computer that has
a more powerful processor,
additional memory and
enhanced capabilities for
performing a special group of
task, such as 3D Graphics or
game development.

12. 3. Minicomputers
• Midsized computer. In size and
power, minicomputers lie between
workstations and mainframes. In
the past decade, the distinction
between large minicomputers and
small mainframes has blurred,
however, as has the distinction
between small minicomputers and
workstations. But in general, a
minicomputer is a multiprocessing
system capable of supporting from
4 to about 200 users
simultaneously.

13. 4. Mainframe Computers
• 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.

14. 5. Supercomputers
• The fastest type of computer. Supercomputers
are very expensive and are employed for
specialized applications that require immense
amounts of mathematical calculations. For
example, weather forecasting requires a
supercomputer. Other uses of supercomputers
include animated graphics, fluid dynamic
calculations, nuclear energy research, and
petroleum exploration.
• The chief difference between a supercomputer
and a mainframe is that a supercomputer
channels all its power into executing a few
programs as fast as possible, whereas a
mainframe uses its power to execute many
programs concurrently

15. 6. Wearable Computers
• The latest trend in
computing is wearable
computers. Essentially,
common computer
applications (e-mail,
database, multimedia,
calendar/scheduler) are
integrated into watches,
cell phones, visors and
even clothing!