Computer systems can be categorized in several ways, including by size, functionality, and type. Mainframe computers are large systems used by large organizations for critical tasks like data processing. Mini computers are mid-sized systems between mainframes and microcomputers. Microcomputers, when equipped with a keyboard, mouse and monitor become personal computers. Personal computers include desktops intended for single location use as well as laptops optimized for mobile use. Tablets are touchscreen mobile computers while wearables are computers worn on the body. Other computer types include servers which provide resources to client machines on a network, and supercomputers capable of highly complex calculations. Operating systems manage basic computer functions and security, and can be classified as multi-user, multiprocessing,

1. UNDERSTANDING
COMPUTER

2. Computer is one of the most brilliant
inventions of mankind. Thanks to the
computer technology, we were able
to achieve storage and processing to
huge amounts of data; we could rest
our brains by employing computer
memory capacities for storing
information
-Speed up daily work
-Carry out critical transactions
-Achieve accuracy and precision in work.

3. DIFFERENT TYPES OF COMPUTERS
Based on the operational principle of computers, they are categorized as analog,
digital and hybrid computers.
ANALOG COMPUTERS
These are almost extinct today. These are different from a digital computer because an
analog computer can only perform several mathematical operations simultaneously. It
uses continues variables for mathematical operations and utilizes mechanical or
electrical energy.

4. DIGITAL COMPUTERS
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 in these computers is represented as a
series of 0s and 1s. Digital computers are suitable for complex computations and have
higher processing speeds.. They are programmable.

5. HYBRID COMPUTERS
These are combination of both digital and analog computers. In this type of computers, the
digital segments perform process control by conversation of analog signals to digital
ones.

6. Classificationof Computers
MAINFRAME COMPUTERS
Large organizations use mainframes for highly critical applications such as bulk data
processing and ERP (Enterprise Resource Planning) Most of the mainframe computers
have the capacities to host multiple operating systems and operate as a number of
virtual machines and can substitute for several small servers.
The following are the classification of the different types of computers
based on their sizes and functionalities..

7. MINI COMPUTERS
In terms of size and processing capacity,
minicomputers lie between mainframes and
minicomputers. 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.

8. SERVERS
They are computers designed to provide services to
client machines in a computer network. 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 crash.

9. SUPER COMPUTER
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.

10. MICROCOMPUTERS
A computer with a microprocessor and its central processing unit it 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. These computers can fit on desks or tables and
prove to be the best choice for single-user tasks.

11. Desktops
DESKTOP COMPUTER
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.

12. Laptops
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.

13. Types of Personal Computer

14. Net books
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.

15. PDA (Personal Digital Assistants)
It is a handheld computer and popularly known as 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 smart phones. Most of them can
access the Internet by means of Bluetooth or Wi-Fi communication

16. TABLET COMPUTERS
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 digital pen. Apple’s iPod redefined the class of tablet computers

17. Wearable Computers
These computers can be worn on the body and are often used in the study of
behavior modeling and human health.

34. DIRECTION: Identify the type of computer being describe in the following
sentences and write your answer on a 1/2 sheet of paper.
____ 1. These are mobile computers that are vey handy to use.
____ 2. They are computers designed to provide services to client machines in a
computer network.
____ 3. They are also called mid-range systems or workstations.
____ 4. A computer with a microprocessor and its central processing unit.
____ 5. They fall in the category of laptops, but are inexpensive and relatively
smaller size.
____ 6. A type of computer which is intended to used on a single location.
____ 7. They use digital circuits and are designed to operate on two states,
namely bits 0 and 1.
____ 8. Computers that have capacities to host multiple operating systems and
operate as a number of virtual machines and can use substitute for
several small servers.
____ 9. It is a handheld computer and popularly known as a palmtop.
____ 10. These computers can be worn on the body and are often used in the
study of behavior modeling and a human health.

36. COMPUTER SYSTEMS, DEVICES AND
PERIPHERALS
WHAT IS AN OPERATING SYSTEM?
> The most important program that runs on a computer.
> Performs basic tasks, such as recognizing input from the keyboard,
sending output to the display screen, keeping track of files
and directories on the disk, and controlling peripheral devices such as disk
drives and printers.
>Responsible for security, ensuring that unauthorized users do not
access the system

37. Operating System can be classified as follows:
Multi-user: Allow two or more users to run programs at the same time.
Some operating systems permit hundreds or even thousands of concurrent
users.
Linux
Unix
Windows 2000

38. Multiprocessing: Supports running a program on more than one CPU.
Linux
Unix
Windows 2000

39. Multitasking: Allows more than one program to run concurrently.
Unix
Windows 7 and Windows multi point

40. Multithreading: Allows different parts of a single program to run
concurrently.
Linux
Unix
Windows 2000 and
Windows 7

41. Real Time: Responds to input instantly. General-purpose operating systems,
such as DOS and UNIX, are not real-time.

42. Microsoft Operating System
Windows 1.0 (1985)
Windows 2.0 (1987)
Windows 3.x (1990, 1992)
Windows 95 (1995)
Windows 98 (1998)
Windows 2000 (2000)
Windows ME (2000)
Windows XP (2001)
Windows Vista (2006)
Windows 7 (2009)
Windows 8 (2012)
Windows 8.1 (2013)
Windows 10 (2015)
Windows 10 (Anniversary Update) (2016

44. DIRECTION: Identify the type of operating system being describe in the following sentences
and write your answer on a 1/4 sheet of paper.
_____ 1. Allows more than one program to run concurrently.
_____ 2. Responds to input instantly.
_____ 3. Allow two or more users to run programs at the same time.
_____ 4. Allows different parts of a single program to run concurrently.
_____ 5. Supports running a program on more than one CPU.
_____ 6. The latest version of Microsoft Office operating system.
_____ 7. What is the logo of the LINUX operating system.
_____ 8. The successor of windows 7.
_____ 9. What is the most important program that runs on a computer?
_____ 10. Other operating system aside from LINUX and Microsoft OS?