Introduction to Computer

Computer
A computer is any electronic device that manipulates data to give desired results. It operates under
the control of instructions stored in its own memory that can accept data (input), process the data
according to specified rules, produce information (output), and store the information for future use.

Processing

Input Output

Computer Components
Any kind of computer consists of HARDWARE and SOFTWARE.
Computer Hardware:

Computer hardware is the collection of physical elements that constitutes a computer system.
Computer hardware refers to the physical parts or components of a computer such as the monitor,
mouse, keyboard, computer data storage, hard drive disk (HDD), system unit (graphic cards, sound
cards, memory, motherboard and chips), etc. all of which are physical objects that can be touched.

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Computer Hardware is further divided into input and output devices:
Input Devices:
Input device is any piece of computer hardware equipment to provide data and control signals to an
information processing system such as a computer or other information appliance.
Input devices translate data from that humans understand to one that the computer can work with.
Most common are keyboard and mouse

Example of Input Devices:

1. Keyboard 2. Mouse (pointing device) 3. Microphone
4. Touch screen 5. Scanner 6. Webcam
7. Touchpads 8. MIDI keyboard
10. Graphics Tablets 11. Cameras 12. Pen Input
13. Video Capture Hardware 14. Microphone 15. Trackballs
16. Barcode reader 17. Digital camera 18. Joystick
19. Gamepad 20. Electronic Whiteboard

Note: The most common use keyboard is the QWERTY keyboard. Generally standard Keyboard
has 104 keys.

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Central Processing Unit (CPU)/ Central Unit
A CPU is brain of a computer. It is responsible for all functions and processes. Regarding computing
power, the CPU is the most important element of a computer system.

Central Processing Unit (CPU) - controls and co-ordinates computer components.

• It performs all calculations and all decisions.
• It controls and co-ordinates all units of the computer
• It interprets instructions of a program
• It stores data temporarily and monitors external requests.

The CPU is sub-divided into the following sub-system.

(i) Control unit
(ii) Arithmetic and logical unit
(iii) Memory unit:
(a) Primary storage
(b) Secondary storage.

Control unit

The control unit instructs the computer how to carry out program instructions. It directs the flow of
data between memory and arithmetic logical unit.

The input unit does not know when to receive data and where to put the data in the storage unit after
receiving it similarly, the control unit instructs the input unit where to store the data after receiving it
from the user.

In the same way, it controls the flow of data and instructions from the storage unit to

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ALU during program execution the control unit fetches instructions from the primary memory,
decodes them to determine the operations required, and then sets up instruction execution.

For example: To add two numbers or to read a character from a keyboard. A number registers are
associated with the control unit.

Arithmetic & Logical Unit

Arithmetic and logical unit performs all the arithmetic and logical operations. Arithmetic operations
like logic gates, logs, addition, subtraction, multiplication and logical operations, such as comparisons
are performed in ALU.

All calculations are performed in the arithmetic and logical unit (ALU) of the computer ALU also
does comparisons and take decision.

Example: it can check if the number 𝒙 is less than equal to or greater than the number y. once the
calculations or the logical operation is performed by ALU, then the result is transferred to the storage
unit.

Memory unit

Memory is the part of computer which holds data for processing and other information it is also called
as main memory or primary memory.

A device that stores program instructions or data used by the CPU when performing a given function.

Memory is a device, which is used to store information temporally/permanently, it is the place where
the information is safe kept. Secondary memory, such as disk storage, is functionality considered I/O
because it is accessed through the I/O system.

(a) Primary storage

The primary storage is also called as “main memory” stores and access information very
fast. This is generally used to hold the program being currently executed in the computer,
the data being received from the input unit, the intermediate and final results of the
program. Primary storage is also known as system memory, internal, temporary and
“RAM”

▪ Installed on the main computer board (motherboard)

▪ Typically comprised of ICs (integrated circuits)

▪ Fast access – usually in the order of nano seconds

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 (b) Secondary storage

The secondary storage is also known as Auxiliary Storage it may store several programs,
documents, databases etc.

The program that we want to run on the computer is first transferred to the primary memory
before it can run. Similarly, after running the program if need to save the result, we will
transfer them to the secondary storage.

The secondary memory is slower and cheaper than the primary memory. Some of the
commonly used secondary memory devices are Floppy diskette, Zip diskette, Hard disk
and Magnetic disks and Tapes etc.

Output devices:

An output device is any piece of computer hardware equipment used to communicate the results of
data processing carried out by an information processing system (such as a computer) which
converts the electronically generated information into human readable form.

Example on Output Devices:

1. Monitor 2. LCD Projection Panels
3. Printers (all types) 4. Computer Output Microfilm (COM)
5. Plotters 6. Speaker(s)
7. Projector

Note Basic types of monitors are Cathode Ray Tube (CRT). B. Liquid Crystal Displays (LCD).
light-emitting diode (LED).
Printer types: 1-Laser Printer. 2-Ink Jet Printer. 3-Dot Matrix Printer

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Essential Computer components And Non-Essential Computer components

Essential components are devices which a computer cannot function without while non-essential
components are those which a computer can function without.

Essential Components Non-Essential Components

Central Unit Keyboard or mouse

Monitor Speakers

Keyboard or Mouse Microphone

Webcam

Computer Software
Software is a generic term for organized collections of computer data and instructions, often broken
into two major categories: system software that provides the basic non-task-specific functions of the
computer, and application software which is used by users to accomplish specific tasks.

Software Types
System software is responsible for controlling, integrating, and managing the individual hardware
components of a computer system so that other software and the users of the system see it as a
functional unit without having to be concerned with the low-level details such as transferring data
from memory to disk, or rendering text onto a display. Generally, system software consists of an
operating system and some fundamental utilities such as disk formatters, file managers, display
managers, text editors, user authentication (login) and management tools, and networking and device
control software.

Application software is used to accomplish specific tasks other than just running the computer
system. Application software may consist of a single program, such as an image viewer; a small
collection of programs (often called a software package) that work closely together to accomplish a
task, such as a spreadsheet or text processing system; a larger collection (often called a software suite)
of related but independent programs and packages that have a common user interface or shared data
format, such as Microsoft Office, which consists of closely integrated word processor, spreadsheet,
database, etc.; or a software system, such as a database management system, which is a collection of
fundamental programs that may provide some service to a variety of other independent applications.

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 Comparison Application Software and System Software

System Software Application Software

Computer software, or just software is a
general term primarily used for digitally
Application software, also known as an
stored data such as computer programs
application or an "app", is computer
and other kinds of information read and
software designed to help the user to
written by computers. App comes under
perform specific tasks.
computer software though it has a wide
scope now.
Example: 1) Opera (Web Browser)
1) Microsoft Windows 2) Microsoft Word (Word
Processing)
2) Linux 3) Microsoft Excel (Spreadsheet software)
3) Unix 4) MySQL (Database Software)
4) Mac OSX 5) Microsoft PowerPoint (Presentation
5) DOS Software)
6) Adobe Photoshop (Graphics Software)
Interaction: Generally, users do not interact with Users always interact with application
system software as it works in the software while doing different activities.
background.
Dependency: System software can run independently Application software cannot run without
of the application software. the presence of the system software.