Introduction
In this lesson,
you will learn about hardware and software courses in depth. Physically a
computer is a combination of different hardware devices such as a System
Unit/CPU, Monitor, Keyboard, Mouse, Printer, etc. And you will also understand
software basics and its types, the operating system, its basic functions,
utility programs, device drivers, and different types of application software.
Hardware Basics of a Computer
Physically a computer is a combination of different hardware devices such as a System Unit/CPU, Monitor, Keyboard, Mouse, Printer, etc. You will learn about the system unit and its internal components such as Motherboard, Processor, RAM, ROM, Expansion Cards, Expansion Slots, etc. You will also learn briefly about cutting-edge technologies such as Bar-code Reader, Fingerprint, and Robots.
Introduction of Hardware
In the previous post Introduction to Computer, we already have the definition of a computer and its basic components, we will review them here again.
“A computer is an electronic machine which solved our problems”
Or
“A computer is an electronic machine which processes raw data (input) into meaningful information (output) and also stores output for later use.”
A computer works with the help of its components. The components of a computer consist of hardware and software.
Computer Components and their Functions
The computer has main two parts as are under:
- Hardware
- Software
Hardware
The physical part of the computer that we can see and touch is known as 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 a 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. These include the input and output devices as well as the system unit.
- Input Devices
- Output Devices
- Storage Devices
- Communication Devices
you will learn about hardware and software courses in depth. Physically a
computer is a combination of different hardware devices such as a System
Unit/CPU, Monitor, Keyboard, Mouse, Printer, etc. And you will also understand
software basics and its types, the operating system, its basic functions,
utility programs, device drivers, and different types of application software.
Computer Components and their Functions
The computer has main two parts as are under:
- Hardware
- Software
Hardware
- Input Devices
- Output Devices
- Storage Devices
- Communication Devices
Input Devices
The input device is any peripheral (a 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 what humans understand to one that the computer can work with. The most common are keyboard and mouse.
Mouse
Without a way to communicate with the computer, the computer would be useless. You need an input device for this. Basically
Keyboard
Like a mouse, a keyboard is an
input device that allows you to talk to your computer. The keyboard is similar
to a typewriter keyboard and is easy to recognize. If your typewriter is older
than you, look for components that are covered with keys with letters, numbers,
and symbols. If you’ve used a typewriter, you’re probably familiar with many of
the keys on your keyboard. In either case, the alphanumerical, symbols, and
punctuation keys are self-explanatory. Then check the remaining keys that apply
to only one (101 and 104) keyboard.
Other
Examples of Input Devices
Digital Camera: A digital camera lets you take pictures that you can transfer to a computer. Once you have transferred your pictures you can print them, insert them in a word processing document, or send them in an E-mail message.
Scanner: A scanner is like a copier. Scanner instead of making a copy converts the image to digital information and saves it on your computer.
Microphone: If your computer has a sound card (and most computers have one) you can plug in the microphone to digitally record sounds to your computer.
Joystick: Primarily used in computer games, are levers that move in all directions and typically control specific movements of the computer.
Light Pen: A light pen is an input device that uses a photosensitive detector to select objects on the display screen. A light pen is similar to a mouse, except that you can use the light pen to move the pointer and point the pen directly at the object to select an object on the display screen.
Webcam: A webcam is a video camera used in conjunction with a computer and its function is to stream audio and video of another person through a computer network internet. The webcam is built-in into the laptop computer. You can also make video calls from the webcam via the internet.
input device that allows you to talk to your computer. The keyboard is similar
to a typewriter keyboard and is easy to recognize. If your typewriter is older
than you, look for components that are covered with keys with letters, numbers,
and symbols. If you’ve used a typewriter, you’re probably familiar with many of
the keys on your keyboard. In either case, the alphanumerical, symbols, and
punctuation keys are self-explanatory. Then check the remaining keys that apply
to only one (101 and 104) keyboard.
Examples of Input Devices
Microphone: If your computer has a sound card (and most computers have one) you can plug in the microphone to digitally record sounds to your computer.
Joystick: Primarily used in computer games, are levers that move in all directions and typically control specific movements of the computer.
Light Pen: A light pen is an input device that uses a photosensitive detector to select objects on the display screen. A light pen is similar to a mouse, except that you can use the light pen to move the pointer and point the pen directly at the object to select an object on the display screen.
Output Devices
The actual components of the computer
that receive input are known as input devices. The CPU process the inputs and
response via the output devices. For output, there exist output devices. The
outputs below, which are the output devices and what they perform, are
described in depth.
- Monitors
- Printers
- Speakers
- Headphone
- Projector Multimedia
Monitors
A monitor or display is an electronic
visual display for computers. The monitor comprises the display device, circuitry,
and an enclosure. The size of a display is usually given as the distance
between two opposite screen corners.
The display screen varies in size from 5 to 30
inches. Output on a monitor is a soft copy, which means it is temporary and
available to the end user only until another display is requested. There are
some kinds of monitors, which are the following:
- Monochrome Monitors
- Color Monitor
- Flat Panel Monitors
- Touchscreen Monitors
Monochrome
Monitors
A monochrome monitor is a type of
computer display that was very common in the early days of computing, from the
1960s through the 1980s, before color monitors became popular. They are
still used today in some computerized cash register systems, amongst other
select applications.
Unlike color monitors, which display
text and graphics in multiple colors monochrome monitors have only one color of
phosphor (mono = one, chrome =color). All text and graphics are displayed in
that color.
Color Monitors
A display monitor that is capable of
displaying many colors. In contrast, a monochrome monitor can display only two
colors one for the background and one for the foreground. Color monitors
implement the RGB color model by using three different phosphors that appear
red, green, and blue when activated. By placing the phosphors directly next to
each other, and activating them with different intensities, color monitors can
create an unlimited number of colors. In practice, however, the real number of
colors that any monitor can display is controlled by the video adapter.
Flat
Panel Monitors
A flat panel monitor can refer to
either a computer or television monitor that does not use cathode ray tube
(CRT) technology, but commonly LCD or plasma technology. This allows the
monitor to have a thin profile, which is how the flat panel monitor gets its
name. Because of its lightweight, clarity, and digital technology, the flat
panel monitor has become the monitor of choice.
Laptop PCs use space-saving flat panel
monitors some less than ½ inches thick. Flat panel monitors use a variety of
technologies, the most common being Liquid Crystal Display (LCD) and Thin
Filament Technology (TFT). LCD displays are more expensive than passive matrix
displays therefore active matrix LCD displays are usually associated with high-end notebook PCs.
Touch
Screen Monitors
A touch screen is an electronic visual
display that can detect the presence and location of a touch within the display
area. The term generally refers to touch or contact with the display of the
device, by a finger or hand. Touch screens can also sense other passive
objects, such as a pen. However, if the object sensed is active, as with a
light pen, the term touch screen is generally not applicable. The ability to
interact physically with what is shown on a display (a form of “direct
manipulation”) typically indicates the presence of a touch screen.
The touch screen has two main
attributes. First, it enables one to interact with what is displayed directly
on the screen, where it is displayed, rather than indirectly with a mouse or
touchpad. Secondly, it lets one do so without requiring any intermediate
device, again, such as a stylus that needs to be held in the hand, such displays
can be attachment computers or, as terminals, to networks. They also play a prominent role in
the design of digital appliances such as personal digital assistants (PDAs),
satellite navigation devices, mobile phones, and video games.
Printers
The printer is also an output device. A printer is a peripheral device used to produce a hard copy of documents stored in
electronic form, usually on physical print media such as paper or
t4ransparencies. Many printers are primarily used as local peripherals and are
attached by a printer cable. In most new printers, a USB cable is used to
attach it to the computer.
There are two broad categories of printers, impact, and non-impact printers. In impact printers printing is achieved by pressing
the soled characters against a ribbon, which in turn prints the impression on
paper almost like a typewriter. A line of print is achieved by moving a print
head across the page. Here are some types of commonly used printers.
- Dot Matrix Printers
- Ink-Jet Printers
- Laser Printers
- Plotters
Dot
Matrix Printers
A dot matrix printer is an impact
printer. It is a type of computer printer with a print head that runs back and
forth, or in an up and down motion, on the page and prints by impact, striking
an ink-soaked cloth ribbon against the paper, much like the print mechanism on
a typewriter. Each dot is produced by a tiny metal rod, also called a “wire” or
“pin”, which is driven forward by the power of a tiny electromagnet or
solenoid.
The moving portion of the printer is called the print head. Most dot
matrix printers have a single vertical line of dot-making equipment on their
print heads, others have a few interleaved rows to improve dot density.
Print heads may have 9 to 24 pins. These pins are activated independently to
form a dotted character image as the print head moves horizontally across the
paper. The quality of the printed output increases with the number of dots in
the letter matrix.
Ink-Jet
Printers
A type of printer that works by
spraying ionized ink on a sheet of paper. Magnetized plates in the ink’s path
direct the ink onto the paper in the desired shapes. A typical ink-jet printer
provides a resolution of 300 dots per inch, although some newer models offer
higher resolutions.
In general, the price of ink-jet
printers is lower than that of laser printers. However, they are also
considerably slower. Another drawback of ink-jet printers is that they require
a special type of ink that does not smudge on inexpensive copier paper.
Because inkjet printers require
smaller mechanical parts than laser printers, they are especially popular as
portable printers. In addition, color ink-jet printers provide an inexpensive
way to print full-color documents.
Laser
Printers
A type of printer that utilized a
laser beam to produce an image on a drum. The light of the laser alters the
electrical charge on the drum wherever it hits. The drum is then rolled through
a reservoir of toner, which is picked up by the charged portions of the drum.
Finally, the toner is transferred to the paper through a combination of heat
and pressure. This is also the way copy machines work. Because an entire page
is transmitted to the drum before the toner is applied, laser printers are
sometimes called page printers. One of the main characteristics of laser
printers is their resolution (how many dots per inch they can print). The
available resolutions range from 300 dpi at the low end to 1200 dpi at the high
end.
Plotters
A device that draws pictures on paper
based on commands from a computer. Plotters differ from printers. Plotters draw
lines using a pen. As a result, they can produce continuous lines, whereas
printers can only simulate lines by printing a closely spaced series of dots.
Multicolor plotters use different colored pens to draw different colors. In
general, plotters are considerably more expensive than printers. They are used
in engineering applications where precision is mandatory.
Speaker
Speakers are also part of output
devices. These help user to get the audio output. Computer speakers range
widely in quality and in price. The computer speakers typically packaged with the computer systems are small plastic boxes.
Some of the slightly better computer
speakers have equalization features such as bass and treble controls, improving
their sound quality somewhat.
Projector
Multimedia
A video projector takes a video signal
and projects the corresponding image on a projection screen using a lens
system. All video projectors use a very bright light to project the image, and
most modern ones can correct any curves, blurriness, and other inconsistencies
through manual settings.
Video projectors are widely used for conference room
presentations, classroom training, home theatre, and live events applications.
Projectors are widely used in many schools and other educational institutes,
connected to an interactive white hoard to interactively teach pupils.
Storage
Devices
The device used for storage and
retrieval of data for later use is called storage devices. These devices
keep the data intact even when we turn off our computers. Storage devices are
commonly classified into two categories.
- Primary Storage
- Secondary Storage
Primary Storage
Primary storage usually refers to a
form of semiconductor storage known as random access memory (RAM) and sometimes
other forms of fast but temporary storage. To manipulate data within a computer
system, we must have a way of storing and retrieving it. Data and instructions
are stored temporarily during processing in Random Access Memory (RAM). RAM is
also known as Primary Storage.
Secondary Storage
Secondary storage also called
auxiliary storage or mass storage bolds data, instructions, and information for
future use. Secondary storage (or external memory) differs from primary storage
in that it is not a directory accessible by the CPU. The computer usually uses
its input/output channels to access secondary storage and transfers the desired
data. Secondary storage does not lose the data when the device is powered off.
It is nonvolatile.
Here are a few examples of secondary
storage devices:
- Magnetic Disks
- Compact Disc
- Magnetic Tape
Magnetics
Disks
Magnetic storage used different
patterns of magnetization on a magnetically coated surface to store
information. Magnetic storage is non-volatile. The information is accessed
using one or more read/write heads which may contain one or more recording
transducers. A read/write head only covers a part of the surface so that the
head or medium or both must be moved relative to another to access
data. In early computers, magnetic storage was also used for primary storage in
a form of magnetic drums or core memory. In modern computers, magnetic storage
takes these forms.
- Floppy Disk
- Hard Disk
- Magnetic Tape
Floppy
Disks
A floppy disk is a data storage medium
that is composed of a disk of thin, flexible magnetic storage medium enclosed
in a square or rectangular plastic shell. Floppy disks are read and written by
a floppy disk drive (FDD). The floppy disk was actually invented by IBM for
recording maintenance information about its mainframes for the service staff.
It was later used by personal computer manufacturers as a convenient way to
distribute software for sale. The 31/2 inch diskette comes in two capacities
720 KB and 1.44 MD. The two diskettes are the same size but have different disk
densities. Disk density refers to the number of bits that can be stored per
unit of area on the disk face surface.
Hard
Disk
A hard disk is part of a unit, often
called a “disk drive,” “hard drive,” or “hard disk drive,” that stores and provides
relatively quick access to large amounts of data on an electromagnetically
charged surface or set of surfaces. Today computers typically come with a hard
disk that contains several billion bytes (gigabytes) of storage.
A hard disk is really a set of stacked
“disks,” each of which, like phonograph records, has data recorded
electromagnetically in concentric circles or “tracks” on the disk. A “head”
(something like a phonograph arm but in a relatively fixed position) records
(writes) or reads the information on the tracks. Two heads, one on each side of
a disk, read or write the data as the disk spins. Each read or write operation
requires that data be located, which is an operation called a “seek”.
A hard disk or drive unit has a rotation
speed varying from 4500 to 7200 RPM. Hard disk manufacturers are working
continuously to achieve two objectives, to put more information in less disk
space and to enable a more rapid transfer of that information to and from RAM.
Generally, the 1 to 5 ¼ inch permanent hard disks have storage capacities from
240 MB to 200 MB.
Magnetic
Tape
A magnetically coated strip of plastic
on which data can be stored. Tapes for computers are similar to tapes used to
store music. Storing data on tapes is considerably cheaper than storing data on
disks. Tapes also have large storage capacities ranging from a few hundred
kilobytes to several gigabytes. Accessing data on tapes, however, is much
slower than accessing data on disks. Tapes are sequential access media, which
means that to get to a particular point on the tape, the tape must go through
all the preceding points. In contrast, disks are random access media because a
disk drive can access any point at random without passing through intervening
points.
Because tapes are so slow, they are
generally used only for long-term storage and backup. Data to be used regularly
is almost always kept on disk. Tapes are also used for transporting large
amounts of data.
CD-ROM
Short for Compact Disc- Read Only
Memory, a type of optical disk capable of storing large amounts of data up to
1GB, although the most common size is 650MB (megabytes). A single CD-ROM has
the storage capacity of 700 floppy disks, and enough memory to store about 300,000
text pages.
CD-ROMs are particularly well-suited to
information that requires large storage capacity. This includes large software
applications that support color, graphics, sound, and especially video.
USB
Flash Drive
The flash memory is usually of the
format of Erasable Electrical Programmable Memory. In contrast to Random
Access Memory, flash memory is also fast. It also retains the data even when
ether is a power failure. Flash memory is a non-volatile type of memory.
Flash memory has a great demand for its application to store data in mobile
phones as well as digital cameras and many other handheld devices. Almost
all the devices that are operated using a battery like the mp3 players, PDA,
and memory cards of various devices. This flash memory is available in
different memory formats with different access speeds.
Flash memory in the coming days will
give tough competition to the present types of memory storage devices. The
regular storage devices may include optical media like CD-ROM, tape storage
devices like floppy drives, etc. even though there are hard drives that use the
technology of flash memory devices. They are like pocket hard drives etc.
Currently, flash memory chips are being used extensively in digital
cameras, USB pen drives, and many other applications.
Computer Software
All computer
programs that we can see or work on are called software. Set of ordered instructions that enable a computer
to carry out a specific task. A program is prepared by first formulating the
task and then expressing it in an appropriate programming language. Following
are the basic types of software:
- System Software
- Application
Software
- Utility Programs
System Software
System software,
which consists of programs that control the operations of the computer and its
devices, serves as the interface between the user and the computer’s hardware.
These programs do not solve specific problems. They are general programs written
to assist humans in the use of the computer system by performing tasks such as
controlling all operations required to move data into and out of a computer and
all the steps in executing an application program. Types of system software are
the operating system and language processors etc.
Operating System
or Operating Software
An operating
system is an integrated set of programs that are used to manage the various
resources and overall operations of a computer system, it is designed to
support the activities of a computer installation. Its prime objective is to
improve the performance and efficiency of a computer system and increase the facility and ease with which as the system can be used. It also makes the computer
system user-friendly.
Every general
purposed computer must have an operating system to run other programs.
Operating systems perform 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.
Operating systems
can be classified as follows:
Multi User:
Allows two or more users to run programs at the same time. Some operating
systems permit hundreds or even thousands of concurrent users.
Multiprocessing:
Supports running a program on more than one CPU.
Multitasking:
Allows more than one program to run concurrently.
Multithreading:
Allows different parts of a single program to run concurrently.
Real-Time:
Response to input instantly. General purpose operating systems, such as DOS and
UNIX, are not real time.
The operating system
provides a software platform on top of which other programs, called application programs,
can run. The application programs must be written to run on top of a particular
operating system. Your choice of the operating system, therefore, determines to a
great extent the applications you can run. For PCs, the most popular operating
systems are DOS, OS/2, and Windows, but others are available, such as Linux.
As a user, you
normally interact with the operating system through a set of commands. For
example, the DOS operating system contains commands some of which are given
below:
Commands
Usage
DIR
This command is used to display the list of all
directories and subdirectories available.
CLS
This command is used to clear the screen.
MD
This command is used to make a directory.
CD
This command is used to change the directory.
EDIT
This command is used to invoke a text file.
COPY
This command is used to copy files from one place to
another place.
XCOPY
This command is used to copy all the files of a folder
from one place to another place.
DATE
This command is used to display the current date.
TIME
This command is used to display the current time.
VER
This command is used to display the version number of
DOS.
RENAME
This command is used to rename a file or directory.
The commands are
accepted and executed by a part of the operating system called the commands
processor or command line interpreter. Graphical user interfaces allow you to
enter commands by pointing and clicking at objects that appear on the screen.
Language
Processors
These are the
programs used to translate high-level language programs into low-level language
programs.
Compiler
A program that
translates source code into object code. The compiler derives its name from the
way it works, looking at the entire piece of source code and collecting and
reorganizing the instructions. Compilers require some time before an executable
program emerges. However, programs produced by compilers run much faster than
the same programs executed by an interpreter. Every high-level programming
language comes with a compiler. Because compilers translate source code into
object code, which is unique for each type of computer, many compilers are
available for the same language. For example, there is a FORTRAN compiler for
PCs and another for Apple Macintosh computers. In addition, the compiler
industry is quite competitive, so there are actually many compilers for each
language on each type of computer. More than a dozen companies develop and sell
C compilers for the PC.
Interpreter
A program that
translates instructions written in a high-level language into low-level language.
There are two ways to run programs written in a high-level language. The most
common is to compile the program, the other method is to pass the program
through an interpreter.
The interpreter
will take a long time for the program is long. The interpreter, on the other hand,
can immediately execute high-level programs. For this reason, interpreters are
sometimes used during the development of a program, when a programmer wants to
add small sections at a time and test them quickly. In addition, interpreters are often used in education because they allow students to program interactively.
Both interpreters
and compilers are available for most high-level languages. However, BASIC and
LISP are specially designed to be executed by an interpreter. In addition,
page description languages, such as PostScript, use an interpreter. Every
PostScript printer, for example, has a built-in interpreter that executes
PostScript instructions.
Assembler
This is a type of
translator. It also works in the same way as compiler and interpreter work. It
is a program, which translates an assembly language program to its machine
language equivalent.
Application
Software
A program or
group of programs designed for end users. Application software consists of
programs designed to perform specific tasks for users. Application software
sits on top of system software because it is unable to run without the
operating system and system utilities. Popular
application software includes word processing software, spreadsheet software,
database software, presentation software, and graphics software. Spreadsheet
software allows you to calculate numbers arranged in rows and columns and often
is used for budgeting, forecasting, and other financial tasks. Database software
is used to store data in an organized fashion as well as to retrieve,
manipulate and display that data in a meaningful form. Presentation software
allows you to create documents called slides that are used in making
presentations. These four applications often are sold together as a single unit
called a suite in which individual applications are packaged in the same box
and sold for a price that is significantly less than buying the applications
individually.
Utility Programs
A program that
performs a very specific task, is usually related to managing system resources.
These are the programs that are used to help the operating systems to smoothly run
a system. Operating systems contain a number of utilities for managing disk
drives, printers, and other devices.
Utilities differ
from applications mostly in terms of size, complexity, and function. For
example, word processors, spreadsheet programs, and database applications are
considered applications because they are large programs that perform a variety
of functions not directly related to managing computer resources.
Programming
Languages
Languages are a
communication medium through which we can express our feelings, thoughts, and
emotions to others.
The language
through which we can communicate with a computer is called computer language.
Computer languages are helpful for creating software and program.
Types of computer
languages
- Low-level
languages
- High-level
languages
- Low-level
languages
It is a language
of 0’s and 1’s. The word “low” refers to a call or nonexistent amount of
abstractions between the language and machine language, because of this, low-level languages are sometimes described as being “close to the hardware.” The circuitry
of a computer is wired in such a way that it immediately recognized the machine
language and converts it into the electrical signals needed to run the
computer. The computer can execute programs written in machine language very
fast. This is mainly because the CPU directly understands machine instructions
and no translation of the program is required.
High-level
Language
A programming language
such as C, FORTRAN, or Pascal enables a programmer to write programs that
are more or less independent of a particular type of computer. Such languages
are considered high level because they are closer to human languages and
farther from machine languages. In contrast, assembly languages are considered
low-level because they are very close to machine languages.
The main
advantage of high-level languages over low-level languages is that they are
easier to read, write and maintain. Ultimately, programs written in a high-level language
must be translated into machine language by a compiler or interpreter.
The first high-level programming languages were designed in the 1950s. Now there are dozens of
different languages including Ada, Algol, BASIC, COBOL, C, C++, FORTRAN, LISP, Pascal,
and Prolog.
Procedural Languages
Programmers could
write a single instruction instead of several cumbersome machine language
instructions. These early languages were procedure languages, requiring programmers to solve problems using traditional programming logic. Programmers’
writing in such languages must develop a proper order of actions in order to
solve the problem, based on knowledge of data processing and programming.
Contrast with non-procedural language.
Object Oriented Languages
A type of
programming in which programmers define not only the data type of a data
structure but also the types of operations (functions) that can be applied to
the data structure. In this way, the data structure becomes an object that
includes both data and functions. In addition, programmers can create
relationships between one object and another. For example, objects can inherit characteristics
from other objects.
One of the
principal advantages of object-oriented programming techniques over procedural
programming techniques is that they enable programmers to create modules that
do not need to be changed when a new type of object is added. A programmer can
simply create a new object that inherits many of its features from existing
objects. This makes object-oriented programs easier to modify.
To perform object-oriented programming, one needs an object-oriented programming language (OOPL),
Java, C++, and Smalltalk are three of the more popular languages, and there are
also object-oriented versions of Pascal.
Database Query Languages
These languages
are based on a special kind of database called a relational database. Many
database management programs in today’s computer world claim to be relational
but actually are not. In order for a database management program to truly use Structure
Query Languages (SQL), it must follow the relational
Conclusion
We have created
this post for the newbies who are beginners in the computer field. It is designed
to develop basic computer skills to enhance your knowledge. Also, you can review
our posts on “What is the computer”, “History of Computer”, “Classification of Computers”. If there is any kind of lack in this post or if liked it, please
comment to us. Thanks.
The actual components of the computer
that receive input are known as input devices. The CPU process the inputs and
response via the output devices. For output, there exist output devices. The
outputs below, which are the output devices and what they perform, are
described in depth.
- Monitors
- Printers
- Speakers
- Headphone
- Projector Multimedia
Monitors
A monitor or display is an electronic
visual display for computers. The monitor comprises the display device, circuitry,
and an enclosure. The size of a display is usually given as the distance
between two opposite screen corners.
The display screen varies in size from 5 to 30
inches. Output on a monitor is a soft copy, which means it is temporary and
available to the end user only until another display is requested. There are
some kinds of monitors, which are the following:
- Monochrome Monitors
- Color Monitor
- Flat Panel Monitors
- Touchscreen Monitors
Monochrome
Monitors
A monochrome monitor is a type of
computer display that was very common in the early days of computing, from the
1960s through the 1980s, before color monitors became popular. They are
still used today in some computerized cash register systems, amongst other
select applications.
Unlike color monitors, which display
text and graphics in multiple colors monochrome monitors have only one color of
phosphor (mono = one, chrome =color). All text and graphics are displayed in
that color.
Color Monitors
A display monitor that is capable of
displaying many colors. In contrast, a monochrome monitor can display only two
colors one for the background and one for the foreground. Color monitors
implement the RGB color model by using three different phosphors that appear
red, green, and blue when activated. By placing the phosphors directly next to
each other, and activating them with different intensities, color monitors can
create an unlimited number of colors. In practice, however, the real number of
colors that any monitor can display is controlled by the video adapter.
Flat
Panel Monitors
A flat panel monitor can refer to
either a computer or television monitor that does not use cathode ray tube
(CRT) technology, but commonly LCD or plasma technology. This allows the
monitor to have a thin profile, which is how the flat panel monitor gets its
name. Because of its lightweight, clarity, and digital technology, the flat
panel monitor has become the monitor of choice.
Laptop PCs use space-saving flat panel
monitors some less than ½ inches thick. Flat panel monitors use a variety of
technologies, the most common being Liquid Crystal Display (LCD) and Thin
Filament Technology (TFT). LCD displays are more expensive than passive matrix
displays therefore active matrix LCD displays are usually associated with high-end notebook PCs.
Touch
Screen Monitors
A touch screen is an electronic visual
display that can detect the presence and location of a touch within the display
area. The term generally refers to touch or contact with the display of the
device, by a finger or hand. Touch screens can also sense other passive
objects, such as a pen. However, if the object sensed is active, as with a
light pen, the term touch screen is generally not applicable. The ability to
interact physically with what is shown on a display (a form of “direct
manipulation”) typically indicates the presence of a touch screen.
The touch screen has two main
attributes. First, it enables one to interact with what is displayed directly
on the screen, where it is displayed, rather than indirectly with a mouse or
touchpad. Secondly, it lets one do so without requiring any intermediate
device, again, such as a stylus that needs to be held in the hand, such displays
can be attachment computers or, as terminals, to networks. They also play a prominent role in
the design of digital appliances such as personal digital assistants (PDAs),
satellite navigation devices, mobile phones, and video games.
Printers
The printer is also an output device. A printer is a peripheral device used to produce a hard copy of documents stored in
electronic form, usually on physical print media such as paper or
t4ransparencies. Many printers are primarily used as local peripherals and are
attached by a printer cable. In most new printers, a USB cable is used to
attach it to the computer.
There are two broad categories of printers, impact, and non-impact printers. In impact printers printing is achieved by pressing
the soled characters against a ribbon, which in turn prints the impression on
paper almost like a typewriter. A line of print is achieved by moving a print
head across the page. Here are some types of commonly used printers.
- Dot Matrix Printers
- Ink-Jet Printers
- Laser Printers
- Plotters
Dot
Matrix Printers
A dot matrix printer is an impact
printer. It is a type of computer printer with a print head that runs back and
forth, or in an up and down motion, on the page and prints by impact, striking
an ink-soaked cloth ribbon against the paper, much like the print mechanism on
a typewriter. Each dot is produced by a tiny metal rod, also called a “wire” or
“pin”, which is driven forward by the power of a tiny electromagnet or
solenoid.
The moving portion of the printer is called the print head. Most dot
matrix printers have a single vertical line of dot-making equipment on their
print heads, others have a few interleaved rows to improve dot density.
Print heads may have 9 to 24 pins. These pins are activated independently to
form a dotted character image as the print head moves horizontally across the
paper. The quality of the printed output increases with the number of dots in
the letter matrix.
Ink-Jet
Printers
A type of printer that works by
spraying ionized ink on a sheet of paper. Magnetized plates in the ink’s path
direct the ink onto the paper in the desired shapes. A typical ink-jet printer
provides a resolution of 300 dots per inch, although some newer models offer
higher resolutions.
In general, the price of ink-jet
printers is lower than that of laser printers. However, they are also
considerably slower. Another drawback of ink-jet printers is that they require
a special type of ink that does not smudge on inexpensive copier paper.
Because inkjet printers require
smaller mechanical parts than laser printers, they are especially popular as
portable printers. In addition, color ink-jet printers provide an inexpensive
way to print full-color documents.
Laser
Printers
A type of printer that utilized a
laser beam to produce an image on a drum. The light of the laser alters the
electrical charge on the drum wherever it hits. The drum is then rolled through
a reservoir of toner, which is picked up by the charged portions of the drum.
Finally, the toner is transferred to the paper through a combination of heat
and pressure. This is also the way copy machines work. Because an entire page
is transmitted to the drum before the toner is applied, laser printers are
sometimes called page printers. One of the main characteristics of laser
printers is their resolution (how many dots per inch they can print). The
available resolutions range from 300 dpi at the low end to 1200 dpi at the high
end.
Plotters
A device that draws pictures on paper
based on commands from a computer. Plotters differ from printers. Plotters draw
lines using a pen. As a result, they can produce continuous lines, whereas
printers can only simulate lines by printing a closely spaced series of dots.
Multicolor plotters use different colored pens to draw different colors. In
general, plotters are considerably more expensive than printers. They are used
in engineering applications where precision is mandatory.
Speaker
Speakers are also part of output
devices. These help user to get the audio output. Computer speakers range
widely in quality and in price. The computer speakers typically packaged with the computer systems are small plastic boxes.
Some of the slightly better computer
speakers have equalization features such as bass and treble controls, improving
their sound quality somewhat.
Projector
Multimedia
A video projector takes a video signal
and projects the corresponding image on a projection screen using a lens
system. All video projectors use a very bright light to project the image, and
most modern ones can correct any curves, blurriness, and other inconsistencies
through manual settings.
Video projectors are widely used for conference room
presentations, classroom training, home theatre, and live events applications.
Projectors are widely used in many schools and other educational institutes,
connected to an interactive white hoard to interactively teach pupils.
Storage
Devices
The device used for storage and
retrieval of data for later use is called storage devices. These devices
keep the data intact even when we turn off our computers. Storage devices are
commonly classified into two categories.
- Primary Storage
- Secondary Storage
Primary Storage
Primary storage usually refers to a
form of semiconductor storage known as random access memory (RAM) and sometimes
other forms of fast but temporary storage. To manipulate data within a computer
system, we must have a way of storing and retrieving it. Data and instructions
are stored temporarily during processing in Random Access Memory (RAM). RAM is
also known as Primary Storage.
Secondary Storage
Secondary storage also called
auxiliary storage or mass storage bolds data, instructions, and information for
future use. Secondary storage (or external memory) differs from primary storage
in that it is not a directory accessible by the CPU. The computer usually uses
its input/output channels to access secondary storage and transfers the desired
data. Secondary storage does not lose the data when the device is powered off.
It is nonvolatile.
Here are a few examples of secondary
storage devices:
- Magnetic Disks
- Compact Disc
- Magnetic Tape
Magnetics
Disks
Magnetic storage used different
patterns of magnetization on a magnetically coated surface to store
information. Magnetic storage is non-volatile. The information is accessed
using one or more read/write heads which may contain one or more recording
transducers. A read/write head only covers a part of the surface so that the
head or medium or both must be moved relative to another to access
data. In early computers, magnetic storage was also used for primary storage in
a form of magnetic drums or core memory. In modern computers, magnetic storage
takes these forms.
- Floppy Disk
- Hard Disk
- Magnetic Tape
Floppy
Disks
A floppy disk is a data storage medium
that is composed of a disk of thin, flexible magnetic storage medium enclosed
in a square or rectangular plastic shell. Floppy disks are read and written by
a floppy disk drive (FDD). The floppy disk was actually invented by IBM for
recording maintenance information about its mainframes for the service staff.
It was later used by personal computer manufacturers as a convenient way to
distribute software for sale. The 31/2 inch diskette comes in two capacities
720 KB and 1.44 MD. The two diskettes are the same size but have different disk
densities. Disk density refers to the number of bits that can be stored per
unit of area on the disk face surface.
Hard
Disk
A hard disk is part of a unit, often
called a “disk drive,” “hard drive,” or “hard disk drive,” that stores and provides
relatively quick access to large amounts of data on an electromagnetically
charged surface or set of surfaces. Today computers typically come with a hard
disk that contains several billion bytes (gigabytes) of storage.
A hard disk is really a set of stacked
“disks,” each of which, like phonograph records, has data recorded
electromagnetically in concentric circles or “tracks” on the disk. A “head”
(something like a phonograph arm but in a relatively fixed position) records
(writes) or reads the information on the tracks. Two heads, one on each side of
a disk, read or write the data as the disk spins. Each read or write operation
requires that data be located, which is an operation called a “seek”.
A hard disk or drive unit has a rotation
speed varying from 4500 to 7200 RPM. Hard disk manufacturers are working
continuously to achieve two objectives, to put more information in less disk
space and to enable a more rapid transfer of that information to and from RAM.
Generally, the 1 to 5 ¼ inch permanent hard disks have storage capacities from
240 MB to 200 MB.
Magnetic
Tape
A magnetically coated strip of plastic
on which data can be stored. Tapes for computers are similar to tapes used to
store music. Storing data on tapes is considerably cheaper than storing data on
disks. Tapes also have large storage capacities ranging from a few hundred
kilobytes to several gigabytes. Accessing data on tapes, however, is much
slower than accessing data on disks. Tapes are sequential access media, which
means that to get to a particular point on the tape, the tape must go through
all the preceding points. In contrast, disks are random access media because a
disk drive can access any point at random without passing through intervening
points.
Because tapes are so slow, they are
generally used only for long-term storage and backup. Data to be used regularly
is almost always kept on disk. Tapes are also used for transporting large
amounts of data.
CD-ROM
Short for Compact Disc- Read Only
Memory, a type of optical disk capable of storing large amounts of data up to
1GB, although the most common size is 650MB (megabytes). A single CD-ROM has
the storage capacity of 700 floppy disks, and enough memory to store about 300,000
text pages.
CD-ROMs are particularly well-suited to
information that requires large storage capacity. This includes large software
applications that support color, graphics, sound, and especially video.
USB
Flash Drive
The flash memory is usually of the
format of Erasable Electrical Programmable Memory. In contrast to Random
Access Memory, flash memory is also fast. It also retains the data even when
ether is a power failure. Flash memory is a non-volatile type of memory.
Flash memory has a great demand for its application to store data in mobile
phones as well as digital cameras and many other handheld devices. Almost
all the devices that are operated using a battery like the mp3 players, PDA,
and memory cards of various devices. This flash memory is available in
different memory formats with different access speeds.
Flash memory in the coming days will
give tough competition to the present types of memory storage devices. The
regular storage devices may include optical media like CD-ROM, tape storage
devices like floppy drives, etc. even though there are hard drives that use the
technology of flash memory devices. They are like pocket hard drives etc.
Currently, flash memory chips are being used extensively in digital
cameras, USB pen drives, and many other applications.
Computer Software
All computer
programs that we can see or work on are called software. Set of ordered instructions that enable a computer
to carry out a specific task. A program is prepared by first formulating the
task and then expressing it in an appropriate programming language. Following
are the basic types of software:
- System Software
- Application
Software - Utility Programs
System Software
System software,
which consists of programs that control the operations of the computer and its
devices, serves as the interface between the user and the computer’s hardware.
These programs do not solve specific problems. They are general programs written
to assist humans in the use of the computer system by performing tasks such as
controlling all operations required to move data into and out of a computer and
all the steps in executing an application program. Types of system software are
the operating system and language processors etc.
Operating System
or Operating Software
An operating
system is an integrated set of programs that are used to manage the various
resources and overall operations of a computer system, it is designed to
support the activities of a computer installation. Its prime objective is to
improve the performance and efficiency of a computer system and increase the facility and ease with which as the system can be used. It also makes the computer
system user-friendly.
Every general
purposed computer must have an operating system to run other programs.
Operating systems perform 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.
Operating systems
can be classified as follows:
Multi User:
Allows two or more users to run programs at the same time. Some operating
systems permit hundreds or even thousands of concurrent users.
Multiprocessing:
Supports running a program on more than one CPU.
Multitasking:
Allows more than one program to run concurrently.
Multithreading:
Allows different parts of a single program to run concurrently.
Real-Time:
Response to input instantly. General purpose operating systems, such as DOS and
UNIX, are not real time.
The operating system
provides a software platform on top of which other programs, called application programs,
can run. The application programs must be written to run on top of a particular
operating system. Your choice of the operating system, therefore, determines to a
great extent the applications you can run. For PCs, the most popular operating
systems are DOS, OS/2, and Windows, but others are available, such as Linux.
As a user, you
normally interact with the operating system through a set of commands. For
example, the DOS operating system contains commands some of which are given
below:
|
Commands |
Usage |
|
DIR |
This command is used to display the list of all |
|
CLS |
This command is used to clear the screen. |
|
MD |
This command is used to make a directory. |
|
CD |
This command is used to change the directory. |
|
EDIT |
This command is used to invoke a text file. |
|
COPY |
This command is used to copy files from one place to |
|
XCOPY |
This command is used to copy all the files of a folder |
|
DATE |
This command is used to display the current date. |
|
TIME |
This command is used to display the current time. |
|
VER |
This command is used to display the version number of |
|
RENAME |
This command is used to rename a file or directory. |
The commands are
accepted and executed by a part of the operating system called the commands
processor or command line interpreter. Graphical user interfaces allow you to
enter commands by pointing and clicking at objects that appear on the screen.
Language
Processors
These are the
programs used to translate high-level language programs into low-level language
programs.
Compiler
A program that
translates source code into object code. The compiler derives its name from the
way it works, looking at the entire piece of source code and collecting and
reorganizing the instructions. Compilers require some time before an executable
program emerges. However, programs produced by compilers run much faster than
the same programs executed by an interpreter. Every high-level programming
language comes with a compiler. Because compilers translate source code into
object code, which is unique for each type of computer, many compilers are
available for the same language. For example, there is a FORTRAN compiler for
PCs and another for Apple Macintosh computers. In addition, the compiler
industry is quite competitive, so there are actually many compilers for each
language on each type of computer. More than a dozen companies develop and sell
C compilers for the PC.
Interpreter
A program that
translates instructions written in a high-level language into low-level language.
There are two ways to run programs written in a high-level language. The most
common is to compile the program, the other method is to pass the program
through an interpreter.
The interpreter
will take a long time for the program is long. The interpreter, on the other hand,
can immediately execute high-level programs. For this reason, interpreters are
sometimes used during the development of a program, when a programmer wants to
add small sections at a time and test them quickly. In addition, interpreters are often used in education because they allow students to program interactively.
Both interpreters
and compilers are available for most high-level languages. However, BASIC and
LISP are specially designed to be executed by an interpreter. In addition,
page description languages, such as PostScript, use an interpreter. Every
PostScript printer, for example, has a built-in interpreter that executes
PostScript instructions.
Assembler
This is a type of
translator. It also works in the same way as compiler and interpreter work. It
is a program, which translates an assembly language program to its machine
language equivalent.
Application
Software
A program or
group of programs designed for end users. Application software consists of
programs designed to perform specific tasks for users. Application software
sits on top of system software because it is unable to run without the
operating system and system utilities. Popular
application software includes word processing software, spreadsheet software,
database software, presentation software, and graphics software. Spreadsheet
software allows you to calculate numbers arranged in rows and columns and often
is used for budgeting, forecasting, and other financial tasks. Database software
is used to store data in an organized fashion as well as to retrieve,
manipulate and display that data in a meaningful form. Presentation software
allows you to create documents called slides that are used in making
presentations. These four applications often are sold together as a single unit
called a suite in which individual applications are packaged in the same box
and sold for a price that is significantly less than buying the applications
individually.
Utility Programs
A program that
performs a very specific task, is usually related to managing system resources.
These are the programs that are used to help the operating systems to smoothly run
a system. Operating systems contain a number of utilities for managing disk
drives, printers, and other devices.
Utilities differ
from applications mostly in terms of size, complexity, and function. For
example, word processors, spreadsheet programs, and database applications are
considered applications because they are large programs that perform a variety
of functions not directly related to managing computer resources.
Programming
Languages
Languages are a
communication medium through which we can express our feelings, thoughts, and
emotions to others.
The language
through which we can communicate with a computer is called computer language.
Computer languages are helpful for creating software and program.
Types of computer
languages
- Low-level
languages - High-level
languages - Low-level
languages
It is a language
of 0’s and 1’s. The word “low” refers to a call or nonexistent amount of
abstractions between the language and machine language, because of this, low-level languages are sometimes described as being “close to the hardware.” The circuitry
of a computer is wired in such a way that it immediately recognized the machine
language and converts it into the electrical signals needed to run the
computer. The computer can execute programs written in machine language very
fast. This is mainly because the CPU directly understands machine instructions
and no translation of the program is required.
High-level
Language
A programming language
such as C, FORTRAN, or Pascal enables a programmer to write programs that
are more or less independent of a particular type of computer. Such languages
are considered high level because they are closer to human languages and
farther from machine languages. In contrast, assembly languages are considered
low-level because they are very close to machine languages.
The main
advantage of high-level languages over low-level languages is that they are
easier to read, write and maintain. Ultimately, programs written in a high-level language
must be translated into machine language by a compiler or interpreter.
The first high-level programming languages were designed in the 1950s. Now there are dozens of
different languages including Ada, Algol, BASIC, COBOL, C, C++, FORTRAN, LISP, Pascal,
and Prolog.
Procedural Languages
Programmers could
write a single instruction instead of several cumbersome machine language
instructions. These early languages were procedure languages, requiring programmers to solve problems using traditional programming logic. Programmers’
writing in such languages must develop a proper order of actions in order to
solve the problem, based on knowledge of data processing and programming.
Contrast with non-procedural language.
Object Oriented Languages
A type of
programming in which programmers define not only the data type of a data
structure but also the types of operations (functions) that can be applied to
the data structure. In this way, the data structure becomes an object that
includes both data and functions. In addition, programmers can create
relationships between one object and another. For example, objects can inherit characteristics
from other objects.
One of the
principal advantages of object-oriented programming techniques over procedural
programming techniques is that they enable programmers to create modules that
do not need to be changed when a new type of object is added. A programmer can
simply create a new object that inherits many of its features from existing
objects. This makes object-oriented programs easier to modify.
To perform object-oriented programming, one needs an object-oriented programming language (OOPL),
Java, C++, and Smalltalk are three of the more popular languages, and there are
also object-oriented versions of Pascal.
Database Query Languages
These languages
are based on a special kind of database called a relational database. Many
database management programs in today’s computer world claim to be relational
but actually are not. In order for a database management program to truly use Structure
Query Languages (SQL), it must follow the relational
Conclusion
We have created
this post for the newbies who are beginners in the computer field. It is designed
to develop basic computer skills to enhance your knowledge. Also, you can review
our posts on “What is the computer”, “History of Computer”, “Classification of Computers”. If there is any kind of lack in this post or if liked it, please
comment to us. Thanks.