Input and Output Devices

Input and Output Devices

This chapter addresses the issue of interaction of humans and the environment with the computer
system. If you need to acquire a comprehensive knowledge about interaction with computers, like
most areas in computer systems you need to have hands on experience in handling these
components.

 Input Devices

Input devices refer to any device that can provide an input of information, data or commands into
the computer system. In a situation where we consider the CPU as the brain of the computer, the
input devices act like the eyes, ears and any other sensory organ of the human body. Advance
systems may have many input devices that can replicate all the senses on the human body. For
example a humanoid robot will have all the sense of a human in addition to many more. In the
case of a primitive and simple computer system the most common input devices are the keyboard
and the mouse.

Keyboard

The keyboard is also referred to as the primary input device of the computer system. This means
that using the keyboard you can do the simplest input functions of entering data and commands to
your computer system. The keyboard has a similar layout to the typewriter but has some
additional keys that provide additional functionality than a typewriter. Keyboards come in
different shapes and sizes but may differ in the number of additional keys.
The keyboards may be connected to the computer system through a wire or as wireless. The
wired connection may be through the DIN-5 connector, PS/2 connector or USB. The wireless
may use radio-frequency or infrared. In addition to the keyboard there is a special unit called a
dongle, which can be connected to the USB interface of the computer system. This device is used
by the computer system to communicate with the wireless keyboard.
 

Standard keyboard

The standard keyboard has one hundred keys. This set of keys can be divided into six
categories.
Alphanumeric keys - These include the alphabetical and numeric keys grouped together on
the left side of the keyboard. The main function of these keys is to simply enter what ever
symbol that is displayed on the particular key. Alphanumeric keys also include the “Tab,
Caps Lock, Backspace, Enter and symbol keys".
• Modifier keys - These keys are located on the bottom left and right corners of the grouping
of the alphanumeric keys. These are the keys that modify the functionality of another key.
This implies that the functionality of a particular key if pressed alone is different from the
functionality if pressed with a modifier key. These keys include “Shift, Ctr l and Alt". For
example “Ctr l + S" does the saving of a file and “Alt + F" will display the file menu of
your application.
• Numeric keypad - These are the set of keys that are located at the right most end of your
keyboard. As the term implies the numeric keypad comprises of number keys from 0 to 9
and mathematical operator, numloc, enter and decimal keys. These help to enter numeric
data faster that using the alphanumeric keys.
• Function keys - these are the keys located on the top most row of the keyboard and a
labeled F1 to F12. These keys are allocated certain functions by different application. For
example most applications allocate the function of showing the “application help" to the
F1 key.
• Cursor-Movement keys - These are the keys that are usually located between the
alphanumeric and number pad keys. These cursor keys include the quad-directional arrows
keys and the “Home, End, Page-up, Page-down" keys are the movement keys.
• Special-purpose keys - These keys are special keys usually located between the
alphanumeric and number pad keys which allow you to carryout special functions. These
keys are the “Insert (also known as the overwrite), Delete, Print screen, Scroll Lock, Pause
and Es c"
• Listed below are some of the functionality of a set of selected keys:
• Caps Lock - All alphabetical character you type will be in capitals
• Num Lock - When is on the number pad will enter numbers when pressed, else it will
function as the cursor-movement keys and special keys printed on them
Es c - Exit of escape from a task
• Delete (Del) - Delete a file or the character on the cursor’s right.
• Insert (Ins) - Overwrite the character on the cursor’s right when Insert is On.
• Home - The cursor goes to the leftmost end
• End - The cursor goes to the rightmost end
• Page-up - Goes to the previous page
• Page-down - Goes to the next page
• Print Screen (PrtScrn) - Take a screen shot of the screen
• Pause/Break - Mainly used to pause and debug programs
• Scroll Lock - Effects the movement of the cursor on scroll lock supporting programs.
When On the cursor will be in the same location relative to the screen but the displayed
file will move according to the arrow keys.

see more at:

Introduction To The Internet & World Wide Web

 

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Computer Based Information Systems

A computer-based information system (CBIS) is a single set of hardware, software,
databases, telecommunications, people, and procedures that are configured to collect,
manipulate, store, and process data into information.
All these components of CBIS define the business’s technology infrastructure since it forms
the foundation of organization's information systems.
Lets identify these components in detail.

Hardware

Computer equipment used to perform input processing and output activities.
Hardware components can also categorize based on the input, processing and output
activities. Other than the main computer system unit, all other hardware devices
are known as peripherals.

• Input devices

Input devices are used to input data that will be processed by the Information
System. They are connected to computers directly to pass data. Most common input
devices are keyboard, mouse, Magnetic ink character readers (MICR), scanners etc.

• Processing devices

Processing devices include the central processing unit (CPU) and main memory. They are
inside the system unit.

• Output devices

Results after processing the data, can be stored in the computer or it can be taken out from
the information system. These results are known as "output" and the devices which facilitate
distributing of the output is known as output devices. Commonly used output devices are the
monitor and the printer.

Software

Software consists of computer programs that govern the operation of the computer. It can
be described as the digital instruction set to a computer. CPU needs software to control its
functions as well as to process the input data. Without software computers are dead
hardware. Software is the component which gives the computer the power to act as an
intelligent machine.
Software is normally classified into two components called application software and system
software.

Example: MS Windows is a system software which control devices including the CPU. MS
Word is an application software which facilitates users to use computers as word processors.
Application Software
Application Software, also is known as an application package, is a set of programs
designed to carry out operations for a specified purpose or task.
Example:
Microsoft Office (MS Office). It consists of several applications which usually are very
useful to carry out activities in an office environment.
An Accounting Package
It may help an account division to carry out all its activities including payroll of
employees in the organization.
System Software
It generally performs tasks of controlling devices attached to a computer system.
Application software cannot run without having system software. Most important system
software of a computer is its operating system. A computer cannot work without an
operating system. It controls all hardware devices and other system software, plus facilitates
running of application software.
Example: Microsoft Windows, Linux, Unix

Databases

A database is an organized collection of data and information in an organization.
Data and information are critical for problem solving and decision-making in an
organization. Hence, most managers and executives consider a database to be the most
valuable and important part of a computer-based information system.
We use special application software to create databases. We call these software as
“Database Management Systems” DBMS. More details are discussed in Lesson 3.
Examples: Access, DBASE.

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Test

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Overview of Computer System

The Parts of a Computer System 

Let us first look at what a Computer and a Computer System is.
A computer can be classified as a device that takes in raw data as input and processes it and provides information as the output. The computer also has the ability to store data and information.  
The computer system consists of hardware (Physical components), software and users (people who use the computer) that are necessary to make the computer function and to processes data in a meaningful way and store data. 
The physical organization of devices and the organization according to functionality of a computer system can be developed by reference to the above definitions. Figure 1.1 and figure 1.2 can be used to illustrate this physical and functional organization of a computer system.

A study of the figure 1.1 and figure 1.2 shows that a computer system has four clear categorizations for hardware and functionality of that hardware. They can be listed as: 

Hardware components of a computer

Logical design of the components of the computer

1.      Processor, memory and integrating devices 

2.      Input devices 

3.      Output devices 

4.      Storage devices 

All hardware components in a computer can be put into one of these four categories. Following are some of the hardware devices that are commonly found in modern day computer. 

Processor, memory and integrating devices 

•         Central Processing Unit (CPU) 

•         Motherboard or Main board 

•         Main Memory 

•         Power supply 

•         VGA card 

•         Sound card 

•         LAN Card 

•         TV Card 

Input Devices 

•         Keyboard 

•         Pointer device (e.g. Mouse, track-ball) 

•         Joystick and Game Pads 

•         Scanner 

•         Microphones, Still Digital Cameras and Video Cameras 

Output Devices 

•         Monitor and LCD Panel 

•         Printers 

•         Speakers 

•         Plotters 

Storage Devices 

•         Hard drives 

•         DVD and CD ROM 

•         Tape Drives 

•         Flash Disks and Memory Cards 

•         Floppy disks 

Computer Hardware 

This section gives a description of the features and the functionality of the parts of a computer. 

The processor 

The human brain can be considered as the organ that does all the analysis of the information we receive through our five senses: sight, smell, touch, hearing and taste (figure 1.3). It then produces appropriate responses to the information we received. The information received by the brain, the thoughts and ideas it generated is retained in the brain. Further more it is the organ that controls the functionality of our body’s organs and parts. The brain is also capable of independent and creative thought and the generation of new ideas. The human brain learns some of its functionality and control through experience (learning) and some through instinct.  

The computer’s equivalent to the brain is referred to as the processor. It is capable of receiving information from its input devices and then processing that information and to provide an output. It also has the capability to store this information in a storage device. The processor is responsible for controlling the various devices of a computer.

Will Continue in another day...... 

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