Input and Input Devices
The objective of this topic is to provide answers to the following questions:
x What is a keyboard?
x What are different keys on keyboard?
x What is their functionality?
It is an input device to give computer some input. It is like pen in writing. It is called keyboard because it is comprised of a board with keys installed. Every key send unique information to computer.
- Keyboard types
There are different types of keyboards. Standard keyboard is the most commonly used keyboard. Key arrangement can be different for these keyboards. Some may have special keys for other tasks than just typing. These special keyboards are usually used for multimedia purposes like video editing, sound design etc.
- Basic Keyboard keys
There are usually 104 keys on standard keyboard. Pressing the key once and releasing it is called a key stroke.
These are used to enter alphabetic characters. These characters become uppercase when pressed with shift key or caps lock is on.
There are 10 numbers or numeric keys (1, 2, 3 to 9 and 0) on standard keyboards. These are used in the same fashion as typewriters’ keyboard to enter numbers. These become symbols or punctuation marks when pressed with the shift key.
1- Shift + 8 will print *
2- Shift + 4 will print $
Shift, Alt and Control(ctrl) keys are special keys and when pressed with other keys, perform special operations. For example ctrl+c will copy the selected file or text, shift+ character key will print that character in capital.
It is used to escape/exit from certain type of applications.
F1, F2, …. F12 are called function keys. These are used for different purposes. For example
F5 is used to refresh the web page in internet browser. F1 will open help window.
There are four keys(arrow Keys) for cursor navigation. Left arrow key, Right arrow key
Up arrow key, Down arrow key
Numeric key pad
On the right side, a separate area is reserved for numeric keys, mathematical operational keys(+, – , * , /) , enter, dot and Num Lock key.
It is horizontal wide key, in the lower most row. It generates space between two characters.
These are keys to enter punctuation and are located on the right side of alphabet keys.
Enter or return key cause cursor to go to next line, form or window to perform its default function.
It launches the menu with the keyboard rather than the usual right mouse button.
Caps lock, Num lock and Scroll lock keys are toggle keys. At the top right corner, there are three small lights to show the status of these locks. When pressed one, corresponding light is turned on.
The keys on numeric key pad act as numbers and dot. When this key is pressed again and the corresponding num lock key light is switched off, the key act as arrow keys, home key, pg up, pg down and end keys.
Characters become capital when the caps lock is on.
Scroll key modifies the functionality of arrow keys. When the scroll lock is on, the arrows keys would scroll the window instead of moving the cursor.
Print screen key
It is the key which is used to save (capture) all the contents of the screen in a temporary area.
Key use to insert or overwrite character(s) within a word is called insert key. The key acts as toggle key. If it is in the insert state than any character pressed while the cursor is placed within a word gets inserted. If the key is pressed and it is in the overwrite state than any char pressed while the cursor is placed with get overwritten.
Home key / End key
It is used to go to start (home key) or end (end key) of the document.
Page up key / Page down key
It is used to go to previous (page up key) or next (page down key) page.
The key used to delete characters.
The key used to delete the preceding characters.
Alt, Ctrl and shift keys are non-typing keys. They don’t print anything when pressed. These when pressed with other keys, modify the usual operation of that key.
For example Alt + F4 close the active window.
Tab key is a typing key and used to put more than one space within characters or words.
In this topic we have learnt:
x What is keyboard? What is its use?
x Keyboard types
x Standard keyboard keys
x Character keys, Numeric keys, Bracket keys, Punctuation keys, Backspace key, Delete key, Tab key, Caps lock key, Num lock key, Scroll lock key, Insert key, Page up/down keys, Functional keys, Special keys
Practice the usage of character keys placed on the keyboard by writing
A quick brown fox jumps over a lazy dog
Write the names and numbers of all the functional keys on your keyboard. State the difference between typing and non-typing keys.
The objective of this topic is to provide the answers to the following question:
x What is a computer mouse?
x What are its different forms?
x Some other pointing devices than mouse x Input devices for image, sound, and video
- Pointing devices
Devices used to point things at the computer screen are called pointing devices. For example mouse, track pad, etc
Mouse is a pointing device that works by detecting motion relative to its supporting surface. Furthermore:
There are many types of computer mouse available in the market. They usually have different shapes or buttons, but they work almost in the same fashion.
There are two buttons on standard mouse
1- Right mouse button 2- Left mouse button
Mouse Pad is a surface used to sense the mouse motion.
Mouse Pointer/Arrow/Cursor shows the position and motion of mouse on screen.
Track pad (also known as touchpad) is a pointing device consisting of a sensitive surface that translates the motion of a user’s finger to a relative position on screen. The trackpad has no moving parts.
The trackball is a ball inserted in a small external box near the keyboard. The ball is rolled with the fingers to move the mouse cursor. Some people like to think of the trackball as an upside- down mouse with a bigger ball at the bottom.
Trackpoints are usually positioned in or near a laptop’s keyboard. They function like miniature
joysticks but are operated with the tip of the finger.
The joystick is a vertical stick that moves the mouse cursor in the direction the stick is pushed. Joysticks are commonly used in video arcade games.
- Other input devices
Microphone is used to input the sound to computer. It is used in motion pictures, radio and television broadcasting etc.
Scanner is a device that scans images, papers etc to store them in computer for later use.
Digital camera/Web cam
These are input devices that input still images or video to computer.
In this topic we have learnt:
x What is computer mouse?
x How to do clicking, double clicking, right clicking and dragging with mouse?
x What is mouse pointer?
x Some other devices e.g track pad, track ball, joystick
x Input devices for image(Scanner), sound(Microphone), Video(Digital camera, webcam)
Survey the market and find four different models of microphone that are used to input the voice into computer. Write their names and numbers.
What are the different devices through which we can input video to a computer?