1. What is input?
n.) Whatever goes into the computer. Input can take a variety of forms, from command you enter from the keyboard to data from another computer or device. A device that feeds data into a computer, such as a keyboard or mouse, is called an input device.
(v.) The act of entering data into a computer.
Differentiate in terms of:
Program
(n) An organized list of instructions that, when executed, causes thecomputer to behave in a predetermined manner. Without programs, computers are useless.
A program is like a recipe. It contains a list of ingredients (called variables) and a list of directions (called statements) that tell the computer what to do with the variables. The variables can represent numeric data, text, or graphical images.
There are many programming languages -- C, C++, Pascal, BASIC, FORTRAN, COBOL, and LISP are just a few. These are all high-level languages. One can also write programs in low-level languages called assembly languages, although this is more difficult. Low-level languages are closer to the language used by a computer, while high-level languages are closer to human languages.
Eventually, every program must be translated into a machine language that the computer can understand. This translation is performed by compilers, interpreters and assemblers.
When you buy software, you normally buy an executable version of a program. This means that the program is already in machine language -- it has already been compiled, and assembled and is ready to execute.
Command
An instruction to a computer or device to perform a specific task. It come in different forms. They can be:
- FunctionKeys
- buttons or other graphical objects on your screen
Every program that interacts with people responds to a specific set of commands. The set of commands and the syntax for entering them is called the user interface and varies from one program to another.
The DOS operating system makes a distinction between internal and external commands. Internal command are commands, such as COPY and DIR, that can be handled by the COMMAND.Com program. External commands include the names of all other COMFiles as well asEXE and BAT Files
Another word for command is directive.
User Response
2. Common Keys and buttons on a desktop computer keyboards
A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or computer commands.
Space Tab,The Escape Key (often abbreviated Esc),The Menu Key or Application key is a key found on Windows-oriented computer keyboards. It is used to launch a context menu with the keyboard rather than with the usual right mouse button.The Break Key or Pause Key.
Navigation keys include a variety of keys which move the cursor to different positions on the screen. Arrow Keys are programmed to move the cursor in a specified direction; page scroll keys, such as the 'Page Up and Page Down Keys', scroll the page up and down. The Home Key is used to return the cursor to the beginning of the line where the cursor is located; the End Key puts the cursor at the end of the line. The Tab Key advances the cursor to the next tab stop.
The Insert Key is mainly used to switch between over type mode, in which the cursor overwrites any text that is present on and after its current location, and insert mode, where the cursor inserts a character at its current position, forcing all characters past it one position further. The Delete Key discards the character ahead of the cursor's position, moving all following characters one position "back" towards the freed place. On many notebook computer keyboards the key labeled Delete (sometimes Delete and Backspace are printed on the same key) serves the same purpose as a Backspace key. The Backspace key deletes the preceding character.
Lock Keys lock part of a keyboard, depending on the settings selected. The lock keys are scattered around the keyboard. Most styles of keyboards have three LEDs indicating which locks are enabled, in the upper right corner above the numpad. The lock keys include Scroll Lock, Num Lock (which allows the use of the numeric keypad), and Caps Lock
Modifiers
The most widely-used modifier keys include the Control Key, Shift Key and the Alt Key. The AltGr Key is used to access additional symbols for keys that have three symbols printed on them. On the Macintosh and Apple keyboards, the modifier keys are the Option Key and Command key, respectively. On MIT computer keyboards, the Meta Key is used as a modifier and for Windows keyboards, there is a Windows Key. Compact keyboard layouts often use a Fn Key. "Dead Keys" allow placement of a diacritic mark, such as an accent, on the following letter (e.g., the Compose key).
The Enter/Return Key typically causes a command line, window form or dialog box to operate its default function, which is typically to finish an "entry" and begin the desired process. In word processing applications, pressing the enter key ends a paragraph and starts a new one.
Differences between mobile computer keyboard to desktop computer.
MOBILE PHONE KEYPAD
The "*" is called the "star key" or "asterisk key". "#" (while technically referred to as "octothorpe") is called the "number sign", "pound key", or "hash key", depending on one's nationality or personal preference. These can be used for special functions.
Most of the keys also bear letters according to the following system:
The "*" is called the "star key" or "asterisk key". "#" (while technically referred to as "octothorpe") is called the "number sign", "pound key", or "hash key", depending on one's nationality or personal preference. These can be used for special functions.
Most of the keys also bear letters according to the following system:
- 0 = none (in some telephones, "OPERATOR" or "OPER")
- 1 = none (in some older telephones, QZ)
- 2 = ABC
- 3 = DEF
- 4 = GHI
- 5 = JKL
- 6 = MNO
- 7 = P(Q)RS
- 8 = TUV
- 9 = WXY(Z)
3. Different mouse types
One of the most interesting mouse technologies invented is the wireless mouse which relies infrared, radio signals or Bluetooth to communicate with the computer. Using no cord, the wireless mouse contains a transmitter to send information to a receiver itself connected to the computer. The wireless mouse is usable from 2m to 10m of the computer.
The cordless mouse uses the wireless communication technology (via infrared, radio or Bluetooth) to transmit data to the computer. And like the wireless, it doesn’t use any cord.
Other specification to consider about different type of mice is the function of the buttons. Depending on the manufacturer a computer mouse can have 1 to 4 buttons. However the most commonly used is the two mouse buttons of which the primary button is located to the left side of the mouse.
Especially for computer games players, some mice have been built with five or more extensive arrays of buttons which give easily access to various functions.
Finally each of the different type of computer mouses seems more usable with the scroll wheel, very effective with long document pages. As a matter of fact the scroll wheel can be rotated up and down to navigate within a page as the arrows “up and down” buttons on the keyboard.
Sometimes instead of the scroll wheel, a center button or a “rocker” button is designed to the same effects. But they have to be pressed at the top or bottom to achieve the same tasks.
4. different types of touch screen
Resistive touchscreen panel is composed of several layers, the most important of which are two thin, electrically conductive layers separated by a narrow gap. When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs. This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing. Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touchscreen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touchscreen. A capacitive touchscreen panel is one which consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location is then sent to the controller for processing. Unlike a resistive touchscreen, one cannot use a capacitive touchscreen through most types of electrically insulating material, such as gloves; one requires a special capacitive stylus, or a special-application glove with finger tips that generate static electricity. This disadvantage especially affects usability in consumer electronics, such as touch tablet PCs and capacitive smartphones. An infrared touchscreen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. These LED beams cross each other in vertical and horizontal patterns. This helps the sensors pick up the exact location of the touch. A major benefit of such a system is that it can detect essentially any input including a finger, gloved finger, stylus or pen. It is generally used in outdoor applications and point of sale systems which can't rely on a conductor (such as a bare finger) to activate the touchscreen. Unlike capacitive touchscreens, infrared touchscreens do not require any patterning on the glass which increases durability and optical clarity of the overall system. Optical imaging is a relatively modern development in touchscreen technology, in which two or more image sensors are placed around the edges (mostly the corners) of the screen. Infrared back lights are placed in the camera's field of view on the other side of the screen. A touch shows up as a shadow and each pair of cameras can then be pinpointed to locate the touch or even measure the size of the touching object (see visual hull). This technology is growing in popularity, due to its scalability, versatility, and affordability, especially for larger units. Dispersive signal technology was introduced in 2002 by 3M, this system uses sensors to detect the mechanical energy in the glass that occurs due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity. Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and stylus. A downside is that after the initial touch the system cannot detect a motionless finger. Acoustic pulse recognition, introduced by Tyco International's Elo division in 2006, uses piezoelectric transducers located at various positions around the screen to turn the mechanical energy of a touch (vibration) into an electronic signal. The screen hardware then uses an algorithm to determine the location of the touch based on the transducer signals. The touchscreen itself is made of ordinary glass, giving it good durability and optical clarity. It is usually able to function with scratches and dust on the screen with good accuracy. The technology is also well suited to displays that are physically larger. As with the Dispersive Signal Technology system, after the initial touch, a motionless finger cannot be detected. However, for the same reason, the touch recognition is not disrupted by any resting objects.
First both techniques utilize the electric charge mechanism to develop a touch screen system but the third uses wave system and do not need a metallic plate. This surface acoustic wave system is free of electric field that’s why there is no resistance in the way of light dispersal. This 100 percent light emission gives extra clarity to the screen which is not possible in first two mechanisms. Resistive system enables 75 % of light emission. However capacitive system allows 90% of light emission so better than resistive. Capacitive system enables sharp image as compared to resistive system even then no comparison with
The mechanical mouse requires a ball to move the cursor on the screen. To get more efficacies with this type of mice, a flat surface named mouse pads is necessary.
The optomechanical or optical-mechanical mouse is a combination of the optical and the mechanical technologies. It uses a ball but detects the mouse movement optically. It is now the most commonly used with PC.
The optical mouse uses a laser; precisely an optical sensor to help detecting the mouse’s moving. More expensive than the two other types, the optical mouses offer more precision and speed and even can be used on any surface.
To be really useful, the mouse has to be connected to your PC. To transmit data to the computer three types of interfaces can be used:
To be really useful, the mouse has to be connected to your PC. To transmit data to the computer three types of interfaces can be used:
The RS-232C serial port connects the mouse to the computer through a thin electrical cord using a 9 pin connector.
The PS/2 port do the same as the first interface mentioned but using a 6 pin connector.
The USB interface receives various types of mice through a USB connector. One of these advantages to use the USB mouse is the possibility to plug-and-play (it) in front or in the back of your computer case, when it contains these kinds of port.
One of the most interesting mouse technologies invented is the wireless mouse which relies infrared, radio signals or Bluetooth to communicate with the computer. Using no cord, the wireless mouse contains a transmitter to send information to a receiver itself connected to the computer. The wireless mouse is usable from 2m to 10m of the computer.
The cordless mouse uses the wireless communication technology (via infrared, radio or Bluetooth) to transmit data to the computer. And like the wireless, it doesn’t use any cord.
Other specification to consider about different type of mice is the function of the buttons. Depending on the manufacturer a computer mouse can have 1 to 4 buttons. However the most commonly used is the two mouse buttons of which the primary button is located to the left side of the mouse.
Especially for computer games players, some mice have been built with five or more extensive arrays of buttons which give easily access to various functions.
Finally each of the different type of computer mouses seems more usable with the scroll wheel, very effective with long document pages. As a matter of fact the scroll wheel can be rotated up and down to navigate within a page as the arrows “up and down” buttons on the keyboard.
Sometimes instead of the scroll wheel, a center button or a “rocker” button is designed to the same effects. But they have to be pressed at the top or bottom to achieve the same tasks.
4. different types of touch screen
Resistive touchscreen panel is composed of several layers, the most important of which are two thin, electrically conductive layers separated by a narrow gap. When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs. This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing. Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touchscreen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touchscreen. A capacitive touchscreen panel is one which consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location is then sent to the controller for processing. Unlike a resistive touchscreen, one cannot use a capacitive touchscreen through most types of electrically insulating material, such as gloves; one requires a special capacitive stylus, or a special-application glove with finger tips that generate static electricity. This disadvantage especially affects usability in consumer electronics, such as touch tablet PCs and capacitive smartphones. An infrared touchscreen uses an array of X-Y infrared LED and photodetector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. These LED beams cross each other in vertical and horizontal patterns. This helps the sensors pick up the exact location of the touch. A major benefit of such a system is that it can detect essentially any input including a finger, gloved finger, stylus or pen. It is generally used in outdoor applications and point of sale systems which can't rely on a conductor (such as a bare finger) to activate the touchscreen. Unlike capacitive touchscreens, infrared touchscreens do not require any patterning on the glass which increases durability and optical clarity of the overall system. Optical imaging is a relatively modern development in touchscreen technology, in which two or more image sensors are placed around the edges (mostly the corners) of the screen. Infrared back lights are placed in the camera's field of view on the other side of the screen. A touch shows up as a shadow and each pair of cameras can then be pinpointed to locate the touch or even measure the size of the touching object (see visual hull). This technology is growing in popularity, due to its scalability, versatility, and affordability, especially for larger units. Dispersive signal technology was introduced in 2002 by 3M, this system uses sensors to detect the mechanical energy in the glass that occurs due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity. Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and stylus. A downside is that after the initial touch the system cannot detect a motionless finger. Acoustic pulse recognition, introduced by Tyco International's Elo division in 2006, uses piezoelectric transducers located at various positions around the screen to turn the mechanical energy of a touch (vibration) into an electronic signal. The screen hardware then uses an algorithm to determine the location of the touch based on the transducer signals. The touchscreen itself is made of ordinary glass, giving it good durability and optical clarity. It is usually able to function with scratches and dust on the screen with good accuracy. The technology is also well suited to displays that are physically larger. As with the Dispersive Signal Technology system, after the initial touch, a motionless finger cannot be detected. However, for the same reason, the touch recognition is not disrupted by any resting objects.
There are three different systems used in the mechanism of touch screen.
1. Resistive System
In this resistive mechanism of touch screen two sheets are used one is conductive and the other is resistive. Both cover the top glass panel. There is a space between two sheets so that current pass when it is toggle. Now touching the screen forced both layers to contact at a certain point. This contact of both layers cause in the electric field a variation which is informed to the main system that a touch is felt. OS transcribe the touch into desired action.
2. Capacitive System
Second method utilizes in touch screen is capacitive. To understand this mechanism, it is better to know about human biology first. Many chemical reactions take place in our body and electricity produced in result to perform different functions. That is the reason why human heart is recharged with electric shocks for the recovery. Considering human body a cell you can better understand this phenomenon. In this system an electric charge sheet (capacitor) is directly placed on the glass. When we touch the screen with finger, a static charge produces and reacts with the capacitor (electric charge sheet). As the touch screen works due to electric current develop when touches the finger.
3. Surface Acoustic Wave System
This type of touch screen works with the help of wave energy. This enables a touch to transform into another form of energy and deliver the command which in response perform the desired action. A pair of transducers is placed on glass plate sides. In the glass plate there are reflectors. On touching the screen wave produced and which transforms into energy for fulfilling the command. It tells where on the screen touch is detected.
Important Information
Important Information
First both techniques utilize the electric charge mechanism to develop a touch screen system but the third uses wave system and do not need a metallic plate. This surface acoustic wave system is free of electric field that’s why there is no resistance in the way of light dispersal. This 100 percent light emission gives extra clarity to the screen which is not possible in first two mechanisms. Resistive system enables 75 % of light emission. However capacitive system allows 90% of light emission so better than resistive. Capacitive system enables sharp image as compared to resistive system even then no comparison with
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