Quiz-comped321

  1. What is input?

Whatever goes into the computer. Input can take a variety of forms, from commands 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.
The act of entering data into a computer.

      
       Program

An organized list of instructions that, when executed, causes the computer 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.

 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.

 An instruction to a computer or device to perform a specific task.

Commands come in different forms.They can be:

• special words (keywords) that a program understands.
• function keys
• choices in a menu
• 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 commands are commands, such as COPY and DIR, that can be handled by the COMMAND.COM program. External commands include the names of all other COM files, as well as EXE and BAT files.

   User Response

 
2. Identify the keys and buttons commonly found on desktop computer keyboards.

  Standard

Standard "full-travel" alphanumeric keyboards have keys that are on three-quarter inch centers (0.750 inches, 19.05 mm), and have a key travel of at least 0.150 inches (3.81 mm). Desktop computer keyboards, such as the 101-key US traditional keyboards or the 104-key Windows keyboards, include alphabetic characters, punctuation symbols, numbers and a variety of function keys. The internationally-common 102/105 key keyboards have a smaller 'left shift' key and an additional key with some more symbols between that and the letter to its right (usually Z or Y). Also the 'enter' key is usually shaped differently. Computer keyboards are similar to electric-typewriter keyboards but contain additional keys. Standard USB keyboards can also be connected to some non-desktop devices.

  Laptop-size

Keyboards on laptops and notebook computers usually have a shorter travel distance for the keystroke and a reduced set of keys. They may not have a numerical keypad, and the function keys may be placed in locations that differ from their placement on a standard, full-sized keyboard.

  Thumb-sized

Smaller keyboards have been introduced for laptops (mainly nettops), PDAs, smartphones, or users who have a limited workspace.
A chorded keyboard allows pressing several keys simultaneously. For example, the GKOS keyboard has been designed for small wireless devices. Other two-handed alternatives more akin to a game controller, such as the AlphaGrip, are also used as a way to input data and text.
A thumb keyboard (thumbboard) is used in some personal digital assistants such as the Palm Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO.
Numeric keyboards contain only numbers, mathematical symbols for addition, subtraction, multiplication, and division, a decimal point, and several function keys. They are often used to facilitate data entry with smaller keyboards that do not have a numeric keypad, commonly those of laptop computers. These keys are collectively known as a numeric pad, numeric keys, or a numeric keypad, and it can consist of the following types of keys:

• arithmetic operators such as +, -, *, /
• numeric digits 0–9
• cursor arrow keys
• navigation keys such as Home, End, PgUp, PgDown, etc.
• Num Lock button, used to enable or disable the numeric pad enter key.

  MOBILE PHONE KEYBOARD

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. For example, in the UK, users can order a 7.30am alarm call from a British Telecom telephone exchange by dialling: *55*0730#.
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. Describe different types of Mouse.

  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:

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.

  How to use the mouse?

The Mouse is the device you will use for most of your interactions with your PC. It is primarily used to move the pointer arrow around the screen and to select and activate options.

The mouse button are used to interact with whatever is on the screen where the pointer is located. The left mouse button is the one you will use most often. Clicking this tells the PC to select an item and is called 'left-clicking'. To activate an item and use it, you will often need to click the button twice or 'double-click'.
If you click and hold the left button and move the mouse, this has the effect of 'dragging' a selected object about the screen until you release the button.
Left-clicking on text in a document will place a flashing cursor at that point, which allows you to begin typing there.
The right mouse button is usually used to bring up a small menu window that gives options specific to the selected object. To use a particular option you just left-click it.
Common right-click menu options for an object include: Open (activate, same as if you double-click), Cut (remove to be placed elsewhere), Copy (make a copy of this object) , Create Shortcut (create a shortcut link elsewhere to give quick access to this object), Delete (remove permanently), Rename (give a new name), and Properties (find out information).
You may have a third smaller button in the center of your mouse that can be rolled forwards and backwards. This mouse-wheel can be used to move up and down through documents.

4. Different types of touchscreen.

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

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 image quality if surface acoustic system.    

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.

 

     Command