Tuesday, July 5, 2011

CompEd 321 IT concepts and SAD

1. 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 devices. 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.
             Difference among:
     .Program-An organized list of instructions that, when executed, causes the computer to behave in a predetermined manner. Without programs, computers are useless.
     .Command-An instruction to a computer or device to perform a specific task
     .User Response-An individual who uses a computer. This includes expert programmers as well as novices. An end user is any individual who runs an application program


2.Keys and buttons commonly found on desktop computer keyboards.
The computer keyboard works much like a mouse; many keyboard shortcuts can eliminate the need for a mouse. Keys are split into different parts of the keyboard, each providing a specific function.

  1. Function Keys

    • Across the top of a keyboard are a row of keys called the Function Keys. Each key is composed of the letter F and a number, ranging from F1 to F12. Each of the Function Keys performs a specific operation based upon what software is being used.

    Numeric Keypad

    • Many larger keyboards have an extra section to the right that contains the Numeric Keypad. This consists of the numbers 1 through 9, an asterisk, a slash, a dash, a plus sign, an enter key and a period. There is also is a "Num Lock" key, which is used to turn on and off the Numeric Keypad.

    Navigation Keys

    • The Navigation Keys, also called the Direction Keys, are used to navigate through documents and websites. Examples of Navigation Keys are the up, down, left and right arrows.

    Typewriter Keyboard

    • The center of the keyboard, which contains the largest amount of keys, includes letters and numbers. Most typing is done with these keys.

    Special Keys

    • Other keys include the Alt and Ctrl keys (used for specific functions), the Tab key (used to insert the curser) and the Shift key (used to make capital letters or symbols that are located on the number keys).

    Escape

    • The Escape key is located in the upper left-hand corner of the keyboard. It is used to cancel operations.
3. Different Mouse types and their uses:
      . Lisa mouse-The name for the mouse that was distributed with Apple's first mouse-controlled computer called the Lisa System (pre-Macintosh) in 1983. The Lisa Mouse (model no. A9M0050) used a steel ball (instead of the rubber ball found in more modern mice), and was rectangular in shape with a raised front panel, and contained a single mouse button.
      .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.
      . 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.


4. Diffferent types of Touch Screen and how a touch screen works.
      .A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. The term generally refers to touching the display of the device with a finger or hand. Touchscreens can also sense other passive objects, such as a stylus. Touchscreens are common in devices such as all-in-one computers, tablet computers, and smartphones.
The touchscreen has two main attributes. First, it enables one to interact directly with what is displayed, rather than indirectly with a pointer controlled by a mouse or touchpad. Secondly, it lets one do so without requiring any intermediate device that would need to be held in the hand. Such displays can be attached to computers, or to networks as terminals. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices, mobile phones, and video games.
Types of touch screen:
    *A 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.
    *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.
    
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