CompEd 321L IT Concepts and SAD

1. Define input and differentiate among a program, command, and user response.  

1. Input is any data or instructions you enter into the memory of a computer.  Once input is in memory, the CPU can access it and process the input into output. A device that feeds data into a computer, such as a keyboard or mouse, is called an input device. Four types of input are data, programs, commands, and user responses:

• Data is a collection of unorganized facts that can include words, numbers, pictures, sounds, and videos.  A computer manipulates and process data into information, which is useful.  

• A program is a series of instructions that tells a computer how to perform the tasks necessary to process data into information.  Programs are kept on storage media such as a floppy disk, hard disk, CD-ROM, or DVD-ROM. Programs respond to commands issued by a user.

• A command is an instruction given to a computer program.  Typing keywords or pressing special keys on the keyboard can issue commands.  A keyword is a specific word, phrase, or code that a program understands as an instruction.

•  A user response is an instruction you issue to the computer by replying to a question posed by a computer program, such as do you want to save the change you made? Based on your response, the program performs certain actions.  

Today, most programs have a graphical user interface that use icons, buttons, and other graphical objects to issue commands.  Of all of these methods, a graphical user interface is the user-friendliest way to issue commands.

2. Identify the keys and buttons commonly found on desktop computer keyboards, and describe how keyboards for mobile computers and devices differ from desktop computer keyboards.

In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. Following the decline of punch cards and paper tape, interaction via teletype-style keyboards became the main input device for computers.  

      The Computer Key Board 

Key types: 

Alphanumeric

    Alphabetical, numeric, and punctuation keys are used in the same fashion as a typewriter keyboard to enter their respective symbol into a word processing program, text editor, data spreadsheet, or other program.

    The alphabetic characters become uppercase when the shift key or Caps Lock key is depressed. The numeric characters become symbols or punctuation marks when the shift key is depressed. 

    Space Bar - a horizontal bar in the lowermost row, which is significantly wider than other keys. Like the alphanumeric characters, it is also descended from the mechanical typewriter. Its main purpose is to enter the space between words during typing.

  
Modifiers

    Modifier Key are special keys that modify the normal action of another key, when the two are pressed in combination. For example, <Alt> + <F4> in Microsoft Windows will close the program in an active window. By themselves, modifier keys usually do nothing.

    The most widely-used modifier keys: Control key, Shift key and the Alt 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.

Navigation and typing modes

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.

Home Key- is used to return the cursor to the beginning of the line where the cursor is located.

End Key- puts the cursor at the end of the line.

Tab Key- advances the cursor to the next tab stop.

Insert key - mainly used to switch between overtype 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. 

Delete key- discards the character ahead of the cursor's position, moving all following characters one position "back" towards the freed place.

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.

System commands

The SysRq / Print screen commands often share the same key. SysRq was used in earlier computers as a "panic" button to recover from crashes.

Print screen command - used to capture the entire screen and send it to the printer, but in the present it usually puts a screenshot in the clipboard.

Break key/Pause key- no longer has a well-defined purpose. Its origins go back to teletype users, who wanted a key that would temporarily interrupt the communications line.

In programming, especially old DOS-style BASIC, Pascal and C, Break is used (in conjunction with Ctrl) to stop program execution. In addition to this, Linux and variants, as well as many DOS programs, treat this combination the same as Ctrl+C. On modern keyboards, the break key is usually labeled Pause/Break. In most Windows environments, the key combination Windows key+Pause brings up the system properties.

Escape key- (often abbreviated Esc) is used to initiate an escape sequence. As most computer users no longer are concerned with the details of controlling their computer's peripherals, the task for which the escape sequences were originally designed, the escape key was appropriated by application programmers, most often to "escape" or back out of a mistaken command. This use continues today in Microsoft Windows's use of escape as a shortcut in dialog boxes for No, Quit, Exit, Cancel, or Abort.

Menu key or Application key - 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.

Mobile computing has three aspects: mobile communication, mobile hardware, and mobile software. The first aspect addresses communication issues in ad-hoc and infrastructure networks as well as communication properties, protocols, data formats and concrete technologies. The second aspect is on the hardware, e.g., mobile devices or device components. The third aspect deals with the characteristics and requirements of mobile applications.

A mobile device (also known as a handheld device, handheld computer or simply handheld) is a pocket-sized computing device, typically having a display screen with touch input and/or a miniature keyboard. In the case of the personal digital assistant (PDA) the input and output are often combined into a touch-screen interface. Smartphones and PDAs are popular amongst those who require the assistance and convenience of certain aspects of a conventional computer, in environments where carrying one would not be practical.

There are a number of different arrangements of alphabetic, numeric, and punctuation symbols on keys. These different keyboard layouts arise mainly because different people need easy access to different symbols, either because they are inputting text in different languages, or because they need a specialized layout for mathematics, accounting, computer programming, or other purposes.

3. Describe different mouse types and explain how to use a mouse.

A mouse is a pointing device used to interact with a PC, there are a few different types of mouse available.

• Serial Mouse - This is a mouse with a serial connector, it requires a free serial port on your PC.
• USB Mouse - This type of mouse has a USB connector and requires a free USB port.
• Cordless Mouse - A cordless mouse (as the name suggests) has no cable, this type of mouse utilises batteries for its power supply.
• Optical Mouse - An optical mouse utilises optical electronics to track the mouse's position and movement, they are preferred over standard mechanical mice as they tend to be more reliable and require less maintenance.

1. Connect the mouse.
2. Hold the mouse correctly.
3. To click, press the button (usually the left one, when there are two) and promptly release it.
4. To double click (for opening applications, documents or folders), you must click (the left button) twice in rapid succession 
5. To drag files, press and hold the (left) button, then move the mouse without letting the button go until the file is where you want it to be.

4. Describe various types of touch screens and explain how a touch-sensitive pad works.

Resistive touchscreens are the most widely used touch screens in mobile phones.
Capacitive touchscreens are basically of two types- one that can recognize multiple touches simultaneously and the other which cannot.

Infrared touchscreens are the most expensive of the all the three mentioned here. It doesn’t require physical force, just a gentle touch is enough.

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. 

The mouse pad is touch sensitive and has coordinates (like a street map that has an index to find a street). It produces events and transmits coordinates for those events. A driver is installed in the operating system that translates events and coordinates into actions in the operating system. It is totally up to the driver as to what actions are performed for events. There are however some generally accepted event / action. For example, contact with the pad at any coordinate for far less than a second followed by no contact with the pad followed again by contact witht he pad at any coordinate for far less than a second is translated to a double click. Touching the pad at a coordinate and moving to another coordinate is considered to be a mouse movement. How far to move the mouse and the direction to move the mouse is up to the driver