- Whenever you enter data into your computer, it is referred to as Input. This can be text typed in a word processing document, keywords entered in a search engine's search box, or data entered into a spreadsheet. It can be something as simple as moving the mouse or clicking the mouse button or it can be as complex as scanning a document or downloading photos from a digital camera. The difference between Program, Command, and User response are as follows:
· 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. .
· Command is a directive to a computer program acting as an interpreter of some kind, in order to perform a specific task. Most commonly a command is a directive to some kind of command line interface, such as a shell.
· User Response is a plan of action aimed at accomplishing a clear business objective, with details on what work is to be done, by whom, when, and what means or resources will be used Programs are written either in one of high-level programming languages (such as BASIC, C, Java) which are easier but execute relatively slowly, or in one of low-level languages (assembly language or machine language) response times should be as fast as possible, but it is also possible for the computer to react so fast that the user cannot keep up with the feedback.
2. 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. Despite the development of alternative input devices, such as the following:
· mouse
The keyboard remains the most commonly used and most versatile device used for direct (human) input into computers. a computer keyboard is a hard ware part of a computer which enables it to input numerical and alphabetical data a keyboard is used to type in data.A desktop computer is a personal computer (PC) in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer.
Desktop and tower computers are two different styles of computer case that use desk space in varying ways. Desktop computers are designed to lay flat on the desk, while towers stand upright.
Prior to the widespread use of microprocessors, a computer that could fit on a desk was considered remarkably small. "Desktop" indicates a horizontally-oriented computer case usually intended to have the display screen placed on top to save space on the desktop. Most modern desktop computers have separate screens and keyboards.
Tower cases are sometimes incorrectly called desktop computers as some will locate them on a desk instead of on the floor under the desk. Cases intended for home theater PC systems are usually considered to be desktop cases in both senses, regardless of orientation and placement.
3. The different types of mouse and its description are as follows:
· 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.
· 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.
· 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.
· 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.
· 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. Three Types of Technology
Touch-screen technology falls into three categories: resistive, capacitive and surface wave. Each technology has strengths suited for specific applications.
· Resistive
Ø Resistive-type screens lack the clarity of other touch screens but they tend to be very durable and can be used in a variety of environments. Resistive-type screens are the most common in use today.
· Capacitive
Ø Capacitive screens are resistant to outside elements, making them very durable, and they still maintain a high clarity. Unlike resistive and surface wave screens, which can be used with stylus, capacitive panels must be touched with a finger.
· Surface Wave
Ø Surface wave touch panels are the more advanced of the three types, offering the highest clarity. But they are more easily damaged by outside elements.
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