Computer Fundamentals

Topics: Touchscreen, Source code, Computer program Pages: 10 (3098 words) Published: June 24, 2011


1.(b) Two types.
2.(b) 1 or more input signals to produce output.
3.(d) Both (a) and (c).
4.(b) Non-volatile.
5.(c) Direct-access storage device.
6.(c) Multiple object program files of any software.
7.(d) None of the above.
8.(b) way in which the network’s nodes are linked together. 9.(a) World wide web
10.(a) General purpose electronic equipment for homes.

The Open Systems Interconnection model was a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a way of sub-dividing a communications system into smaller parts called layers. Similar communication functions are grouped into logical layers. A layer provides services to its upper layer while receiving services from the layer below. On each layer, an instance provides service to the instances at the layer above and requests service from the layer below. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of that path. Two instances at one layer are connected by a horizontal connection on that layer.

A touch screen is a computer display screen that is also an input device. The screens are sensitive to pressure; a user interacts with the computer by touching pictures or words on the screen. There are three types of touch screen technology:

Resistive: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Resistive touch screen panels are generally more affordable but offer only 75% clarity and the layer can be damaged by sharp objects. Resistive touch screen panels are not affected by outside elements such as dust or water. Surface wave: Surface wave technology uses ultrasonic waves that pass over the touch screen 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 touch screen panels are the most advanced of the three types, but they can be damaged by outside elements. Capacitive: A capacitive touch screen panel is coated with a material that stores electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus. Capacitive touch screens are not affected by outside elements and have high clarity.

Open-source software (OSS) is computer software that is available in source code form: the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, improve and at times also to distribute the software. Some open source licenses meet the requirements of the Open Source Definition. Some open source software is available within the public domain. Open source software is very often developed in a public, collaborative manner. Open-source software is the most prominent example of open-source development and often compared to (technically defined) user-generated content or (legally defined) open content movements. A report states that adoption of open-source software models has resulted in savings of about $60 billion per year to consumers. Generically, open source refers to a...
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