Computer network

A network of computers, also called network computer or computer network, is a set of equipment (hardware and / or devices) connected by wires, signals, waves or any other method of transporting data, they share information (files) , resources (CD-ROM, printers, etc..), services (Internet access, e-mail, chat, games, etc.).

A communications network is a set of technical means of distance communication between autonomous teams (non-hierarchical -master/slave-). This is usually transmit data, audio and video by electromagnetic waves through different media (air, vacuum, copper cable, fiber optics, etc.).

Classification of networks

In scope:

Personal Area Network (PAN)

Local Area Network (LAN)

Campus Area Network (CAN)

Metropolitan Area Network (MAN)

Wide Area Network (WAN)

Simple Area Network (SPL)

Storage Area Network (SAN)

For the connection method:

Guided media: coaxial cable, twisted pair, fiber optic and other cables.

Unguided media: radio, infrared, microwave, laser and other wireless networks.

For functional relationship:

Client-server

Peer-to-peer (P2P)

Network Architectures

For network topology:

Bus network

Star network

Ring network (or double ring)

Mesh network (or fully connected)

Red Tree

Red Mixed (any combination of the above)

On the directionality of the data (transmission rate)

Simplex (unidirectional): Data terminal equipment transmits and another receives. (eg. streaming)

Half-duplex (bidirectional): only one computer transmits at a time. Also called Semi-Duplex (eg. Communication by radio, if teams are not full duplex, you could not transmit (speak) if the other person is also transmitting (talking) because his team would be receiving (listening ) at the time).

Full-duplex (bidirectional): both can transmit and receive the same information simultaneously.(eg. videoconferencing).

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Network types .

Public: a public network is defined as a network that anyone can use and not the networks that are configured with personal password. It is a network of interconnected computers capable of sharing information and allows users to communicate regardless of geographical location.

Private Network: A private network would be defined as a network that can use only some people and they are set to personal password.

Personal Area Network (PAN): (Personal Area Network) is a computer network used for communication among computer devices (phones, including personal digital assistants) close to a person. The devices may or may not belong to the person in question. The scope of a PAN is typically a few meters. PANs can be used for communication between personal devices themselves (intrapersonal communication) or to connect to a high level network and the Internet (an uplink). Personal area networks can be connected to cables with computer buses such as USB and FireWire. A network wireless personal area (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth.

Local Area Network (LAN): a network that is limited to a relatively small spatial area such as a room, a single building, a ship or an airplane. Local area networks are sometimes called single-location network. Note: For administrative purposes, large LANs are often divided into smaller logical segments called Workgroups. A Workgroups is a group of computers that share a common set of resources within a LAN.

Virtual Local Area Network (VLAN): A Virtual LAN or VLAN commonly called, is a group of computers, with a common set of shared resources and requirements that communicate as if attached to a logical division of networks computers in which all nodes can reach out to others through broadcast (broadcast domain) in the data link layer, despite their different physical location. This can be logically grouped computers to the network location is no longer so closely associated with and restricted to the physical location of each computer, as with a LAN, also providing security, flexibility and resource savings. To achieve this, it has been established as the IEEE 802.1Q standard designed to address the problem of how to separate physically very large networks into smaller pieces and provide a high level of security between segments of internal networks have the freedom to manage without of their physical location

Campus Area Network (CAN): The drift to a network that connects two or more LANs which should be connected in a specific geographic area such as a university campus, an industrial park or military base.

Metropolitan Area Network (MAN): A network that connects the networks of two or more local area together but does not extend beyond the immediate city limits, or metropolitan area.Routers (routers) multiple switches (switch) and the hubs are connected to create a MAN.

Wide Area Network (WAN) is a data communications network covering a relatively broad geographic area and often uses transmission facilities provided by common carriers such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer and network layer.

Storage Area Network (SAN): A network designed to connect servers, arrays (arrays) disks and supporting libraries. It is mainly based on technology of fiber or iSCSI. Its function is to connect in a fast, secure and reliable storage of the different elements that constitute it.

Irregular network: A system of wires and buses that connect through a modem, and resulting in the connection of one or more computers. This network is similar to mixed with one that does not follow the parameters set out in it. Many of these cases are widely used in most networks.

Bachiller : Luisa Nuñez C.I: 21.146.188

NEWS!!!

Apple could replace Google for Microsoft on the iPhone

Gone are the days now that Apple and Google kept such good relations shared by some government advisers. Competition between the two companies has intensified with the launch of Nexus One by Google, so much so that some sources suggest that Apple is already negotiating with Microsoft to take the form of software giant Bing as the new default search engine in iPhone, thus replacing the Google service. At least two persons familiar with the situation told Bloomberg have said that Apple and Microsoft (to turn former archrivals) are negotiating for several weeks, although not yet reached any agreement. The discussion would focus on the percentage of search revenue that Microsoft would bow to Apple. Apple and Google are already competing in the mobile advertising: the end of 2009, Google acquired the AdMob advertising network, which Apple also was interested, also according to Bloomberg, or Google have privileged access to the performance of your applications App Store Store. Finally it was Google who got AdMob, but Apple responded by buying Quattro Wireless, a rival network.


Posted by: Geraldine Avila

Operating Systems



An operating system is a software system, ie, a set of computer programs designed to perform many tasks among which the management of peripheral devices.

When voltage is applied to the processor of an electronic device, it runs a small assembly language code located in a specific address in ROM (address reset) and known as reset code, which in turn executes a routine which initializes accompanying hardware processor. Also in this phase usually initialized controller interrupts. Following this stage runs the boot code (startup code), also code in assembly language, whose most important task is to run the main program (main ()) application software [1].

An operating system can be found in most electronic devices that use microprocessors to operate, because thanks to them we can understand the machine and that it fulfills its functions (cell phones, DVD players, radios, computers, radios, etc. ).


luisa Nuñez c.i:21.146.188

SAP R/3

SAP R/3

SAP R / 3 software can be defined as an open, technology-based client / server, designed to handle the information needs of a company. SAP R / 3 is the software of this kind of wider dissemination throughout the world, with over 18,000 installations in over 100 countries. It is the enhanced version of an earlier product (system R / 2) that has enabled SAP AG to become the leading enterprise software, which is basically what is SAP R / 3 . However, not limited to being just a software package, SAP R / 3 goes beyond this is a whole team (staff, programs, communications, partners ...) working 24 hours a day for the company it is installed.

The R / 3 system is a system "On-line real-time and designed to comprehensively cover the needs of corporate management or type information medium / large. It consists of a set of fully integrated modules that cover a wide range of business functions among which include: Economic and Financial Management (General Accounting, Analytical Accounting, Fixed Assets, Financial Module, etc.)., Logistics, Sales and Distribution, Production (Planning, Control, Serial Production Systems, lots, JIT, etc.)., Quality Control, Maintenance, Integrated Projects, Human Resources, Workflow, etc.

In short, one can argue that covers all functional areas of the company. Also, are being developed and where appropriate improve, the so-called Industrial Solutions, which means better aligning the SAP system to the particularities of each business sector: Oil, Automotive, Publishing, Pharmaceutical Laboratories, Retail, Food, Public Sector, Telecommunications etc.

Features of the R / 3:

SAP R / 3 has been so successful because it combines unique features that are ideal when working in business management.

SAP is very flexible. Helps streamline the daily tasks of any business regardless of sector and country you work, its size (although that seems to be directed more to large enterprises) and other factors that may pose a problem with other software.

Another important aspect that is highly integrated: Beat the hierarchical and functional limitations typical of the company. Everything is integrated in one software that coordinates the different structures, processes and events of all departments and functional areas, allowing each employee to have all the necessary information at all times. This will not only updates the information in real time (important feature of SAP is a huge advantage), but also just enter data once, since it is the system is responsible for passing and updating the data in the rest modules or programs.

So the interface between central offices, production facilities, etc. is ensured. Before SAP systems, all operations could be done in each department, office, factory .... with specific programs for each (software for materials management, software to control wages, sales, purchasing, etc.. and each of them working with their own protocols, with your own information, adapted to different hardware without connecting or share information) with what worked twice: the data are repeated in different areas are handled several times (for example, in the warehouse and administration) and, not being interconnected, (although there is an internal network, the programs could work with various formats, data, incompatible machines) is necessary for someone to be devoted to pass information from one to another, wasting time that could be spent on improving the strategy.

Posted by Geraldine Avila

Free Software

The issue of freedom Free Software

Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it means that users of programs have the four essential freedoms.

-The freedom to run the program, for any purpose (freedom 0).
-The freedom to study how the program works, and change it to do what you want (freedom 1). Access to the source code is a precondition for this.
-The freedom to redistribute copies so you can help your neighbor (freedom 2).
-The freedom to improve the program and publish their improvements, and modified versions in general to the whole community benefits (freedom 3). Access to the source code is a necessary condition.

A program is free software if users have all these freedoms. Then, you should be free to redistribute copies, either with or without modifications, either gratis or charging a fee for distribution, to anyone anywhere. Being free to do these things means, among other things, that does not have to ask permission or pay.

You should also have the freedom to make modifications and use them privately in their own work or play, without even mentioning that they exist. If you publish your changes, should not be obliged to notify someone, or some particular form

The freedom to run the program means the freedom for any person or organizaion to use in any computer system for any type of work and purpose, without being obliged to tell your programmer, or any other specific entity. In this freedom, the purpose of users is what matters, not the purpose of programmers. As a user is free to run a program for their purposes, and if distributed to another person, also free to run for their purposes, but you have no right to impose their own purposes.

Posted by Geraldine Avila

Programming Languages

Visual Basic Programming

Programming in Visual Basic is an agile and simple way to create applications for Microsoft Windows.
The programming language in Visual Basic provides all the necessary tools for rapid application development.

We could define programming in Visual Basic as the method used to develop graphical user interface.
With programming in Visual Basic you can develop almost any program you can imagine.

In addition to ActiveX technology, Visual Basic provides a tool for creating unlimited applications in the network.

Programming in Visual Basic allows to quickly build Windows applications. It is not necessary to know other programming languages to program in Visual Basic podersaber.

Programming in Visual Basic is a simple way to create applications besides language offers a number of tools to simplify this work, including projects, templates, forms, objects, custom controls, add-ins and a database manager.

Version 6.0 of Visual Basic programming is specially designed for the Internet. Using executable ActiveX controls operate like Visual Basic application is independent and through which they can access Internet Explorer.

Key features of programming in Visual Basic 6.0:

-The ability to access data from the database, client / server and scalable applications such as Microsoft SQL Server.
-ActiveX Technology
-ActiveX Controls
-Internet programming, web servers, DHTML, etc. ..
-Creating. Exe files, allowing circulated plication with great freedom.

Creado por Geraldine Avila

Database management systems

Database management systems

Main article: Database management system

A database management system (DBMS) consists of software that organizes the storage of data. A DBMS controls the creation, maintenance, and use of the database storage structures of social organizations and of their users. It allows organizations to place control of organization wide database development in the hands of Database Administrators (DBAs) and other specialists. In large systems, a DBMS allows users and other softwares to store and retrieve data in a structured way.

Database management systems are usually categorized according to the database model that they support, such as the network, relational or object model. The model tends to determine the query languages that are available to access the database. One commonly used query language for the relational database is SQL, although SQL syntax and function can vary from one DBMS to another. A common query language for the object database is OQL, although not all vendors of object databases implement this, majority of them do implement this method. A great deal of the internal engineering of a DBMS is independent of the data model, and is concerned with managing factors such as performance, concurrency, integrity, and recovery from hardware failures. In these areas there are large differences between the products.

A relational database management system (RDBMS) implements features of the relational model. In this context, Date's "Information Principle" states: "the entire information content of the database is represented in one and only one way. Namely as explicit values in column positions (attributes) and rows in relations (tuples). Therefore, there are no explicit pointers between related tables." This contrasts with the object database management system (ODBMS), which does store explicit pointers between related types.