Growth of Telecommunications Systems
Books
Wright, Michael and Mukul Patel. 2000. Scientific American – How Things Work Today. London: Marshall Publishing Ltd.
B.1 The world is currently in the middle of a communications revolution as dramatic as the Industrial Revolution that created our modern society two centuries ago. The growth of telecommunications systems, the arrival of the Internet, and the proliferation of computers in every aspect of our lives are transforming both industrial and knowledge-based economies round the world. Higher disposable incomes and increased leisure time are also fuelling demand for luxury electronic goods and new forms of entertainment. Since the British inventor Alexander Graham Bell patented the telephone in 1877, telephony has become the most important form of distance communication. The telephone network is now truly global, with submarine cables and communications satellites linking every continent. This globe-spanning network handles phone calls, fax transmissions, and internet traffic. The long-distance “backbones” of the telephone network are high capacity optical-fiber cables. Lower-capacity copper cables connect individual phones to the network. The analog signal from an ordinary phone is sampled 4,000 times per second and converted into an 8-bit digital signal. Several conversations can then be transmitted simultaneously down the same cable, using a technique known as multiplexing, which increases the capacity of the network. Routing calls through the telephone network is done automatically be telephone exchanges. In near future, the telephone network may also carry video and music channels, interactive televisions, videophone calls.
Analog signal – Analog electric signals from ordinary phones are carried by copper cable to the local exchange.
Base station – The base station receiving the strongest signal from a cell phone routes the call to the cell phone exchange.
Cell – The cell phone network is divided into hexagonal cells, each with a base station in the middle.
Cell phone exchange – Calls are routed to the main exchange or direct to a base station by the cell phone exchange.
Cell phone network – Base stations send digital information to the cell phone exchange over optical-fiber or copper cable.
Communication satellite – Orbiting satellites are used to route calls between places not linked by a cable.
Digital signal – Digital information is multiplexed, allowing multiple signals to be transmitted simultaneously.
Fax machine – Fax transmissions are sent over the telephone network.
Line-of-sight microwave link – Digitized call from local exchanges are often routed to the main exchange via terrestrial microwave links.
Local exchange – The local exchange digitizes calls for long-distance transmission.
Long-distance or international connection – Optical fibers are used to transmit long-distance calls, many optical fiber cables are laid on the seabed.
Main exchange – The main exchange handles communications between ordinary phones and the cell phone network and routes long-distance and international calls.
Microwaves – Digital information is sent from cell phones to base stations using microwave frequencies.
Moving cell phone – Mobility is the prime asset of the cell phone.
Optical fibers – Transmitting digital information by light pulses enables many calls to be sent down one fiber simultaneously.
Satellite uplink – Encrypted digital information is sent to satellites using microwave frequencies.
Seamless reconnection – As the cell phone moves from one cell to another, the call is rerouted from one base station to the next, without the break in the conversation.
Urban cell – Cell are smaller in urban areas, giving the network greater capacity.
Weakening Signal – As the cell phone moves farther away from the base station, the signal weakens.
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Tanenbaum, Andrew S. and Maareten van Steen. 2002. Distributed Systems Principles and Paradigms. New Jersey: Prentice-Hall, Inc.
B.2 A process is often defined as a program in execution, that is, a program that is currently being executed on one of the operating system’s virtual processors. An important issue is that the operating system takes great care to ensure that independent processes cannot maliciously or inadvertently affect the correctness of each other’s behavior. In other words, the fact that multiple processes may be concurrently sharing the same CPU and other hardware resources is made transparent. Usually, the operating system requires hardware support to enforce this separation.
B.2
Threads in Distributed Systems – An important property of threads is that they can provide a convenient means of allowing blocking system calls without blocking the entire process in which the thread is running. This property makes threads particularly attractive to use in distributed systems as it makes it much easier to express communication in the form of maintaining multiple logical connections at the same time. We illustrate this point by taking a closer look at multithreaded clients and servers, respectively.
B.2
Clients and Servers – In the basic client-server model, processes in a distributed system are divided into two (possibly overlapping) groups. A server is a process implementing a specific service, for example, a file system service or a database service. A client is a process that requests a service from a server by sending it a request and subsequently waiting for the server’s reply. This client-server interaction, also known as request-reply behavior.
B.2 Communication between a client and a server can be implemented by means of a simple connectionless protocol when the underlying network is fairly reliable as in many local-area networks. In these cases, when a client requests a service, it simply packages a message for the server, identifying the service it wants, along with the necessary input data. The message in then sent to the server. The latter, in turn, will always wait for an incoming request, subsequently process it, and package the results in a reply message that is then sent to the client.
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Communication – All communication in the Web between clients and servers is based on the Hypertext transfer Protocol (HTTP). HTTP is a relatively simple client-server protocol; a client sends a request message to a server and waits for a response message. An important property of HTTP is that it is stateless. In other words, it does not have any concept of open connection and does not require a server to maintain information on its clients. The most recent version of HTTP is described in (Fielding et al., 1999).
Page 648 The World Wide Web (WWW) can be viewed as a huge distributed system consisting of millions of clients and servers for accessing linked documents. Servers maintain collections of documents, while clients provide users an easy-to-use interface for presenting and accessing those documents. The Web started as a project at CERN, the European Particle Physics Laboratory in Geneva, to let its large and geographically dispersed group of researchers provide access to shared documents using a simple hypertext system. A document could be anything that could be displayed on a user’s computer terminal, such as personal notes, reports, figures, blueprints, drawings, and so on. By linking documents to each other, it became easy to integrate documents from different projects into a new document without the necessity for centralized changes. The only thing needed was to construct a document providing links to other relevant documents (see also Berners-Lee et al., 1994). Since 1994, Web developments are primarily initiated and controlled by the World Wide Web Consortium, a collaboration between CERN and M.I.T. this consortium is responsible for standardizing protocols, improving interoperability, and further enhancing the capabilities of the Web. Its home page can be found at http://www.w3.org/.
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London, Sherry. 2000. Illustrator 9 f/x & Design. Arizona: The Coriolis Group, LLC.
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Image resolution seems to be a tricky and complex topic the most people. I usually urge folks to work in pixels inside the Photoshop because pixels are fixed: A 900-pixel-wide image contains 900 pixels, regardless of its ppl. However, if the ppl is set to 300, the 900-pixel image prints at 3 inches wide; if the ppl is set to 100, the 900-pixel image prints 9 inches wide – but it still contains only 900 pixel across. Therefore, I find it much easier to think in pixels.
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Harb, M. 1989. Modern Telephony. New Jersey: Prentice-Hall, Inc.
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The Telephone of Today
The end user or subscriber is the main concern in any communication link. The subscriber can be either a private part or a business. In all cases, the telephone set is used to transmit and receive, sequentially or simultaneously.
The Telephone Set
The telephone set is an instrument used to transmit and receive information or calls sequentially or simultaneously, thus permitting one party to communicate with another. For this communicate to take place, the telephone set must have the following component: a transmitter, a receiver, bell, a dialer, and a switchhook.
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Cellular mobile communication is considered to be the breakthrough that could revolutionize the way businesses think about and use the most common of communication tools – the telephone. The cellular mobile telephone is found most often in cars, using low-power radio-frequency carriers to transmit and receive messages in small geographical units called cells. Before the introduction of cellular technology, most North American cities were using high-power radio-frequency transmitters for mobile telephone transmission. Even if a subscriber was lucky enough to have the service, the number of channels was limited, and consequently the possibility of having access to a free line was very slim. Furthermore, once the subscriber got access to a line, the voice quality was poor and privacy almost nonexistent. This is not the case with the cellular mobile system. With the new technology, subscribers are guaranteed access to a free line 99.9% of the time. The quality of the voice is comparable to that of regular telephone transmission, and privacy is guaranteed. Cellular mobiles became available in the United States in 1979, when Ameritech Mobile Communications began serving 2000 subscribers in the city of Chicago. By 1985, over 30,000 subscribers in the United Stated were using cellular mobiles, and this number continues to grow in the United States as well as in Canada, the European nations, Japan, and many more.
Operation of a Cellular Mobile System
Since is not feasible to set up a communication link between two moving cars using a standard telephone line, it is necessary to use a wireless system with a radio antenna to send and receive telephone conversation over the air. The term “cellular” is derived from the word “cell.” Cities or towns are divided into geographic areas called cells, each with its own transmitter and receiver. Each cell has a low-power transmission capability, thus making its signal too weak to interfere with other cells with similar frequencies. Generally, the frequency occupied by two subscribers within the same cell cannot be used by any other subscribers within that cell. The diagram of a cellular system shown in Figure 12.1 demonstrates the process of relaying messages from car telephone (or portable telephone) to the cell site’s low-powered transmitter, to the Cantel switching office or MTSO (mobile telephone switching office), and to the wireline telephone company’s switching office, to allow interconnection with the existing telephone system. The message is “handed off” from one cell site transmitter to the next as the caller crosses a cell boundary, without interruption. A master computer keeps track of which cells are using which frequencies (see Figure 12.1), and when a subscriber wishes to call a subscriber outside his or her cell, the computer may reassign frequencies. As a subscriber moves from one cell to the next, the assigned frequency may change, but the subscriber will at all times be served without interference (Figure 12.2).
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Meyers, Mike. 2003. Introduction to PC Hardware and Troubleshooting. Asia: McGraw-Hill / Osborne.
Page 390 Much of what makes modern computers so powerful is their ability to connection in small or large groups, or networks, and share files and resources. Every PC tech worth knowing the basics of networking. After all, why get into computing if you can’t while away an afternoon gaming with your buddies, all from the comfort of your computer chair?
How Networks Work A network enables two or more computers to share data, hardware such as printers, and even applications. The computers must have some connectivity, of course: some way for the signal from one machine to reach the other. In addition, the hardware must be compatible and the software set up so that the receiving computer can understand what the sending machine sends. Think of two kids chatting over walkie-talkie as a network for communication to occur, the hardware has to be in range for the signal, and it has to be from the same set, and the kids need to speak the same language. Networks work similarly. Computers connect in two basic ways: In dial-up networks in Local Area Networks. In dial-up connection, your computer uses a telephone line to connect to an Internet Service Provider (ISP), which then gives you access to other computers, perhaps at your office or somewhere on the Internet. Computers in a Local Area Network, on the other hand, are connected to a central box – either by cables or by radio waves – through which they can communicate with each other and, if some machine on the network has the appreciate connection, with other computers on the Internet. Let’s look at how both types of network function before we turn to the nuts and bolts of installing and setting up networks.
Dial-Up Networks The most common network connection consists of three pieces: a modem, a working telephone line, and an ISP. The modem enables the computer to communicate via phone lines. The phone line provides the link between the modem and the computers at the ISP. The ISP computers connect to the Big Kahuna of all networks, the Internet. Property installed you to surf, shop, and otherwise explore websites hosted by computers all over the world. Tune in and turn on to dial-up networking. The venerable modem has to recent years been challenged by two new consumer technologies for accessing the Internet so-called “cable-modems” and DSL (Digital Subscriber Line) service. Your computer’s basic need for some kind of pipeline to communicate over hasn’t charged – just the choice of pipeline and the way it’s used. Both technologies take advantage of unused capacity on widely available transmission media. Cable modems use the cables already in place in many homes for receiving cable TV signals as their pipeline to the Internet, rather than the telephone system. The cable TV companies take advantage of the fact that their cable TV signals occupy only a fraction of the capacity of the coaxial cables running into your home. Adding a cable modem to your computer enables it to use the cable TV connection as its pipeline to the Internet. Cable modems aren’t actually “modems” at all in the sense that the signals they send and receive are entirely digital, but because they perform the same function, they go by the same name. you can install an external cable modem to a port (usually USB) on your computer.
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Modem Technology The modem solves one of the problems with the use of analog voice lines to move digital data. Modems take incoming analog serial data – in this case, the signal coming over the telephone line- and turn it into digital serial data. Likewise, modems turn the signal flowing out of the PC into analog data than can be transferred over the telephone line. This process – called modulation / demodulation – provides the name for the technology: MOdulation / DEModulation, get it! Phone lines have a speed based on a unit called a baud, which is one cycle per second. The fastest rate that a phone line can achieve is 2,400 baud. Modem can pack multiple bits of data into each baud; a 33.6 kilobits per second (Kbps) modem, for example, packs 14 bits into every baud: 2,400 x 14 = 33.6 Kbps. It is technically incorrect to say, “I have a 56 K baud modem.” You should instead say, “’I have a 56 Kbps modem.” However, people use the term baud instead of bps so other that the terms have become functionally synonymous.
Page 415 A network enables two or more computers to share data, hardware such as printers, and even applications. Computers connect in two basic ways: dial-up networks and Local Area Networks. A standard dial-up network connection consists of these pieces: a modem, a working telephone line, and an Internet Service Provider (ISP). To make a LAN work, you need to ensure those things: connectivity, compatibility, and proper setup of hardware and software. Data is broken up and sent between computers in small chunks called packets and then reassembled.
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Everything in your computer fits into one of two categories: hardware or software. Anything on your computer that you can touch is hardware.
However, hardware alone cannot handle all of the PC’s complex activities – it needs the help of software. Software is the technical word for computer programs, the sets of instructions that tell the hardware how to do things. Computer programs are often compared to cooking recipes. The recipe tells you how to use the tools to manipulate the ingredients, and if all goes well, you produce something edible. In the same way, software instruct the hardware has it manipulates data to produce the desired results, whether that’s a memo, a digital picture, or an email message. Figure 1.1 shows a sample of program code.
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Stamper, David A. 2001. Local Area Networks – Third Edition. New Jersey: Prentice-Hall, Inc.
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Classes of Software
The reason for having a computing system is to solve problems and accomplish the business’ work. The software that does this is called application software. Ordinarily, application software operates in an environment that makes writing and using the application software easier. The environment-creating software can be separated into network management, development and network access.
Application Software
As we mentioned at the beginning of this section, the main reason we use computing system is to solve business or scientific problems. Thus, the computer and its extension, the network, are simply problem-solving tools. Throughout history, humankind has constantly built new tools and improved on those already invented. At the beginning of the computer era, computers were quite primitive tools (at least by today’s standards). Programmers at the dawn of the computing age needed to know not only the nuances of the business problem they were solving but also many of the intricacies of the hardware their solution would be running on. In today’s application environment, we have a supporting cast of software that helps to create an application environment that is mostly hardware independent.
Operating System Software
Today, we are so need to using OSs to create the system environment that we take them for granted. However, we were into the second generation of computers before OSs appeared and into the third generation of computers before OSs became common. You may correctly infer from this that OSs are not absolutely necessary and, in the early years of personal computing, a variety of applications run without using the services of an OS. The IBM Personal Computer (PC) came equipped with a BASIC interpreter in a read-only memory. Thus, if you did not have the disk operating system (DOS), you could still use your computer by writing and running BASIC programs. Without DOS, BASIC was the operating environment. Furthermore, a few early programs functioned in a stand-alone mode. These programs where on a diskette and were loaded when the computer was loaded. In this mode, if you wanted to run another program, you swapped disk and rebooted. Without an OS, the application program is responsible for accomplishing many hardware-oriented functions such as input/output (I/O) and memory management. Because these task are common to all applications, software engineers developed OS software. The OS manages the resources of the computer and creates an application environment in which it is easier to develop and use application software because the OS takes care of a variety of functions formerly done by applications. Some of these functions are: • Memory management • File management • User interface • I/O interfaces • Resource allocation • Accounting • Protection/security
Today, systems running on a LAN are more sophisticated that the early systems that ran without an OS; a LAN node without an OS is unthinkable.
Memory Management – When the computer is started, the OS is loaded into memory a certain portion of the available memory is constantly occupied by the resident portion of the OS. The OS manages the remaining memory and allocates it among itself and the requesting processes according to a memory management scheme adopted by the OS designers. Most current OSs use a memory management algorithm called virtual memory. With virtual memory, the disk is used as an extension of real memory. A process may be thought of as consisting of pages of data and code.
File Management – A disk is a raw storage device. It has the ability to store bits of data but inherently does not have the ability to organize those bits into files, files into directories, and so on. The OS provides this level of disk organization. it establish the data structure that allows users to create partitions, directories volumes, and other disk subdivisions. Some file management systems allow multiple disks to be combines into one logical disk. The file management system allows users to create, delete, and access files. The file management system maintains the directory structure and store directory and file information such as the date and time last modified, end-of-file pointer, and the file or directories’ locations on disk. Obviously, there are fundamental aspects of using a system.
User Interface – When a programmer begins to write a program, an environment is created for that user.
If you are a programmer, you may need to use a text editor, compiler, link editor, and application program interface (API), which allows you to use OS procedures to carry out activities such as creating a new file, or starting a new process. Sometimes a compiler or interpreter includes the API interfaces.
Protection Security – Today, nearly everyone is aware that security is an important aspect of computer usage. The OS provides the base on which security is established. We expect the OS to prevent user programs from crashing the system and to eliminate the intrusion of one program into the memory occupied by another program’s data. In shared systems, we also expect the OS and the file management system to provide certain levels of file security. Commonly, an OS will at least provide capabilities that allow administrators to define which users can read, write, or erase a file. Furthermore, most OSs allow file attributes that define a file as read-only, hidden (so it will not appear in a standard directory listing), and execute-only (so the file cannot be illegally copied).
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BACKUP HARDWARE, SOFTWARE, AND PROCEDURES
Data backups and restorations require both hardware and software. The hardware provides the medium to which the backup is written or from which data to be restored is read. The software provides the logic to write the correct file to the backup medium or to read those files from the backup medium for restoration. Good backup/restore software also provides a variety of options.
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Recovery
At some point, every LAN fails and recovery must be done. Whenever data or data integrity is lost, it must be restored.
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Essential Elements of Communications
Networks are communications mechanism. For communication of any type to occur, there must be four basic elements present: a message, a sender, a receiver, and a medium. Figure 1-1 shows the sender, receiver, medium, and message in a telephone connection. In addition to these four basic elements, the message should be understandable and there should be an ability to detect errors that may be occur during data transmission. Moreover, in data communications network we often have an additional requirements of security.
Message – are various formats and lengths.
The sender is the transmitter of the message – either a person, an application, or a machine with enough intelligence to originate a message or response without human intervention.
The Receiver
The Medium
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Peñaflorida, Arlene R., Andrew B. Vizcarra, Proceso L. Fernandez Jr. and Teresita P. Pasadas. 2005. Computer Advantage Series – Understanding Structured Programming – Textbook for High School. Quezon City: Vibal Publishing House, Inc.
Page iii
There are two basic types of software – the system software and the application software. Both types are important. The system software starts up your computer and coordinates all hardware components and application software. The application software, on the other hand, is designed to satisfy your needs, such a word processing, database management, creation of spreadsheets and playing games, among others. But have you ever wondered where all these software come from? All software (sing. or pl.) are creating using another software, which is called programming language software. Programming is the art and science of creating programs. A program is a list or sequence of instructions that can be executed by a computer.
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Programming tools such as flowcharts and pseudocodes may be used before coding your program using a programming language such as BASIC.
Programming is the art and science of creating computer program – a program being a list of instructions that the computer must follow in order to process data into information. The instructions consist of statements written in a programming language, such as Pascal, BASIC, and C. Computers are rigorously logical machines, and programming requires a similarly logical approach to designing, coding (writing), testing and debugging (eliminating errors) a program.
Page 3 Computers are not intelligent. Yes, computers are fast; they are able to calculate complex computations in mere seconds. However, being fast does not make computers make intelligent. It only makes them high-speed followers, nothing more. In reality, computers are only as good as the programs they are running. This is a very important point to consider if you are programming. Computers are only as good as the instructions or programs you feed them. As the programmer, it is entirely up to you whether you want the computer to “act intelligently” or not. The computer will follow your instructions to the last detail. So, if you made a mistake in your program, expect the computer to deliver the result as you instructed it – also a mistake. As the computing axiom states: “Garbage In, Garbage Out” (GIGO). Many problems in programming are attributed to poor programming practices rather than to lack of knowledge of a specific computer language.
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Program Development Process You might think that programming is simply typing words and numbers onto a computer. Actually, this activity called coding, is only a small part of the whole programming process. Programming, also called software engineering, is a multistep process for creating a program. Basically, programming is a method of solving problem. Programming uses algorithms – an algorithm being a set of ordered steps for solving a problem, and which is essentially synonymous with logic. Analytical and critical thinking is needed in the formulation of solutions to a problem.
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Gibbs, Mark. 1993. Absolute Beginner’s Guide to Networking. Indiana: SAMS Publishing.
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Sneaker Net
Sneaker net raised a lot of problems. How could you ensure that your document were up-to-date if various copies, modified by any number of people, were all calculating on different disk. How could you stop documents from being stolen? What if the only up-to-date version was on the floppy disk and someone used the disk as a coffee coaster? What if ….. There were a hundred of problems with the Sneakers net approach and all of them pointed in the same direction: the need – the absolute necessity – to pass the documents between computers electronically. Combine that need with the desirability of sharing expensive disk storage and printers and you have a problem looking for a solution. It was this need to share data and peripherals that stimulated the creations of the first local area networks, but, as you shall see, the need to share data became the central issue.
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Rule for Communications
This chapter looks at the major standards that computers use to communicate with each other. The reason that this is an important topic is that unless rules defining kinds of messages and how they are constructed are agreed upon, it is virtually impossible for two computers to talk to each other. This set of rules is called a protocol. A protocol defines not only who will speak when, but what language they will use.
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Uffenbeck, John. 1985. Microcomputers and Microprocessors: The 8080, 8085, and Z-80 Programming, Interfacing, and Troubleshooting. New Jersey: Prentice-Hall, Inc.
There are so many operations required that it makes you wonder about the usefulness of the computer in the first place! Of course, the computer can do each operation rather quickly – usually in just a few microseconds. Once the program to add two numbers has been written, it will do so a lightning speed and never make a mistake. Of course, this is the advantage the computer has over us – once programmed to perform a task, it will flawlessly perform that task at rates approaching millions of operations per seconds. The problem becomes one of the programming the computer, that is telling it what we want it to do. Unfortunately, the computer does not speak our language and seems unwillingly to learn (people are working on it, through). Therefore, the burden is on us to learn the instructions that will programs the computer to perform a particular task.
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Manual – Other Publications
ELECTRONICS – Project Method, Home Training – Lesson No. 1
National Technical Schools. 1905. Los Angeles, USA.
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The Story of Communications Many factors have affected the progress of civilization, some for better, some for worse, but few activities have had such a profound influenced as Communications down through the ages. It is our sincere belief that Communications has been one of the most, if not the most, vital influence affecting the progress and development of our highly technical world. With this thought in mind, we present a chronological history of Communications in the pages which follow. From the far off yesterday – when the first beat of the Aborigines tom-tom sent its message of warning into the jungle over slow sound waves – to the present time when orbiting satellites carry pictorial and voice communications to the four corners of the earth with the speed of light, there unfolds in this introductory lesson the narrative of man’s determination to improve his means of communicating with his fellow beings. It is of special interest to note that although the science of communications originally came into existence for the sole purpose of transmitting messages between points located at some distance from each other, it eventually resulted in the birth of the gigantic field of electronics as we know it today – which also includes television, radar, telemetering, guidance controls, computers, automation and many other electronic devices and systems. It is our hope that the chronological portrayal of the events, as outlined in these pages, will bring you both knowledge and enjoyment as you take the first step in your journey into the marvelous realm of electronics.
Drums War, hunting, fishing, sickness, death, were all of prime importance to early man. Men went far into the jungle forests to hunt. Women traveled to cultivate distant gardens clearings. Word came to settlements that enemy tribes were on the warpath; or perhaps some important member of the tribe had met death and his funeral was a major importance; a man’s wife ran away, messages must be sent along her pathway of escape to catch and hold her. The practical answer to all these important needs was the drum which, by relay, sent messages from one settlement. Messages were sent by “tone” rather than by words spelled out. Certain tone-rhythms conveyed certain understood sentences.
Wireless Communication James C. Maxwell, Heinrich Hertz and Guglielmo Marconi have been called the “stepping stones to Wireless.” Maxwell was born in Edinburgh, Scotland, in 1831. he entered the University of Edinburgh and later went to Cambridge. From 1860 to 1865 he was professor of physics at Kings College in London. There he met Michael Faraday, whose theories and surmises on the subjects of time and spare intrigued him greatly. Heinrich Hertz was born in Hamburg, Germany in 1857, the son of a lawyer. He became a student of technical science but soon decided to devote himself entirely to physics. After three years of study in Munich and Berlin he became assistant to Helmholtz and later entered Kiel University. He taught of Karlsruhe Technical High School in 1888, and there the Hertzian or radio wave was born.
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Mercene, Floro. This Is On Me. Tempo. Vol. 28. No. 088. March 29, 2010.
Manila Bulletin Publishing Corporation. Intramuros, Manila.
Growth of internet
By 2005, the global population of Internet users had reached at least 300 million. At this rate, by 2010 some 95 percent of the people on the industrialized world and half of those in the developing world will be online. By 2002, the Africa ONE project was ringing that continent with broadband fiber-optic lines cable of carrying 40 gigabits of data per second – enough to provide high-speed Net access for all of Africa. India and 650,000 Internet subscribers in 1999. It expected to have 4 million by the end of 2001, 8 million a year later. Despite Beijing’s desire to control communications, Net service is expanding rapidly in China. By 2003, China had as many as 33 million people online and 85 million by 2005 – but that is still less than 7 percent of the population. In Contrast, 60 percent of Japan’s population was online by 2005. By 2010 most of United States will be “wired” for high-speed data access. By 2015, most of the rest of the world will follow. Most Internet communication is commercial, business-to-business, rather than personal e-mail. Internet-based commerce achieved sales of over $1 trillion per year by 2002, in part because the internet is the largest tax-free zone in the world. Estimated world savings in business expenses thanks to B2B sales and services on the Internet: $1.3 trillion by 2002.
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Mercene, Floro. This Is On Me. Tempo. Vol. 28. No. 116. April 26, 2010
Manila Bulletin Publishing Corporation. Intramuros, Manila.
The Internet alters politics
The Internet is beginning to have a significant impact on public policy, according to the Foundation for Public Affairs, a thin tank in Washington D.C. There has been a great deal of talk about e-commerce, but the effects of the Internet on “idea commerce” are also profound,” says Douglas C. Pinkham, president of the Foundation for Public Affairs. In a recent study, foundation researchers interviewed 41 leading politicians, journalists, activists, and corporate professionals discussing the Internet’s impact on the political process. The Internet is altering how congressmen, lobbyists, government officials, activists, and journalists shape public policy. All US senators and 94 percent of house members had Web sites in 1999, according to researchers. All congressional committees had Web sites and 88 percent of Capitol Hill staffers use the Internet to read the Washington Post. The Internet is giving wired activities of various political persuasions the capacity to bombard government agencies and congressional offices with political e-mail messages. It also enables interest groups with modest budget to become influential in helping them to quickly launch large-scale advocacy campaigns, raise money, mobilize support, and become better organized. “Governments have been surprised from the beginning by now we take the lead in having the best information and the most in depth information, and having the information before they do,” says Mary Wareham, US coordinator for a land mine company. The Internet is making larger amounts of raw information, as well as misinformation, available to a growing audience of Web suffers. The news media are gathering material at an unprecedented rate and publishing it more rapidly online.
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Cellular Telephone Cellular telephones are wireless devices that are broadcast radio signals as their medium of communications. Developed in the early 1980s for telephone and automobiles, the cellular system divides an area into cluster of “cells,” each cell covering a radius of about 13 to 19 km (8 to 12 mi), and each with its own radio transmitter with some 120 two-way radio channels. To eliminate interference, neighboring cells do not use precisely the same radio frequencies, but the frequencies used in each cluster may be repeated in adjacent clusters. As the phone user moves away from the transmitter, the signal is switched automatically to the neighboring cell. In the years since its introduction, cellular telephones technology has been miniaturized to the point where a typical mobile phone today can fit into a pocket and the typical cellphone user is just as often on foot as in an automobile. In the future, this radio-based wireless technology will become the nexus for a whole range of digitized “Personal Communications Services” (PCS) that will also include transmission of computer data, visual images, paging, and voice-mail messages. In 1994 the Federal Communication Commission announce plans to sell auction more than 2,000 local and regional licenses that will use the radio bandwidths for PCS systems. Plans also under way to transmit PCS signals worldwide through a ring of small Communications Satellites.
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Feuerstein, M.J., and Rappaport, T.S., eds., Wireless Personal Communications (1992).
Academic American Encyclopedia Volume 4 p 238
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Telecommunications Telecommunications means communication over a distance (tele means “far off” in Greek), and refers mainly to electronic forms such as radio, television, telephone, facsimile (“fax”). and computer communications. In modern distance-applications of telecommunications, typically the message is encoded on the energy form (electrical, electromagnetic, or optical) that link source and destination. Most other form of communication-over-a-distance requires that the message be recorded on encoded in some medium (print, handwriting, photograph, disc, audio- or videotape) that is then physically transported between source and destination. This difference is especially notable after the invention of the telegraph (early 19th century), when the speed of most communication over long distance leaped from the speed of the fastest transportation system around (40 km/h, or 25 mph) to the speed of light (299,000 km/sec , 186,000 mi/sec). Older forms of communication like smoke signals, semaphore, mirror-flashing, drums, or light or fire beacons – as contrasted with books, magazines, or newspaper – are telecommunications-like in literal definition but are very limited in distance and message-carrying complexity. In the 1980s and ‘90s, telecommunications has come increasingly to refer to systems that simultaneously accommodate voice, sound, text, graphic, image, calculation, and moving-image message form.
Basic Components. The basic components of a telecommunications system are usually identified as the devices that link source and destination: transmitter, signal, medium, and receiver; noise that may interfere with this process; and feedback that represents a reversal of message flow. Source and destination are defined as any entities – people or machines – capable of creating or responding to messages. A source selects a message, which is converted by transmitter into an energy form, or signal, that can travel by a medium, usually broadcasting or wire, to a receiver that converts the message back to a form that can be understood by the destination. Any loss or distortion of the signal is called noise.
----- http://en.wikipedia.org/wiki/Windows_XP Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops, and media centers. It was released in 2001. The name "XP" is short for "eXPerience."
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http://en.wikipedia.org/wiki/File_manager
A file manager or file browser is a computer program that provides a user interface to work with file systems. The most common operations used are create, open, edit, view, print, play, rename, move, copy, delete, attributes, properties, search/find, and permissions. Files are typically displayed in a hierarchy. Some file managers contain features inspired by web browsers, including forward and back navigational buttons.
----- http://en.wikipedia.org/wiki/Visual_studio Microsoft Visual Studio is an Integrated Development Environment (IDE) from Microsoft. It can be used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all platforms supported by Microsoft Windows, Windows Mobile, Windows CE, .NET Framework, .NET Compact Framework and Microsoft Silverlight.
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http://www.mahalo.com/operating-system
An operating system (OS) is the computer program which translates user input into instructions for the hardware components of a computer or other technological device. An OS may provide a graphical interface through which a user can manage file systems, maintain hardware and install additional programs.
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http://www.nodevice.com/help/5/Phone_drivers.html
Mobile phone drivers offer a way to make better use of your cell phone. These drivers for cell phones and mobile phones allow you to attach your cell to your PC just like any other hardware device. Like other hardware, each mobile phone manufacturer will offer certain features for their cell phone that are unique or at least slightly different to the competition. Each manufacturer builds their phone in their own way, and different commands call up different features. Anyone who has swapped their cell phone handset for another model or make will know this! If you connect your cell to your PC then the computer will need the specific set of instruction to know what functions to use. Some mobile computer users use their cell phone to get their internet connection while mobile. For this the computer needs a specific driver. Similarly if you want to edit your mobile phone from your computer, you need to have the driver installed that is specific to your model and make of phone. With this in place it is possible to transfer ring tones, logos and java games that you’ve downloaded to your PC from the internet. There are many freeware, trial ware and commercial software programs that help you with these task. For instance there are easy to use ring tone composers that you can use of your PC before transferring them to your phone. For most people this is a much more convenient way of programming their cell phone. The other thing that you need to think about is how to make the actual connection. Cell phones can be plugged in via the USB port of you PC if you have the cable that connects your mobile phone output plug to a lead with a USB on the end. Usually this means buying one. If your phone and PC are both Bluetooth enabled, then you can use this connection method. In either case you are likely to need the right driver. Connecting your mobile or cell phone to your computer just needs the right driver and either a cable or a Bluetooth connection. Once you’ve got it you can take more control of your phone, and make use of the much more user friendly keyboard, mouse and screen that your PC offers. You can download software that makes it easy to design your own logos, write your own ring tones and manage your Java games.
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http://en.wikipedia.org/wiki/Java_Development_Kit
The Java Development Kit (JDK) is a Sun Microsystems product aimed at Java developers. Since the introduction of Java, it has been by far the most widely used Java SDK. On 17 November 2006, Sun announced that it would be released under the GNU General Public License (GPL), thus making it free software. This happened in large part on 8 May 2007 and the source code was contributed to the OpenJDK.
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http://www.filehippo.com/download_jre_32/
Java Runtime Environment
Java software allows you to run applications called "applets" that are written in the Java programming language. These applets allow you to have a much richer experience online than simply interacting with static HTML pages.
----- http://en.wikipedia.org/wiki/Macromedia_Studio#Macromedia_Studio Macromedia Studio was a suite of programs designed for web content creation designed and distributed by Macromedia. After Adobe's acquisition of Macromedia, Macromedia Studio 8 was replaced, modified, and integrated into two editions of the Adobe Creative Suite family of software from version 2.3 onwards. The closest relatives of Macromedia Studio 8 are now called Adobe Creative Suite Web Premium.
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http://en.wikipedia.org/wiki/Adobe_Photoshop
Adobe Photoshop, or simply Photoshop, is a graphics editing program developed and published by Adobe Systems. It is the current market leader for commercial bitmap and image manipulation software, and is the flagship product of Adobe Systems. It has been described as "an industry standard for graphics professionals"[1] and was one of the early "killer applications" on the Macintosh, later also for MS Windows.
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http://www.yourdictionary.com/computer/file-manager
File Manger. Software used to organize files on a disk. It provides functions to delete, copy, move and rename files as well as create and manage folders. File managers typically provide file viewing. When clicking on an image name or icon, file managers usually because a separate application to launch that actually renders the file's contents.
Wright, Michael and Mukul Patel. 2000. Scientific American – How Things Work Today. London: Marshall Publishing Ltd.
B.1 The world is currently in the middle of a communications revolution as dramatic as the Industrial Revolution that created our modern society two centuries ago. The growth of telecommunications systems, the arrival of the Internet, and the proliferation of computers in every aspect of our lives are transforming both industrial and knowledge-based economies round the world. Higher disposable incomes and increased leisure time are also fuelling demand for luxury electronic goods and new forms of entertainment. Since the British inventor Alexander Graham Bell patented the telephone in 1877, telephony has become the most important form of distance communication. The telephone network is now truly global, with submarine cables and communications satellites linking every continent. This globe-spanning network handles phone calls, fax transmissions, and internet traffic. The long-distance “backbones” of the telephone network are high capacity optical-fiber cables. Lower-capacity copper cables connect individual phones to the network. The analog signal from an ordinary phone is sampled 4,000 times per second and converted into an 8-bit digital signal. Several conversations can then be transmitted simultaneously down the same cable, using a technique known as multiplexing, which increases the capacity of the network. Routing calls through the telephone network is done automatically be telephone exchanges. In near future, the telephone network may also carry video and music channels, interactive televisions, videophone calls.
Analog signal – Analog electric signals from ordinary phones are carried by copper cable to the local exchange.
Base station – The base station receiving the strongest signal from a cell phone routes the call to the cell phone exchange.
Cell – The cell phone network is divided into hexagonal cells, each with a base station in the middle.
Cell phone exchange – Calls are routed to the main exchange or direct to a base station by the cell phone exchange.
Cell phone network – Base stations send digital information to the cell phone exchange over optical-fiber or copper cable.
Communication satellite – Orbiting satellites are used to route calls between places not linked by a cable.
Digital signal – Digital information is multiplexed, allowing multiple signals to be transmitted simultaneously.
Fax machine – Fax transmissions are sent over the telephone network.
Line-of-sight microwave link – Digitized call from local exchanges are often routed to the main exchange via terrestrial microwave links.
Local exchange – The local exchange digitizes calls for long-distance transmission.
Long-distance or international connection – Optical fibers are used to transmit long-distance calls, many optical fiber cables are laid on the seabed.
Main exchange – The main exchange handles communications between ordinary phones and the cell phone network and routes long-distance and international calls.
Microwaves – Digital information is sent from cell phones to base stations using microwave frequencies.
Moving cell phone – Mobility is the prime asset of the cell phone.
Optical fibers – Transmitting digital information by light pulses enables many calls to be sent down one fiber simultaneously.
Satellite uplink – Encrypted digital information is sent to satellites using microwave frequencies.
Seamless reconnection – As the cell phone moves from one cell to another, the call is rerouted from one base station to the next, without the break in the conversation.
Urban cell – Cell are smaller in urban areas, giving the network greater capacity.
Weakening Signal – As the cell phone moves farther away from the base station, the signal weakens.
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Tanenbaum, Andrew S. and Maareten van Steen. 2002. Distributed Systems Principles and Paradigms. New Jersey: Prentice-Hall, Inc.
B.2 A process is often defined as a program in execution, that is, a program that is currently being executed on one of the operating system’s virtual processors. An important issue is that the operating system takes great care to ensure that independent processes cannot maliciously or inadvertently affect the correctness of each other’s behavior. In other words, the fact that multiple processes may be concurrently sharing the same CPU and other hardware resources is made transparent. Usually, the operating system requires hardware support to enforce this separation.
B.2
Threads in Distributed Systems – An important property of threads is that they can provide a convenient means of allowing blocking system calls without blocking the entire process in which the thread is running. This property makes threads particularly attractive to use in distributed systems as it makes it much easier to express communication in the form of maintaining multiple logical connections at the same time. We illustrate this point by taking a closer look at multithreaded clients and servers, respectively.
B.2
Clients and Servers – In the basic client-server model, processes in a distributed system are divided into two (possibly overlapping) groups. A server is a process implementing a specific service, for example, a file system service or a database service. A client is a process that requests a service from a server by sending it a request and subsequently waiting for the server’s reply. This client-server interaction, also known as request-reply behavior.
B.2 Communication between a client and a server can be implemented by means of a simple connectionless protocol when the underlying network is fairly reliable as in many local-area networks. In these cases, when a client requests a service, it simply packages a message for the server, identifying the service it wants, along with the necessary input data. The message in then sent to the server. The latter, in turn, will always wait for an incoming request, subsequently process it, and package the results in a reply message that is then sent to the client.
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Communication – All communication in the Web between clients and servers is based on the Hypertext transfer Protocol (HTTP). HTTP is a relatively simple client-server protocol; a client sends a request message to a server and waits for a response message. An important property of HTTP is that it is stateless. In other words, it does not have any concept of open connection and does not require a server to maintain information on its clients. The most recent version of HTTP is described in (Fielding et al., 1999).
Page 648 The World Wide Web (WWW) can be viewed as a huge distributed system consisting of millions of clients and servers for accessing linked documents. Servers maintain collections of documents, while clients provide users an easy-to-use interface for presenting and accessing those documents. The Web started as a project at CERN, the European Particle Physics Laboratory in Geneva, to let its large and geographically dispersed group of researchers provide access to shared documents using a simple hypertext system. A document could be anything that could be displayed on a user’s computer terminal, such as personal notes, reports, figures, blueprints, drawings, and so on. By linking documents to each other, it became easy to integrate documents from different projects into a new document without the necessity for centralized changes. The only thing needed was to construct a document providing links to other relevant documents (see also Berners-Lee et al., 1994). Since 1994, Web developments are primarily initiated and controlled by the World Wide Web Consortium, a collaboration between CERN and M.I.T. this consortium is responsible for standardizing protocols, improving interoperability, and further enhancing the capabilities of the Web. Its home page can be found at http://www.w3.org/.
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London, Sherry. 2000. Illustrator 9 f/x & Design. Arizona: The Coriolis Group, LLC.
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Image resolution seems to be a tricky and complex topic the most people. I usually urge folks to work in pixels inside the Photoshop because pixels are fixed: A 900-pixel-wide image contains 900 pixels, regardless of its ppl. However, if the ppl is set to 300, the 900-pixel image prints at 3 inches wide; if the ppl is set to 100, the 900-pixel image prints 9 inches wide – but it still contains only 900 pixel across. Therefore, I find it much easier to think in pixels.
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Harb, M. 1989. Modern Telephony. New Jersey: Prentice-Hall, Inc.
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The Telephone of Today
The end user or subscriber is the main concern in any communication link. The subscriber can be either a private part or a business. In all cases, the telephone set is used to transmit and receive, sequentially or simultaneously.
The Telephone Set
The telephone set is an instrument used to transmit and receive information or calls sequentially or simultaneously, thus permitting one party to communicate with another. For this communicate to take place, the telephone set must have the following component: a transmitter, a receiver, bell, a dialer, and a switchhook.
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Cellular mobile communication is considered to be the breakthrough that could revolutionize the way businesses think about and use the most common of communication tools – the telephone. The cellular mobile telephone is found most often in cars, using low-power radio-frequency carriers to transmit and receive messages in small geographical units called cells. Before the introduction of cellular technology, most North American cities were using high-power radio-frequency transmitters for mobile telephone transmission. Even if a subscriber was lucky enough to have the service, the number of channels was limited, and consequently the possibility of having access to a free line was very slim. Furthermore, once the subscriber got access to a line, the voice quality was poor and privacy almost nonexistent. This is not the case with the cellular mobile system. With the new technology, subscribers are guaranteed access to a free line 99.9% of the time. The quality of the voice is comparable to that of regular telephone transmission, and privacy is guaranteed. Cellular mobiles became available in the United States in 1979, when Ameritech Mobile Communications began serving 2000 subscribers in the city of Chicago. By 1985, over 30,000 subscribers in the United Stated were using cellular mobiles, and this number continues to grow in the United States as well as in Canada, the European nations, Japan, and many more.
Operation of a Cellular Mobile System
Since is not feasible to set up a communication link between two moving cars using a standard telephone line, it is necessary to use a wireless system with a radio antenna to send and receive telephone conversation over the air. The term “cellular” is derived from the word “cell.” Cities or towns are divided into geographic areas called cells, each with its own transmitter and receiver. Each cell has a low-power transmission capability, thus making its signal too weak to interfere with other cells with similar frequencies. Generally, the frequency occupied by two subscribers within the same cell cannot be used by any other subscribers within that cell. The diagram of a cellular system shown in Figure 12.1 demonstrates the process of relaying messages from car telephone (or portable telephone) to the cell site’s low-powered transmitter, to the Cantel switching office or MTSO (mobile telephone switching office), and to the wireline telephone company’s switching office, to allow interconnection with the existing telephone system. The message is “handed off” from one cell site transmitter to the next as the caller crosses a cell boundary, without interruption. A master computer keeps track of which cells are using which frequencies (see Figure 12.1), and when a subscriber wishes to call a subscriber outside his or her cell, the computer may reassign frequencies. As a subscriber moves from one cell to the next, the assigned frequency may change, but the subscriber will at all times be served without interference (Figure 12.2).
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Meyers, Mike. 2003. Introduction to PC Hardware and Troubleshooting. Asia: McGraw-Hill / Osborne.
Page 390 Much of what makes modern computers so powerful is their ability to connection in small or large groups, or networks, and share files and resources. Every PC tech worth knowing the basics of networking. After all, why get into computing if you can’t while away an afternoon gaming with your buddies, all from the comfort of your computer chair?
How Networks Work A network enables two or more computers to share data, hardware such as printers, and even applications. The computers must have some connectivity, of course: some way for the signal from one machine to reach the other. In addition, the hardware must be compatible and the software set up so that the receiving computer can understand what the sending machine sends. Think of two kids chatting over walkie-talkie as a network for communication to occur, the hardware has to be in range for the signal, and it has to be from the same set, and the kids need to speak the same language. Networks work similarly. Computers connect in two basic ways: In dial-up networks in Local Area Networks. In dial-up connection, your computer uses a telephone line to connect to an Internet Service Provider (ISP), which then gives you access to other computers, perhaps at your office or somewhere on the Internet. Computers in a Local Area Network, on the other hand, are connected to a central box – either by cables or by radio waves – through which they can communicate with each other and, if some machine on the network has the appreciate connection, with other computers on the Internet. Let’s look at how both types of network function before we turn to the nuts and bolts of installing and setting up networks.
Dial-Up Networks The most common network connection consists of three pieces: a modem, a working telephone line, and an ISP. The modem enables the computer to communicate via phone lines. The phone line provides the link between the modem and the computers at the ISP. The ISP computers connect to the Big Kahuna of all networks, the Internet. Property installed you to surf, shop, and otherwise explore websites hosted by computers all over the world. Tune in and turn on to dial-up networking. The venerable modem has to recent years been challenged by two new consumer technologies for accessing the Internet so-called “cable-modems” and DSL (Digital Subscriber Line) service. Your computer’s basic need for some kind of pipeline to communicate over hasn’t charged – just the choice of pipeline and the way it’s used. Both technologies take advantage of unused capacity on widely available transmission media. Cable modems use the cables already in place in many homes for receiving cable TV signals as their pipeline to the Internet, rather than the telephone system. The cable TV companies take advantage of the fact that their cable TV signals occupy only a fraction of the capacity of the coaxial cables running into your home. Adding a cable modem to your computer enables it to use the cable TV connection as its pipeline to the Internet. Cable modems aren’t actually “modems” at all in the sense that the signals they send and receive are entirely digital, but because they perform the same function, they go by the same name. you can install an external cable modem to a port (usually USB) on your computer.
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Modem Technology The modem solves one of the problems with the use of analog voice lines to move digital data. Modems take incoming analog serial data – in this case, the signal coming over the telephone line- and turn it into digital serial data. Likewise, modems turn the signal flowing out of the PC into analog data than can be transferred over the telephone line. This process – called modulation / demodulation – provides the name for the technology: MOdulation / DEModulation, get it! Phone lines have a speed based on a unit called a baud, which is one cycle per second. The fastest rate that a phone line can achieve is 2,400 baud. Modem can pack multiple bits of data into each baud; a 33.6 kilobits per second (Kbps) modem, for example, packs 14 bits into every baud: 2,400 x 14 = 33.6 Kbps. It is technically incorrect to say, “I have a 56 K baud modem.” You should instead say, “’I have a 56 Kbps modem.” However, people use the term baud instead of bps so other that the terms have become functionally synonymous.
Page 415 A network enables two or more computers to share data, hardware such as printers, and even applications. Computers connect in two basic ways: dial-up networks and Local Area Networks. A standard dial-up network connection consists of these pieces: a modem, a working telephone line, and an Internet Service Provider (ISP). To make a LAN work, you need to ensure those things: connectivity, compatibility, and proper setup of hardware and software. Data is broken up and sent between computers in small chunks called packets and then reassembled.
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Everything in your computer fits into one of two categories: hardware or software. Anything on your computer that you can touch is hardware.
However, hardware alone cannot handle all of the PC’s complex activities – it needs the help of software. Software is the technical word for computer programs, the sets of instructions that tell the hardware how to do things. Computer programs are often compared to cooking recipes. The recipe tells you how to use the tools to manipulate the ingredients, and if all goes well, you produce something edible. In the same way, software instruct the hardware has it manipulates data to produce the desired results, whether that’s a memo, a digital picture, or an email message. Figure 1.1 shows a sample of program code.
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Stamper, David A. 2001. Local Area Networks – Third Edition. New Jersey: Prentice-Hall, Inc.
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Classes of Software
The reason for having a computing system is to solve problems and accomplish the business’ work. The software that does this is called application software. Ordinarily, application software operates in an environment that makes writing and using the application software easier. The environment-creating software can be separated into network management, development and network access.
Application Software
As we mentioned at the beginning of this section, the main reason we use computing system is to solve business or scientific problems. Thus, the computer and its extension, the network, are simply problem-solving tools. Throughout history, humankind has constantly built new tools and improved on those already invented. At the beginning of the computer era, computers were quite primitive tools (at least by today’s standards). Programmers at the dawn of the computing age needed to know not only the nuances of the business problem they were solving but also many of the intricacies of the hardware their solution would be running on. In today’s application environment, we have a supporting cast of software that helps to create an application environment that is mostly hardware independent.
Operating System Software
Today, we are so need to using OSs to create the system environment that we take them for granted. However, we were into the second generation of computers before OSs appeared and into the third generation of computers before OSs became common. You may correctly infer from this that OSs are not absolutely necessary and, in the early years of personal computing, a variety of applications run without using the services of an OS. The IBM Personal Computer (PC) came equipped with a BASIC interpreter in a read-only memory. Thus, if you did not have the disk operating system (DOS), you could still use your computer by writing and running BASIC programs. Without DOS, BASIC was the operating environment. Furthermore, a few early programs functioned in a stand-alone mode. These programs where on a diskette and were loaded when the computer was loaded. In this mode, if you wanted to run another program, you swapped disk and rebooted. Without an OS, the application program is responsible for accomplishing many hardware-oriented functions such as input/output (I/O) and memory management. Because these task are common to all applications, software engineers developed OS software. The OS manages the resources of the computer and creates an application environment in which it is easier to develop and use application software because the OS takes care of a variety of functions formerly done by applications. Some of these functions are: • Memory management • File management • User interface • I/O interfaces • Resource allocation • Accounting • Protection/security
Today, systems running on a LAN are more sophisticated that the early systems that ran without an OS; a LAN node without an OS is unthinkable.
Memory Management – When the computer is started, the OS is loaded into memory a certain portion of the available memory is constantly occupied by the resident portion of the OS. The OS manages the remaining memory and allocates it among itself and the requesting processes according to a memory management scheme adopted by the OS designers. Most current OSs use a memory management algorithm called virtual memory. With virtual memory, the disk is used as an extension of real memory. A process may be thought of as consisting of pages of data and code.
File Management – A disk is a raw storage device. It has the ability to store bits of data but inherently does not have the ability to organize those bits into files, files into directories, and so on. The OS provides this level of disk organization. it establish the data structure that allows users to create partitions, directories volumes, and other disk subdivisions. Some file management systems allow multiple disks to be combines into one logical disk. The file management system allows users to create, delete, and access files. The file management system maintains the directory structure and store directory and file information such as the date and time last modified, end-of-file pointer, and the file or directories’ locations on disk. Obviously, there are fundamental aspects of using a system.
User Interface – When a programmer begins to write a program, an environment is created for that user.
If you are a programmer, you may need to use a text editor, compiler, link editor, and application program interface (API), which allows you to use OS procedures to carry out activities such as creating a new file, or starting a new process. Sometimes a compiler or interpreter includes the API interfaces.
Protection Security – Today, nearly everyone is aware that security is an important aspect of computer usage. The OS provides the base on which security is established. We expect the OS to prevent user programs from crashing the system and to eliminate the intrusion of one program into the memory occupied by another program’s data. In shared systems, we also expect the OS and the file management system to provide certain levels of file security. Commonly, an OS will at least provide capabilities that allow administrators to define which users can read, write, or erase a file. Furthermore, most OSs allow file attributes that define a file as read-only, hidden (so it will not appear in a standard directory listing), and execute-only (so the file cannot be illegally copied).
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BACKUP HARDWARE, SOFTWARE, AND PROCEDURES
Data backups and restorations require both hardware and software. The hardware provides the medium to which the backup is written or from which data to be restored is read. The software provides the logic to write the correct file to the backup medium or to read those files from the backup medium for restoration. Good backup/restore software also provides a variety of options.
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Recovery
At some point, every LAN fails and recovery must be done. Whenever data or data integrity is lost, it must be restored.
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Essential Elements of Communications
Networks are communications mechanism. For communication of any type to occur, there must be four basic elements present: a message, a sender, a receiver, and a medium. Figure 1-1 shows the sender, receiver, medium, and message in a telephone connection. In addition to these four basic elements, the message should be understandable and there should be an ability to detect errors that may be occur during data transmission. Moreover, in data communications network we often have an additional requirements of security.
Message – are various formats and lengths.
The sender is the transmitter of the message – either a person, an application, or a machine with enough intelligence to originate a message or response without human intervention.
The Receiver
The Medium
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Peñaflorida, Arlene R., Andrew B. Vizcarra, Proceso L. Fernandez Jr. and Teresita P. Pasadas. 2005. Computer Advantage Series – Understanding Structured Programming – Textbook for High School. Quezon City: Vibal Publishing House, Inc.
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There are two basic types of software – the system software and the application software. Both types are important. The system software starts up your computer and coordinates all hardware components and application software. The application software, on the other hand, is designed to satisfy your needs, such a word processing, database management, creation of spreadsheets and playing games, among others. But have you ever wondered where all these software come from? All software (sing. or pl.) are creating using another software, which is called programming language software. Programming is the art and science of creating programs. A program is a list or sequence of instructions that can be executed by a computer.
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Programming tools such as flowcharts and pseudocodes may be used before coding your program using a programming language such as BASIC.
Programming is the art and science of creating computer program – a program being a list of instructions that the computer must follow in order to process data into information. The instructions consist of statements written in a programming language, such as Pascal, BASIC, and C. Computers are rigorously logical machines, and programming requires a similarly logical approach to designing, coding (writing), testing and debugging (eliminating errors) a program.
Page 3 Computers are not intelligent. Yes, computers are fast; they are able to calculate complex computations in mere seconds. However, being fast does not make computers make intelligent. It only makes them high-speed followers, nothing more. In reality, computers are only as good as the programs they are running. This is a very important point to consider if you are programming. Computers are only as good as the instructions or programs you feed them. As the programmer, it is entirely up to you whether you want the computer to “act intelligently” or not. The computer will follow your instructions to the last detail. So, if you made a mistake in your program, expect the computer to deliver the result as you instructed it – also a mistake. As the computing axiom states: “Garbage In, Garbage Out” (GIGO). Many problems in programming are attributed to poor programming practices rather than to lack of knowledge of a specific computer language.
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Program Development Process You might think that programming is simply typing words and numbers onto a computer. Actually, this activity called coding, is only a small part of the whole programming process. Programming, also called software engineering, is a multistep process for creating a program. Basically, programming is a method of solving problem. Programming uses algorithms – an algorithm being a set of ordered steps for solving a problem, and which is essentially synonymous with logic. Analytical and critical thinking is needed in the formulation of solutions to a problem.
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Gibbs, Mark. 1993. Absolute Beginner’s Guide to Networking. Indiana: SAMS Publishing.
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Sneaker Net
Sneaker net raised a lot of problems. How could you ensure that your document were up-to-date if various copies, modified by any number of people, were all calculating on different disk. How could you stop documents from being stolen? What if the only up-to-date version was on the floppy disk and someone used the disk as a coffee coaster? What if ….. There were a hundred of problems with the Sneakers net approach and all of them pointed in the same direction: the need – the absolute necessity – to pass the documents between computers electronically. Combine that need with the desirability of sharing expensive disk storage and printers and you have a problem looking for a solution. It was this need to share data and peripherals that stimulated the creations of the first local area networks, but, as you shall see, the need to share data became the central issue.
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Rule for Communications
This chapter looks at the major standards that computers use to communicate with each other. The reason that this is an important topic is that unless rules defining kinds of messages and how they are constructed are agreed upon, it is virtually impossible for two computers to talk to each other. This set of rules is called a protocol. A protocol defines not only who will speak when, but what language they will use.
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Uffenbeck, John. 1985. Microcomputers and Microprocessors: The 8080, 8085, and Z-80 Programming, Interfacing, and Troubleshooting. New Jersey: Prentice-Hall, Inc.
There are so many operations required that it makes you wonder about the usefulness of the computer in the first place! Of course, the computer can do each operation rather quickly – usually in just a few microseconds. Once the program to add two numbers has been written, it will do so a lightning speed and never make a mistake. Of course, this is the advantage the computer has over us – once programmed to perform a task, it will flawlessly perform that task at rates approaching millions of operations per seconds. The problem becomes one of the programming the computer, that is telling it what we want it to do. Unfortunately, the computer does not speak our language and seems unwillingly to learn (people are working on it, through). Therefore, the burden is on us to learn the instructions that will programs the computer to perform a particular task.
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Manual – Other Publications
ELECTRONICS – Project Method, Home Training – Lesson No. 1
National Technical Schools. 1905. Los Angeles, USA.
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The Story of Communications Many factors have affected the progress of civilization, some for better, some for worse, but few activities have had such a profound influenced as Communications down through the ages. It is our sincere belief that Communications has been one of the most, if not the most, vital influence affecting the progress and development of our highly technical world. With this thought in mind, we present a chronological history of Communications in the pages which follow. From the far off yesterday – when the first beat of the Aborigines tom-tom sent its message of warning into the jungle over slow sound waves – to the present time when orbiting satellites carry pictorial and voice communications to the four corners of the earth with the speed of light, there unfolds in this introductory lesson the narrative of man’s determination to improve his means of communicating with his fellow beings. It is of special interest to note that although the science of communications originally came into existence for the sole purpose of transmitting messages between points located at some distance from each other, it eventually resulted in the birth of the gigantic field of electronics as we know it today – which also includes television, radar, telemetering, guidance controls, computers, automation and many other electronic devices and systems. It is our hope that the chronological portrayal of the events, as outlined in these pages, will bring you both knowledge and enjoyment as you take the first step in your journey into the marvelous realm of electronics.
Drums War, hunting, fishing, sickness, death, were all of prime importance to early man. Men went far into the jungle forests to hunt. Women traveled to cultivate distant gardens clearings. Word came to settlements that enemy tribes were on the warpath; or perhaps some important member of the tribe had met death and his funeral was a major importance; a man’s wife ran away, messages must be sent along her pathway of escape to catch and hold her. The practical answer to all these important needs was the drum which, by relay, sent messages from one settlement. Messages were sent by “tone” rather than by words spelled out. Certain tone-rhythms conveyed certain understood sentences.
Wireless Communication James C. Maxwell, Heinrich Hertz and Guglielmo Marconi have been called the “stepping stones to Wireless.” Maxwell was born in Edinburgh, Scotland, in 1831. he entered the University of Edinburgh and later went to Cambridge. From 1860 to 1865 he was professor of physics at Kings College in London. There he met Michael Faraday, whose theories and surmises on the subjects of time and spare intrigued him greatly. Heinrich Hertz was born in Hamburg, Germany in 1857, the son of a lawyer. He became a student of technical science but soon decided to devote himself entirely to physics. After three years of study in Munich and Berlin he became assistant to Helmholtz and later entered Kiel University. He taught of Karlsruhe Technical High School in 1888, and there the Hertzian or radio wave was born.
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Mercene, Floro. This Is On Me. Tempo. Vol. 28. No. 088. March 29, 2010.
Manila Bulletin Publishing Corporation. Intramuros, Manila.
Growth of internet
By 2005, the global population of Internet users had reached at least 300 million. At this rate, by 2010 some 95 percent of the people on the industrialized world and half of those in the developing world will be online. By 2002, the Africa ONE project was ringing that continent with broadband fiber-optic lines cable of carrying 40 gigabits of data per second – enough to provide high-speed Net access for all of Africa. India and 650,000 Internet subscribers in 1999. It expected to have 4 million by the end of 2001, 8 million a year later. Despite Beijing’s desire to control communications, Net service is expanding rapidly in China. By 2003, China had as many as 33 million people online and 85 million by 2005 – but that is still less than 7 percent of the population. In Contrast, 60 percent of Japan’s population was online by 2005. By 2010 most of United States will be “wired” for high-speed data access. By 2015, most of the rest of the world will follow. Most Internet communication is commercial, business-to-business, rather than personal e-mail. Internet-based commerce achieved sales of over $1 trillion per year by 2002, in part because the internet is the largest tax-free zone in the world. Estimated world savings in business expenses thanks to B2B sales and services on the Internet: $1.3 trillion by 2002.
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Mercene, Floro. This Is On Me. Tempo. Vol. 28. No. 116. April 26, 2010
Manila Bulletin Publishing Corporation. Intramuros, Manila.
The Internet alters politics
The Internet is beginning to have a significant impact on public policy, according to the Foundation for Public Affairs, a thin tank in Washington D.C. There has been a great deal of talk about e-commerce, but the effects of the Internet on “idea commerce” are also profound,” says Douglas C. Pinkham, president of the Foundation for Public Affairs. In a recent study, foundation researchers interviewed 41 leading politicians, journalists, activists, and corporate professionals discussing the Internet’s impact on the political process. The Internet is altering how congressmen, lobbyists, government officials, activists, and journalists shape public policy. All US senators and 94 percent of house members had Web sites in 1999, according to researchers. All congressional committees had Web sites and 88 percent of Capitol Hill staffers use the Internet to read the Washington Post. The Internet is giving wired activities of various political persuasions the capacity to bombard government agencies and congressional offices with political e-mail messages. It also enables interest groups with modest budget to become influential in helping them to quickly launch large-scale advocacy campaigns, raise money, mobilize support, and become better organized. “Governments have been surprised from the beginning by now we take the lead in having the best information and the most in depth information, and having the information before they do,” says Mary Wareham, US coordinator for a land mine company. The Internet is making larger amounts of raw information, as well as misinformation, available to a growing audience of Web suffers. The news media are gathering material at an unprecedented rate and publishing it more rapidly online.
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Cellular Telephone Cellular telephones are wireless devices that are broadcast radio signals as their medium of communications. Developed in the early 1980s for telephone and automobiles, the cellular system divides an area into cluster of “cells,” each cell covering a radius of about 13 to 19 km (8 to 12 mi), and each with its own radio transmitter with some 120 two-way radio channels. To eliminate interference, neighboring cells do not use precisely the same radio frequencies, but the frequencies used in each cluster may be repeated in adjacent clusters. As the phone user moves away from the transmitter, the signal is switched automatically to the neighboring cell. In the years since its introduction, cellular telephones technology has been miniaturized to the point where a typical mobile phone today can fit into a pocket and the typical cellphone user is just as often on foot as in an automobile. In the future, this radio-based wireless technology will become the nexus for a whole range of digitized “Personal Communications Services” (PCS) that will also include transmission of computer data, visual images, paging, and voice-mail messages. In 1994 the Federal Communication Commission announce plans to sell auction more than 2,000 local and regional licenses that will use the radio bandwidths for PCS systems. Plans also under way to transmit PCS signals worldwide through a ring of small Communications Satellites.
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Feuerstein, M.J., and Rappaport, T.S., eds., Wireless Personal Communications (1992).
Academic American Encyclopedia Volume 4 p 238
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Telecommunications Telecommunications means communication over a distance (tele means “far off” in Greek), and refers mainly to electronic forms such as radio, television, telephone, facsimile (“fax”). and computer communications. In modern distance-applications of telecommunications, typically the message is encoded on the energy form (electrical, electromagnetic, or optical) that link source and destination. Most other form of communication-over-a-distance requires that the message be recorded on encoded in some medium (print, handwriting, photograph, disc, audio- or videotape) that is then physically transported between source and destination. This difference is especially notable after the invention of the telegraph (early 19th century), when the speed of most communication over long distance leaped from the speed of the fastest transportation system around (40 km/h, or 25 mph) to the speed of light (299,000 km/sec , 186,000 mi/sec). Older forms of communication like smoke signals, semaphore, mirror-flashing, drums, or light or fire beacons – as contrasted with books, magazines, or newspaper – are telecommunications-like in literal definition but are very limited in distance and message-carrying complexity. In the 1980s and ‘90s, telecommunications has come increasingly to refer to systems that simultaneously accommodate voice, sound, text, graphic, image, calculation, and moving-image message form.
Basic Components. The basic components of a telecommunications system are usually identified as the devices that link source and destination: transmitter, signal, medium, and receiver; noise that may interfere with this process; and feedback that represents a reversal of message flow. Source and destination are defined as any entities – people or machines – capable of creating or responding to messages. A source selects a message, which is converted by transmitter into an energy form, or signal, that can travel by a medium, usually broadcasting or wire, to a receiver that converts the message back to a form that can be understood by the destination. Any loss or distortion of the signal is called noise.
----- http://en.wikipedia.org/wiki/Windows_XP Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops, and media centers. It was released in 2001. The name "XP" is short for "eXPerience."
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http://en.wikipedia.org/wiki/File_manager
A file manager or file browser is a computer program that provides a user interface to work with file systems. The most common operations used are create, open, edit, view, print, play, rename, move, copy, delete, attributes, properties, search/find, and permissions. Files are typically displayed in a hierarchy. Some file managers contain features inspired by web browsers, including forward and back navigational buttons.
----- http://en.wikipedia.org/wiki/Visual_studio Microsoft Visual Studio is an Integrated Development Environment (IDE) from Microsoft. It can be used to develop console and graphical user interface applications along with Windows Forms applications, web sites, web applications, and web services in both native code together with managed code for all platforms supported by Microsoft Windows, Windows Mobile, Windows CE, .NET Framework, .NET Compact Framework and Microsoft Silverlight.
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http://www.mahalo.com/operating-system
An operating system (OS) is the computer program which translates user input into instructions for the hardware components of a computer or other technological device. An OS may provide a graphical interface through which a user can manage file systems, maintain hardware and install additional programs.
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http://www.nodevice.com/help/5/Phone_drivers.html
Mobile phone drivers offer a way to make better use of your cell phone. These drivers for cell phones and mobile phones allow you to attach your cell to your PC just like any other hardware device. Like other hardware, each mobile phone manufacturer will offer certain features for their cell phone that are unique or at least slightly different to the competition. Each manufacturer builds their phone in their own way, and different commands call up different features. Anyone who has swapped their cell phone handset for another model or make will know this! If you connect your cell to your PC then the computer will need the specific set of instruction to know what functions to use. Some mobile computer users use their cell phone to get their internet connection while mobile. For this the computer needs a specific driver. Similarly if you want to edit your mobile phone from your computer, you need to have the driver installed that is specific to your model and make of phone. With this in place it is possible to transfer ring tones, logos and java games that you’ve downloaded to your PC from the internet. There are many freeware, trial ware and commercial software programs that help you with these task. For instance there are easy to use ring tone composers that you can use of your PC before transferring them to your phone. For most people this is a much more convenient way of programming their cell phone. The other thing that you need to think about is how to make the actual connection. Cell phones can be plugged in via the USB port of you PC if you have the cable that connects your mobile phone output plug to a lead with a USB on the end. Usually this means buying one. If your phone and PC are both Bluetooth enabled, then you can use this connection method. In either case you are likely to need the right driver. Connecting your mobile or cell phone to your computer just needs the right driver and either a cable or a Bluetooth connection. Once you’ve got it you can take more control of your phone, and make use of the much more user friendly keyboard, mouse and screen that your PC offers. You can download software that makes it easy to design your own logos, write your own ring tones and manage your Java games.
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http://en.wikipedia.org/wiki/Java_Development_Kit
The Java Development Kit (JDK) is a Sun Microsystems product aimed at Java developers. Since the introduction of Java, it has been by far the most widely used Java SDK. On 17 November 2006, Sun announced that it would be released under the GNU General Public License (GPL), thus making it free software. This happened in large part on 8 May 2007 and the source code was contributed to the OpenJDK.
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http://www.filehippo.com/download_jre_32/
Java Runtime Environment
Java software allows you to run applications called "applets" that are written in the Java programming language. These applets allow you to have a much richer experience online than simply interacting with static HTML pages.
----- http://en.wikipedia.org/wiki/Macromedia_Studio#Macromedia_Studio Macromedia Studio was a suite of programs designed for web content creation designed and distributed by Macromedia. After Adobe's acquisition of Macromedia, Macromedia Studio 8 was replaced, modified, and integrated into two editions of the Adobe Creative Suite family of software from version 2.3 onwards. The closest relatives of Macromedia Studio 8 are now called Adobe Creative Suite Web Premium.
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http://en.wikipedia.org/wiki/Adobe_Photoshop
Adobe Photoshop, or simply Photoshop, is a graphics editing program developed and published by Adobe Systems. It is the current market leader for commercial bitmap and image manipulation software, and is the flagship product of Adobe Systems. It has been described as "an industry standard for graphics professionals"[1] and was one of the early "killer applications" on the Macintosh, later also for MS Windows.
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http://www.yourdictionary.com/computer/file-manager
File Manger. Software used to organize files on a disk. It provides functions to delete, copy, move and rename files as well as create and manage folders. File managers typically provide file viewing. When clicking on an image name or icon, file managers usually because a separate application to launch that actually renders the file's contents.
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