IT THEORY
2marks
N.B-keep the answers “short and simple”. Here the answers are in an elaborate manner. study the first paragraphs.
1.OPERATING SYSTEM
The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on thedisk, and controlling peripheral devices such as disk drives andprinters.
Operating systems can be classified as follows:
· multi-user : Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.
· multiprocessing : Supports running a program on more than one CPU.
· multitasking : Allows more than one program to run concurrently.
· multithreading : Allows different parts of a single program to run concurrently.
· real time: Responds to input instantly. General-purpose operating systems, such as DOS and UNIX, are not real-time.
Eg. For PCs, the most popular operating systems are DOS,OS/2, and Windows, but others are available, such as Linux.
2.computer generation
answer-page no.24 study material.
3.Application software
A program or group of programs designed for end users.Software can be divided into two general classes: systems software and applications software. Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources.
In contrast, applications software (also called end-userprograms) includes database programs, word processors, andspreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.
4.library network
ans:see in library and society material page:99
0R
page no.12(it study material)
5.WWW
The World Wide Web (commonly abbreviated as "the Web") is a system of interlinked hypertextdocuments accessed via the Internet. With a Web browser, one can view Web pages that may contain text,images, videos, and other multimedia and navigate between them using hyperlinks. Using concepts from earlier hypertext systems, the World Wide Web was begun in 1992 by MIT professor Tim Berners-Lee andRobert Cailliau, a Belgian computer scientist, both working at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland.
Or
A system of Internet servers that support specially formatted documents. The documents are formatted in a markup language called HTML (HyperText Markup Language) that supports links to other documents, as well as graphics, audio, and video files. This means you can jump from one document to another simply by clicking on hot spots. Not all Internet servers are part of the World Wide Web.
There are several applications called Web browsers that make it easy to access the World Wide Web; Two of the most popular being Netscape Navigator and Microsoft's Internet Explorer.
6.DIFFERENCE b/w INTERNET and WWW
The Internet is a massive network of networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known as protocols.
The World Wide Web, or simply Web, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. Web services, which use HTTP to allow applications to communicate in order to exchange business logic, use the the Web to share information. The Web also utilizes browsers, such as Internet Explorer orFirefox, to access Web documents called Web pages that are linked to each other via hyperlinks. Web documents also contain graphics, sounds, text and video.
7.Switching techniques
page number 194(library science unleashed)
8.expert systems
A computer application that performs a task that would otherwise be performed by a human expert. For example, there are expert systems that can diagnose human illnesses, make financial forecasts, and schedule routes for delivery vehicles. Some expert systems are designed to take the place of human experts, while others are designed to aid them.
Expert systems are part of a general category of computer applications known as artificial intelligence . To design an expert system, one needs a knowledge engineer, an individual who studies how human experts make decisions and translates the rules into terms that a computer can understand.
9.electronic mail
page 199(library science unleashed)
10.cpu
Abbreviation for central processing unit. The CPU is the brain of the computer. Sometimes referred to simply as the central processor,but more commonly called processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.
Two typical components of a CPU are the following:
- The arithmetic logic unit (ALU), which performs arithmetic and logical operations.
- The control unit (CU), which extracts instructions frommemory and decodes and executes them, calling on the ALU when necessary.
11.hypermedia
An extension to hypertext that supports linking graphics, sound, and video elements in addition to text elements. TheWorld Wide Web is a partial hypermedia system since is supports graphical hyperlinks and links to sound and video files. New hypermedia systems under development will allow objects in computer videos to be hyperlinked.
12.Hypertext
A special type of database system, invented by Ted Nelson in the 1960s, in which objects (text, pictures, music,programs, and so on) can be creatively linked to each other. When you select an object, you can see all the other objects that are linked to it. You can move from one object to another even though they might have very different forms.
13.database
Often abbreviated DB. A collection of information organized in such a way that a computer program can quickly selectdesired pieces of data. You can think of a database as an electronic filing system.
Traditional databases are organized by fields, records, andfiles. A field is a single piece of information; a record is one complete set of fields; and a file is a collection of records. For example, a telephone book is analogous to a file. It contains a list of records, each of which consists of three fields: name, address, and telephone number.
14.database management system (DBMS).
To access information from a database, you need a database management system (DBMS). This is a collection of programs that enables you to enter, organize, and select data in a database.
15.website
A site (location) on the World Wide Web. Each Web site contains a home page, which is the first document users see when they enter the site. The site might also contain additional documents and files. Each site is owned and managed by an individual, company or organization.
16.Ms windows
A family of operating systems for personal computers. Windows dominates the personal computer world, running, by some estimates, on 90% of all personal computers. The remaining 10% are mostly Macintosh computers. Like the Macintosh operating environment, Windows provides agraphical user interface (GUI), virtual memory management,multitasking, and support for many peripheral devices.
17.LAN(local area network)
A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN).
Most LANs connect workstations and personal computers. Each node (individual computer ) in a LAN has its own CPUwith which it executes programs, but it also is able to accessdata and devices anywhere on the LAN. This means that manyusers can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.
There are many different types of LANs Ethernets being the most common for PCs. Most Apple Macintosh networks are based on Apple's AppleTalk network system, which is built into Macintosh computers.
The following characteristics differentiate one LAN from another:
· topology : The geometric arrangement of devices on the network. For example, devices can be arranged in a ring or in a straight line.
· protocols : The rules and encoding specifications for sending data. The protocols also determine whether the network uses a peer-to-peer or client/server architecture.
· media : Devices can be connected by twisted-pair wire, coaxial cables, or fiber optic cables. Some networks do without connecting media altogether, communicating instead via radio waves.
LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN.
18.WAN(wide area network)
A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs).
Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites. The largest WAN in existence is the Internet.
19.HTML
Short for HyperText Markup Language, the authoring language used to create documents on the World Wide Web.
HTML defines the structure and layout of a Web document by using a variety of tags and attributes. The correct structure for an HTML document starts with (enter here what document is about) and ends with . All the information you'd like to include in your Web page fits in between the and tags.
There are hundreds of other tags used to format and layout the information in a Web page. Tags are also used to specify hypertext links. These allow Web developers to direct users to other Web pages with only a click of the mouse on either an image or word(s).
20.Ms office
Office Application software by Microsoft corporation.ncludes word ,excel,powerpoint etc.
21.cd rom technology
page no.11 study material
22.online database
An online database is a database accessible via a network, now generally the internet.
23.bibliographic database
A bibliographic or library database is a database of bibliographic records. It may be a database containing information about booksand other materials held in a library (e.g. an online library catalog, or OPAC) or, as the term is more often used, an electronic index tojournal or magazine articles, containing citations, abstracts and often either the full text of the articles indexed, or links to the full text.
Many scientific databases are bibliographic databases, but some are not. Within Chemical Abstracts, for example, there are databases of chemical structures and within Entrez there are databases of sequences. Outside of science, the same holds — there are databases of citations to articles in art history journals, and there are databases of images, such as ARTstor.
24.search engines
A program that searches documents for specified keywords and returns a list of the documents where the keywords were found. Although search engine is really a general class of programs, the term is often used to specifically describe systems like Google, Alta Vistaand Excite that enable users to search for documents on the World Wide Web and USENET newsgroups.
Typically, a search engine works by sending out aspider to fetch as many documents as possible. Another program, called an indexer, then reads these documents and creates an index based on the words contained in each document. Each search engine uses aproprietary algorithm to create its indices such that, ideally, only meaningful results are returned for each query.
25.OCR
page 27 study material
OR
Often abbreviated OCR, optical character recognition refers to the branch of computer science that involves reading textfrom paper and translating the images into a form that thecomputer can manipulate (for example, into ASCII codes). An OCR system enables you to take a book or a magazine article, feed it directly into an electronic computer file, and then edit the file using a word processor.
All OCR systems include an optical scanner for reading text, and sophisticated software for analyzing images. Most OCR systems use a combination of hardware (specialized circuit boards) and software to recognize characters, although some inexpensive systems do it entirely through software. Advanced OCR systems can read text in large variety of fonts, but they still have difficulty with handwritten text.
The potential of OCR systems is enormous because they enableusers to harness the power of computers to access printeddocuments. OCR is already being used widely in the legal profession, where searches that once required hours or days can now be accomplished in a few seconds.
26.METASEARCH ENGINE
A search engine that queries other search engines and then combines the results that are received from all. In effect, the user is not using just one search engine but a combination of many search engines at once to optimize Web searching. For example, Dogpile is a metasearch engine.
27.ring network
page 92 study material
28.compilers and interpreters
page 56 study mat.
28.algorithm
A formula or set of steps for solving a particular problem. To be an algorithm, a set of rules must be unambiguous and have a clear stopping point. Algorithms can be expressed in any language, from natural languages like English or French to programming languages like FORTRAN.
We use algorithms every day. For example, a recipe for baking a cake is an algorithm. Most programs, with the exception of some artificial intelligence applications, consist of algorithms. Inventing elegant algorithms -- algorithms that are simple and require the fewest steps possible -- is one of the principal challenges in programming.
29.programming language
A vocabulary and set of grammatical rules for instructing acomputer to perform specific tasks. The term programming language usually refers to high-level languages, such as BASIC,C, C++, COBOL, FORTRAN, Ada, and Pascal. Eachlanguage has a unique set of keywords (words that it understands) and a special syntax for organizing programinstructions.
High-level programming languages, while simple compared to human languages, are more complex than the languages thecomputer actually understands, called machine languages. Each different type of CPU has its own unique machine language.
30.assembly language
Lying between machine languages and high-level languages are languages called assembly languages. Assembly languages are similar to machine languages, but they are much easier to program in because they allow a programmer to substitutenames for numbers. Machine languages consist of numbers only.
Lying above high-level languages are languages called fourth-generation languages (usually abbreviated 4GL). 4GLs are far removed from machine languages and represent the class of computer languages closest to human languages.
Regardless of what language you use, you eventually need toconvert your program into machine language so that the computer can understand it. There are two ways to do this:
· compile the program
- interpret the program
31. compilers and interpreters
see answer of question 28
32. modem
Short for modulator-demodulator. A modem is a device or program that enables a computer to transmit dataover, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms.
Fortunately, there is one standard interface for connectingexternal modems to computers called RS-232. Consequently, any external modem can be attached to any computer that has an RS-232 port, which almost all personal computers have. There are also modems that come as an expansion board that you can insert into a vacant expansion slot. These are sometimes called onboard or internal modems.
33. multimedia
The use of computers to present text, graphics, video, animation, and sound in an integrated way. Long touted as the future revolution in computing, multimediaapplications were, until the mid-90s, uncommon due to the expensive hardware required. With increases in performance and decreases in price, however, multimedia is now commonplace. Nearly all PCs are capable of displaying video, though the resolution available depends on the power of the computer's video adapter and CPU.
34.virus
A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all availablememory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networksand bypassing security systems.
Since 1987, when a virus infected ARPANET, a large network used by the Defense Department and many universities, manyantivirus programs have become available. These programsperiodically check your computer system for the best-known types of viruses.
Some people distinguish between general viruses and worms. A worm is a special type of virus that can replicate itself and use memory, but cannot attach itself to other programs.
35.boolean logic
Boolean Searching on the Internet
A Primer in Boolean Logic
The Internet is a vast computer database. As such, its contents must be searched according to the rules of computer database searching. Much database searching is based on the principles of Boolean logic. Boolean logic refers to the logical relationship among search terms, and is named for the British-born Irish mathematician George Boole.
On Internet search engines, the options for constructing logical relationships among search terms extend beyond the traditional practice of Boolean searching. This will be covered in the section below, Boolean Searching on the Internet.
Boolean logic consists of three logical operators:
- OR
- AND
- NOT
Each operator can be visually described by using Venn diagrams, as shown below.
OR
college OR university
Query: I would like information about college.
- In this search, we will retrieve records in which AT LEAST ONE of the search terms is present. We are searching on the terms college and also university since documents containing either of these words might be relevant.
- This is illustrated by:
o the shaded circle with the word college representing all the records that contain the word "college"
o the shaded circle with the word university representing all the records that contain the word "university"
o the shaded overlap area representing all the records that contain both "college" and "university"
OR logic is most commonly used to search for synonymous terms or concepts.
Here is an example of how OR logic works:
| Search terms | Results |
| college | 396,482 |
| university | 590,791 |
| college OR university | 819,214 |
OR logic collates the results to retrieve all the unique records containing one term, the other, or both.
The more terms or concepts we combine in a search with OR logic, the more records we will retrieve.
For example:
| Search terms | Results |
| college | 396,482 |
| university | 590,791 |
| college OR university | 819,214 |
| college OR university OR campus | 929,677 |
AND
poverty AND crime
Query: I'm interested in the relationship between poverty and crime.
- In this search, we retrieve records in which BOTH of the search terms are present
- This is illustrated by the shaded area overlapping the two circles representing all the records that contain both the word "poverty" and the word "crime"
- Notice how we do not retrieve any records with only "poverty" or only "crime"
Here is an example of how AND logic works:
| Search terms | Results |
| poverty | 76,342 |
| crime | 348,252 |
| poverty AND crime | 12,998 |
The more terms or concepts we combine in a search with AND logic, the fewer records we will retrieve.
For example:
| Search terms | Results |
| poverty | 76,342 |
| crime | 348,252 |
| poverty AND crime | 12,998 |
| poverty AND crime AND gender | 1,220 |
A few Internet search engines make use of the proximity operator NEAR. A proximity operator determines the closeness of terms within the text of a source document. NEAR is a restrictive
NOT
cats NOT dogs
Query: I want information about cats, but I want to avoid anything about dogs.
- In this search, we retrieve records in which ONLY ONE of the terms is present
- This is illustrated by the shaded area with the word cats representing all the records containing the word "cats"
- No records are retrieved in which the word "dogs" appears, even if the word "cats" appears there too
Here is an example of how NOT logic works:
| Search terms | Results |
| cats | 86,747 |
| dogs | 130,424 |
| cats NOT dogs | 65,223 |
NOT logic excludes records from your search results. Be careful when you use NOT: the term you do want may be present in an important way in documents that also contain the word you wish to avoid.
Boolean Searching on the Internet
When you use an Internet search engine, the use of Boolean logic may be manifested in three distinct ways:
- Full Boolean logic with the use of the logical operators
- Implied Boolean logic with keyword searching
- Predetermined language in a user fill-in template
1. Full Boolean logic with the use of the logical operators
Few search engines nowadays offer the option to do full Boolean searching with the use of the Boolean logical operators. It is more common for them to offer simpler methods of constructing search statements, specifically implied Boolean logic and template language. These methods are covered below.
If you want to construct search queries using Boolean logical opeartors, you will need to experiment with search engines and see what happens when you search. You can try some of the search statements shown below.
Examples:
Query: I need information about cats.
Boolean logic: OR
Search: cats OR felines
Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: dyslexia AND adults
Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: radiation NOT nuclear
Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search: (cats OR felines) AND behavior
Note: Use of parentheses in this search is known as forcing the order of processing. In this case, we surround the OR words with parentheses so that the search engine will process the two related terms first. Next, the search engine will combine this result with the last part of the search that involves the second concept. Using this method, we are assured that the semantically-related OR terms are kept together as a logical unit.
2. Implied Boolean logic with keyword searching
Keyword searching refers to a search type in which you enter terms representing the concepts you wish to retrieve. Boolean operators are not used.
Implied Boolean logic refers to a search in which symbols are used to represent Boolean logical operators. In this type of search on the Internet, the absence of a symbol is also significant, as the space between keywords defaults to either OR logic or AND logic. Nowadays, most search engines default to AND.
Implied Boolean logic has become so common in Web searching that it may be considered a de facto standard.
Examples:
Query: I need information about cats.
Boolean logic: OR
Search: [None]
It is extremely rare for a search engine to interpret the space between keywords as the Boolean OR. Rather, the space between keywords is interpreted as AND. To do an OR search, choose either option #1 above (full Boolean logic) or option #3 below (user fill-in template).
Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: +dyslexia +adults
Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: radiation -nuclear
Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search: [none]
Since this query involves an OR search, it cannot be done with keyword searching. To conduct this type of search, choose either option #1 above (full Boolean logic) or option #3 below (user fill-in template).
3. Predetermined language in a user fill-in template
Some search engines offer a search template which allows the user to choose the Boolean operator from a menu. Usually the logical operator is expressed with substitute language rather than with the operator itself.
Examples:
Query: I need information about cats
Boolean logic: OR
Search: Any of these words/Can contain the words/Should contain the words
Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: All of these words/Must contain the words
Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: Must not contain the words/Should not contain the words
Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search: Combine options as above if the template allows multiple search statements
Quick Comparison Chart:
Full Boolean vs. Implied Boolean vs. Templates
| | Full Boolean | Implied Boolean | Template Terminology |
| OR | college or university | [rarely available]
| any of these words
|
| AND | poverty and crime | +poverty +crime | all of these words
|
| NOT | cats not dogs | cats -dogs | must not contain the words
|
| NEAR, etc. | cats near dogs | N/A | near |
* Most multi-term search statements will resolve to AND logic at search engines that use AND as the default. Nowadays most search engines default to AND. Always play it safe, however, and consult the Help files at each site to find out which logic is the default.
Where to Search:
A Selected List
| Feature | Search Engine |
| Boolean operators | |
| Full Boolean logic with parentheses, e.g.,
| AlltheWeb Advanced Search | AltaVista Advanced Web Search | Ixquick | Live Search |
| Implied Boolean +/- | Most search engines offer this option |
| Boolean logic
| Most advanced search options offer this, including:
|
| Proximity operators |
5 marks
markup language
A markup language is an artificial language using a set of annotations to text that give instructions regarding the structure of text or how it is to be displayed. Markup languages have been in use for centuries, and in recent years have been used in computer typesetting and word-processing systems.
A well-known example of a markup language in use today in computing is HyperText Markup Language (HTML), one of the most used in the World Wide Web. HTML follows some of the markup conventions used in the publishing industry in the communication of printed work among authors, editors, and printers.
History
The term markup is derived from the traditional publishing practice of "marking up"' a manuscript, which involves adding symbolicprinter's instructions in the margins of a paper manuscript. For centuries, this task was done primarily by skilled typographers known as "markup men"[1] who marked up text to indicate what typeface, style, and size should be applied to each part, and then passed the manuscript to others for typesetting by hand. Markup was also commonly applied by editors, proofreaders, publishers, and graphic designers.
[edit]GenCode
The idea of markup languages was apparently first publicly presented by publishing executive William W. Tunnicliffe at a conference in 1967, although he preferred to call it "generic coding." In the 1970s, Tunnicliffe led the development of a standard called GenCode for the publishing industry and later was the first chair of the International Organization for Standardization committee that created SGML, the first widely used descriptive markup language. Book designer Stanley Rice published vague speculation along similar lines in the late 1960s. Brian Reid, in his 1980 dissertation at Carnegie Mellon University, developed the theory and a working implementation of descriptive markup in actual use.
However, IBM researcher Charles Goldfarb is more commonly seen today as the "father" of markup languages. Goldfarb hit upon the basic idea while working on a primitive document management system intended for law firms in 1969, and helped invent IBM GMLlater that same year. GML was first publicly disclosed in 1973.
.
].
[edit]HTML
Main article: HTML
By 1991, it appeared to many that SGML would be limited to commercial and data-based applications while WYSIWYG tools (which stored documents in proprietary binary formats) would suffice for other document processing applications.
The situation changed when Sir Tim Berners-Lee, learning of SGML from co-worker Anders Berglund and others at CERN, used SGML syntax to create HTML. HTML resembles other SGML-based tag languages, although it began as simpler than most and a formal DTD was not developed until later. Steven DeRose[3] argues that HTML's use of descriptive markup (and SGML in particular) was a major factor in the success of the Web, because of the flexibility and extensibility that it enabled (other factors include the notion of URLs and the free distribution of browsers). HTML is quite likely the most used markup language in the world today.
Main article: XML
XML (Extensible Markup Language) is a meta markup language that is now widely used. XML was developed by the World Wide Web Consortium, in a committee created and chaired by Jon Bosak. The main purpose of XML was to simplify SGML by focusing on a particular problem — documents on the Internet.[4] XML remains a meta-language like SGML, allowing users to create any tags needed (hence "extensible") and then describing those tags and their permitted uses.
XML was designed primarily for semi-structured environments such as documents and publications. However, it appeared to strike a happy medium between simplicity and flexibility, and was rapidly adopted for many other uses. XML is now widely used for communicating data between applications. Like HTML, it can be described as a 'container' language.
[edit]XHTML
Main article: XHTML
Since January 2000 all W3C Recommendations for HTML have been based on XML rather than SGML, using the abbreviation XHTML(Extensible HyperText Markup Language). The language specification requires that XHTML Web documents must be well-formed XML documents – this allows for more rigorous and robust documents while using tags familiar from HTML.
One of the most noticeable differences between HTML and XHTML is the rule that all tags must be closed: empty HTML tags such as/' on the end tag is optional, but frequently used because it enables some pre-XML Web browsers, and SGML parsers, to accept the tag). Another is that all attribute values in tags must be quoted. Finally, all tag and attribute names must be lowercase in order to be valid; HTML, on the other hand, was case-insensitive.
[edit]Other XML-based applications
Many XML-based applications now exist, including Resource Description Framework (RDF), XForms, DocBook, SOAP and the Web Ontology Language (OWL). For a partial list of these see List of XML markup languages.
[edit] general purpose markup languages:
§ ASN.1 (Abstract Syntax Notation One)
§ EBML
§ GML - the predecessor of SGML
§ XML
§ YAML
2.search engine and search techniques
page 238-239 (Photostat book)(unleshead)
3.database models
Types of Databases
As with just about everything else in the world, there are many different types of databases. There are also different ways to classify these types of databases. Two popular ways to differentiate between databases is by the function of the database and by the data model of the database.
Function:
First, we shall take a look at classifying by the function of the database. There are different databases that are used for different tasks and jobs. The two categories here are analytic databases and operational databases:
Analytic Databases:
Analytic databases, also called On Line Analytical Processing (OLAP), are databases that are primarily used to keep track of statistics. Usually, they are read-only, meaning that you can only retrieve data, but you can't modify the data in any way. They are often used by stores as inventory catalogs. They keep track of the company's sales, and then can be read and analyzed to determine how and when more products are sold. These databases can hold all sorts of descriptive information about the goods stored in a company's inventory.
Operational Databases:
Operational databases, also called On Line Transaction Processing (OLTP), are databases that have a completely different job. These databases, unlike the analytic databases, let you actually change and manipulate the data. While analytic databases only let you view the data, these databases let you modify the data in any way you would like- you can add data, delete data, or even change the data.
Data Model:
Another way of classifying databases is by their data model. So, what's a data model? A data model is the intangible form in which data is stored. It is kind of like the structure of a database, but data models are only a theoretical idea; they are abstract concepts that you cannot touch. Data models are used to describe how the data is stored and retrieved in a database. Now, we will discuss a few of the types of data models.
Flat-file Database Model:
The flat-file data model is generally used by the old paper-based databases. In this system, data was stored in numerous files. However, the files were not linked, so often, data might be repeated in more than one file. This caused everything to be quite redundant. The original "database," flat-file databases inspired scientists to find a way to link files so that they would not be repetitive.
Hierarchical Database Model:
The hierarchical database model took steps to get rid of the repetitiveness of the flat-file database model, but although it was somewhat successful, it did not completely succeed. There is still a level of redundant data in hierarchical databases.
A hierarchical database consists of a series of databases that are grouped together to resemble a family tree:
Each of the boxes in the diagram represents one database. The top database in the hierarchical model is called the "parent" database. The databases under it are called "child" databases. One "parent" can have many "children," but a "child" can only have one "parent." The child databases are all connected to the parent database via links called "pointers."
To get to a child database in the hierarchical database model, you must first go through the parent database, and then through the levels above it. If you have Microsoft Windows, you might realize that this is how Windows Explorer works. First, you open up a file- usually it's "My Computer." Under "My Computer," you can then choose from a list of drives. Pretend you clicked on the "Disk Drive C" icon. Then, under this, you can choose from a series of folders. After opening one folder, you can open another folder, and another, until you reach the file that you want.
Notice in the diagram above how the child databases on the same level are not connected. This presents a problem in the hierarchical database model and makes searching for data extremely difficult. Another problem is that data cannot be entered into the child databases until that field has been added to the parent database. This method was quite inefficient. Thus, although the hierarchical database model reduced some repetitiveness of data, it also presented many new problems.
Network Database Model:
The network database model was designed to help resolve some of the hierarchical database model's problems. For one thing, it allowed for links between the child databases. This no only reduces the chance of redundant data, but also makes searching for data much easier!
Another improvement of the network database model over the hierarchical model is that while in the hierarchical model a child database can only have one parent, in the network model, a child database can have more than one parent!
However, the network database model still had its share of problems. For one thing, it was difficult to execute and maintain. Only database experts could successfully use these databases. It was difficult for the general public to use network databases for real-life applications.
Relational Database Model:
The relational database model came in at full swing during the 1980s. Modeled after the work of Dr. E. F. Codd of IBM, the relational database model is extremely popular because it solved many of the problems displayed in the hierarchical and network database models.
The relational database model is different from the hierarchical and network database models in that there are no "parent" and "child" databases. Rather, all of the databases in the relational database model are equal.
Data can be stored in any number of separate databases. Then, these databases are connected by a "key" field. A key field is a field (in case you don't remember, a field is the columns in the database where the data is stored- see "Parts of a Database" for more details) that is found in all of the databases that are being linked together. All of the databases can be used to hold different types of data. For example, let's pretend that we have an address book, which is a paper-based database. If we were to use the relational database model, then we would store all of the data in separate databases. One database could hold a person's address; another could hold the person's phone number, etc. However, all of the databases might have one field that is the same, like, for example, the person's name.
This makes it easy to search for and extract data from the databases. It is also very efficient and easy to use. No wonder why this database model is so popular!
Object-oriented Databases:
You might realize that databases can not only store text and numeric values, but that there are special databases that can also store photos, sounds, videos, and all sorts of graphics. How is this possible? Well, I can tell you one thing, the old hierarchical, network, and relational databases couldn't store all of these types of data! As a matter of fact, this is where the object-oriented database models come in.
Object-oriented database models let databases store and manipulate not only text, but also sounds, images, and all sorts of media clips! They are extremely useful, but unfortunately, they are large in size and are extremely expensive. Thus, they are only found in large commercial or governmental organizations.
Client/Server Databases
As you probably know, the Internet is one of the most popular usages of a computer. Client/server databases are the databases that you will use for the Internet and for the World Wide Web. The database is left on 24 hours a day, 7 days a week. This is so that users, or clients, can access the web sites or whatever other data is contained in the database at any time they want. This is especially necessary if you want to make the applications available to anybody, anywhere in the world. There is a special type of interface that lets the clients submit certain data requests from the database. Then, the database will handle and process the requests!
4.search strategies
Successful searching combines creative guessing of Uniform Resource Locators (URLs) along with smart use of subject directories and search engines. Here are three general strategies. Before using any of them, be sure to consider what organization might be a likely source for providing the necessary information.
Strategy 1: URL Guessing and Cutting
For many sites, do not even bother with a directory or search engines. When you are searching for a specific organization's Web site, first try guessing the central URL for the organization. The following steps may help:
- With Netscape and Internet Explorer, leave off http://
- Try the common www to start the machine address
- Use the name, acronym, or brief name of the organization (nra, honda, uwyo) in the middle
- Add the appropriate top level domain, most often .com. See a complete list or try one of the following common endings:
| | com for commercial
| |
URL guessing can help in finding pages for URLs that no longer work and links that lead to dead ends. Try chopping off parts of the URL starting on the right-hand side and stopping at every /
Strategy 2: Subject Directories for Organizations
Subject directories select and classify resources into subject categories and subcategories. Some include reviews and/or ratings. Access is by keyword search or by browsing the classifications. Use these for finding
3. Top Level Sites for Organizations
4. General Topics
5. Commercial Products
6. Current Events
7.
Strategy 3: Search Engines for Large Searches
Search Engines attempt to find and index as many sites as possible. Search features vary greatly, as does the actual scope, size, and accuracy of the databases. Use these for
- Unique Keywords
- Combinations of unique keywords
- Field searching and limiting
- Pages buried deep in a Web site
For a quick overview list of strategies to consider see the list below. It repeats some of what is is in the three above as well as in the online tutorials below.
- Determine likely organization with answer
- Guess organization's URL before trying search engines
- Search for organization URL otherwise
- Use "phrase searching" and unique words as much as possible
- Use directories (Yahoo!, ODP, LookSmart) for broad, general topics
- Use multiple step approach – can be several clicks to an answer
- Folders to narrow large search sets: Teoma, WiseNut, Vivisimo, or NLResearch
- Try a title field search to focus results more by subject
- Use specialized search engines for news, Usenet postings, phone numbers, etc.
5.input/output devices
see page 26 study material
6.switching techniques
There are a number of ways to perform switching:
Circuit Switching
This method involves the physical interconnection of two devices. A good example of circuit switching involves the Public phone network. A data example would be the classic A/B switch!
Packet Switching
Packet Switching techniques switch packets of data between destinations. Traditionally, this applied to X.25 techniques, but this also applies to TCP/IP and IPX/SPX routers also. Proprietary Frame Relay switches can switch voice signals.
Message Switching
Message Switching techniques were originally used in data communications. An example would be early "store and forward" paper tape relay systems. E-Mail delivery is another example of message switching. In voice systems, you can find Voice Mail delivery systems on the Internet. The classic "forward voice mail" capability in some voice mail systems is another example.
Cell Switching
Cell Switching is similar to packet switching, except that the switching does not necessarily occur on packet boundaries. This is ideal for an integrated environment and is found within Cell-based networks, such as ATM. Cell-switching can handle both digital voice and data signals.
7.data trasmission modes
page 88 (study material)
8.indexed sequential file organization
Indexed sequential
An index file can be used to effectively overcome the above mentioned problem, and to speed up the key search as well. The simplest indexing structure is the single-level one: a file whose records are pairs key-pointer, where the pointer is the position in the data file of the record with the given key. Only a subset of data records, evenly spaced along the data file, are indexed, so to mark intervals of data records.
A key search then proceeds as follows: the search key is compared with the index ones to find the highest index key preceding the search one, and a linear search is performed from the record the index key points onward, until the search key is matched or until the record pointed by the next index entry is reached. In spite of the double file access (index + data) needed by this kind of search, the decrease in access time with respect to a sequential file is significant.
Consider, for example, the case of simple linear search on a file with 1,000 records. With the sequential organization, an average of 500 key comparisons are necessary (assuming uniformly distributed search key among the data ones). However, using and evenly spaced index with 100 entries, the number of comparisons is reduced to 50 in the index file plus 50 in the data file: a 5:1 reduction in the number of operations.
This scheme can obviously be hyerarchically extended: an index is a sequential file in itself, amenable to be indexed in turn by a second-level index, and so on, thus exploiting more and more the hyerarchical decomposition of the searches to decrease the access time. Obviously, if the layering of indexes is pushed too far, a point is reached when the advantages of indexing are hampered by the increased storage costs, and by the index access times as well.
9.artificial intelligence
Artificial intelligence (AI) is the intelligence of machines and the branch of computer science which aims to create it. Major AI textbooks define the field as "the study and design of intelligent agents,"[1] where an intelligent agent is a system that perceives its environment and takes actions which maximize its chances of success.[2] John McCarthy, who coined the term in 1956,[3] defines it as "the science and engineering of making intelligent machines."[4]
The field was founded on the claim that a central property of human beings, intelligence—the sapience of Homo sapiens—can be so precisely described that it can be simulated by a machine.[5] This raises philosophical issues about the nature of the mind and limits of scientific hubris, issues which have been addressed by myth, fiction and philosophy since antiquity.[6] Artificial intelligence has been the subject of breathtaking optimism,[7] has suffered stunning setbacks[8] and, today, has become an essential part of the technology industry, providing the heavy lifting for many of the most difficult problems in computer science.
AI research is highly technical and specialized, so much so that some critics decry the "fragmentation" of the field.[9] Subfields of AI are organized around particular problems, the application of particular tools and around long standing theoretical differences of opinion. The central problems of AI include such traits as reasoning, knowledge, planning, learning, communication, perception and the ability to move and manipulate objects.[10] General intelligence (or "strong AI") is still a long term goal of (some) research.[11]
10.internet services
Common uses
E-mail
For more details on this topic, see E-mail.
The concept of sending electronic text messages between parties in a way analogous to mailing letters or memos predates the creation of the Internet. Even today it can be important to distinguish between Internet and internal e-mail systems. Internet e-mail may travel and be stored unencrypted on many other networks and machines out of both the sender's and the recipient's control. During this time it is quite possible for the content to be read and even tampered with by third parties, if anyone considers it important enough. Purely internal or intranet mail systems, where the information never leaves the corporate or organization's network, are much more secure, although in any organization there will be IT and other personnel whose job may involve monitoring, and occasionally accessing, the e-mail of other employees not addressed to them. Today you can send pictures and attach files on e-mail. Most e-mail servers today also feature the ability to send e-mail to multiple e-mail addresses.
E-Mail E-mail is a means or system of transmitting messages electronically. It is any method of creating, transmitting, or storing. E-mails are what allow people to keep in touch with other people in an easy and fast way because of the invention of the Internet. It is a quick way to send a message or document or eve a file or just anything to someone or the other. Not only can the email be sent to one person but it can also be sent to as many people as it is needed to be sent to. If one receives an email that they need to send to others they are able to forward the message to anyone they chose to There are many different types of websites such as Google, yahoo, msn, etc. to create email accounts on. Creating an account in any of these still allows for one to communicate with anyone from any of the different types of accounts. All email accounts created are free and anyone is allowed to create one. E-mails are very secure and private between the sender and recipient and allow for information to be very easily sent and replied to.
The World Wide Web
Many people use the terms Internet and World Wide Web (or just the Web) interchangeably, but, as discussed above, the two terms are notsynonymous.
The World Wide Web is a huge set of interlinked documents, images and other resources, linked by hyperlinks and URLs. These hyperlinks and URLs allow the web servers and other machines that store originals, and cached copies of, these resources to deliver them as required using HTTP (Hypertext Transfer Protocol). HTTP is only one of the communication protocols used on the Internet.
Web services also use HTTP to allow software systems to communicate in order to share and exchange business logic and data.
Software products that can access the resources of the Web are correctly termed user agents. In normal use, web browsers, such as Internet Explorer,Firefox and Apple Safari, access web pages and allow users to navigate from one to another via hyperlinks. Web documents may contain almost any combination of computer data including graphics, sounds,text, video, multimedia and interactive content including games, office applications and scientific demonstrations.
Through keyword-driven Internet research using search engines like Yahoo! and Google, millions of people worldwide have easy, instant access to a vast and diverse amount of online information. Compared to encyclopedias and traditional libraries, the World Wide Web has enabled a sudden and extreme decentralization of information and data.
Using the Web, it is also easier than ever before for individuals and organisations to publish ideas and information to an extremely large audience. Anyone can find ways to publish a web page, a blog or build a website for very little initial cost. Publishing and maintaining large, professional websites full of attractive, diverse and up-to-date information is still a difficult and expensive proposition, however.
Many individuals and some companies and groups use "web logs" or blogs, which are largely used as easily updatable online diaries. Some commercial organisations encourage staff to fill them with advice on their areas of specialization in the hope that visitors will be impressed by the expert knowledge and free information, and be attracted to the corporation as a result. One example of this practice is Microsoft, whose product developers publish their personal blogs in order to pique the public's interest in their work.
Collections of personal web pages published by large service providers remain popular, and have become increasingly sophisticated. Whereas operations such as Angelfire and GeoCities have existed since the early days of the Web, newer offerings from, for example,Facebook and MySpace currently have large followings. These operations often brand themselves as social network services rather than simply as web page hosts.
Advertising on popular web pages can be lucrative, and e-commerce or the sale of products and services directly via the Web continues to grow.
In the early days, web pages were usually created as sets of complete and isolated HTML text files stored on a web server. More recently, websites are more often created using content management or wiki software with, initially, very little content. Contributors to these systems, who may be paid staff, members of a club or other organisation or members of the public, fill underlying databases with content using editing pages designed for that purpose, while casual visitors view and read this content in its final HTML form. There may or may not be editorial, approval and security systems built into the process of taking newly entered content and making it available to the target visitors.
Remote access
Further information: Remote access
The Internet allows computer users to connect to other computers and information stores easily, wherever they may be across the world. They may do this with or without the use of security, authentication and encryption technologies, depending on the requirements.
This is encouraging new ways of working from home, collaboration and information sharing in many industries. An accountant sitting at home can audit the books of a company based in another country, on a server situated in a third country that is remotely maintained by IT specialists in a fourth. These accounts could have been created by home-working bookkeepers, in other remote locations, based on information e-mailed to them from offices all over the world. Some of these things were possible before the widespread use of the Internet, but the cost of private leased lines would have made many of them infeasible in practice.
An office worker away from his desk, perhaps on the other side of the world on a business trip or a holiday, can open a remote desktop session into his normal office PC using a secure Virtual Private Network (VPN) connection via the Internet. This gives the worker complete access to all of his or her normal files and data, including e-mail and other applications, while away from the office.
This concept is also referred to by some network security people as the Virtual Private Nightmare, because it extends the secure perimeter of a corporate network into its employees' homes.
Collaboration
See also: Collaborative software
The low cost and nearly instantaneous sharing of ideas, knowledge, and skills has made collaborative work dramatically easier. Not only can a group cheaply communicate and share ideas, but the wide reach of the Internet allows such groups to easily form in the first place. An example of this is the free software movement, which has produced Linux, Mozilla Firefox, OpenOffice.org etc.
Internet "chat", whether in the form of IRC chat rooms or channels, or via instant messaging systems, allow colleagues to stay in touch in a very convenient way when working at their computers during the day. Messages can be exchanged even more quickly and conveniently than via e-mail. Extensions to these systems may allow files to be exchanged, "whiteboard" drawings to be shared or voice and video contact between team members.
Version control systems allow collaborating teams to work on shared sets of documents without either accidentally overwriting each other's work or having members wait until they get "sent" documents to be able to make their contributions.
Business and project teams can share calendars as well as documents and other information. Such collaboration occurs in a wide variety of areas including scientific research, software development, conference planning, political activism and creative writing.
File sharing
For more details on this topic, see File sharing.
A computer file can be e-mailed to customers, colleagues and friends as an attachment. It can be uploaded to a website or FTPserver for easy download by others. It can be put into a "shared location" or onto a file server for instant use by colleagues. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks.
In any of these cases, access to the file may be controlled by user authentication, the transit of the file over the Internet may be obscured by encryption, and money may change hands for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—hopefully fully encrypted—across the Internet. The origin and authenticity of the file received may be checked by digital signatures or by MD5 or other message digests.
These simple features of the Internet, over a worldwide basis, are changing the production, sale, and distribution of anything that can be reduced to a computer file for transmission. This includes all manner of print publications, software products, news, music, film, video, photography, graphics and the other arts. This in turn has caused seismic shifts in each of the existing industries that previously controlled the production and distribution of these products.
Streaming media
Many existing radio and television broadcasters provide Internet "feeds" of their live audio and video streams (for example, the BBC). They may also allow time-shift viewing or listening such as Preview, Classic Clips and Listen Again features. These providers have been joined by a range of pure Internet "broadcasters" who never had on-air licenses. This means that an Internet-connected device, such as a computer or something more specific, can be used to access on-line media in much the same way as was previously possible only with a television or radio receiver. The range of material is much wider, from pornography to highly specialized, technicalwebcasts. Podcasting is a variation on this theme, where—usually audio—material is downloaded and played back on a computer or shifted to a portable media player to be listened to on the move. These techniques using simple equipment allow anybody, with little censorship or licensing control, to broadcast audio-visual material on a worldwide basis.
Webcams can be seen as an even lower-budget extension of this phenomenon. While some webcams can give full-frame-rate video, the picture is usually either small or updates slowly. Internet users can watch animals around an African waterhole, ships in thePanama Canal, traffic at a local roundabout or monitor their own premises, live and in real time. Video chat rooms and video conferencing are also popular with many uses being found for personal webcams, with and without two-way sound.
YouTube was founded on
Internet Telephony (VoIP)
For more details on this topic, see VoIP.
VoIP stands for Voice-over-Internet Protocol, referring to the protocol that underlies all Internet communication. The idea began in the early 1990s with walkie-talkie-like voice applications for personal computers. In recent years many VoIP systems have become as easy to use and as convenient as a normal telephone. The benefit is that, as the Internet carries the voice traffic, VoIP can be free or cost much less than a traditional telephone call, especially over long distances and especially for those with always-on Internet connections such as cable or ADSL.
VoIP is maturing into a competitive alternative to traditional telephone service. Interoperability between different providers has improved and the ability to call or receive a call from a traditional telephone is available. Simple, inexpensive VoIP network adapters are available that eliminate the need for a personal computer.
Voice quality can still vary from call to call but is often equal to and can even exceed that of traditional calls.
Remaining problems for VoIP include emergency telephone number dialling and reliability. Currently, a few VoIP providers provide an emergency service, but it is not universally available. Traditional phones are line-powered and operate during a power failure; VoIP does not do so without a backup power source for the phone equipment and the Internet access devices.
VoIP has also become increasingly popular for gaming applications, as a form of communication between players. Popular VoIP clients for gaming include Ventrilo and Teamspeak, and others. PlayStation 3 and Xbox 360 also offer VoIP chat features.
12.cds/isis
page 72 study material
13.DBMS
A database management system (DBMS) is computer softwarethat manages databases. DBMSes may use any of a variety ofdatabase models, such as the network model or relational model. In large systems, a DBMS allows users and other software to store and retrieve data in a structured way.
A DBMS is a set of software programs that controls the organization, storage, management, and retrieval of data in a database. DBMS are categorized according to their data structures or types. It is a set of prewritten programs that are used to store, update and retrieve a Database. The DBMS accepts requests for data from the application program and instructs the operating system to transfer the appropriate data. When a DBMS is used, information systems can be changed much more easily as the organization's information requirements change. New categories of data can be added to the database without disruption to the existing system.
Organizations may use one kind of DBMS for daily transaction processing and then move the detail onto another computer that uses another DBMS better suited for random inquiries and analysis. Overall systems design decisions are performed by data administrators and systems analysts. Detailed database design is performed by database administrators.
Database servers are computers that hold the actual databases and run only the DBMS and related software. Database servers are usually multiprocessor computers, with generous memory and RAID disk arrays used for stable storage. Connected to one or more servers via a high-speed channel, hardware database accelerators are also used in large volume transaction processing environments. DBMSs are found at the heart of most database applications. Sometimes DBMSs are built around a private multitasking kernel with built-in networking support although nowadays these functions are left to the operating system.
IT THEORY
Essays
1.major input/output devices of a computer?
answer:page 26-31(study material)
2.define information technology?explain the application of IT in library and info.centres?(must study question)
answer page 8-14(study material)
3.recent developments in communication media?
4.history of secondary storage media?
Page 33.study material
5.library automation
page 98-101 study material
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