A computer program that translates an assembly language program to its machine language equivalent is called assembler.
High level programming language to work on the computer it must be translated into machine language. There are two types of translators like.
Compiler: A translator program (software package) that translates a high-level language program into its equivalent machine language program is called compiler. In brief it reads whole program and converts it into machine language.
Complier translates the whole program into machine language all at a time.
The translation processor is called compilation.
The programmer’s program is called source code but its machine language code is called object code.
Interpreters: A language processor that translates a statement of high-level language, and immediately executes it before translating the next source language statement is called interpreter. In brief it reads a line and converts into machine language; one statement at a time. Interpreters translate each program statement into machine code just before the program statement is to be executed. This process continues till whole process completes. But compiler language is better than interpreted language as they can be executed later. Complier is used in COBOL, C, C++ and FORTRAN. On the other hand interpreter language in BASIC programming. Interpreter do not need object code and so usually easier to develop. (i.e. to code &test). Thus, there are code complier, C compiler and BASIC Interpreter.
Linker: A program that is used to properly combine all objects program files (modules) of a software, and to convert them into software’s final executable form is called linker.
The Compilation Process:
Source files are complied into object files, then through linkers object files using routine libraries it produces executable programs. Thus object codes pass through linkers. The linker combines modules and gives real values to all symbolic address.
Hence, the linker translates object files into executables program files.
General Software Features &Trends:
We know the series of instructions that performs a particular task in the computer is called a program. There are two categories of programs like system software and application software.
A system software means combination of operating system, control program, database management and communication software. An application, software means any program that processes the data for the user. In short, the software tells hardware how to process the data.
At present, in the world software projects are becoming more and more complex in size, sophistication, and technologies used. Now most software products manage to millions of users in different shape and size. For example word processors, ERP packages and SCM tools, which run mainframes and client server systems; different versions of web browsers for the PC and MAC; we have DBMS that run on MVS, UNIX, Windows NT, Linux and so on. The competition and the advancements in technology are driving software.
Now computer and communication are becoming integral part of our lives. The driving force behind all these advancement is the computer software. They are becoming more and more complex. For example, the software is being used in controlling satellites, operating. Intercontinental, Ballistic Missiles, running banks, hospitals, airlines, hostels, etc, including door locking system and robotics.
Software may communicate via internet, using e-mail or videoconferencing technologies. Thus its development is in advance and changing very fast. Now the general software features are given below.
Easy to Use:
Presently, most of the software companies are producing more and more user’s friendly, software's. The software developers are developing the software’s including facilities like user's interface, displaying error message, self leaning type etc. Thus software are becoming easier to use,
Graphical User Interface (GUI):
Now-a-days interface, most of the software applications are graphical user interface (GUI) brand. That is software's are self learning type, which are very easier to use. In the software, there will be self guided dialog box. Most of the tasks could be performed by mouse click. This almost software guided uses using icons, dialog boxes and other graphical elements.
In order to service the software companies they have to be constantly innovative and be always ahead of the competition. So they are producing better producers for the end-users. That means new software will be coded by more features at affordable price. Micro-soft companies products could be the good examples for the more features in the new products every year.
Requirement Of The Powerful Hardware:
As you know, as the facilities are increasing in the software, it wants more and more advanced computers. About 10 years back there were 386 types of machines which can run only Windows95. Now-a-days users are running Windows XP on Pentium IV computers. Hence the new software wants more and more powerful computers. Otherwise the new software will not be able to run.
Now-a-days, most of the application software supports multiplatform both hardware and software platforms. There are software applications that support hardware platforms from PCs to mainframe and different software platforms like windows to UNIX, AIX, Solaris and MVS. Similarly other important feature of today's application software is that they support in many languages like Japanese, Arabic, Chinese and English. Likewise they support different national currencies too.
As the popularity of computers network increase, the demand of software that can run on the computers connected on the network are increasing. The idea behind network computers is that many users who are connected to a network do not need all the computer power they get from a typical personal computer. Instead they can rely on the power of network server.
Compatibility With Other Software:
There are many software companies in the world market. Software vendors are battling for the market share. It means that the users will get better products. To make salable software, vendors are making their software compatible with other competitors. For example, you can import WordPerfect documents, text documents, and HTML documents and so on into a MS-word document. Almost all vendors practice this technique to stay and service in the business. Similarly, most of the vendors maintain compatibility with easier version, as they release the new version. For example Ms-word 2000 supports all previous versions words, word97, and word95.
Object Linking And Embedding:
While you are working in MS-word, you can open and link MS-Excel. If you want you can import a table and a graphical picture from MS-Excel to your word document. To call a table and a picture from external software to the running software is called linked and embedded object. Thus Micro soft company has developed a method to integrate external tool into an application using the Object Linking and Embedding(OLE) architecture. Now OLE is a compound document. If enables you to create objects with one application and then link or embed them in a second application changes made to the embedded object effort only the document that contents it. Support for OLE is built into the Windows and Macintosh Operating System. This embedding and linking of components enables applications to share components.
Group Work Capabilities:
To work in a group using computer terminals sharing files, software tools and facilities of the common file server are called group-ware and work flow automation. In another word groupware is an umbrella term describing the electronic technologies that support person-to-person collaboration. Groupware includes E-mail, Electronic Meeting System (EMS), Desktop Video Conferencing (DVC) as well as systems for work flow and Business Process Reengineering (BPR).
To-day software vendors are integrating collaboration technologies into their products. Groupware maximizes human interaction while minimizing technologies interference. The term 'Groupware' and ‘Collaborative Computing' are often used interchangeably when in fact they are different. Groupware is basically a subset of collaborative computing. Collaborative computing refers to the technology that is hardware, software and structures that support group working.
As you know windows program has a "Send" command and windows 2000 has a "Send to" command in its "File Menu". If you choose and click on "Send to" command of File Menu you will find mail recipient menu, Fax recipient, etc. When you click on mail recipient, then the document will be sent as an attachment using your default e-mail client to the address you specify. This is the new facilities added to the application software. This is an example of the advanced and more sophisticated mail enabled applications software. Mail enabled applications are designed to capitalize on e-mail.
As you know to-day most of the information are available in the internet. Therefore software vendors are adding the facilities into their product to link the internet and down load the required information. Most software applications are now web-enabled. During installation, most of the applications will automatically connect to the internet and to the vender's web site and will register their products.
For example, Word 2000 can now connect to the Microsoft's website and get clipart new images if the user wants to put in his computer, thus the options available to the user are more now. In the future also they will have more and more web enabling facilities in the new software.
The Data is a collection of facts or observations in unorganized form but able to be organized into useful information. It may be any words, numerical numbers, codes or any mixture of numerical numbers and alphabets. It could be voice, text, images or any numeric data too. Data means a file of records of raw facts. Record means a set of fields.
Data processing means the processing of data to make it more usable and meaningful information. It means to collect, manipulate and organize the data in a logical order. It analyzed, evaluated and placed it into a proper order for the end user. Thus the raw data is manipulated by calculating, sorting, comparing, classifying and summarizing to convert into the required information. Data processing is a series of actions or operations that convert data into useful information .It include resource such as people, procedures, and devices used to process input data for producing desirable output.
Data Versus Information,
Data is a collection of facts or instruction received from input device of the in raw form and the information means the refinement of data after proper processing and organization .In fact anything which is received/accept from input device of the computer is called data and after suitable processing and organization it becomes information. These are relative terms also any information will become data for another purpose or another task. Information in one purpose becomes data for another purpose. For example the result of +2 level is a information for those student who appear in the board examination but this will become data for those person/researcher who want to analyze this result for the improvement of examination system in this level
Standard Method of Organizing Data
There are two standard methods of organizing data:
File –Oriented Method /File Management Method: - After collection data, it is kept in separate files. Collected data is organized into one or more files and application program processes them to generate the desired output. This process is called file management or file oriented method. A file management system supports following file types
Transaction file: Store input data until it can be processed.
Master file: Contains all current data relevant to an application.
Output file:Stores output produced by one program that is used as input to another program.
Report file:Holds a copy of a report generated by an application.
Backup file:Copy of a file, created as a safety precaution against lost of data.
The method of keeping file also divided into two categories like sequential and direct access.
Sequential Method: The collected data are stored one after another in ascending or descending order determined by the value of the key field of the records. The tape is in a sequence order. If such data is managed in this method that is called sequential data management or sequential file method. Some time there will be group wise data collection (batch wise e.g. district wise or date wise or others) in the different files. Those data files will be merged into a file. Then the master file will be sorted in some sequence and lastly processed it. This type of processing is called sequential file processing.
Direct- Access Method: - The data can have direct access in a file stored in a tape. But except tape it has direct access into the data stored floppy disk, hard disk or compact disk (CD).For the direct access file management, the data file must be organized for the direct access that means the data file must be created in the floppy or hard disk or CD with some unique codes or index numbers.
Database–Oriented Method /Database Management Method: A database means a self describing collection of integrated records. Most of the databases contain a directory of its contents. It can contain multiple related files. A file means a collection of records. A record consists of different fields. User defines data fields and makes entry of fields into records. Then they combine records to a file. Now users can manipulate and retrieve stored data in database in various ways to prepare reports and collect certain desired information arranged in some order.
The database-oriented method facilitates data from multiple related files are integrated together to form a database:
It makes data independent of the application programs
It includes data security features at database level, record level, and field level.
The data of one file is related to the data of another file through the use of common field. The database management packages have also data manipulating and data analyzing capability. It can also produce graphs from data in the database. All these activities are called database management.
A number of database management packages are available such as dBASE, ORACLE, UNIFY, FOXBASE, SAYBASE and INFORMIX, etc. In database processing the database management system (DBMS) acts as an intermediary between user and the database.
Database Management System:
Information is the most important resource of the organization or knowledge. It helps managers to make right decision for the future planning of the organization. Data, images, texts, documents and voice can be an input data to convert into information. The user receives the information and then makes a decision and takes an action. Information is power.
Quality Of Information:
In any aspect the quality of information must be maintained. That means, the information must be accurate, timely and relevant.
Accuracy of information means error free information.
Timelines means that the user can get the information when they need it. In fact it is prompt.
Relevancy means the use of a piece of information for a particular person. It is very subjective and personal matter. Information relevant for a one person may not be relevant or useful for another.
An organization of data in usable form to the user is called database. In other word a database is an organized collection of related information about particular subject or purpose. For example, to create a database of a library it is designed in such a fashion that the user can find out the price wise, edition wise, author wise or publication wise etc. at any time. In computer a database is also like a box containing index cards. The only difference is that instead of index cards, a computer database is filled with records. While each index cards in a box contains information’s written in many lines, a record in a database contains all the information related to an item in just one line. Information in a database is stored in rows (records) and columns (fields) in a sequence of unique number.
Database Management System
In database–oriented approach of organizing data, a set of programs is provided to facilitate users in organizing, creating, deleting updating, and manipulating data in a database all these programs together form a Database Management System (DBMS).In another words DBMS is a set of programs or software which provides services for accessing a database, while maintaining all the required features of the data. Hence DBMS is software that creates, manages, protects, and provides access to a database.
Some of the major services of a DBMS are as given below.
A transaction of data means creating, updating, deleting one record or modifying a set of records in sequence. Similarly transaction processing means daily processing of records in sequence. For example any accountant officer users computer for entering new records steps by steps and processor it accordingly
DBMS can make sure that only authorized users are given access to the data in the database. This is called the security management or a protection of a database from the unauthorized persons.
Recovery management is a facility used in the DBMS. Recovery mechanisms in a DBMS make sure that the database is returned to a consistent state after a transaction fails or aborts. For example a DBMS, if a record is incomplete or damaged the program skips it and does process again during processing time.
The DBMS provides support programming languages used for the definition and manipulation of the data in the database. The data structures are created using the data definition language commands. The data manipulation is done using the data manipulation command. This is the example of language interface management of the DBMS.
Concurrency management means co-coordinating the actions of database manipulations concurrently in the shared data during data processing. For example if one user manipulates a record, the effect is distributed in the other shared records too.
The DBMS provides a facility of permanently storing of the data. The storage manager interfaces with the operating system to access the physical storage. The internal schema defines how the data should be stored by the storage management mechanism.
In any type of DBMS there is a data catalog system. Data catalog or Data Dictionary is a system database that contains the descriptions of data in the database. It contains information about data, relationship, constrains and the entire schema that organize these features into a unified database.
Services provided by a DBMS
A DBMS provides a secure and survivable medium for the permanent storage and retrieval of data. It can provide many facilities like transaction processing, programming interface, security management, recovery management, concurrency management and storage management, etc. DBMS is very easy to use, access and manipulate the data in the database.
As we know, database is an organized collection of related data. It is an integrated collection of records which contains different fields like name, address and telephone number. The telephone directory could be a simple example to answer this question. The user Mr. A can use this database for finding telephone number of a particular person or Mr. B can use it for finding a person’s name of a particular telephone number and third user Mr. C can use the same diary to find a list of similar names and their telephone numbers within the same city code. Thus a telephone diary (a database) could be used in three ways or more. Therefore the database is created to fulfill user’s need for different purpose.
Similarly from a database of a library file, the user can find the list of books like edition wise, publisher wise, subject wise, or writer wise etc. But to find these four lists, the user must needs to process the database four times. Therefore, to run a database there must be software and a system to arrange the records within the database. Such system software is called database management system (DBMS). Without this software, if somebody creates the database, there will be many problems during the database preparation. The problems may be as follows until a final database is prepared.
Types of problems in creating a database:
(i) Data repetition
(ii) Data inconsistency
(iii) Data security to maintain
(iv) Wrong coding within the range
(v) Wrongly entered data
(vi) Data sharing may not be possible
(vi) Data lost etc.
At last, the user prepares a final error free and clean database after facing all the above mentioned problems. Then the characters of the data in a database should be as follows.
Shared - Among different users, the data in a database can be shared.
Security - The data of the database is totally secured from the unauthorized persons.
Consistency - The data of the database is maintained the consistency.
Validity/ Correctness - The data of the database is error free. Using all the methods all the errors is already deleted.
Type Of Database Management System:
There are five types of the database management system like (i) Hierarchical (ii) Network (iii) Relational (iv) Object oriented and (v) Deductive. These are the five DBMS models, which are running in the world markets at present.
Hierarchical Model is running since 1950 AD. It is an oldest DBMS Model. It assumes that a tree structure is the most frequently occurring relationship. This assumption is recognized today a misleading.
For example, hierarchical model is similar to company’s organizational structure. At the top we have GM. Under him there are 2, 3 deputy general managers (DGM). Just below DGM there are 6,7 department heads and so-on. Here the row position implies the relationship to each other from top to bottom. It looks like a tree structure.
To-day, the hierarchical model is replaced by Network model. The Network model can be used in a book distributor as an example. A book can have many attributes like Title, Author, Publisher, Year of publication, distributor, cost etc. Similarly on the other hand, a distributor can have attributes like Name, Contact address, Discount and others. We can use these both examples in the network model.
A relational database organizes data in a table format consisting or related rows and columns. Each location in a table contains a single piece of data, known as data item. Each column of a table represents a field, which consists of data items. A full set of data in any given row is called a record. The whole related records makeup a file. In a relational database a file is also called a relation. The relational model uses the rows and columns of tables to organize the data elements. The relational model is currently the most popular database mode.
The transmission of data to the long range through different media (web, cable, satellite, etc) is known as telecommunication. It refers to all types of data transmission. It may be sound, video, text; etc whatever may be that is acceptable to sender (transmitter) and receiver.
Analog & Digital Signals
The data are transmitted either in analog or digital form .An analog form means the electrical signals that propagate (transmit ) in the form of continuous wave or graph is called analog signal. The data which transmit by means of discrete representation or numerical representation is called digital signals. Most of the analog signal can be simulated digitally and digital signal are in analog signal.
To carry the audio signals, a high frequency carrier wave is used .The process of changing some characteristics (amplitude, frequency or phase) of carrier wave in accordance with the intensity of the signal is known as modulation. In brief modulation means to change; In modulation some characteristics of the carrier wave are changed in accordance with the intensity (amplitude) of the signals. The resultant wave is called the modulation wave or radio wave and contains the audio signals. Therefore, modulation permits the transmission to occur at high frequencies where it simultaneously allows the carrier of the audio signals.
Types of Modulation
The modulation is process of changing of amplifier or frequency. There are three types of modulation.
Amplitude modulation (AM)
When the amplitude of the high frequency carries wave is changed in accordance with intensifies of the signal, it is called amplitude modulation (AM).
In the case of amplitude modulation
The amplitude of the carrier wave changes according to the intensify of the signal
The amplitude variation of the carrier wave is at the single frequency.
The frequency of the amplitude modulated wave remains the same carrier frequency.
When the frequency of the carrier wave is changed in accordance with the intensity of the signal, it is called Frequency Modulation .In frequency modulation, only the frequency of the carrier wave is changed. However the amplitude of the modulation wave remains the same.
The frequency modulation has following properties:
It produces noiseless reception. Noise is a form of amplitude vibrations and FM receivers reject such signals.
Opening range is quite large.
It gives high fidelity reception.
The efficiency of transmission is very high.
Phase Modulation (PM)
Phase modulation is changed in the carrier phase angle .The Phase cannot change without effecting the change in frequency. Therefore phase modulation is in reality a second form of frequency modulation.
A chain of interconnecting two or more the two computer for transmission of data and is known as computer network. A network is a way to connect computers for communication, data exchange and resource sharing. We can see in the computer networking in business organization like bank, shopping center, corporate office, academic institution,
etc. The main purpose of computer networking is to share data to each other. If there is main or master computer which share the data to other computers then this computer known as server and client or node to the rest computer.
Overview Of Network
In general a communication network means any arrangement, where a sender transmits a message to a reviver over a channel consisting of some types of medium. It maybe in office room, one building, local area or wide range. For communication network we need five basic components as follows.
The media over which, data are transmitted and received are called communication channels. In other words the media or channels that are used to transmit data is said to be communication media. For telecommunication there are different types of channels or media such as copper wire, co-axial cables, fiber optical cable, micro wave system and communication satellite system to inter connect to other devices of a network.
The device which helps to transmit and received data between terminals is called communication processor. In other words it is a processing unit that coordinates network and data communication. Within a computer network, it ensures that data flows to and from different computer systems correctly and efficiently. It is also a kind of simple CPU processor. It includes modem, message switchers, multiplexers, front-end processor.
The software that enables transfer of data and programs from one computer system to another in a network of computers. It is main part communication network .Communication software’s are store in the host computer in the front end computer s and other communication processor. In a large computer networks communication software package is called teleprocessing (TP).
Terminals means a set of computer including video display terminals and other end user work stations .Any Input/ Output device that uses a network to transmit or receive data is a terminals this includes micro computers, telephone fax machine ,etc.
No matter how large and complex the real world networks may appear to be, the above five basic categories of component must be at work to support a network.
Types of Network
There are mainly two types of networks.
Local –Area Network (LAN)
A computer network interconnecting computers and other peripheral devices within a limited geographical area is called local area network (LAN).They are in same room or floor or a same building etc.
Wide –Area Network (WAN)
A computer network interconnecting computers spread over a large geographical area is called wide area network (WAN).They are connected by telephone lines or radio waves; they are geographically apart, like in the different buildings, cities or countries.
A set of rules and procedure established to interconnect and communicate between computers is called network protocol. It provides the method for orderly and efficient exchange of data by establishing rules for proper interpretation of controls and data transmitted as raw bits and bytes.
In other words a network protocols is a set of rules for the exchange of data between two or more than two computers. Protocols are handled by software related to the network.
The international standards organization (ISO) based in Geneva Switzerland, has define a set of protocols called Open System Interconnection (OSI)model.OSI model has been endorsed by the United Nations. The protocols determine the following points.
The type of error checking to be used.
Data compression method ,if any
How the sending device will indicate that it has finished sending a message.
How the receiving device will indicate that it has received message.
The protocol can be implemented either in hardware or software. Some of the popular protocols are TCP/IP, HTTP, FTP, SMTP, POP, Token Ring, Ethernet, Modem, Kermit, MNP etc. These are the examples of the standard protocols.
A method or system of communicating data to the computers in a networking system is called Network Architecture; that is how the data are sent and received in networking system .It is either peer to peer or client/ server architecture .
Peer to peer Architecture
The architecture in which all computers are in peer-to peer arrangement, they are in equal status, no one is in control is known as Peer to Peer Architecture. In this architecture each computer will distributes all files and peripheral devices facilities across several computers working in LAN. They share each other’s data and devices as and when needed. The main disadvantage is lack of speed in the most peer to peer networks system. This system slow down under heavy use of terminals.
The architecture in which one computer serve as a master computer called server; it controls the networks and rest of the computer received and sent data to this computer called client or node is known as client/server architecture .in particular, a server has the hard disk holding shared files and often has the highest quality printers, which can be used by all the nodes. Under this architecture processing is usually done by the server and only the results are sent to the client or node .sometimes the server is called file server and the client is called workstation. Server is stronger the node/client.
The structure of interconnecting of nodes of a computer networking is called network topology. It is the inter-connection pattern of the network or geographical arrangements of a computer system .There are various types of networks. Some of them are
The networking topology in which one or more computers or peripheral devices are connected to the host computer or CPU is called star topology. In fact the each client /node is connected to the server in center it looks as a star so it is called star topology. This system is frequently used everywhere, in this system several users are able to share a control processor and time sharing system.
The networking topology in which two or more than two computers are connected one to one in a simple and closed ring is called ring topology. In other words all the computers or nodes are connected in a closed loop. Message travel around a ring, with each node reading those messages addressed in it. Access and control of ring networks are typically maintained by a “token passing” system.
The networking topology in which all client/nodes are connected in a single communication cable. In other words the data are passing through server to client is highway and each nodes are station of this topology. Access and control of bus networks are typically maintained by a method called CONTIENTION