Generations of computer.

Over the years, many computing devices were invented that are usrd by humans to solve different types of problems. All these computing devices can be classified into five generations which refer to the phase of improvement made to different computing devices results in a small,cheap,fast,reliable and productive computer. The technological development in the field od computer not only refers to the improvements made to the hardware technologies, but also improvement made to software twchnologies.
(i) First Generation (1940-1956) - The first generation of compuyer used the vacuum tubes technology for calculation as well as for storage control purposes. So, these computers are also called as vacuum tubes or thermionic valves based machines. A vacuum tube is a fragile glass device device, which use filament inside it. These vacuum tube computers could perform computation in milliseconds. The memory of these computers was constructed using electromagnetic relays, and all data and instructions were fed into the system from punced cards. These instructions were written in machine and assembly languages because high-level programming languages were introduced later. These first generation computers were mainly used for scientific computations. Some examples of these type of computers are-
ENIAC,
EDVAC,
EDSAC,
UNIVAC I,
IBM 710.
(ii) Second Generation (1956-1963) - A new electronic switching device, called transistor, was invented at Bell Laboratories in 1947 by John bardeen, Willam Shochley and Walter Brattain for which they won Noble Prize. A transistor is asemiconductor device that is used to increase the power of the incoming signals by preserving the shape of the original signal. It had three connections which are emitter (E), base(B), and collector(C). The base of transistor is the gate through the base through which the signal, needed to be amplified, is sent. The signal sent through the base terminal also acts as the input gate for the transistor. The collector of transistor is used to collect the amplified signal. The emitter of a transistor act as a output gate for emitting the amplified signal to the external environment. The second generation computers were manufactured using transistors in plqce of vacuum tubes to build the basic logic circuits.
The memory of these computers was composed of magnetic cores. Another major technological development made to these computers was thereplacement of the machine language with the assembly language. In second generation computers, an increasing usage of computer was seen in business and industry for commercial data processing applications like payrol, inventory control, marketing and producing planning. Some examples of second generation computers are-
PDP-8,
IBM1401,
IBM 7090.
Third Generation (1964-1975) - In 1958, Jach St. Clair Kilby and Robert Noyce inverted the first integrated circuit. The major Characteristics features of third generation computer systems was the use of Integrated circuits like transistors, resistors and capacitors grown on a single chip of silicon, eliminating wired interconnection between componets. The IC technology was also known as "microelectronics" tecnology because it made it possible to integrate large no. Of circuits components into very small surface of silicon , known as "chip". Initially ,the ICs contained only about ten to twenty componets. This technology was named small scale integration (SSI). So.e examples of third generation computers are-
NCR 395,
B6500,
IBM 370,
PDP 11,
CDC 7600.
(iv) Fourth Generation (1975-1989) - The average number of electronic components packed on a silicon chip doubled each year after 1965. This progress soon led to the era of large scale integration (LSI) when it was possible to integrate over 30000 electronic components in a single chip. As a result, the manufactures were able to reduce the size of the computers and made them cheaper as compared to the other generation of computers. The progress in  LSI and VLSI technologies led to the development of microprocessor. A microprocessor incorporates various components of a computer- such as CPU, memory and I/o control-onto a single chip. The intel P4004P mircoprocessor chip developed in 1971. Some popular later microprocessor include Intel 386, Intel 486, and pantium. The term personal computer (pc) became known to the people during this era.
During the fourth generation, magnatic core memories were replaced by semiconductor memories, resulting in larger random access memories with very fast access time. LANs became popular for connecting several dozen or even several hundred computers within an organization and WANs became popular for connection computer located at larger distances. This gave rise to network of computers and distributed system. Some examples of fourth generation computers are IBM PC, IBM PC/AT, Apple and CRAY-1.
(v) Fifth Generation (1989- present) - The different types of morden digital computers come under the catogaries of fifth generation computers. The fifth generation computers are based on ultra large scale integration (ULSI) technology rhat allows almost ten million electronic components to be fabricated one one small chip. The ULSI technology help in increasing the power and speed of miroprocessor chip and the capacity of primary and secondry to a great extent. As a result fifth generation computers are faster, cheaper and more efficient, as compared to fourt generation computers.

What is operating system ?

An operating system is an integrated set of programs that controls the resources such as CPU, memory, I/O devices etc., of a computer systemand provides its users with an interface or virtual machine that is more convenient to use that the bare machine.

An operating system is master control program that runs the computer and acts as a scheduler. It controls the flow of signals from CPU to various parts of the computer. It is first program loaded into the memory when the computer is tured on. Popular operating systems are MS-DOS, Windows and UNIX.

An operating system (also called as OS) supervises and provides services to computer users. It permits the computer to supervise its own operations by automatically calling in the applications programs and managing the data needed to produce the output desired by users. It isolates the hardware from the user. The functions provided by OS are transparent or invisible to the users.

Multimedia and Animation

Computers can be used to integrate two or more types of media, such as text, graphics, image, audio, and video, for the purpose of generation, storage, representation, manipulation ans access of multimedia information. Multimedia is one of the most commonly used terms in entertainment industry, which produces various entertainment products such as movies and video games.

Computer animation deals with the generation, sequencing, and display of a set of images to create an effect of visual change or motion, similar to a movie film (video). Animation is an important component of multimedia, because just as a picture is a powerful way to illustrate information, a small animation clip is even more powerful and useful for illustrating concepts, which involve movement.
For example, in the multimedia application meant for educating small children, an animation clip will be very effective in illustrating the difference in the movment of a horse during a gallop versus a walk. Several movies and advertisements now contain many visual tricks, which could never be accomplished without the aid of computers. For example, if you carefully watch the advertisements for detergent soaps/powders, toothpastes, insecticides for mosquitoes and cockroaches, etc., you will notice avenge in them, which cannot be videographed. These scenes are produced by using computer animation.

Ethics in Computing

Ethical conduct goes beyond merely adhering to laws. All professions have a code of ethics that broadly sets standards for professionals. Such ethical standards may not be covered by specific legislation. For example, what should you do if you are analyst or programmer responsible for a program that invades privacy ? Or how responsible are you if you create a software package that produces erroneous results ? After all, is it reasonable to expect software packages to be totally free of errors?

Of course, there are no simple answers to questions such as these. Many people with high ethical standards have argued against holding computer professionals totally responsible for their work, because the way a system is used may not be under the programmer's or analyst's control. Some people argue that, just as Alfred Nobel cannot be hold accountable for the immoral use of his invention of dynamite, computer professionals should not be hold accountable for programs that are used illegally or unethically.

As the debate over these ethical issues goes on, many leaders in the computing field believe that code of ethics is of primary importance and that it would be far better for professionals to police themselves before the government finds it necessary to pass laws.

Remote sensing and GIS

Remote sensing is the science of deriving information about the earth's land water areas form images acquired by using sensing devices operated from a remote location. It relies upon measurement of electromagnetic energy reflected or emitted from the features of interest.

The field of GIS and remote sensing has been referred to as the technology of today. The largest primary source of digital data for use in GIS is undoubtedly that created by remote sensing technology on board of sattellites and other aircraft's. Different schools of thought have different and varied definitions for geographic information system ( GIS). Tomlin defines a GIS as a configuration of computer and hardware and software specially designed for the acquisitions, maintenance and use of cartographic data. Burrough defines a GIS as a powerful set of tools for collecting storing and retrieving at will, transforming and displaying spatial data from the real world.

Thus, a GIS is a computer-assisted system for the acquisition, storage, analysis and display of geographically are spatially reference data.

Computer Gaming

Computers are also being used for playing video games. With the advent of multimedia, there has been a boom in the different type of video games available on computer systems. Sound and animation have been particularly important in these applications to make the games thrilling and exciting for the user. Because the sequence of events in such games depends on the action of the player, these programs are very interactive in nature.

Bio-informatics -Application of computer

Bio-informatics is the application of the computer technology to the management of biological information. Computers are used to gather, store, analyze and integrate biological and genetic information which can then be applied to gene-based drug discovery and development. The need for Bio-informatics capabilities has been precipitated by the explosion of publicly available genomic information resulting from the human genome project. The science of Bio-informatics, which is the melding of molecular biology with computer science, is essential to the use of genomic information in understanding human disease and in the identification of new molecular target for drug discovery. 

Health Care - one of the application of computer

Computers are also being used for planning and control purposes by health-care professionals. Computer equipment is used to monitor pulse rate, blood pressure and other vital signs. This leads to correct and fast diagnosis. Medical researchers are using computers as a tool in their search for cures of deadly diseases like cancer and AIDS.

E-business

E-business is about using Internet technologies to transform the way business processes are performed. Its most visible form is purchasing using PC and Internet. Every day, more companies and people gain access to the Internet, more purchases are executed electronically.

Custom-made Software

There are situations when none of the available pre-written software packages can meet the specific requirements of a user ( an organization or an individual ), either partially or fully. In such a situation, it becomes necessary to create a customized software package to satisfy the specific requirements. If the user has an in-hour software development team, the software package can be create in house. However, if such a team does not exist, the user must get it created by placing an order for it.

Database software

A database is a collection of records with fields. A database software is a set of one or more programs, which enables us to create a database, maintain it (i.e. add, delete and update its records), organize its data in disired fashion, and to selectively retrieve useful information from it.

Application Software

Application software or application packages are sets of one or more programs designed to carry out operations for a specified application. For example, every month a payroll package produces the payslips for the workers of a company.

Application software may be defined as software that provides an interface between the user and the system software to allow the user to perform specific tasks.

Some of the most commanly known application software are-

I) Word Processing software

II) Database software

III) Spreadsheet Software

IV) Graphics Software 

Utility Programs

Utility programs also called as utilities, are a set of programs, which helps users in system maintenance, and performing tasks of routine nature such as formatting of hard disks or floppy disks, taking backup of files, sorting of the records stored in a file, etc.

Communications software

In a network environment, communications software enables transfer of data and programs from one computer system to another.

Programming Language Translation

These are the system software, which transform the instructions prepared by programmers into a programming language into a form, which can be interpreted and executed by a computer system.

Operating Systems (pre-written software )

Every computer has an operating system software, which takes care of the effective and efficient utilization of the hardware and software components of the computer system.

System Software

A set of a one or more programs designed to operate, control and extend the processing capabilities of a computer system. These are general programs written to assist humans in the use of computer system and for making the operations of the computer system more effectively and efficient.

System software supports the following -
1) Running of other software.

2) Communicating with and controls peripheral devices such as printers, card readers, disk and tape etc.

3) Development of other application software.

4) Monitoring the effective use of various hardware resources such as memory, peripherals, CPU , etc.

The most common types of system are-

1) Operating systares
2) Programming Language Translator 3) Communications Software
4) Utility Programs

Voice Reproduction system

A voice reproduction system produces audio output by selecting an appropriate audio output from a set of pre-recorded audio responses. The set of pre-recorded responses include words, phrases or sentences spoken by human beings, music or alarms generated by musical instruments.
The application of voice reproduction system are-
I) Audio help for guiding how to operate a system. For example, bank uses voice reproduction system in ATM (automatic teller machines) to guide customers about transactions.
II) Automatic answering machines. For example, telephone enquiries for new telephone numbers in place of an old number, or vacancy status of a particular flight or train is taken care by an automatic answering machines.

Difference between inkjet and Dot Matrix Printer

Dot Matrix Printer and Inkjet Printer-
1) Inkjet printer is a non-impact printer while dot matrix printer is a impact printes.

2) Inkjet printer provide better printing quality than dot matrix printer.

3) Inkjet printers are less noisy than dot matrix printer.

4) Inkjet printer is expensive than dot matrix printer.

5) Inkjet printer resolution id good about 100 dots/cm while dot matrix printer has average resolution. 

Difference between Chain Printer and Drum Printer

Drum Printer and chain printer -
1)Chain printer uses a chain mechanism. There is one print hammer for each print position on the line. The characters are printed when the hammer presses the paper against the ribbon while in drum printer a metallic cylinder having column on the drum contains all the characters. Ad the drum rotates, each character that is to print reaches the appropriate position and a hammer then strikes that character.

2) Drum Printers are costly than chain printers.
3) In chain printers, chains may be changed easily while in drum Printers drums cannot be changed often.