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- 1. Introduction In developed countries. Life in twenty first century depends on different types of computers right from coffeepot to the microwave that cooks your breakfast to the automobile that you drive to work to the automated teller machine you stop for cash, virtually every aspect of life depends on computers. What is a computer? Definition: A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve , and process data. You probably already know that you can use a computer to type documents, send email, play games, and browse the Web. You can also use it to edit or create spreadsheets , presentations, and even videos. (Or) A computer is a device that accepts information (in the form of digitalized data) and manipulates it for some result based on a program or sequence of instructions on how the data is to be processed. Complex computers also include the means for storing data (including the program, which is also a form of data) for some necessary duration. A program may be invariable and built into the computer (and called logic circuitry as it is on microprocessors) or different programs may be provided to the computer (loaded into its storage and then started by an administrator or user). Today's computers have both kinds of programming.
- 2. The following are some more common of computer abbreviations that you may have heard but do not know exactly what they mean. Common Computer Abbreviations • BIOS - This is the Basic Input Output System which controls the computer, telling it what operations to perform. These instructions are on a chip that connects to the motherboard. • BYTE - A byte is a storage unit for data. • "K" is a Kilobyte which is 1024 bytes. • "MB" is a Megabyte which is a million bytes. • "GB" is a Gigabyte, which equals 1000 megabytes. • CPU - This stands for the Central Processing Unit of the computer. This is like the computer’s brain. • MAC - This is an abbreviation for Macintosh, which is a type of personal computer made by the Apple Computer company. • OS - This is the Operating System of the computer. It is the main program that runs on a computer and begins automatically when the computer is turned on. • PC - This is the abbreviation for personal computer. It refers to computers that are IBM compatible. • PDF - This represents the Portable Document Format which displays files in a format that is ready for the web. • RAM - This stands for Random Access Memory which is the space inside the computer that can be accessed at one time. If you increase the amount of RAM, then you will increase the computer’s speed. This is because more of a particular program is able to be loaded at one time. • ROM - This is Read Only Memory which is the instruction for the computer and can not be altered. • VGA - The Video Graphics Array is a system for displaying graphics. It was developed by IBM. • WYSIWYG - This initialism stands for What You See Is What You Get. It is pronounced "wizziwig" and basically means that the printer will print what you see on your monitor. Program Definition Computer programs are collections of instructions that tell a computer how to interact with the user, interact with the computer hardware and process data. In the modern computer that John von Neumann outlined in 1945, the program contains a one-at-a- time sequence of instructions that the computer follows. or A computer program, or just a program, is a sequence of instructions, written to perform a specified task on a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. Learn C Programming Language with Example - Tutorial for Beginners What is a programming language? We, human beings need language to communicate between us. Similarly, for us to communicate with computers we need a medium. And that’s exactly what a programming language is. All our needs can be communicated to computers with the
- 3. help of a programming language. And now coming to our topic, C is the basic of all programming languages. Before the introduction of C we had only Machine level languages. Once you are thorough with C programming language, you can learn other programming language with ease. To learn C we just need to know the basic syntax of C programs i.e. the order and form in which we have to write the actual code. This website is intended to introduce C programming to novice programmers. Over several years of experience, Computer programs are collections of instructions that tell a computer how to interact with the user, interact with the computer hardware and process data. The first programmable computers required the programmers to write explicit instructions to directly manipulate the hardware of the computer. This “machine language” was very tedious to write by hand since even simple tasks such as printing some output on the screen require 10 or 20 machine language commands. Machine language is often referred to as a “low level language” since the code directly manipulates the hardware of the computer. Language types Machine and assembly languages A machine language consists of the numeric codes for the operations that a particular computer can execute directly. The codes are strings of 0s and 1s, or binary digits (“bits”), which are frequently converted both from and to hexadecimal (base 16) for human viewing and modification. Machine language instructions typically use some bits to represent operations, such as addition, and some to represent operands, or perhaps the location of the next instruction. Machine language is difficult to read and write, since it does not resemble conventional mathematical notation or human language, and its codes vary from computer to computer. Assembly language is one level above machine language. It uses short mnemonic codes for instructions and allows the programmer to introduce names for blocks of
- 4. memory that hold data. One might thus write “add pay, total” instead of “0110101100101000” for an instruction that adds two numbers. Assembly language is designed to be easily translated into machine language. Although blocks of data may be referred to by name instead of by their machine addresses, assembly language does not provide more sophisticated means of organizing complex information. Like machine language, assembly language requires detailed knowledge of internal computer architecture. It is useful when such details are important, as in programming a computer to interact with input/output devices (printers, scanners, storage devices, and so forth). Algorithmic languages Algorithmic languages are designed to express mathematical or symbolic computations. They can express algebraic operations in notation similar to mathematics and allow the use of subprograms that package commonly used operations for reuse. They were the first high-level languages. FORTRAN The first important algorithmic language was FORTRAN (formula translation), designed in 1957 by an IBM team led by John Backus. It was intended for scientific computations with real numbers and collections of them organized as one- or multidimensional arrays. Its control structures included conditional IF statements, repetitive loops (so- called DO loops), and a GOTO statement that allowed nonsequential execution of program code. FORTRAN made it convenient to have subprograms for common mathematical operations, and built libraries of them. FORTRAN was also designed to translate into efficient machine language. It was immediately successful and continues to evolve. ALGOL ALGOL (algorithmic language) was designed by a committee of American and European computer scientists during 1958–60 for publishing algorithms, as well as for doing computations. Like LISP (described in the next section), ALGOL had recursive subprograms—procedures that could invoke themselves to solve a problem by reducing it to a smaller problem of the same kind. ALGOL introducedblock structure, in which a program is composed of blocks that might contain both data and instructions and have the same structure as an entire program. Block structure became a powerful tool for building large programs out of small components. ALGOL contributed a notation for describing the structure of a programming language, Backus–Naur Form, which in some variation became the standard tool for stating the syntax (grammar) of programming languages. ALGOL was widely used in Europe, and for many years it remained the language in which computer algorithms were published. Many important languages, such as Pascal and Ada (both described later), are its descendants. LISP LISP (list processing) was developed about 1960 by John McCarthy at the Massachusetts Institute of Technology (MIT) and was founded on the mathematical theory of recursive functions (in which a function appears in its own definition). A LISP program is a function applied to data, rather than being a sequence of procedural steps as in FORTRAN and ALGOL. LISP uses a very simple notation in which operations and their operands are given in a parenthesized list. For example, (+ a (* b c)) stands for a + b*c. Although this appears awkward, the notation works well for computers. LISP also uses the list structure to represent data, and, because programs and data use the same structure, it is easy for a LISP program to operate on other programs as data.
- 5. LISP became a common language for artificial intelligence (AI) programming, partly owing to the confluence of LISP and AI work at MIT and partly because AI programs capable of “learning” could be written in LISP as self-modifying programs. LISP has evolved through numerous dialects, such as Scheme and Common LISP. C The C programming language was developed in 1972 by Dennis Ritchie and Brian Kernighan at the AT&T Corporation for programming computer operating systems. Its capacity to structure data and programs through the composition of smaller units is comparable to that of ALGOL. It uses a compact notation and provides the programmer with the ability to operate with the addresses of data as well as with their values. This ability is important in systems programming, and C shares with assembly language the power to exploit all the features of a computer’s internal architecture. C++++, along with its descendant C++++, remains one of the most common languages. Business-oriented languages COBOL COBOL (common business oriented language) has been heavily used by businesses since its inception in 1959. A committee of computer manufacturers and users and U.S. government organizations established CODASYL (Committee on Data Systems and Languages) to develop and oversee the language standard in order to ensure its portability across diverse systems. COBOL uses an English-like notation—novel when introduced. Business computations organize and manipulate large quantities of data, and COBOL introduced the record data structure for such tasks. A record clusters heterogeneous data such as a name, ID number, age, and address into a single unit. This contrasts with scientific languages, in which homogeneous arrays of numbers are common. Records are an important example of “chunking” data into a single object, and they appear in nearly all modern languages. Electronic Computers Then and Now In our everyday life, we come in contact with computers frequently, some of using computers for creating presentations and other documents, tabulating data in spreadsheets, or even having studied programming in school and colleges etc.. The first electronic computer was built in the late 1930’s by Dr. John Atanasoff abd Clifford Berry at lowa State Univesrsity. He designed his computer to assist graduate students in nuclear physics with their mathematical computations.
- 6. The first, general- purpose electronic digital computer, called the ENIAC (Electronic Numerical Integrator And Computer), was completed in 1946 at the University of Pennsylvania with funding from the U.S Army. Weighing 30 tons and occupying a 30- by-50- foot space, the ENIAC was used to compute ballistics tables( Ballistics from Greek "to throw") is the science of mechanics that deals with the launching, flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance), predict the whether, and make atomic energy calculations. These early computers used vaccum tubes as their basic electronic component. Technological advances in the design and manufacture of electronic components led to new generations of computers that were considerably smaller, faster and less expensive than previous ones. With advances in technology today, the entire circuitry of a computer processor is packed in a single electronic component called a microprocessor chip. Which is less than one fourth size of a postal stamp. This small size enable computer chip to be installed in watches, cellphones, GPS systems, Cameras, Home appliances, automobiles and computers. Today, personnel computers where used in offices and homes,which can cost less than $1000 and sit on the desk and yet more computational power as one that 40 years ago cost more than $100000 and filled a 9-by-12-foot room. Even smaller computers can fit inside a briefcase or purse or your hand. Modern computers are categorized according to their size and performance. Personnel computers are used by a single person at a time. Large real-time transaction processing systems, such as ATM’s and other banking networks and corporate
- 7. reservations systems for hotels, airlines, and rental cars use mainframes, very powerful and reliable computers. The largest capacity and fastest computers are called supercomputers and are used by research laboratories and in computationally intensive applications such as whether forecasting. The Elements of a computer system fall into two major categories: Hardware and Software HARDWARE: is the equipment used to perform the necessary computations and includes the central processing unit (CPU), monitor, keyboard, mouse, printer,and speakers SOFTWARE: consists of the programs that enable us to solve problems with a computer by providing it with lists of instructions to perform. COMPUTER HARDWARE Some of the hardware components are: 1. Main Memory 2. Secondary memory, which includes storage devices such as hard disks, CD’s, DVDs, and flash drives. 3. Central Processing unit. 4. Input devices, such as keyboards, mouses, touch pads, scanners, and joysticks Output devices, such as monitors, printers, and speakers. The above figure shows how these components interact in a computer, with the arrows pointing in the direction of information flow. The program must first be transferred from secondary storage to main memory before it can be executed