Basic Words - Program and Data

A "program" is a set of instructions for the computer. A program tells the computer how to do something. Some examples of programs are a game like Solitaire or Hearts, a "word processing" program for doing typing on, a "spreadsheet" program for doing calculations on, a genealogy program for recording and keeping track of your genealogy information, and a "paint" or "drawing" program for drawing pictures on.
"Data" is your information, your work. Some people think of data as "facts" (either written facts or numbers). This could be a letter you typed in, some addresses, some calculations, your tax information, a short story, genealogy information, a picture or photograph, etc. Data is what you put in the computer.
Everything put in the computer is either a program or data.

Data is distinct pieces of information, usually formatted in a special way. All software is divided into two general categories:data and programs. Programs are collections of instructions for manipulating data.

Data can exist in a variety of forms -- as numbers or text on pieces of paper, as bits and bytes stored in electronic memory, or as facts stored in a person's mind.

The program is your tool. The data is your work. You use the "program" to work on "your data."

Digital and Analogue Transmission

Data is propagated from one point to another by means of electrical signals, which may be in the digital or analog form. As shown in the figure below,

analog signals are continuous in nature. They have continuous amplitude levels. Since they are continuous, it is very difficult to remove physically any noise and distortion from them, which is added during transmission or otherwise. The telephone lines used for data communication in computer networks are usually meant for carrying analog signals.

A digital signal is a sequence of voltage pulses represented in the binary form. These signals are well-defined with discrete amplitude levels. Computer generated data is digital in form.

Data Communication

Message and Structured Data

The term data communication describes the transmission of computer related records, which have a structured format, from source to destination over transmission media like telephone line, optical fibre, microwave link, etc.

Other forms of digital transmission such as digitized voice, facsimile or video do not use structured data except in the case of telemetry, which can use fixed data field and formats.

Each record of a structured data type is identified by a transaction code; the data is organized into predefined fields, each of which contains a specified maximum number of characters.

Bits Streams and Symbols

The characters which make up a message are transmitted one after another as a bit stream, where a bit is the fundamental data unit represented as 1 or 0, mark or space in digital systems.

A symbol is the basic transmission element, which is used to transmit a group of bits.

Data Rate

Data Rate is measured as bits per second. When group of k bits is combined to form a transmission symbol which has a transmit duration T, then

Data Rate = k/T

Baud Rate

Baud rate is the transmit speed of a communication channel in bits per second. For example, 4800 baud is 4,800 bits/second of data transfer.

Computer Overviiew

Introduction

The word 'compute' comes from the word 'compute' which means to calculate. So, a computer is normally considered to be calculating device that can speedily perform arithmetic and logical operations.

the original objective for inventing a computer was to create a fast calculating machine, through a major part of work done by computers nowafays is non-mathematical. Therefore, defining a computer assembly only as a calculatinng device is not justified.

The computer is an electronic device designed to accept and store input data, manipulate it and output results under the direction of detailed, step-by-step stored programs and instructions.

Data

It denotes raw facts and figures such as numbers, words, amount, quantity, that can be processed, manipulated or produced by the computer. for example: Rita, 18, XI B. This is raw data.

Information

It is a meaningful and arranged form of data. Raw data does not make any sense on its own. So, it has to be arranged in a meaningful manner such that it makes sense. For example, Information that makes sense can be Rita aged 18 is in class XI B.

Hardware andSoftware

A computer consists of two fundamental components. One is called hardware, the other sothe software. Hardware refers to the physical components or blocks, for example, CPU, memory, input and output devices. Software is the package of instructions designed to operate the conserened hardware, for example, MS-DOS, Microsoft Office, etc. In fact, we can divide software into two broad categories:

1) System Software: It runs the basic functioning of a computer system. It consists of operating systems, compilers, translators, etc.

2) Application Software: the basic aim of making and running a computer is to get work done from it. So, programs which are developed in order to serve a particular application are known as application software. For example, Microsoft Office, Tally, etc.