HSC ICT APK

 

Click here to download the apk

Read More

 (a) What is a Nuclear Family?
(b) How many types of family we can find?
(c) Why this type of family is getting popular today?

Database            Programming            HTML               Numbure System

(d) What are the advantages of a nuclear family?
(e) Is there any disadvantage of a nuclear family?
(f) What type of family do you like most and why?
(g) How is Nuclear family different from extended family?

Read More

A Handbook For English Literature.pdf

20. Nuclear Family

(a) What is a Nuclear Family?
(b) How many types of family we can find?
(c) Why this type of family is getting popular today?
(d) What are the advantages of a nuclear family?
(e) Is there any disadvantage of a nuclear family?
(f) What type of family do you like most and why?
(g) How is Nuclear family different from extended family?

Click here to download the book.

A nuclear family is a small one containing father, mother and their children. There are two types of families we can in our society, one is nuclear family and the other is extended family. In a nuclear family only parents and children live, but in an extended family there might be grandparents, grand children, uncle and aunts live together. Life is becoming more expensive day by day. That’s why nuclear family is preferred. This type of family gives any one the opportunity to concentrate on his own activities. An extended family consists of many members. All members in this family deserve attention. But they can’t concentrate on their own activities. Personal freedom and privacy are hampered in an extended family. It is true that a nuclear family is boring and tiresome to some extent. The members seldom get anyone to share their feelings, joy or sorrows. But these drawbacks can be overcome if the members spend their leisure in a productive way. They can also do some social works or engage themselves in cultural or any educative activities. They can also visit their relatives to avoid their monotony. Despite some disadvantages I like nuclear family, because I think to cope with the modern world. We have to prepare ourselves in an organized way. And it is possible only by staying in a calm and cool family environment. A nuclear family can give us an effective and proper opportunity to do something with full concentration. Money is also a factor. In a nuclear family its members are limited, so we can easily fulfill our demand within our limited income. So considering all these positive sides we should make a consciousness among ourselves to make our family small.

Read More

You Can Win in Bangla.pdf

12. A Trade Fair 

(a) What do you mean by a trade fair?
(b) Why is a trade fair organized?
(c) In Bangladesh where is a trade fair normally arranged?
(d) How is the fair arranged? (e) What things are found in a trade fair?

Click here to download the book

A trade fair is a fair for the display of industrial goods to the foreign buyers to get them acquainted with the exportable items of the country. By arranging trade fair we can make people aware of the market price. We can inform the customers about the quality of the product. In a trade fair a lot of companies take active part. In our country every year we arrange a lot of trade fairs. The government organizes an international trade fair every year in Sher-e-Bangla Nagar. A trade fair gives immense pleasure and opportunity to the customers. So it cannot be organized by an individual. It is normally held once a year. A great publicity is done for this purpose. And this publicity is made through advertisement in the national and international dailies to draw the attention of the industrialists and producers. The host country also advises friendly countries to install stalls in trade fair to display their exportable goods to the importers of the host country. As a trade fair gives scope to a country to display her products, friendly countries gladly respond to the call of the host countries. There are also arrangements for recreation, food etc, for the visitors. Thus a trade fair is very much useful. A host country can know the other parts of the globe through a trade fair. A trade fair should be held every year to encourage importers of foreign countries to import goods from our country. The day is no more so far when we shall be able to import necessary goods keeping the balance of trade in our favour.

Read More

Microsoft Word 2007.pdf

Input/Output Methods 

There are three basic methods by which data can be read (or input) from or written (or output) to a peripheral device and RAM. These methods are referred to as: programmed I/O, interrupt I/O, and direct memory access. In programmed I/O, the MPU directly controls all data transfers and other I/O operations. 

Click here to download the book

This is accomplished with input or output instructions. When an input operation is desired, the MPU issues an input command and awaits the arrival of the data at the bus. From the bus the data are moved to memory. Similarly for an output operation, the MPU transmits the data to the bus and issues a command to the output device through the appropriate interface. Once data transfer is initiated, the MPU should wait for its completion and the bus to be freed before beginning a new transfer. This method is commonly used in personal computers. In the interrupt I/O method, the MPU does not wait for the input/output devices to complete their tasks. The control of the operation is given to a channel. The channel signals the MPU when the operation has been completed. This is accomplished by means of an interrupt. Upon completion of the execution of the current instruction, the MPU may then initiate another I/O operation. Direct memory address method is the fastest of the three methods. It requires a multibus architecture and allows the MPU to be bypassed completely. A direct memory access controller is connected between RAM and an input or output device. This method is the most expensive of the all and therefore is not used except with very high-speed input/output devices. 

Telecommunications Between Microcomputers 

Most microcomputers also support the transfer of data through telephone line. This is facilitated by means of an add-on device known as a modem. In telecommunications, one computer or terminal issues a command, or some form of output. This digital output from the computer, is modulated, or converted to an analog signal, by a modem interfaced to the sending computer. The signal is then carried over the telephone line and received at another modem some distance away. This second modem then demodulates, or converts the analog signal back to a computer-compatible digital signal. The name modem performs the functions of modulation and demodulation. Thus, with the aid of a modem and a serial interface to a microcomputer, communication can take place over long distances. The speed with which these communications take place is dependent on the modem employed.

Read More

English For Today For Class Eleven. pdf

Lesson 1: Microcomputer and Organization 

1.1 Learning Objectives 
On completion of this lesson you will be able to:
• understand structure of a microcomputer
• understand communication techniques between processor and other devices
• understand telecommunications for distant microcomputer.

Click here to download the book

1.2 Architecture of a Microcomputer 

The most modern microcomputers utilize a motherboard, a single large circuit board containing the microprocessor unit (MPU), ROM, RAM, and other associated circuits. These elements are linked through a series of parallel metal lines etched into the motherboard called the system bus. The system bus carries three types of information; these are: control, address, and data. Control information is carried by a number of control lines, addresses by a number of address lines and data by data lines. The width of the bus is important to the performance of the computer. The wider the bus, the more information can be carried at one time and the greater the throughput of the system. Most 16-bit microcomputers use 8 or 16-bit buses, 32-bit microcomputers use 8-bit, 16-bit, and 32-bit buses, while 64-bit microcomputers use 16-bit, 32-bit and 64-bit buses. A number of slots provide access to the system bus (Figure 3.1). Input/output devices can be connected to the microcomputer through the slots and appropriate interface circuit boards. The slots can also be used to expand the RAM capability of the microcomputer.

I/O Interface

Communications between an input/output device and the MPU take place through an interface. The interface converts the data from a form used by one of these devices to a form acceptable by the other. It must also adjust for speed differences between the processor and the other device. The interface circuits of microcomputers correspond to the I/O control units used on larger computer systems.

Read More

HSC Biology Book.pdf

3.3 Computer Generations 

Developments over the years have resulted in machines with greatly increased speeds, storage or memory, and computing power. These developments were so far-reaching and numerous that they are generally categorized by generations. Each generation is initiated by significant advances in computer hardware or computer software that run the machines. 

Click here to download the book

First Generation (1942-1959) 

First-generation computers utilized vacuum tubes in their circuitry and for the storage of data and instructions. The vacuum tube was bulky, caused tremendous heat problems, and was never a completely reliable device, it caused a great number of breakdowns and inefficient operations. Magnetic cores began to replace the vacuum tube as the principal memory device in the early machines. Small doughnut-shaped cores were strung on wires within the computer. Programs were written in machine language employing combinations of binary digits 0 and 1. 

Second Generation (1959-1965) 

The second generation of computers saw the replacement of the vacuum tubes with the transistors. A transistor can be thought of as a switch, but with no moving parts. Because of the high speed operation and its small size, computers were developed that were able to perform a single operation in microseconds and were capable of storing tens of thousands of characters. Manufacturers began producing business-oriented computers with more efficient storage and faster input and output capabilities. Second generation computers were reliable, compact in size, and virtually free of heat problems. Programming was done in both machine and symbolic language. Symbolic language utilized symbolic names of representations for computer commands and allowed the use of symbolic names for items of data. This language is also known as assembly language. 

Third Generation (1965-1970) 

These computers were characterized by integrated circuits with components so small that in many cases they were hardly visible to the naked eye. Third generation computers were characterized by increased input/output, storage, and processing capabilities. Input/output devices could communicate with computers over great distances via ordinary telephone lines or special communication lines, could scan a page and input the “observed” information directly into the computer, could display pictures on a television-like screen, could make musical sounds, and could even accept limited voice input. Storage capabilities were increased and millions of characters could be stored and randomly accessed in fractions of a second. Third-generation computers could process instructions in nanoseconds. In addition, computers were able to process several programs or sets of instructions simultaneously. Programmers were able to make use of high-level problem oriented and procedure oriented languages that closely resemble the commonly used form of expressions. 

Fourth Generation (1970 - ) 

The fourth generation computers pass still greater input, output storage, and processing capabilities. In the fourth generation of computers monolithic storage devices were introduced. In the early 1970s IBM introduced the concept of virtual storage into their 5000 and 370 series of computers. Machines previously limited to a maximum internal storage capability of approximately 1 million characters now possessed a virtual storage capability in billions and trillions of characters. With this capability a machine could execute a program many times the size of the machine’s actual memory capacity. Now a days, the compact disk (CD) promises to become the data storage medium of choice. A compact disk read-only memory (CD ROM) is encoded with on and off bits. Bits are stored on the disk’s (3.5-inch dia) aluminum surface as tiny pits at varying depths. The average CD can store about 4,800 million bits or 600 million characters of data. This is approximately a quarter of a million pages of text. The most impressive advancement has occurred with respect to software. As a result of these changes, access to substantial computer power, previously only affordable by very large business concerns, is now economically feasible for the small business and personal applications.

Fifth Generation 

Fifth generation of computers is on the horizon. They will be unlike any computer existing today. They will be capable of reasoning, learning, making inferences and otherwise behaving in ways usually considered exclusive of humans. These computers will be equipped with massive primary-storage capabilities and extremely fast processing speeds. Software will proliferate and get much bigger and much cheaper. Hardware will continue to shrink in size but internal memory will increase dramatically. “Talking machines” will be common place. Voice-recognition, the ability for a machine to understand and obey spoken words, will also advance. Industrial and personal robots will roll and walk into our lives. Expert systems software will place the knowledge of experts and consultants (such as doctors, lawyers, teachers) at our disposal. Huge computers will be linked in parallel offering computing power of an inconceivable magnitude.

Read More

HSC Biology.pdf

Lesson 3: History and Generations of Computers 

3.1 Learning Objectives 
On completion of this lesson you will be able to :
• trace the history of computers
• follow the computer generations.

Click here to download the book

3.2 The Beginning 

Different devices and tools have been employed in calculation and processing of data. An ancient calculating device is the abacus, a mechanical calculating device first used around 2500 B.C. to add and subtract. Scientists and mathematicians later sought other means to aid their endeavors. John Napier, a Scottish mathematician, developed (about 1610) a series of rods made of bones (commonly called Napier's bones) that could be arranged to produce the products of selected numbers. He used these rods to produce the first table of logarithms. In 1865 the French mathematician Blasé Pascal improved on this concept and produced a mechanical calculator called Pascaline. It was more compact and easier to use than Napier's bones. The Pascaline was capable of performing addition and subtraction. All attempts to produce a calculator capable of performing all the four arithmetic operations and producing mathematical tables quickly and accurately were not successful until 1820. Thomas de Colmar of France produced the arithmometer, the first four-function practical mechanical calculator. A young English mathematician named Charles Babbage, of Cambridge University contributed substantially towards the development of computers. Babbage gave much thought to the design of a device to produce mathematical and navigational tables and came upon a principle that used the “differences” between previous values in a table to produce new values. Babbage was able to construct a working model to illustrate the principle of the difference engine. Babbage started work on a steamdriven version of the difference engine capable of calculating and printing results at a rate of two twenty-digit numbers per minute. Babbage built part of the machine but abandoned it in favor of a more powerful and versatile machine, the analytical engine. The analytical engine was designed to use punched cards to provide a constant flow of information through the machine's elaborate series of columns, gears, wheels, and levers. The analytical engine included all the functional units of modern computers: input of data, arithmetic unit for computation, memory for data and instructions, and display for output. This was an ambitious project during a time when electronics,transistors, and chips did not exist. The engine was a puzzle to all but a few mathematicians. This machine, however, was never built. Nearly a century later a new generation of scientists and engineers equipped with new developments brought Babbage's vision back into focus for future advancements in computer technology. Insignificant progress took place over the next decades. In the United States the 1890 census was approaching, and there was no foreseeable way that it could be completed by 1900, as required by the constitution. Herman Hollerith, an employee of the Census Office in Washington, started to develop an automated device to complete this task in the allotted ten years. The result was Hollerith's tabulator. A manual card puncher, a card reader, and an electromechanical card sorter were the main components of the census tabulator. With this tabulator, Hollerith was able to complete the census count in only two years. Hollerith's success paved the way for further research and development. Analog computers, a new class of computing devices, emerged. These devices used electrical voltages to represent physical quantities. They functioned by establishing an analogy between a physical quantity and a voltage level. They were very fast but not sufficiently exact, or dependable. The first electronic computers, the ABC (Atanasoff Berry Computer) and the ENIAC (Electronic Numerator, Integrator, Analyzer, and Computer) were built in the early 1940s. The ABC, built by Atanasoff and Berry, was the first, electronic computer using vacuum tubes. The ENIAC, built by Eckert and Mauchly, was an extensively used specialpurpose computer. In 1949, at Cambridge, the first general-purpose electronic computer operating under the control of a stored program, the EDSAC (Electronic Delay Storage Automatic Computer), was completed. A stored program is a set of instructions stored in memory that guides the computer, step by step, through a process. John Von Neumann, an originator of the stored-program concept, developed the IAS (Institute for Advanced Study) computer at Princeton University. This machine was the realization of John Von Neumann, ideas on computer design. Most computers built after the IAS computers have “Von Neumann” characteristics. A group of MIT scientists headed by Ken Olsen developed the Whirlwind computer, more than twenty times faster than the ENIAC. Both the IAS and Whirlwind computers introduced computational innovations of astronomical proportions.

Read More