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.

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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.

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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. 

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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.

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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.

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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.

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Mainframe Computers

Larger computers generally consist of modules mounted on a chassis or mainframe and are known as mainframe computers. They vary in size, from those slightly larger than a minicomputer to supercomputers (like the Cray and Control Data Cyber computers). 

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Mainframe computer systems offer substantial advantages over mini-computers or microcomputers. Some of these are; greater processing speed, greater storage capacity, a larger variety of input/output devices, support for a number of high-speed secondary storage devices, multiprogramming, and time sharing. Owing to tremendous expense in operating a mainframe computer, this computer system must be operated efficiently. Operating a mainframe at the required level of efficiency requires a very large and highly trained staff. Mainframe Computer systems are generally used by large businesses, universities, governmental agencies, and the military. These systems are often coupled with other computer systems in a large network to provide enormous computing power. This is what is referred to as a distributed data processing system. 

Supercomputers The large and powerful mainframe computer is called a supercomputer. The astronomical cost of the super-computers has limited their development to only a few hundred worldwide. The Cray X-MP, Cray XTS-HE is an example of a supercomputer. Such supercomputers are applied to the solution of very complex and sophisticated scientific problems and for national security purposes of some advanced nations. Smaller, less costly minisupercomputers have been developed by several manufacturers. These computers provide approximately half the power of the supercomputer but at a fraction of the cost. The relative low cost has made the minisupercomputer an attractive to buy for mid-sized to large applications. Many Wall Street brokerage firms in the United States use computers to speed up the processing of large financial models to keep track of securities that have tendencies to fluctuate greatly.

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English For Today pdf

Lesson 2 : Types of Computers 

2.1 Learning Objectives
On completion of this lesson you will be able to
• classify computers based on purposes
• classify computers based on types
• classify computers based on capacity.

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2.2 Outline 

The computer systems are available in various sizes and with a variety of peripheral or support devices to cover just about every processing need. Because of the variety of computer power and functions available, computers are classified on the basis of purpose, type, and capacity. 

2.3 Purpose 

There are either special-purpose or general-purpose computers. Specialpurpose computers are designed for a specific application or type of application. They are also known as dedicated computers. Many such computers have instructions permanently programmed into them that are designed to perform only one major function. Special-purpose computers are used, to control traffic lights, to control the collection of tolls on certain highways, and in automobiles, weapons, appliances and games etc. 

General-purpose computers are used to handle a variety of tasks. This is possible by the stored-program concept. By this concept, a program containing a series of instructions is prepared for each application and input to and temporarily stored in the computer. Once stored in the computer's memory, this program can be executed, causing the computer to perform the specific function. After the completion of the execution of this program, another program can be input to the computer and the cycle repeated. That is, the same combination of hardware can be used to execute many different programs. 

General-purpose computers have the advantage of versatility over special-purpose computers. But typically general purpose computers are less efficient and slower than special-purpose computers when applied to the same task.

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Humanware 

Humanware refers to the persons who design, program, and operate a computer installation. There are numerous categories of jobs, but the three principal positions required in a large computer installation are system analyst, programmer, and computer operator. 

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People in each of these areas generally perform special-purpose tasks under the supervision of a director or manager. The position of a systems analyst requires the broad background and extensive understanding of the above three job categories. The main task of the system analyst is to study information and processing requirements. A systems analyst defines the applications problem, determines systems specifications, recommends hardware and software changes, and designs information processing procedures. A programmer requires a comprehensive knowledge of one or more programming languages and standard coding procedures. This position does not require the broader understanding of the structure and inner workings of an application. A programmer's principal job is to code or prepare programs based on the specifications made by the systems analyst.

A computer operator requires the least extensive background of the three categories. A computer operator generally performs a series of well defined tasks that will keep the computer operating at maximum efficiency. The operational efficiency of a computer installation is dependent on the quality and abilities of the operational staff.

Procedures

Operations of a data processing center require an extensive and clearly defined set of procedures for performing the essential functions of the installation. These functions generally include obtaining, preparing, and entering data into the computer, processing jobs, initiating new programs and changing or deleting old ones etc. Such procedures must have provision for actions to be taken in the event of hardware or software malfunctions.

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Chemistry Second Paper book. pdf

1.3 Components of a Computer System 

A computer is used to process data and a data processing system must consist of more than just machines. A computer system must contain: hardware, software, humanware and operational procedures. 

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Hardware 
Hardware generally refers to the machine or physical equipment t hat performs the basic functions of the data processing cycle. In addition to the computer itself, other hardware devices are also required. These devices may be off-line that is detached from the computer and operating independently or they may be on-line that is directly connected to and controlled by the computer. A printer is an off-line device and a keyboard is an on-line device.

Software 

A program is a sequence of instructions which directs a computer to perform certain functions. A computer must have access to prewritten, stored programs to input and store data, make decisions, arithmetically manipulate and output data in the correct sequence. Programs are referred to as software. Computer system must be supported by extensive software systems. Software is generally categorized as either system software or application software. System software consists of programs that facilitate the use of computer by a user. These programs are sometimes referred to as utility programs. They perform such standard tasks as organizing and maintaining data files, translating programs written in various languages to a language acceptable to the computer, scheduling jobs through the computer, as well as aiding in other areas of general operations. Of all the systems software supplied by the manufacturer of a computer, the most important one is known as the operating system. Application software consists of programs to perform specific user applications. A computer program giving instructions for the steps involved in preparing results of a public examination is an example of applications software. Application programs are either purchased or written by the computer users for specific applications.

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Civics and Citizenship Second Paper.

১ম অধ্যায়	বৃটিশ ভারতে  প্রতিনিধিত্বশীল সরকারের বিকাশ
২য় অধ্যায়	পাকিস্থান থেকে বাংলাদেশ (১৯৪৭-১৯৭১)
৩য় অধ্যায়	রাজনৈতিক ব্যক্তিত্ব: বাংলাদেশের স্বাধীনতা লাভ
৪র্থ অধ্যায়	বাংলাদেশের সংবিধান
৫ম অধ্যায়	বাংলাদেশের সরকার ও প্রশাসনিক কাঠামো
৬ষ্ঠ অধ্যায়	স্থানীয় শাসন
৭ম অধ্যায়	সাংবিধানিক প্রতিষ্ঠান
৮ম অধ্যায়	বাংলাদেশের নির্বাচন ব্যবস্থা
৯ম অধ্যায়	বাংলাদেশের বৈদেশিক নীতি
১০ম অধ্যায়	নাগরিক সমস্যা ও আমাদের করণীয়
	সকল অধ্যায়ের গুরুত্বপুর্ণ তত্ত্বসমুহ

They kept the old 62-line slot connectors and added another 36-wire connector, placing it in line with the older 62-line connector to provide some of these features:
 Eight more data lines, bringing the data bus to 16 bits in width.
 Four more address lines, bringing the address bus to 24 bits in width.
 Four more DMA channels, 4 through 7.
 Five more IRQ levels: IRQ 10, 11, 12, 14, and 15.

These two-slot connectors are called 16-bit slots. You can see these rivo kinds of connectors in Figure 6.1.

For a while, this 16-hit bus was called the AT bus. Since 1988, however, most people have referred to these types of bus slots as Industry Standard Architecture, or ISA, slots. You can tell the difference between an 8-bit and a 16-bit ISA board by looking at the edge connector on the bottom of it (Fig. 6.1).

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Civics and Citizenship First Paper.

১ম অধ্যায়	পৌরনীতি ও সুশাসন পরিচিতি
২য় অধ্যায়	সুশাসন
৩য় অধ্যায়	মুল্যবোধ, আইন, স্বাধীনতা ও সাম্য
৪র্থ অধ্যায়	ই গর্ভনেন্স ও সুশাসন
৫ম অধ্যায়	নাগরিক অধিকার, কর্তব্য ও মানবাধিকার
৬ষ্ঠ অধ্যায়	রাজনৈতিক দল ও সুশাসন
৭ম অধ্যায়	সরকার কাঠামো ও সরকারের অঙ্গসমুহ
৮ম অধ্যায়	জনমত ও রাজনৈতিক সংস্কৃতি
৯ম অধ্যায়	জনসেবা ও আমলাতন্ত্র
১০ম অধ্যায়	দেশপ্রেম ও জাতীয়তা
	সকল অধ্যায়ের গুরুত্বপুর্ণ তত্ত্বসমুহ

6.5. PCI: Intel’s High Performance Local Bus
To support the faster processors like 80486 or Pentium Intel designed a newer faster bus slot called PCI, short for Peripheral Component Interconnect. Some features of this bus is given below.

6.5.1. Processor Independence

The PCI bus doesn't directly interface to the CPU. Rather, it communicates with the CPU via a "bridge circuit" that can act as a buffer between a particular CPU and the bus.

It means really good news for non-PC computer users. Macintosh PCs and RISC-based machines like the DEC Alpha are now out with PCI slots. That means a bigger market for PCI boards and an avenue for board makers to reach the PC, Mac, and RISC markets with a single board.

6.5.2. Wider Data Path

PCI distinguishes itself first because it is a 64-bit bus. PCI supports a data path appropriate for the newer Pentium-based computers, which require 64 bits at each clock cycle. PCI also supports a 32-bit data path, however, making it appropriate for use in high-performance 486 systems.

6.5.3. High Speed
The PCI bus runs in 33 to 100 MHz which much higher than the older 5 to 20 MHz buses.

6.5.4. Backward Compatibility
Although ISA boards cannot fit in PCI slots, the chipset that supports PCI also supports ISA. That means that it's easy to build a PC with PCI, and ISA slots all on the same motherboard.

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Islamic History and Culture Second Paper.

১ম অধ্যায়	ভারতে মুসলিম শাসন প্রতিষ্ঠা
২য় অধ্যায়	দিল্লী সালতানাত যুগ
৩য় অধ্যায়	ভারত উপমহাদেশে মুঘল শাসন
৪র্থ অধ্যায়	বাংলার কোম্পানি ঔপনিবেশিক শাসন
৫ম অধ্যায়	বাংলার ইতিহাস (পাকিস্থানি আমল)
৬ষ্ঠ অধ্যায়	স্বাধনি ও সাবভৌম বাংলাদেশের অভ্যুদ্য়
৭ম অধ্যায়	সকল অধ্যায়ের গুরুত্বপুর্ণ তত্ত্বাবলী

6.5.5. Software Setup

PCI supports the Plug-and-Play standard developed in 1992 by hardware vendors. There will be, in general, no jumpers or DIP switches on PCI boards. To set up a PCI board, you just run the PCI Configuration Program. Reconfiguring a system can be done without popping the top on the computer, a great convenience to users and support people.

6.6. PC Card (PCMCIA): The Portable Bus

This bus standard is used for laptop computers. As the laptop computers take very little volume so it is difficult to use the large expansion cards in laptop computers. This is why PC card or PCMCIA standard was designed.

Let's compare PC Card to the other buses that we've discussed:

 Memory address space: PC Card supports a 64MB addressing ability. This will be adequate for current machines, but will look sparse in a few years, as more demanding operating systems like OS/2 and NT become more popular.

 Bus Mastering: PC Card does not support bus mastering or DMA.

 Plug-and-play setup: PC Card allows and also requires that hardware setups be done with software. Because of the physical size of a PC Card, you'll never see jumpers or DIP switches.

 Number of PCMCIA slots possible in a single system: Most of the other buses support no more than 16 slots. The PC Card standard can, theoretically, support 4080 PC Card slots on a PC.

 Data path: The data path for PC Card is only 16 bits, a real shame but one that will probably be fixed in the next version of the standard.

 Speed: Like other modern bus standards, PC Card is not limited to 33 MHz clock rate. It may go up to 150 MHz.

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Islamic History and Culture First Paper MCQ with Answer

১ম অধ্যায়	পাক-ইসলামি আরব
২য় অধ্যায়	হযরত মুহাম্মদ (স:)
৩য় অধ্যায়	খোলাফায়ে রাশেদীন
৪র্থ অধ্যায়	উমাইয়া খিলাফত
৫ম অধ্যায়	আব্বাসি খিলাফত
৬ষ্ঠ অধ্যায়	স্পেনে উমাইয়া শাসন
৭ম অধ্যায়	উত্তর আফ্রিকায় ফাতেমি খিলাফত
	সকল অধ্যায়ের গুরুত্বপুর্ণ তত্ত্বাবলী

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