Lesson 3: History and Generations

3.1 Learning Objectives

On completion of this lesson you will know:

·         History of computers

·         Generations of computers

3.2 Beginning

Different devices and tools have been used in calculation and processing of data. Anancient calculating device is the abacus, a mechanical calculating device first usedaround 2500 BC to add and subtract. Scientists and mathematicians later sought othermeans for calculations. John Napier, a Scottish mathematician, developed (about 1610) aseries of rods made of bones (commonly called Napier's bones) that could be arranged togenerate the products of selected numbers. He used these rods to produce the first tableof logarithms. In 1865 French mathematician Blasé Pascal improved on this concept andproduced a mechanical calculator called Pascaline. It was more compact and easier touse than Napier's bones. The Pascaline was capable of performing addition andsubtraction. All attempts to produce a calculator capable of performing all the fourarithmetic operations and producing mathematical tables quickly and accurately were notsuccessful until 1820. Thomas de Colmar of France produced the arithmometer, the firstfour-function practical mechanical calculator in 1920.

A young English mathematician named Charles Babbage of Cambridge Universitycontributed substantially towards the development of computers. Babbage gave muchthought to the design of a device to produce mathematical and navigational tables andcame upon a principle that used the differences between previous values in a table toproduce new values. Babbage was able to construct a working model to illustrate theprinciple of the difference engine. Babbage thought of a steam-driven version of thedifference engine capable of calculating and printing results at a rate of two twenty-digitnumbers per minute.

Babbage built part of the difference engine but abandoned it in favor of a more powerfuland versatile machine, the analytical engine. The analytical engine was designed to usepunched cards to provide a constant flow of information through the machine's elaborateseries of columns, gears, wheels, and levers. The analytical engine included all thefunctional units of a modern computer: input of data, arithmeticunit for computation

memory for data and instructions, and display for output. This was an ambitiousprojectduring a time when electronics, transistors, and chips did not exist. The engine was apuzzle to all but a few mathematicians. This machine, however, was never built. Nearly a century Tater a new generation of scientists and engineers equipped with newdevelopments brought Babbage's vision back into focus.

Insignificant progress took place over the next decades. In the United States the 1890census was approaching, and there was no way that it could be completed by 1900, asrequired by the constitution. Herman Hollerith, an employee of the Census Office inWashington, started to develop an automated device to complete this task in ten years.The result was Hollerith's tabulator. A manual card puncher, a card reader, and anelectromechanical card sorter were the main components of this machine.accurate.

With this tabulator, Hollerith was able to complete the census calculations in onlytwoyears. Hollerith's success paved the way for further research and development. Analogcomputers, a new class of computing devices, emerged. These devices used electricalvoltages to represent physical quantities. They functioned by establishing an analogybetween a physical quantity and a voltage level. They were very fast but not sufficiently accurate.

The first electronic computers, the ABC (Atanasoff Berry Computer) and the ENIAC(Electronic Numerical Integrator and Calculator) were built in USA in the early 1940s.The ABC, built by Atanasoff and Berry, was the first electronic computer using vacuumtubes. The ENIAC, built by Eckert and Mauchly, was a special-purpose computer. In1949, at Cambridge, the EDSAC (Electronic Delay Storage Automatic Computer), thefirst general-purpose electronic computer operating under the control of a storedprogram, was completed. A stored program is a set of instructions stored in memory thatguides the computer, step by step, through a process.

John Von Neumann, originator of the stored-program concept, developed the IAS(Institute for Advanced Study) computer at Princeton University. This machine was therealization of John Von Neumann ideas on computer design. Most computers built afterthe IAS computer have "Von Neumann" characteristics.

Agroupofscientists at MIT in USA headed by Ken Olsen developed the Whirlwindcomputer, which was more than twenty times faster than the ENIAC. Both the IAS andWhirlwindcomputers introduced computational innovations of astronomical proportions.Computers were not available commercially until early 1951. In 1951, the Sperry RandCorporation of USAbuilt the UNIVAC Universal Automatic Computer). The

UNIVAC I built for the Bureau of Census of the United States was the firstcommercially available computer. The first computer installation to handle businessapplications was set up in 1954 at Louisville, Kentucky, USA. The UNIVAC I is nowon display in the Smithsonian Institution in Washington D.C. in USA.

Day by day computers were becoming smaller, faster, and more powerful. In 1956, MITin the USA introduced its compact TX-0 transistorized computer system. A few yearslater, in 1960, the first integrated circuit was produced by Jack Kilby of TexasInstruments in USA and the DEC PDP-1 minicomputer was developed. In the Mid1960s, minicomputers began appearing as a forerunner of mainframes and supercomputers.The invention of microprocessor in 1971 began a new era and microcomputers based onmicroprocessors began to appear from the Mid-1970's. Microcomputers provide thedriving force of the present information age.

3.3 Computer Generations

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

First Generation (1942-1959)

First-generation computers utilized vacuum tubes in their circuitry and for storage ofdata and instructions. The vacuum tube was bulky, caused tremendous heat problems,and was never a reliable device, it caused a great number of breakdowns and inefficientoperations. Magneticcores began to replace vacuum tubes as the principal memorydevice in the early machines. Small doughnut-shaped cores were strung on wires withinthe computer. Programs were written in machine language employing combinations of 0and 1. Examples of first generation computers are IBM 650, IBM 704, IBM 705, IBM709, Mark II, Mark III etc.

Second Generation (1960-1965)

The second generation computers saw the replacement of the vacuum tubes bytransistors. A transistor can be thought of as a switch, but with no moving parts. Becauseof high speedoperation and small size, computers of this generation could perform asingle operation in microseconds and were capable of storing tens of thousands ofcharacters. Manufacturers began producing business-oriented computers with moreefficient storage and faster input and output capabilities. Second generation computers

were reliable, compact in size, and virtually free of heat problems. Programming wasdone in both machine and symbolic languages. Symbolic languages utilize symbolicnames for computer commands and allow the use of symbolic names for items of data.This language is also known as assembly language. Examples of second generationcomputers are: IBM 1400, CDC 1604, RCA 501, NCR 300, GE 200, IBM 1600 etc.

Third Generation (1965-1971)

These computers were characterized by integrated circuits with components so small thatin many cases they were hardly visible to the naked eye. Third generation computerswere characterized by increased input/output, storage, and processing capabilities,Input/output devices could communicate with computers over distances via ordinarytelephone lines or could scan a page and input the information directly into the computer,could display pictures on a television-like screen, could make musical sounds, and couldeven accept voice input.

Storage capabilities were increased and millions of characters could be stored andrandomly accessed in fra ions of a second. Third-generation computers could processinstructions in nanoseconds. In addition, computers were able to process severalprograms or sets of instructions simultaneously. Programmers were able to make use ofhigh-level problem oriented and procedure oriented languages that closely resembles thecommonly used form of expressions. Examples of third generation computers are IBM360, IBM 370, PDP-8, PDP-11, GE 600 etc.

Fourth Generation (1972 - Present)

The fourth generation computers possess still greater input/output, storage, andprocessing capabilities. In the fourthgeneration computers, semiconductor storagedevices were introduced. In the early 1970s IBM introduced the concept of virtualstorage into their 5000 and 370 series of computers. Machines previously limited to amaximum internal storage capability of approximately one million characters nowpossessed a virtual storage capability in billions and trillions of characters. With thiscapability a machine could execute a program many times the size of the machine'sactual memory. Microcomputers using microprocessors as the CPU proliferated in thefourth generation.

Now a days, the compact disk (CD) promises to become the data storage medium ofchoice. 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 diameter) aluminum surface as tiny pits at varyingdepths. 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. 101 101 2000The most impressive advancement has occurred in software. As a result of these changes,access to substantial computer power, previously only affordable by very large businessconcerns, is now economically feasible for small business and personal applications.Personal computers are examples of fourth generation microcomputers.

Fifth Generation

Fifth generation of computers is yet to come. They will be capable of reasoning,learning, making inferences and behaving in ways usually considered exclusive ofhumans. These computers will be equipped with massive primary-storage capabilitiesand extremely fast processing speeds. Software will proliferate and get much bigger.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 machineto understand and obey spoken words will be developed. Industrial and personal robotswill roll and walk. Expert systems software will place the knowledge of experts andconsultants (such as doctors, lawyers and teachers) at the disposal of general users. Hugenumber of computers will be linked in parallel offering computing power of aninconceivable magnitude. Artificial intelligence will be used extensively to enhance thesystem behavior in the future.

3.4 Exercise

Multiple choice questions

1. Who developed the stored program concept?

a. Blaise Pascal.b. John Von Neumann.

c. Herman Hollerith.d. Charles Babbage.

2. Influence of artificial intelligence is considered in:

a. First generationb. Third generation

c. Fourth generationd. Fifth generation

3. Who developed the concept of the difference engine?

a. Blaise Pascal.b. John Von Neumann.

c. Herman Hollerith.d. Charles Babbage.

Questions for short answers

4. Who was Charles Babbage? Mention his contributions in the history of computers?

5. What is meant by computer generations?

6. What is the name of first commercial computer?

7. Who was John Von Neuman? What is his contribution in the history of computer?

Analytical questions

8. Write an essay on the history of computers.

9. Briefly describe the computer generations.

10. Describe the trend and features of fifth generation computers.

Lesson 2: Types of Computers

2.1 Learning Objectives

On completion of this lesson you will know classification of computers:

·         On the basis of purposes

·         On the basis of signals

·         On the basis of Capacity.

2.2 Classification based on purposes

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

General-purpose computers are used to handle a variety of tasks. This is possible by thestored-program concept. By this concept, a program containing a series of instructionsprepared for an application and temporarily stored in memory. Once stored in thecomputer's memory, the program can be executed to perform the specific function. Afterthe completion of the execution of one program, another program can be used for someother task. That is, the same hardware can be used to execute many different programs.

General-purpose computers are more versatile than special-purpose computers. Buttypically general-purpose computers are less efficient and slower than special-purposecomputers when applied to the same task. roll 100 mm

2.3 Classification based on signals

Two types of computers based on internal signaling are analog computers and digitalcomputers, an analog computer represents quantities by physical analogies. It representsphysical quantities, such as distance, velocity, acceleration, temperature, pressure, orangular position, force etc. by mechanical or electrical parameters.

An automobile speedometer is an example of an analog-computing device. It converts therotational rate of the drive shaft of an automobile into the numerical value of the speed ofthe vehicle. Similarly, a thermometer functions as an analog device by converting themovement of a column of mercury into a temperature reading.

Analog computers are ideal in situations where data can be accepted directly frommeasuring instruments The ability to collect data at high speeds and to process data atequally highspeeds, makes analog computers uniquely suited to controlling processes ofoil refineries, steel mills, weapon systems and similar other operations. An analogcomputer does not require any storage capability. The out from an analog computer isgenerally in the form of readings on a dial (as in the speedometer of a car) or a graphplotted on paper.

Analog computers were in use before the invention of the digital computers. There arefar more digital computers in use today than analog computers. This book concentrateson digital computers.

2.4 Classification based on capacity

Capacity of a computer refers to the volume of data that a computer system can process.Previously a computer's size was an indication of its capacity. With the current state ofminiaturization, measurement of capacity is based on throughput of the computer.Throughput is the amount of processing that can be performed in a given amount of time.Based on throughput computer systems can be divided into four major categories:

·         Microcomputers

·         Minicomputers

·         Mainframe computers and

·         Supercomputers.

Microcomputers

Microcomputers (also known as personal computers - PCs) are microprocessor basedsmall laptop or desktop or notebook systems with varying capability. Personaldigitalassistants (PDAs) are very small portable computers.PDAs are also known as palmtopcomputers. The brain of a microcomputer is the microprocessor, it is a silicon chipcontaining necessary circuits to perform arithmetic/logic operations and to controlInput/output operations. A microprocessor is an integrated circuit (IC) whichgenerallycontain millions of transistors squeezed onto a tiny chip of silicon. A microcomputersystem is formed by adding input/output capability and memory to the microprocessor.

Early microcomputers had limited processing power and limited choice of input/outputdevices. Present day microcomputers have wider processing capabilities and they supporta wide range of input/output devices. Today microcomputers are available with aselection of input/output devices varying from a cassette recorder to a voice synthesizer.In addition to general-purpose computations, microcomputers are also used for specialpurpose applications in automobiles, airplanes, toys, clocks, appliances etc.

Workstations: High-end microcomputers are known as workstations. The workstationrepresents the bridge between the microcomputers and minicomputers. It is amicrocomputer with many of the capabilities of larger minicomputers but costing muchless. Initially it was designed for use by engineers and designers who need exceptionallypowerful processing and output capabilities.

Servers: Servers are not designed to be used directly. They make programs and dataavailable for users having access to a computer network. A computer network is acollection of computers connected together.

Clients: To use servers, users run desktop programs called clients, which know how tocontact the server and obtain information from the server. Use of desktop clients andcentralized servers is called client/server computing.

Terminals: Although terminals look like the personal computers, they have somelimitations when compared with personal computers. Terminals have only a screen and akeyboard and the electronics that allow them to communicate with the computer towhich they are connected. Because they lack the ability to process data on their own,they are called dumb terminals. There is a variety of dumb terminals that can performlimited processing. These are called smart (or intelligent) terminals. A personal computeris an example of a smart terminal.

Minicomputers

A minicomputer system performs the basic arithmetic and logic functions and supportssome of the programming languages used with large computer systems. They arephysically smaller, less expensive, and have small storage capacity compared tomainframes. Minicomputers are ideally suited for processing tasks that do not requireaccess to huge volumes of stored data. As a result of low cost, ease of operation, andversatility, minicomputers have gained rapid acceptance since their introduction in themid-sixties. Some of the larger and expensive minicomputers are capable of supporting anumber of terminals in a time-shared mode. Use of minicomputers are gradually beingdiminished with the rapid development of microcomputers.

Mainframe Computers

A larger computer generally consists of modules mounted on a chassis (or mainframe)and is known as a mainframe computer. They vary in size, from those slightly larger thana minicomputer to supercomputers. Mainframe computer systems offer substantialadvantages over minicomputers or microcomputers. Some of these are: greaterprocessing speed, greater storage capacity, a larger variety of input/output devices,support for a number of high-speed storage devices, multiprogramming, and timesharing.

Owing to tremendous expense, a mainframe computer system must be operatedefficiently. Operating a mainframe at the required level of efficiency requires a verylarge and highly trained staff. Mainframe Computers are generally used by largebusinesses, universities, governmental agencies, and the military. These systems areoften coupled with other computer systems in a large network to provide enormouscomputing power. This is referred to as a distributed data processing system.

Supercomputers

A very large and very powerful mainframe computer is called a supercomputer. Theastronomical cost of super-computers has limited their development to only a fewhundred worldwide. The Cray X-MP is an example of a supercomputer. Suchsupercomputers are applied to the solution of very complex and sophisticated scientificproblems and for national security purposes of some advanced nations.

2.5 Exercise

Multiple choice questions

1. A PC is a:

a. General purpose computer b. Microprocessor Good

c. Special purpose computer c. None of the above

2. Based on capacity, types of computer systems are:

a.      Microcomputers, minicomputers, mainframe computers andsupercomputers.

b.      Microcomputers, personal computers and IBM computers.

c.       Minicomputers, supercomputers and digital computers.com

d.      Analog computers and digital computers.

Questions for short answers

3. Distinguish between an analog computer and a digital computer.

4. Classify computer systems on the basis of capacity.

5. What is a PC? Differentiate between a client and a server?

Analytical questions

6. Briefly describe the classification of computer systems based on purposes andinternalsignaling.

7. What are the classes of computers based on capacity? Describe with examples of each class.

Questions for short answers

3. What is a computer?

4. Name the elements of a computer system.

5. What is the difference between system software and application software?

6. What is meant by operational procedures?

7. What are the limitations of a computer

Analytical questions

8. What is data processing cycle? Discuss the elements of the cycle.

9. Describe the components of a computer system.

10. Write the importance and limitations of computer

11. Name and briefly explain important criteria, which may be used to justify the use ofcomputers.

CONTENTS

1: Introduction to Computers                                                                                                                 

Lesson 1 : Basic Organization                                                                                                                 

Lesson 2 : Types of Computers                                                                                                                

Lesson 3: History and Generations                                                                                                          

2: Number Systems and Codes                                                                                                              

Lesson 1 : Number Systems 

Lesson 2: Conversion of Numbers                                                                                                        

Lesson 3: Binary Arithmetic  

Lesson 4 : Data Representation and Codes   

3: Digital Circuits 

Lesson 1 : Logic Functions and Logic gates                                                                                            

Lesson 2: Boolean Algebra and Logic Simplification                                                                            

Lesson 3: Karnaugh Map and Logic Simplification                                                                               

Lesson 4: Latches and Flip-flops                                                                                                              

Lesson 5: Shift Registers and Counters                                                                                                   

4: Microcomputer System                       

Lesson 1 : Microcomputer Basics           

Lesson 2 : Organization of a Microcomputer 

Lesson 3 : Bus Organized Architecture  

Lesson 4: Working Principal of a Microcomputer 

Lesson 5: Motherboard and Adapter                                                                                       

5: Input and Output Devices  

Lesson 1 : Input/Output Operations and 

Lesson 2: Input Devices  

Lesson 3: Output Devices 

Lesson 4: Other Peripheral Devices  

6: Microprocessors 

Lesson 1: Introduction to Microprocessors 

Lesson 2: ALU and Control 

Lesson 3 : Microprocessors: Past, Present and Future 

Lesson 4: Parallel Processing 

7: Memory Organization                          

Lesson 1 : Memory Basics 

Lesson 2: Main Memory 

Lesson 3 : Secondary Memory 

8: Computer Software 

Lesson 1: Introduction and Classification 

Lesson 2: Application Package Programs 

Lesson 3 : Programming Languages 

9: System Software and Operating Systems 

Lesson 1: System Software 

Lesson 2: Introduction to Operating Systems 

Lesson 3: Processing and Services 

Lesson 4: Popular Operating Systems 

10: Database Concepts 

Lesson 1: Introduction to Databases            

Lesson 2: Database Software  

Lesson 3: Database Structures 

Lesson 4 : Database Access and Development 

11 : Software Development 

Lesson 1: Introduction to Software Development  

Lesson 2: System Analysis 

Lesson 3: System Design 

Lesson 4 : System Development                  

Lesson 5: System Implementation 

12: Computer Networks and the Internet 

Lesson 1: Introduction to Computer Networks 

Lesson 2 : Local Area Networks 

Lesson 3: Wide Area Networks 

Lesson 4 : Introduction to the Internet  

Lesson 5: Internet Services and Protocols how 

Lesson 6: Intranet and Extranet                                                                                                         

13: Information Technology 

Lesson 1: IT Concepts and Applications and  

Lesson 2: Multimedia Basics 

Lesson 3 : Multimedia System Development 

Lesson 4: Electronic Commerce                                                                                                         

14: Computers and Society 

Lesson 1 : Impact of Computers on Society                                           

Lesson 2: Access, Security and Privacy  

Lesson 3 : General Maintenance  

Lesson 4 : Selection of Microcomputers 

END