1st Year Computer Notes CH# 03 Classification of Computers

Classification of Computers

Types of Computers
1. Analog Computers

Analog computers are used to process continuous data. Analog computers represent variables by physical quantities. Thus any computer which solve problem by translating physical conditions such as flow, temperature, pressure, angular position or voltage into related mechanical or electrical related circuits as an analog for the physical phenomenon being investigated in general it is a computer which uses an analog quantity and produces analog values as output. Thus an analog computer measures continuously. Analog computers are very much speedy. They produce their results very fast. But their results are approximately correct. All the analog computers are special purpose computers.
2. Digital Computers

Digital computer represents physical quantities with the help of digits or numbers. These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user.
3. Hybrid Computers

Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system. Hybrid computers are being used extensively in process control system where it is necessary to have a close representation with the physical world.

The hybrid system provides the good precision that can be attained with analog computers and the greater control that is possible with digital computers, plus the ability to accept the input data in either form.

Classification of Computers According to Size
1. Super Computers

Large scientific and research laboratories as well as the government organizations have extra ordinary demand for processing data which required tremendous processing speed, memory and other services which may not be provided with any other category to meet their needs. Therefore very large computers used are called Super Computers. These computers are extremely expensive and the speed is measured in billions of instructions per seconds.
2. Main Frame Computers

The most expensive, largest and the most quickest or speedy computer are called mainframe computers. These computers are used in large companies, factories, organizations etc. the mainframe computers are the most expensive computers, they cost more than 20 million rupees. In this computers 150 users are able to work on one C.P.U. The mainframes are able to process 1 to 8 bits at a time. They have several hundreds of megabytes of primary storage and operate at a speed measured in nano second.
3. Mini Computers

Mini computers are smaller than mainframes, both in size and other facilities such as speed, storage capacity and other services. They are versatile that they can be fitted where ever they are needed. Their speeds are rated between one and fifty million instructions per second (MIPS). They have primary storage in hundred to three hundred megabytes range with direct access storage device.
4. Micro Computers

These are the smallest range of computers. They were introduced in the early 70’s having less storing space and processing speed. Micro computers of todays are equivalent to the mini computers of yesterday in terms of performing and processing. They are also called “computer of a chip” because its entire circuitry is contained in one tiny chip. The micro computers have a wide range of applications including uses as portable computer that can be plugged into any wall.
5. Laptop Computers

The smallest computer in size has been developed. This type of small computers look like an office brief case and called "LAPTOP" computer. The laptops are also termed as "PORTABLE COMPUTERS." Due to the small size and light weight, they become popular among the computer users. The businessmen found laptop very useful, during traveling and when they are far away frm their desktop computers. A typical laptop computer has all the facilities available in microcomputer. The smallest laptops are called "PALMTOP".

1st Year Computer Notes CH# 02 History of Computers

History of Computers

At the early age people used pebbles, stones, sticks, scratches, symbols and finger tips to count, which were later replaced by numbers.

The history of computing is divided into three ages during which man invented and improved different types of calculating machines. These ages are,

* Dark age - 300 BC to 1890

* Middle age - 1890 AD to 1944

* Modern age - since 1944 AD


Dark Age (3000 BC to 1890 AD

ABACUS

About 3000 years BC, Chinese developed the first calculating machine named Abacus or Soroban.

Abacus consists of a rectangular wooden frame having rods which carry round beads. Counting is done by shifting the beads from one side to another.


OUGHTRED’S SLIDE RULES

In 1632 AD William Oughtred, an English mathematician developed a slide rule. This device consists of two movable rules placed side by side on which number were marked.


PASCAL’S CALCULATOR

Blasé Pascal (1623-1662), a French developed the first mechanical calculating machine in 1642. This machine consists of gears, wheels and dials. It was capable of adding and subtracting operations.


GOTTEFRIED WILHOLM LEIBNITZ

In 1671, a German, Gottfried Von Leibnitz (1646-1716) improved Pascal’s calculator to make it capable of performing all maths operations.


JACQUARD’S LOOM

In 1801, a French, Joseph Marie Jacquard developed the first punch card machine.


BABBAGE DIFFERENCE ENGINE

Charles Babbage (1792-1871) an English mathematician also called Father of modern computer. As he gave the true concept of computer at Cambridge University, he developed Babbage Difference Engine in 1823 and Babbage Analytical Engine in 1833.

Lady Ada Augusta an assistant of Babbage is called the first programmer.

Middle Age (1890 AD TO 1944 AD)

DOCTOR HERMAN HOLLERITH

In 1880s Herman Hollerith an American developed a machine which used punch card system. The machine could sense and punch holes, recognize the number and make required calculations. This machine was first used in 1890s by American Census Bureau.


HOWARD AIKEN- MARK-1 COMPUTER

In 1937, Professor Howard Aiken build the first electro-mechanical computer Mark-1, by trying to combine Babbage’s theory and Hollerith’s punching technologies. He completed his project in 1944 with the help of IBM Engineers.

Mark 1 could multiply two, twenty digit numbers in 5 seconds and made a lot of noise. It had a shape like a monster about 50 feet long, 8 feet high, having wiring of length equal to distance from Lahore to Gilgit or Karachi to Bahawalpur (800km) and had thousand ends of electro-magnetic relays.


ABC (ATANASOFF BERRY COMPUTER)

ABC a special purpose computer was developed in 1938 by Dr. John Vincent Atanasoff and Clifford Berry at Iowa State College, USA.


Modern Ages (Since 1944 AD)

JOHN VON NEUMAN

In 1945, Dr. John Von Neuman suggested the concept of Automatic Data Processing (ADP) according to the stored program and data. ENIAC


(FIRST ELECTRONIC COMPUTER)

Electronic Numerical Integrator And Calculator (ENIAC) was the first electronic computer made in 1946 by John Presper Eckert and John Williams Mauchly, at the University of Pennsylvania, USA. This was based on decimal number system and it has no memory.

It could perform 5000 additions or 350 multiplications in one second. It contained 18000 vacuum tubes, 70,000 resistors, 10,000 capacitors and 60,000 switches and occupied a two room car garage. It consumed 150 kW of power. It weighed 27 tons.


EDSAC (FIRST STORED PROGRAM COMPUTER)


Electronic Delay Storage Automatic Computer (EDSAC) was first computer based on stored program concept. It was completed by Mourice Wilkes at Cambridge University in 1949.


EDVAC

Electronic Discrete Variable Automatic Computer (EDVAC) was built by John Williams Mauchly, John Presper Eckert at Moore School, Pennsylvania in 1951.


UNIVAC (FIRST COMMERCIAL COMPUTER)

UNIVersal Automatic Computer (UNIVAC) was the first commercially used computer made by John Presper Eckert and John Williams Mauchly in June 14, 1951.


Generations of Computer
First Generation of Computer (1946-1959)

Main Features

* Major Innovation - Vacuum Tubes

* Main Memory - Punched Cards

* Input Output Devices - Punched cards and papers

* Languages - Low level machine language

* Operating System - No operating system, human operators to set

switches

* Size - Main frame for example ENIAC, EDVAC, UNIVAC

The duration lasted from 1946-1959 was based on vacuum tubes. These vacuum tubes were about the size of 100 watt light bulb and used as the internal computer component. However because thousands of such bulbs were used, the computers were very large and generate a large amount of heat, causing many problems in temperature regulation and climate control.

In this generation input and out put device (punched card) that was used fro data storing purpose were very slow. The computers were operating manually and the language used was a low level machine language (symbolic language) with binary code that required a high programming skill. ENIAC, EDVAC, UNIVAC and Mark-1 were some of the major inventions of this generation.

Advantages of First Generation

1. Vacuum tubes were used as electronic component.

2. Electronic digital computers were developed for the first time.

3. These computers were the fastest calculating devices of their time.

4. Computations were performed in millisecond.


Disadvantages of First Generation

1. Too large in size.

2. They were unreliable.

3. Induce a large amount of heat due to the vacuum tubes.

5. Not portable.

6. Limited commercial use.


Second Generation of Computers (1959-1964)

Main Features

* Major Innovation - Transistors as main component.

* Main Memory - RAM and ROM.

* External Storage - Magnetic tapes and Magnetic Disk.

* Input Output Devices - Magnetic tapes and Magnetic Disk.

* Languages - Assembly language, some high level languages for Example BASIC, COBOL, FORTRAN.

* Operating System - Human handles punched card.

* Size - Main frame for example IBM-1401, NCR-300, IBM-600 etc.

The period of this generation is from 1959 to 1964. During this period transistor were used for internal logic circuits of computers. These computers could execute 200000 instructions per second. The input/output devices became much faster by the use of magnetic table. During this period the low level programing language were used however the high level programming languages such as FORTRAN and COBOL were also used. The problem of heat maintenance was solved and size of computer reduced, while speed and reliability were increased. Many companies manufactured second generation computers and many of those for business applications. The most popular second generation computer was IBM-1401, introduced in 1960, while the following computers were used by many business organizations. IBM-1400 series, IBM-1600 series, UNIVAC-III, NCR-300 etc.


Advantages of Second Generation

1. Smaller in size as compares to 1st generation.

2. Much more reliable.

3. Less heat generated.

4. Computation was performing in micro second.

5. Less hardware and maintenance problem.

6. Could be used for commercial use.


Disadvantages of Second Generation

1. Very costly for commercial use.

2. It still required frequent maintenance.

3. Frequent cooling also required.


Third Generation of Computers (1965-1970)

Main Features

* Major Innovation - Integrated circuit (ICs) as basic electronic component.

* Main Memory - PROM and DRAM.

* External Storage - Improve disk (Floppy Disk)

* Input and Output Devices - Keyboard for input, monitor for output.

* Languages - More high level languages.

* Operating System - Complete operating systems were introduced.

* Size - Mini, for example: IBM SYSTEM / 360, ICH-360, HONEY WELL-316 etc.

In this generation the integrated circuits (IC) were used. Integrated circuits contain many electronic components on a single chip. The disk oriented systems wee made at the end of this generation. The size of computer became very small with better performance and reliability. High level programming languages were extensively used. In 1969 the first microprocessor chip INTEL 4004 was developed but it was used only in calculators. The faster input/output devices made possible multi-processing and multi programming. Where by a number of input terminals could be run virtually at the same time on a single centrally located computer. The famous computer were IBM-360, IBM-370, UNIVAC 9000 series etc.


Advantages of Third Generation

1. Smaller in size as compared to second generation.

2. More reliable.

3. Portable

4. Less electricity consumption.

5. Heat generation was rare.

6. General purpose computer.


Disadvantages of Third Generation

1. Air conditioning was required in many cases due to ICs.

2. Very advance technology was required to make the ICs.


Fourth Generation of Computers (1971-1981)

Main Features

* Major Innovation - LSIC and VLSIC (Micro Processor)

* Main Memory - EPROM and SRAM.

* External Storage - Floppy Disk and Hard Disk.

* Input and Output Devices - Monitor for output.

* Languages - Languages and application softwares.

* Operating System - MS-DOS and PC-DOS

* Size - Micro computer e.g. IBM-PC, Apple Macintosh etc.

The Integrated circuits were more developed and called Small scale integration (SSI), after some time the SSI were more developed and termed as Large scale integration (LSI). There was a great versatility of input/output devices. In 1971, a powerful microprocessor chip INTEL 8008 was introduced. The first microprocessor which is used in personal computers (PC) was INTEL 8080. The 8 inch floppy disk was also introduced in 1971, while hard disk was introduced in 1973. The 5.25 floppy disk was first time used in 1978. The optical disk was developed in 1980. First portable computer "Osborne I" was marketed in 1981. IBM-3033, IBM-370, IBM system 34, IBM system 36, Cray-I, CP/M etc were introduced in this generation.


Advantages of Fourth Generation

1. Smaller in size and much reliable.

2. No cooling system required in many cases.

3. Much faster computation.

4. Portable and cheap.

5. The heat generated was negligible.

6. Totally general purpose computer.


Disadvantages of Fourth Generation

1. Very advanced technology was required to fabricate to the ICs.

Fifth Generation (1981-Onward)

Main Features

* Major Innovations - ULSIC (Ultra large scale integrated circuit)

* Main Memory - EEPROM, SIMM and DIMM.

* External Storage - Modified magnetic and Optical disks.

* Input/output Devices - Keyboard, Pointing Device, Scanner as input and Monitor as main output.

* Languages - AI (Artificial Intelligence) Expert systems.

* Operating System - GUI based e.g. Windows 95, Windows NT.

* Size - Very small in size example: Laptop, Note book, Digital Diary, Palm top and Pocket PC.

This generation is started from 1981 and still continued, new technologies are adopted to fabricate IC chips, such as electron beam, X-rays or laser rays. The Very Large Scale Integration

(VLSI) was developed, so the computer became much smaller than ever before. New memory storage device like bubble memory, optical or memory are being designed. the new computer will be controlled by using human voice and will work by giving command in our own language. Future computer will in some way to be intelligent and capable of making decision.


Advantages of Fifth Generation

1. Very large storage capacity.

2. Long bit processor builds.

3. Artificial Intelligence Language developed.

ICS 1st YEAR CH # 01 (IT introduction)

IT introduction - Introduction To IT & Definition of IT

Definition of Information Technology

The concept and the term information technology is so broad that no precise and comprehensive definition, encompassing all the aspects of IT, can be given. Because information technology is set of various diversified and multidimensional technologies. Despite that we may try to define

IT is a set of technologies that merge computing with high speed communication communication links carrying data, sound and videos.

Examples of information technology include personal computers, of course, but also new forms of telephones, televisions and various handheld devices, such as personal digital assistants.

It should be noted that there are two parts of this definition, the computers and communications.

A computer is a programmable, multi-use machine that accepts data, the raw facts and figure, and process or manipulates it into information that we can use, such as summaries totals or reports. Its purpose is to speed up problem solving and to increase productivity.

Communication technology also called telecommunication technology consists of electromagnetic devices and systems communicating over long distances. The principle examples are telephone, radio broadcast, television and cable TV. More recently, there has been an addition of communication among computers, when people tell you that they "went online" with the Internet. To be online means using a computer or other device connected through a voice or data network, to access information and services from another computer or information device.

Now the students may be convinced that there a use of computer is not information technology, rather it is a set of technologies. Computer is just a part of it, through the most important and amazing.

Importance of Computers

The computer is truly an amazing machine. Few tools, other than computers, can help you perform so many different tasks in so many areas of life. That's why computers have become so fundamental to modern society that without them our society would be a primitive one. They are such flexible tools that most people in the business community use them every day. Office workers use them to write letters, keep employee rosters, create budgets communicate with coworkers, find information, manage projects and so on. Many business people even when they are away from the office, for instance, salespeople use computers to manage accounts and make presentation.

Computers are also vital accounting departments. For organizing and manipulating large sets of numbers, which accounting departments do daily, computers are now considered essential. Even small business, which can comprise just a single person can afford to set up sophisticated accounting systems using a personal computer and affordable accounting and financial packages.

Even if you do work in a business computers effect you every day. Any time you go to the bank call information for a phone number or buy something out of a catalog, you are benefiting from the power and speed of computers. Even when you buy groceries and gasoline, you may be interacting with computers.


Capabilities of Computer

Besides being a multi-use device a computer has a number of remarkable capabilities namely very fast speed, accuracy, consistency, reliability and sufficiently large memory.


Speed

A computer can perform various activities by executing programs at a very fast speed. For example it can perform tedious calculations immediately. While a man would take very large time to perform the same job.


Accuracy

Along side speed the tasks performed by a computer are almost accurate. However you may some times come across program logic error, a procedural error or an error in data. But these error are not of computer rather these are human error, i.e. it is the man who makes these error while interacting with computer.


Consistency

During performing a tedious task a man can get tired and he may want to change the nature of the job he is performing or at least he may to change the way he perform his task. But as computer works according to a preprogrammed way. i.e. it has to follow the instruction given to it in the form of a program computer has to perform required tasks with consistency.


Reliability

As mentioned above, the computers have the capabilities to perform a required task in accordance with the preprogrammed instructions with a great speed, accuracy and consistency. Hence the job performed by a computer is highly reliable.


Memory Capability

Man has very limited memory and recalling ability, whereas computer not only have a great capability of storing data in its memory but can also recall this huge amount of data instantly. For example, insurance companies use mainframe computers to process information about millions of policy holders. Obviously no man, even the genius people, can store such huge amount of data in his memory. Even if he could it would be impossible for him to recall required information instantly. While computer can do this job easily.


Uses of Computers

Can you think of a field where you can perform your job efficiently and productively, without the use of computer? Certainly you can't. No matter what career you choose the use of computers will affect you life for this wonderful machine has encompassed almost all the aspects of human life. Some of the fields where in computers are being used extensively are:


Information Management

As computers are excellent tools for managing large quantities of information, they are being extensively used by various organizations for various purposes like airline reservations, student registration, billing and countless others.


Communication

Computer specially combined with tools of telecommunications has become the most effective tool of communication. All the organizations need to communicate with each other, besides communicating with the various departments of the same organization in order to run their day to day business efficiently. The use of computers has facilited this task. Moreover now one can instantly communicate with the people all around the world through internet.


Education and research

Perhaps the most fruitful and productive use of computers has been in the fields of education, scientific and engineering research. The use of computers has converted education into edutainment. Engineers and scientists are utilizing computers as a tool of experimentation design and development. In this respect computerized design (CAD) provides a sophisticated array of tools.


Business and E-Commerce

The emergence of the concept of e-commerce is the result of wide spread use of computers in business. This has motivated almost all the business community to redefine the customer-salesperson relationship. Now you need not to go to super market for shopping for you may place you orders electronically. E-banking and E-commerce has reduce the costs of distribution of commodities and services tremendous.


E-Government

The idea of e-government i.e. providing government service electronically using computers is under its way. The NADRA is an example of utilizing computers for this purpose. Besides the use of computers in the field of health and medicine, agriculture and industries has not only revolutionized these fields but has reduced the cost of production and distribution of goods and services resulting in an over all increase in the standard of living of a common man.

The Impact of Information Technology

The rapid advancement in the field of computers and information technology is having its consequences not only on the organizations but not individuals too. In this connection the most important impact of computers and information technology is undoubtedly the emergence of globalization. Computer based communication is turning the world into a global village. We can communicate electronically using the tools of information technology with the people on the other side of the world as easily as we might have a coversation with a neighbor. Besides the process of globalization information technology is influencing the society in the following ways.


Better Planning and Decision Making

Computer based information systems are facilitating decision making through better planning. As the information technology has improved the communication to the unbelievable extent, the multinational organizations are pooling their information for the better future forecast and planning.


Better Control of Resources

It is essential particularly in business organizations to check whether the planned goals and objectives are being achieved or not. In this respect computer system due to their power and reliability for accuracy can be utilized to measure actual performance levels and to compare these levels with panned standards. Not only this rapid communication of information through the use of information technology provides the business firms with an opportunity to compare its operational efficiency with that of other firms.


Greater Efficiency of Operation

Not to speak of IT and computer experts and professionals even a lay man in the street can realize that the use of computers along with other tools of information technology has improved the efficiency of operation particularly in industrial process.