on the basis of working principle

 We have following computers on the basis of working principle/mechanism.

1)Analog computers

2)digital computers

3)Hybrid computers

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Let's know in detail.

1)Analog computers:-

                         An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. In contrast, digital computers represent varying quantities symbolically, as their numerical values change.

       Features:      

1. uses variable like pressure,temperature etc whose values vary continuously.

2. uses sine wave.

3. It records waveforms as they are.

4. may subject to deterioration of wave by noise.

5. more likely have low accuracy

6. hardware is not so flexible

7. best suited for audio and video transmission

8. consumes less bandwidth

9. error prone

e.g. Plesley,speedometer etc

2)digital computers:-

                    Digital computer is a computer which stores data in terms of digital numbers and proceeds in discrete steps from one state to another.

        Features:-

            

1. does not use variable concept; rather uses discrete values to represent information.

2. uses square wave (for max and min voltage)

3. waveforms are converted into numbers to record information.

4.  without deterioration during transmission 

5. high level of accuracy

6. Digital hardware is flexible

7. for any type of computing

8. consumes more bandwidth

9. mostly free from errors

                                                                picture source:theintactone.com

3)Hybrid computers:-

                    Hybrid computers are computers that exhibit features of analog computers and digital computers. The digital component normally serves as the controller and provides logical operations, while the analog component normally serves as a solver of differential equations.

        Features:-

        
It is combination of qualities analog and digital computers.

2.  It can process both continuous and discrete data.

3.  It has capability to convert one type of data to another.

4.  It is the special purpose machine.

5.  It is mostly used in airplane, hospital, weather forecasting.

6.  It usually has high cost compared to analog and digital.

Examples: HRS 100, radar, XPC 100, GVS 100.

Types of computers

 We have different category of computers. All the computers are classified into following categories.

1.)On the basis of working principle/mechanism

2)On the basis of size

3)On the basis of brand

4) On the basis of model

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know about About mobile computing:

Fifth generation computers

 Features:-

• Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today.

• Artificial Intelligence is the branch of computer science concerned with making computers behave like humans and we can say that this is the main component of fifth generation computers.

• The greatest advances have occurred in the field of games playing. In the area of robotics, computers are now widely used in assembly plants, but they are capable only of very limited tasks.

• The fifth generation of computers have the following features:

1. These computers will be fully parallel processing capacity.

2. Computers will be intelligent and knowledge based of AI.

3. The language of operating system will be PROLOG.

4. The language of AI in fifth generation computer has also enabled expert system.

5. Computers will use super conductor memory like bio-chips &Gallium Arsenide as memory device to increase its speed even further.

ARTIFICIAL INTELLIGENCE:

• It is the intelligence of machines and the branch of computer science that aims to create it.

• For variety of machines and computers various components are used.

• The purpose of artificial intelligence have uncountable uses and advantages such as in calculations, gaming, defense, etc.

• Followings are the features of artificial intelligence:

1. it can perform many tasks itself,

2. It can be a great help in medical science,

3. It can be very useful in defense system,

4. It may have problem to find things know objects, differentiate between them, etc. in the case of robots,

5. It can perform tasks without stopping, etc.

6. 
   

summarized features:

Fifth Generation Computers (Present & Beyond)

1. ULSI technology 

2.  Development of true artificial intelligence

3.   Development of Natural language processing  

4. Advancement in Parallel Processing  

5. has capability to interpret just like human being. 

6. supports to make expert system to take decision in real time system.

7. More user friendly interfaces with multimedia features  

8. quantum computing using qubits (Quantum bits)(is exponentially faster than conventional computers).

9. more processors on same computer .

10. more storage capacity using semiconductor technology.

11. advancement in input and output devices.

12. uses high level languages like, java,.net 

e.g.   Desktop  Laptop  NoteBook  UltraBook,Clout

Fourth generation computers

 Features:

• The microprocessor brought the fourth generation of computers, as thousands of integrated circuits we rebuilt onto a single silicon chip. 

• Two typical components of a CPU are:

• The arithmetic logic unit (ALU), which performs arithmetic and logical operations.

• The control unit, which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.

• Microprocessors control the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles.

• The features of this generation computers are as follows:

1. These computers were based on micro processor.

2. these small computer could be linked together to form networks,

3. Processing speed increased up to picoseconds.

4. These computers are powerful, affordable, fast, portable and reliable.

5. Fourth generation computers are the cheapest among all the other generation computers.

Summarized features:

1. VLSI technology used  

2. Fourth Generation computers became more powerful, compact, reliable, and affordable

3. Use of PC's (development of microcomputer with microprocessor )

4. Very small size  

5. Pipeline processing

6.   No A.C. needed 

7.  Concept of internet was introduced

8.   Great developments in the fields of networks  

9. development of mouse, GUIs concept with handheld devices.

10. In this generation Time sharing, Real time, Networks, Distributed Operating System were used.

11. High level language was used.

e.g.  PDP 11

Third generation computers

 Features:-

• he development of the integrated circuit was the hallmark of the third generation of computers.

• It consisted of computer chips, both for CPU and memory, composed of semiconductor materials. Semiconductors make it possible to miniaturize electronic components, such as transistors.

• This generation of computers helped in operating system to be more faster and allowed many programs to perform at once

• These are the following features of third generation computers:

a) Transistors were miniaturized and placed on silicon chips, called semiconductors

b) These computers were based on integrated circuit (IC) technology.

c) Processing speed was increased to nanoseconds.

d) Operating system for automatic processing and multi programming was introduced.

e) Magnetic disk was used as primary memory.

f) Semi conductor memory was used as primary memory.

Some more features in summarized form:-

1. IC was used.

2. More reliable,Smaller in size,Generated less heat and Faster  in comparison to previous two generations

3. Lesser maintenance

4. Still costly

5. supported Remote processing, Time-sharing, Real-time, Multiprogramming Operating System.

6. Consumed lesser electricity

7. Supported high-level language

8. used semiconductor memory

9. keyboard,monitor interfaced with an operating system(DOS)

10. many applications could be run on computer.

e.g. IBM-360 series

Second generation computers

 Features:

• Transistors replaced vacuum tubes and ushered in the second generation computer. Transistor is a device composed of semiconductor material that amplifies a signal or opens or closes a circuit.

• They usually had magnetic core, transistor, digital circuits, etc.

• The first computers of this generation were developed for the atomic energy industry..

• The following are its features:

1. These computers were based on transistor technology.

2. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. 

3. Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words.

4. These computers still require air conditioning.

5. Processing or operating speed was increased from microseconds to milliseconds.

summarized features:-

1. transistors were used.

2. Smaller in size ,better speed as compared to the first generation computers.

3. The 2nd generation Computers were more reliable

4. multiprogramming was possible

5. Wider commercial use

6. Better portability as compared to the first generation computers.

7. Used faster peripherals like tape drives, magnetic disks, printer and magnetic core as primary memory etc.

8. Supported machine and assembly languages

9. Accuracy improved.

10. batch processing system was used.

11. Punched cards were used for input.

e.g. IBM 1620 

First generation computers

 Features:-

• The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms.

• Magnetic drums were once use das a primary storage device but have since been implemented as auxiliary storage devices. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat.

• field of application included weather prediction, atomic-energy calculations, cosmic-ray studies, thermal ignition, random-number studies, wind-tunnel design, and other scientific uses. 

• Its features are as follows:

1. these computers were based on vacuum tube technology.

2. Punched cards were used as input device.

3. These machines were unreliable and lack of versatility and speed.

4. They were very expensive to operate and in addition to using a great deal of electricity.

5. First generation computers relied on machine language to perform operations.

More ever we can put some more features in first generation:

1. Vacuum tubes were the only electronic component used in them. 

2. The computers were very large in size,slow in speed and not so reliable.

3. They heated very soon due to thousands of vacuum tubes.They consumed a large amount of energy.

4. Air conditioning was required.

5. Constant maintenance was required.

6. Non-portable.

7. Costly commercial production.

8. Limited commercial use.

9. Used machine language only.

10. Used magnetic drums which provide very less data storage and punch cards for input. batch processing was used. 

11. Not versatile and very faulty.

e.g. UNIVAC-1