Computer Its Classification and Generation IBPS SBI PO Clerk SSC

Meaning of Computer

Computer is an electronic device that transforms data into meaningful information. Data can be anything like marks obtained by you in various subjects. It can also be name, age, sex, weight, height, etc. of all the students in a class. A computer can take in data and process it. It can store the data either in raw form or as processed results and can deliver the raw or processed data to the outside world on demand.

Computer can also be defined in terms of functions it can perform.

1. It accepts data

2. It stores data

3. It processes data as desired

4. It retrieves the stored data as and

5. It prints the result in desired format.

The major characteristics of a computer are

1. High speed

2. Accuracy

3. Diligence

4. Versatility

5. Storage

6. Programmability

Components of Computer

1. Input: This is the process of entering data and programs into the computer system.

2. Control Unit (CU): The process of input, output, processing and storage is performed under the supervision of a unit called 'Control Unit'. It decides when to start receiving data, when to stop it, where to store data, etc. It takes care of step-by-step processing of all operations inside the computer.

3. Memory Unit: Computer is used to store data and instructions in Computer’s memory.

4. Arithmetic Logic Unit (ALU): The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison.

5. Output: This is the process of producing results from the data for getting useful information. The ALU and the CU of a computer system are jointly known as the central processing unit (CPU). You may call CPU as the brain of any computer system.

Classification of Computers

Computers can be classified into three major classes based on the mode of data representation used.

1. Analog Computers

2. Digital Computers

3. Hybrid Computers

1. Analog Computers

1.An analog computer is a form of computer that uses continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved.

It operates by measuring rather than counting.

It uses continuous signals as input.

Examples: Thermometer, Speedometer etc.

2. Digital Computers

1. A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system

2. These are the systems that are computationally complete and capable of solving all of the problems that can be solved algorithmically.

Examples: Desktop, laptop etc

Hybrid Computers (Analog + Digital)

1. A combination of computers those are capable of inputting and outputting in both digital and analog signals. A hybrid computer system setup offers a cost effective method of performing complex simulations.

2. It use both types of signals – analog as well as digital – as input.

3. Mostly used with process control equipments in continuous production plants e.g., oil refineries, Areas of application are nuclear power plants, mines, intensive care units of hospitals (ICUs), chemical process plants etc.

Classification of Digital Computers On the basis of Size

The digital computers that are available nowadays vary in their sizes and types. The computers are broadly classified into four categories based on their size and type

1. Microcomputers

2. Minicomputers

3. Mainframe computers

4. Supercomputer

1. Microcomputers

Microcomputers are small, low-cost and single-user digital computer. They consist of CPU, input unit, output unit, storage unit and the software.

IBM PC based on Pentium microprocessor and Apple Macintosh are some examples of microcomputers. Microcomputers include desktop computers, notebook computers or laptop, tablet computer, handheld computer, smart phones and netbook,

(a) Desktop Computer or Personal Computer (PC) - It is the most common type of microcomputer. It consists of three units—keyboard, monitor, and a system unit containing the CPU, memory, hard disk drive, etc. It is not very expensive and is suited to the needs of a single user at home, small business units, and organizations. Apple, Microsoft, HP, Dell and Lenovo are some of the PC manufacturers.

(b) Notebook Computers or Laptop - They are portable and have all the features of a desktop computer. The advantage of the laptop is that it is small in size, can be carried anywhere. Laptops can be placed on the lap while working. Laptops are costlier than the desktop machines.

(c) Netbook - These are smaller notebooks optimized for low weight and low cost, and are designed for accessing web-based applications. Netbooks deliver the performance needed to enjoy popular activities like streaming videos or music, emailing, Web surfing or instant messaging.

(d) Tablet - Tablet Computer has features of the notebook computer but it can accept input from a stylus or a pen instead of the keyboard or mouse. It is a portable computer. Tablet computer are the new kind of PCs.

(e) Handheld Computer or Personal Digital Assistant (PDA) - It is a small computer that can be held on the top of the palm. It is small in size. PDA uses a pen or a stylus for input, Instead of the keyboard. They have a limited memory and are less powerful. PDAs can be connected to the Internet via a wireless connection. Example Casio and Apple are some of the manufacturers of PDA.

(f) Smart Phones - These are cellular phones that function both as a phone and as a small PC. They may use a stylus or a pen, or may have a small keyboard. They can be connected to the Internet wirelessly. They are used to access the electronic-mail, download music, play games, etc. Blackberry, Apple, HTC, Nokia and LG are some of the manufacturers of smart phones.

2. Minicomputers

Minicomputers are digital computers, generally used in multi-user systems. Minicomputers are mainly used as small or midrange servers operating business and scientific applications. They have high processing speed and high storage capacity than the microcomputers. Minicomputers can support 4–200 users simultaneously. The users can access the minicomputer through their PCs or terminal. Example Digital Alpha, Sun Ultra.

3. Mainframe Computers

Mainframe computers are multi-user, multi-programming and high performance computers. They operate at a very high speed, have very large storage capacity and can handle the workload of many users. Mainframe computers are large and powerful systems generally used in centralized databases. Computers with large storage capacities and very high speed of processing (compared to mini- or microcomputers) are known as mainframe computers. They support a large number of terminals for simultaneous use by a number of users like ATM transactions. They are also used as central host computers in distributed data processing system. Mainframe computers are used in organizations like banks or companies, where many people require frequent access to the same data.

Examples: - IBM 370, S/390.

4. Supercomputers

Supercomputers are the fastest and the most expensive machines. They have high processing speed compared to other computers. The speed of a supercomputer is generally measured in FLOPS (Floating point Operations per Second). Some of the faster supercomputers can perform trillions of calculations per second.

Supercomputers are used for highly calculation-intensive tasks, such as, weather forecasting, climate research (global warming), molecular research, biological research, nuclear research and aircraft design. They are also used in major universities, military agencies and scientific research laboratories.

Some examples of supercomputers are IBM Roadrunner, IBM Blue gene and Intel ASCI red. PARAM is a series of supercomputer assembled in India by C-DAC (Center for Development of Advanced Computing), in Pune. PARAM Padma is the latest machine in this series. The peak computing power of PARAM Padma is 1 Tera FLOP (TFLOP).

What Others Are Reading

Generations of Computers :-

First Generation Computers (1942-1955)

1. They used vacuum tubes.

2. They were very expensive.

3. Consume more power with limited performance.

4. Magnetic tape / magnetic drum were used for storage.

5. They were heavy and large in size.

6. They generated a lot of heat.

7. Examples: (ENIAC - Electronic Numerical Integrator and Calculator, EDSAC – Electronic Delay Storage Automatic Calculator, EDVAC – Electronic Discrete Variable Automatic Computer, UNIVAC – Universal Automatic Computer IBM 701)

Second Generation Computers (1956-1964)

1. Transistors were used in place of vacuum tubes. (Invented at AT&T Bell lab in 1947)

2. Lesser power consumption and better performance

3.Lower cost than First Generation.

4. They were smaller in size than first generation computers.

5. They were faster than first generation computers and also less expensive.

6. Magnetic tapes and magnetic disks were used as secondary memory

7. High level languages such as FORTRAN, COBOL etc were used - Compilers were developed to translate high-level program into corresponding assembly language program which was then translated into machine language.

8. Examples: ENIAC 1401, CDC 160, IBM 700, – IBM 7030, Digital Data Corporation’s PDP 1/5/8 Honeywell 400

Third Generation Computers (1965-1971)

1. They used electronic devices called Integrated Circuits (ICs) instead of Transistors.

2. They were smaller in size than second generation computers and also less expensive.

3. They were faster and more accurate than second generation computers.

4. Small Scale Integration and Medium Scale Integration technology were implemented in CPU, I/O processors etc.

5. Smaller & better performance

6. Comparatively lesser cost

7. Faster processors

8. In the beginning magnetic core memories were used. Later they were replaced by semiconductor memories (RAM & ROM)

9. Introduced microprogramming

10. High level languages were standardized by ANSI e.g. ANSI FORTRAN, ANSI COBOL etc

11. Cache and virtual memories were introduced (Cache memory makes the main memory appear faster than it really is. Virtual memory makes it appear larger)

12. Operating system software were introduced (efficient sharing of a computer system by several user programs)

13. Microprogramming, parallel processing (pipelining, multiprocessor system etc), multiprogramming, multi-user system (time shared system) etc were introduced.

14. Examples: VAX-750, IBM 360, ICL 1900, System 360 Mainframe from IBM, PDP-8 Mini Computer from Digital Equipment Corporation

15. An integrated circuit (IC) is a small electronic device made out of a semiconductor material.

Fourth Generation Computers -Microprocessors (1972 onwards)

1. They use a device called microprocessor instead of ICs

2. They are smaller in size.

3. They are cheaper and faster.

4. They are very easy to handle.

5. All present day computers come under this category.

6. Microprocessors were introduced as CPU– Complete processors and large section of main memory could be implemented in a single chip

7. Tens of thousands of transistors can be placed in a single chip (VLSI design implemented)

8. CRT screen, laser & ink jet printers, scanners etc were developed.

9. Semiconductor memory chips were used as the main memory.

10. Secondary memory was composed of hard disks – Floppy disks & magnetic tapes were used for backup memory

11. Parallelism, pipelining cache memory and virtual memory were applied in a better way

12. LAN and WANS were developed (where desktop work stations interconnected)

13. Introduced C language and Unix OS

14. Introduced Graphical User Interface

15. Less power consumption

16. High performance, lower cost and very compact

17. Much increase in the speed of operation

18. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh.

Fifth Generation Computers (Future Computers)

1. They will be intelligent like human beings, and will use Artificial Intelligence (AI) for working.

2. They will be able to think and take decisions like us.

3. They will be used in areas such as robotics, designing, defence.

4. Object oriented language like JAVA suitable for internet programming has been developed.

5. Portable note book computers introduced

6. Storage technology advanced – large main memory and disk storage available

7. Introduced World Wide Web. (And other existing applications like e-mail, e Commerce, Virtual libraries/Classrooms, multimedia applications etc.)

8. New operating systems developed – Windows 95/98/XP/LINUX, etc.

9. IBM notebooks, Pentium PCs-Pentium 1/2/3/4/Dual core/Quad core... SUN work stations, Origin 2000, PARAM 10000, IBM SP/2).