Unit- One: Computer System grade 11 note

Unit-One: Computer System grade 11 note

Definition of Computer:

A computer is an electronic machine that accepts data and instruction, stores it until the data is needed, processes large amount of data according to the instructions provided by the user, and finally returns the results to the user.

A computer can be defined as a multipurpose, programmable, electronic data processing device that is capable of accepting input, processing it and producing information as output at enormous speed.  

A computer may be defined as a machine that can solve problems by accepting data, performing certain operations, and presenting results of those operations in sequential instruction. Such a set of sequenced instructions, which cause a computer program to perform particular operations, is called a program.

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1.1.1 Characteristics (Features) of Computer:

1. Speed: The data processing speed of the electronic computer is very fast because the signals can pass at the speed of electricity which is near to that of speed of light. Thus millions of calculations can be done in a second. Such speeds are beyond the comprehension of the human brain. 
2. Accuracy:The accuracy of a computer is consistently high, and every calculation is performed with the same accuracy. i.e. almost 100% accurate results are always the same as per design. The degree of accuracy of a particular computer depends upon it’s designed. (GIGO)
3. Word length:Digital computer operates on binary digits (bits), a combination of 1 (one or high) and 0 (zero or low), which means all data or information are kept in a computer or its memory it terms of 0’s and 1’s. 8 bits is equal to one byte. The number of bits that a computer can process at a time in parallel is called its word length.  
4. Automation:A computer is an automatic machine, capable of functioning automatically, once the appropriate set of instructions (program) and data are provided to the computer. Once a task is initiated in a computer, it can proceed automatically.
5. Diligence:The computer can perform repetitive tasks without being bored and never gets tired. Diligence means being constant and earnest in effort and application. It can continuously work for several hours or day after the data and programs are fed in it.
6. Reliability:The computer system is particularly master a lot of work without any mistakes and tiredness. That’s why they are widely used everywhere because of their reliability. On the other hand, unreliable can occur if the end- user feeds incorrect data and instructions, or faulty instructions for processing the data automatically lead to faulty results.
7. Versatility: Computer can perform different tasks depending upon the different program fed to it, is known as versatility.  It has a wide range of application areas i.e. it can do man types of jobs. It can perform operation ranging from simple mathematical calculations to highly complex and logical manipulations.
8. Storage Capacity:A computer can store a huge amount of data. it has a data storage area, called memory. Any data stored in the memory can be retrieved at any time at a very fast speed. The memory can be divided into primary memory and secondary memory. Primary memory is the working memory of the computer and is capable of sending and retrieving data at very high speed, whereas secondary memory storage is long-term memory and memory and operates more slowly but capable of storing large amounts of data. i.e. hard disk, magnetic tape, floppy disk etc.

Capabilities and Limitations of Computer:

Capabilities of Computer:

• The computer is capable of producing 100% accurate outputs, performing calculations complicated and difficult work at extremely high speed using correct data and instructions.
• It is capable of permanently storing huge amounts of data and retrieving (access) it whenever required.
• It can perform the repetitive tasks with the same speed and accuracy.
• It is capable of performing different types of tasks in different areas.

Limitations of Computer:

• The computer is the non-intelligent machine. It cannot think and give the right decision as a human being.
• It cannot operate without a battery or electricity.
• Failure in devices and wrong information by users makes it unreliable.
• It requires instruction to perform a task. It cannot perform any task by itself.

Advantages and Disadvantages of Computer

Advantages of Computer:

• The computer is faster than a human being and any other device ever invented.
• It is always accurate and reliable.
• It is versatile i.e. master in all types of work and fields like education, hospital, bank etc.
• It can be used for communication among many users.
• It has a large and permanent storage facility. As a result, data and programs can be stored modified and used for different purposes.
• It is used to develop and control simulators.
• With the help of computers and its technology, complex tasks will be easier, like sitting in computer exploring place3s of the world using Google Maps.

Disadvantages of Computer:

• Is has increased dependency on the machine.
• It is still expensive.
• The computer can be used for computer crime like hacking, cracking, creating and sending malicious software (like virus, worm, Trojan horse).
• Repair and maintenance are required frequently.
• Skilled manpower is required to work on the computer.

Application of Computer:

1. Computer in Education: In education, most schools and universities in the world are using computers for learning purpose. It has been proved that learning with computers has been more successful and this is why numerous forms of new teaching methods have been introduced. This enhances the knowledge of computers in our daily life – whether we are at the cinema, the school, or the public library. The beginning of computer literacy is already apparent.

In educational institution, the computer is used as teaching aids, information resources and computing and research means or tools. The computer has generated a new subject of study in terms of computer science, computer engineering and ICT. It also used to prepare documents, reports, presentations etc.

• Computer in Business: In the business sector, a Point of Sale (POS)- terminal is mostly used in department Malls, shops and other retail centers to process sale transactions. The computer prints name of the item, rate, and price validated to data and other details on the receipt and issues the receipt to the customer, then the total amount to be paid. 
• Computer in Office: Modern computers are very necessary and useful resources in office. In offices, computers are used in preparing the reports, letters, notice, salary sheet, income and expenditure reports etc. so that efficiency and work speed of the employees will be improved. Generally, Microsoft Office and Accounting Package are used in an office to handle the daily works.
• Computer in Communication: the computer in massively used in communication. Communication is done by email, chat, online conferencing (computer conferencing, teleconferencing or audio or video conferencing), e-fax throughout a computer network that connects a number of computer or workstations with the help of internet. In communications, computer are used to view and post news on computer bulletin board system (BBS), for electronic shopping, banking and brokerage and to get information services.
• Computer in Bank: Bank use the computer for general purpose computations, to handle the transaction, to maintain the ledger, to issue fixed deposit receipts, to make withdrawals and deposits to customers, to provide online service to customers who want to perform bank transactions form terminals and to answer customers regarding their balance. This day, banks provide 24 hours ATM service, where user can withdraw their money anytime form the ATM machine by using the ATM card. Online banking service is being popular, which is the process of performing banking transactions using the internet.
• Computer in Health and Medical Field: The computer is widely used in hospitals to help doctors in diagnosis, getting information about patient’s diseases, required treatments, keeping patient records, online booking. It is also used in administration for keeping patient records. Doctors can get information from distant data banks and expert system. They can discuss with colleagues suing teleconferencing or online conferencing. One of the most important things is that the Magnetic Resonance Imaging (MRI), CT scan machine, eye testing machines, ultrasonic machine are attached or built within the computers.
• Computer in Industry: In industry, the computer is extensively used for automatic control of machines, processes, measurement, and display of electrical and physical quantities. For example automatic control of temperature of a heating system, the speed of a motor, the voltage of generator, the pressure of boiler, testing of products, all is a microprocessor-based computer system.
• Computer in Military: The computer widely used for defense purpose. At present, sophisticated weapons are being widely used in military operations with refined microprocessor-based control systems. These are modern tanks, missiles, fighter planes. In guided missile, tanks, fighter planes or even arms use the internal computer for their control.
• Computer in Aviation: In aviation, computer stores all necessary information regarding ticket reservations, such as flight number, flight route, flight distance, number of seats available for each flight in each class, ticket fare. It also stores information regarding persons who have already reserved. It is also used in the air traffic control system to control landing and takeoff of airplanes to minimize any accidental risk and increase the number of flight in a airport.
• Computer in Robotics:
• Computer in Graphics:
• Computer in Design and Research Work:
• Computer in CAM(Computer-Aided Manufacture)/CAD (Computer Aided Design):
• Computer in Desktop Publishing System
• Computer in some other places:

Unit-One: Computer System grade 11 note

1.1.2. Evolution of Computer Technology:

Evolution of computer is a study of the past development of computer; i.e it is meant by the gradual improvement of accuracy, speed and efficiency of computers through generations whereas generations of computers may be defined as the development of computer an average period of time in which old computer technology may be replaced by newer technology.

Each generation of computer is characterized by a major technological development that basically changed the way of computer operation as a result, it is an increasingly smaller, cheaper, more powerful and more reliable device.

The Mechanical Era (Zeroth Generation)

The calculator of this age was developed by using mechanical components like wood, metal, stone, bone. It was used for simple mathematical calculations. Some of the popular calculators used in this age are:

Abacus:

Historians started the history of calculation with the first mechanical tool Abacus, also known as Suan-pan. It was used for performing simple calculations like counting, addition, subtraction and multiplication of numbers.

An abacus consists of a rectangular frame carrying a number of wooden rods. Mid-bar divides each of these rods into unequal- upper and lower parts. The upper parts is called heaven, whereas the lower part is called the earth. Heaven consists of two beads, whereas the earth part consists of five beads to each rod.

Napier Bone:

THE SCOTTISH mathematician John Napier first published the table of logarithms in 1614 AD. It was very useful in simplifying the multiplication of large numbers. He invented bone rods and used bones to demonstrate division by subtraction and multiplication by addition, according to the principle of logarithms.

Slide Rule:

THE ENGLISH MAN William Oughtred invented a rectangular device Slide-rule in 1620 AD.  Is was a calculating device based on the principles of the logarithm. A slide rule consists of two graduated scales, one of which slips upon the other. The scales are devised in such a manner that suitable alignment of one scale against the other makes it possible to find products and Quotient of any numbers.

Pascaline:THE FRENCH MAN Bilaise Pascal was a brilliant mathematician and religious thinker. Hi was the founder of the modern theory of probability. He formulated Pascal’s principle: in a liquid and gas, pressure applied to one point is transmitted equally to all parts of the fluid. To assist his father in his accounting work, Pascal invent the first numerical mechanical calculating machine in Paris. In this machine, number was were entered by dialing a series of numbered wheels each wheel having number from 0 to 9.

Leibniz Calculator:

Jacquard Loom:

Charles Babbage (1791-1871 AD):

The English professor and mathematician Charles Babbage invented the Difference Engine at Cambridge University in 1822 AD. Theoretically, it can solve differential equations and calculate various mathematical function, logarithmic tables, polynomial and trigonometric the functions. His new idea was the construction of a general-purpose, fully programmable automatic mechanical counting machine. Babbage called his machine an Analytical Engine in 1933 AD.

Lady Augusta Ada Byron Lovelace (1815-1852 AD):

John Von Neumann (1903-1957 AD)

THE HUNGARIAN mathematician, Jonvon Neumann gave the idea of a stored-program computer in the sense that the program is stored in internally in the main memory of the computer along with its associated data in 1945. So he is called the “Father of Stored Program“

The Electro-Mechanical Era:

            The calculator of this age was developed by using a mechanical and electronic component vacuum tube.

The Mark I Computer (1937-1944 AD):

A professor of Physics Howard H. Aiken designed a general-purpose mechanical computer in Harvard University and IBM while working on his doctorate in physics, in the year 1937. The machine was called BIM Automatic Sequence Controlled Calculate (BIM ASCC). It was the fully automatic calculating machine and later as Harvard Mark I. It was constructed in IBM, leading manufacture of office equipment at the time. Mark I is completed in 19944.

It used binary numbers for its operation. It utilized a number of input/output (I/O) devices including a punch-card and a card reader.

Features of Marks I:

• It used about 18 thousand vacuum tubes (valves) as main memory devices with 7 lakes 50 thousand part
• It’s about 51 feet long, 8 feet height and 3 feet wide.
• Punch card, and card readers are used for input/ output operation
• It was capable of performing five basic arithmetic operation: addition, subtraction, multiplication, division and table reference.
• The time taken for average multiplication and division was about four and eleven seconds respectively.
• The results were printed at the rate of one result per five seconds.

The Ananasoff Berry Computer (1939-1942 AD)

In 1939, John Vincent Atanasoff and Clifford Berry designed Atanasoff-Berry computer or ABC for solving systems of mathematical simultaneous equations. If used 18000 valves (Vacuum tubes ) and other 45 valves for internal logic and capacitors for storage. It used punched cards as input and output operation i.e. secondary storage.

The Colossus (1941-1944AD)

In 1944, Colossus computer is a design by Alan M. Turing and built by British mathematician Alan Mathison, Neuman, along with some colleagues, created a computer named colossus at the University of Manchester, England, which comprised 1800 vacuum tubes. Also colossus was built as a special-purpose computer, it proved flexible enough to be programmed to execute a variety of different routines.

The Electronic Computer Era

The ENIAC (1943-1946 AD):

In 1946 John W. Mauchly and J. Presper Eckert construct ENIAC (Electronic Numerical Integrated And Calculator) at the Moore School of Engineering of the University of Pennsylvania, UAS. ENIAC was the first popular general purpose all electronic digital computers.

The EDVAC (1946-1952 AD):

EDVAC (Electronic Discrete Variable Automatic Computer) was developed by Dr. John Von Neumann and a member of the Moore School of Engineering of the University of Pennsylvania, J.P Eckert and J.W.. Mauchly.

The EDSAC (1947-1949 AD):

The EDSAC (Electronic Delay Storage Automatic Calculator) was invented by a group of scientists headed by Professor Maurice Wilkes at Cambridge University in May 1949. It was used vacuum tubes.

Generation of computer:

• In simple words, generation of computer is step ahead in technology used in manufacturing of the computers. 
• Based on the period of development and the features incorporated, the computers are classified into different generations- from first generation to fifth generation computer.
• However, each generation is characterized by a major technological advancement which changed the way computer operate.

First Generation (1946-1955)  Vacuum Tubes

Second Generation (1956-1965)  Transistor

Third Generation (1966-1975)  Integrated Circuit (IC)

Fourth Generation (1975-present)  Microprocessor

Fifth Generation (coming generation)  Artificial Intelligence, Biochips, expert System Natural Language

Smaller in size More reliable Cheaper Faster

1. First Generation (1946-1955)

Technology used	Vacuum Tubes
Input	Punched Cards
Output	Punched Cards
Language	Machine Language
Storage	Punched Paper Tape

• The first generation of computer used vacuum tubes for circuitry and magnetic drums for memory. The input to the computer was through punched cards and paper tapes. The output was displayed as printouts.
• Vacuum tubes was invented by Lee De Forest in 1980 A.D. Each vacuum tube consumed about half a watt power. The vacuum tubes allowed flow of electrons in only one direction.
• The instructions were written in machine language. Machine language used 0’s and 1’s for coding of the instructions. The first generation computer could solve one problem at a time.
• The computation time was in milliseconds. These computers were enormous in size and required a large room for installation.
• Example of first generation computer are : ENIAC, EDSAC, EDVAC, LEO, UNIVAC-I, IBM701, IBM650 etc.
• Second Generation (1956-1965):

Technology used	Transistors
Input	Punched Cards
Output	Paper
Language	Assembly Language
Storage	Magnetic Cores

• The computer which used transistors as memory device were grouped into second generation computer.
• Transistors replaced the vacuum tubes of the first generation of computer.
• Transistors allowed computers to become smaller, faster, cheaper, energy efficient and reliable.
• The 2^nd generation computer used magnetic core technology for primary memory.
• The instructions were written using the assembly language.(ADD, SUB).
• It is easier to write instructions in assembly language, as compared to writing instructions in machine language.
• The computation time was in microseconds.
• Transistors are smaller in size compared to vacuum tubes thus the size of the computer was also introduced.
• Example of 2^nd generation computer are: RCA 501,IBM 1620, IBM 1401, IBM 7094, Mark III, IBM 650.

• Third Generation (1966-1975):

Technology used	Integrated Circuits
Input	Keyboard
Output	Monitor
Language	High Level Language
Storage	Improved Disk Storage

• IC was the memory device used in third generation computer.
• The operating speed in this generation computer increased up to nanosecond range.
• The internal storage capacity of computer of this generation increased and bout one half million characters could be accommodated in the computer of this generation.
• Programming was done with high level language.
• Computer started to use keyboard as input device and monitor as output device. Before third generation computer were not equipped with monitor and keyboard.
• The size of these computers was quite small compared to the second generation computers.

We can categorize the IC into following types on the basis of number of electronic components used on them.

1. SSI (Small Scale Integration): it is the types of IC where upto 100 electronic components were used per IC.
2. MIS (Medium Scale Integration): where 100 to 3000 electronic components were used per IC.
3. LSI (Large Scale Integration): where 3000 to 1 lakh electronic components were used per IC.
4. VLSI(Very LSI): where 1 lakh to 10 lakh electronic components were used per IC.
5. ULSI(Ultra LSI): where more than 10 lakh electronic components were used per IC.

• Fourth Generation (1975- Present):

Technology used	Very large scale integrated circuits(VLSIC), Microprocessor
Input	Keyboard/mouse/scanner
Output	Monitor
Language	High level language
Storage	Hard disk

• The operating speed increased up-to pico second and even beyond it. Speed began to be measured in terms of MIPS (million of instruction per second).
• Microprocessor was the memory devices used in these computer.
• These computers were very user friendly and even the software used in these computer are the friendly.
• From this generation onward multi-processing, multiprogramming, distributed computing were possible.
• The internal storage capacity increased up-to 1GB and it’s still increasing.
• The computer were available for general purpose as well as for special purpose.
• The computer were smaller in size and less expensive than previous generation computer.
• Power consumption and Heat emission has been less than previous generation computer.
• Computer have become portable because of the  development of Personal or Desktop computer, laptop, Notebook etc.
• Example: IBM PC, Apple, Pentium PC etc.

• Fifth Generation(coming generation):

This generation of computer have not come yet in reality, but computers scientist are trying since 1990 A.D. It is said that the computer of this generation will use AI (Artificial Intelligence) and bio-chips as memory device so that they can think and decide like a human being. This computer will have power of sense, logic and decision making capacity.

Features of this computer are as follows:

• They will be capable of fully parallel processing.
• Computer will use super conductor memory like bio-chips so that the speed will be very fast.
• The computers will be intelligent and knowledge base because of AI.
• Instead of HLL, natural language like English, Nepali, Hindi etc. will be used giving instruction and making computer program.
• They try to simulate the human way of thinking and reasoning.

2.         On the basis of Size – Super, Mainframe, Mini and Micro Computers.

1. Super Computer:

            The super computer is the most powerful and fastest computer among digital computers. This computer is special purpose and is capable of handling huge amounts of calculations that are beyond human capabilities. It can perform at billions of instruction per second (BIPS) and more. Some of today’s super computer has the computing capability equal to that of 40,000 micro-computers. This computer is the most expensive computer (cost around 15-20 million-dollar range). Due to it’s high cost and size, it is relatively rare. It used only by large corporations, universities, and government agencies mainly in the areas of defense and weaponry, weather forecasting, scientific research, satellite communication etc.

Example: CRAY X-MP/24, NEC-500 PARAM, ANURAG etc.

2. Mainframe Computer:

            A mainframe computer is a large computer with hundreds of processors. It can process a larger amount of smaller tasks quickly. A mainframe computer is smaller than a supercomputer. The supercomputer is the larger and fastest computer ever made.

Mainframe computers have the size of a refrigerator. Before 2000, these computers were big in size covering the whole room. But now these computers have decreased in size and improve in performance. It occupies very largely with an approximate area of 1000 sq. ft. it supports a large number of I/O terminals, more than 100 terminals.

Advantages of mainframe computer

High-end scalability: They are scalable in the sense that more hardware i.e. processors and memory can be added if needed. In mainframe computer, more than 600 processors are directly managed by the operating system while many other processors are connected whose work is to move data within the mainframe computer.

Security: The security of these computers is very high. As these computers are used in banks so the security is very important. In banks, these computers are used for managing online transactions, processing of credit and debit cards.

Long-lasting performance: These computers have a minimum time limit of 10 years. So they can perform well for 10 years and after that period companies can upgrade the mainframe computer or replace it.

Continuing compatibility: Mainframe computers have their own operating system e.g. IBM have their own operating system that can manage these computers. These computers are highly compatible with the processors and other hardware and software.

Huge memory storage: Due to a high number of processors these computers have huge memory that can store and process large amount data at a time.

Virtualization: These systems have a logical partition which can help mainframe to overcome memory limitation.

Can run multiple OS: In mainframe computer, more than one operating system can be run at a time to boost the performance of the system.

Real-time monitoring and control: If any fault comes in the system then the administrator of the system is notified instantly. Suppose there is hardware failure then that hardware should be replaced to resume the work.

Disadvantages of mainframe computer

High cost: These computers have a very high price and they cannot be used in homes. Mainframes are only used by big organization, banks, large websites and government agencies.

Hardware/software is expensive: Windows and mac are not run on mainframe computers. These computers have custom software and hardware that are expensive for the normal user.

A lot of space required: Mainframe computers need a large space and also the temperature of the place should not be hot.

High technical staff: For maintaining mainframe computer specialized staff is needed. A normal computer user cannot operate and debug the system.

Command drove interface: The terminal connected to the mainframe computer have the text and a command-based interface that is difficult to understand.

Hardware crash: If any hardware crashed then the whole system stops working.

Examples of mainframe computer

• IBM Z-series
• BIM 1401
• System z10 servers
• HP mainframe

Mainframe Features

In this Mainframe tutorial, you will learn about features of Mainframe – Processing power, memory capacity, performance, computing, multiple operating system, time sharing, reliability, serviceability, availability, clustering technology and other features available in Mainframe.

Large Number of CPU with Greatest Processing Power:

The mainframe has greatest processing capacity and to support this there is large number of CPU’s with high processing power embedded within the frame.

Huge Memory Capacity:

As explained before the mainframe applications takes its presence in large scale operations and to support this facility the memory capacity embedded within mainframe is very huge, in some cases it could even be about more than 8 Gigabyte.

Increased Performance by Sharing workload:

Mainframes systems have the ability to share the workload among different processors and input and output devices. This makes its processing ability and power to be efficient and increases its performance.

Centralized Computing:

The mainframe system handles centralized computing by which all the operations takes place in the processor section of mainframe and the results are seen in the desktop monitor with the help of a utility or program running on the mainframe background.

Ability to Run in Multiple Operating System:

Mainframes have the ability to run multiple operating systems and by this feature it is possible to function mainframe systems not as a single computer but as a number of virtual machines.

Supports Time Sharing Ability:

By the feature of Time Sharing Ability supported by mainframes it is possible for thousands of users to operate and use the machine simultaneously with efficiency.

Supports Sophisticated Operating system:

Mainframe system supports sophisticated operating systems like UNIX, Linux and VMS and IBM operating systems like Z/OS, Z/VM, and VSE/ESA.

Reliability:

The main important feature of mainframe system was its Reliability which made its usage wide spread among commercial customers. Mainframe systems are Reliable systems which gives high performance, which is essential for reasonable operations against a database.

Availability:

As we have seen the mainframe system and application takes its presence in critical and complex business applications which requires the system to be available at all times with 100% throughput. This is completely achievable and provided by mainframe system and it’s really impossible to hear any system outage for any reasons in a mainframe system making its availability for applications throughout. The above is achieved by mainframe system by its great design where Memory chips, memory busses, I/O channels and power supplies are provided with a pair more, ensuring the system availability throughout.

Serviceability:

It is possible to replace most of the components in the mainframe system with the system operating concurrently. Certain components like CPU if needed to be replaced of course requires the system operation to be shut down in which case this is done during the scheduled outage as per the users convenience.

Note: IBM 1401 was the first computer brought to Nepal

3. Minicomputer:

            First released in the 1960s, minicomputer got its name because of its smaller size and cost compared to a mainframe computer. The capabilities of a minicomputer are somewhere between mainframe and microcomputer. For this reason, a minicomputer is often called a midrange computer. It is a work group computer system, a smaller but powerful multiuser system computer with excellent memories and processing speed. Like mainframe, minicomputer can handle much more input and output than a microcomputer. It can support about 50 terminals and requires an area of around 100 sq ft. users can access a central minicomputer through a terminal or a standard PC. Example: Prime 9755, VAX 7500, HP3000 series etc.

4.  Microcomputer:

            A computer, which is based on a microprocessor is called a microcomputer. It is a small, low cost digital compute. It requires small space, can be placed on a table, or even kept inside a briefcase. This computer has a central processing unit on a single chip. It is mainly used in office, house, school, shop, and store. The smallest of this category are laptop, notebook, palmtop, and PAD. Example: IBM PC, Apple/ Macintosh. 

2.1.      On the basis of application – Analog, Digital and Hybrid computers.

Analog Computer:

• It works on continuous data. It is used to measure natural or physical values.
• It is specific to a particular task. It is not versatile.
• Accuracy of analog computer is not so high in comparison to digital computer.
• Generally analog computer does not have storage capacity as it works on real time basis
• It also gives the output in the form of curve line or graph so it may not be meaningful to all

Digital Computer:

• Digital computer operates by counting rather than measuring.
• Digital computer is based on digital signal.
• They are the general purpose computer.
• They have storage capacity. They can store data internally or in external device also.
• These computers are programmable and can be used for multipurpose.
• The accuracy of digital computer is very high.
• It has faster processing speed.

Hybrid Computer:

Hybrid means the production of something by mixing two or more different components. Hybrid computer is also the combination of two distinct analog computer and digital computers. Generally, hybrid computer used in Aeroplane, Industries, Hospital etc.

• It works on continuous as well as discrete value.
• It also specific to a particular work and not versatile machine.
• It converts the analog values to digital values and vice-versa.
• It is not easily reprogrammable computer.
• It is very high cost.
• The examples: CT scan, Ultra Sonogram etc.

Difference between Micro Computer and Super computer:

Micro Computer	Super Computer
It is a less powerful computer	It is a more powerful computer
It is a slower computer in terms of processing	It is a faster computer in terms of processing
It is a general purpose computer	It is a special purpose computer
It is the smallest computer on the basis of size	It is a larger in size
It can be portable as well as non-portable	It is non-portable computer
It can be handled by only one person	Is requires numbers of experts or users to operate
It has less memory and storage capacity	It usually contains larger memory and storage capacity
It is the most popular computer among all	It is a rarely used for some specific tasks
It is used in office, home	It is used in weather forecasting, scientific research
Example: Desktop PC, laptop, Tablet PC	Example: CRAY X-MP/24, NEC-500, PRAM

Difference between Digital Computer and Analog computer:

Digital Computer	Analog Computer
These computer works with digits	These computers work with natural or physical values
It works upon discrete data	It works upon continuous data
It operates by counting and adding, i.e. it calculates	It operates by measuring and comparing
Its accuracy is high	Its accuracy is low
Results are obtained after complete computation	The output is continuous
It is general purpose in nature	It is a special purpose computer
Larger storage capacity (memory)	No or smaller storage capacity
Higher cost compared to analog computers	Lower cost compared to digital computer
It can be reprogrammed	Normally, it cannot be reprogrammed
Desktop computer is an example of a digital computer	Presley is an example of analog computer

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