Introduction To Computer
Introduction to Computer
Unit-1
A computer is an electronic machine, operating under the control of instructions stored in its own memory that can accept data, manipulate the data according to specified rules, produce results, and store the results for future use. Computers process data to create information. Data is a collection of raw unprocessed facts, figures, and symbols. Information is data that is organized, meaningful, and useful. To process data into information, a computer uses hardware and software. Hardware is the electric, electronic, and mechanical equipment that makes up a computer. Software is the series of instructions that tells the hardware how to perform tasks. Characteristics of computer
1. Speed: - As you know computer can work very fast. It takes only few seconds for calculations that we take hours to complete. You will be surprised to know that computer can perform millions (1,000,000) of instructions and even more per second. Therefore, we determine the speed of computer in terms of microsecond (10-6 part of a second) or nanosecond (10 to the power -9 part of a second). From this you can imagine how fast your computer performs work. 1/1000 or (10-3) sec……………………………..1 Millisecond (ms)
1/1000000 or (10-6) sec………………………....1 Microsecond (μs)
1/1000000000 or (10-9) sec …………………….1 Nanosecond (ns)
1/000000000000 or (10-12) sec…………………1 Picosecond (ps)
1/000000000000000 or (10-15) sec……………..1 Femtosecond (fm)
2. Accuracy: - The degree of accuracy of computer is very high and every calculation is performed with the same accuracy. The accuracy level is determined on the basis of design of computer. The errors in computer are due to human and inaccurate data.
3. Diligence: - A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it overpowers human being in routine type of work.
4. Versatility: - It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electric bills.
5. Storage: - The Computer has an in-built memory where it can store a large amount of data. You can also store data in secondary storage devices such as floppies, which can be kept outside your computer and can be carried to other computers.
4 bits………………………..................................1 Nibble
8 bits………………………..................................1 Byte
1024 Bytes ............................................................1 Kilobyte (KB)
1024 Kilobytes.......................................................1 Megabyte (MB)
1024 Megabytes.....................................................1 Gigabyte (GB)
1024 Gigabytes .....................................................1 Terabyte (TB)
6. No Feeling: - It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.
7. No IQ: - Computer is a dumb machine and it cannot do any work without instruction from the user. It performs the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in what sequence. So a computer cannot take its own decision as you can.
8. Power of Remembering: - Computer has the power of storing any amount of information or data. Any information can be stored and recalled as long as you require it, for any numbers of years. It depends entirely upon you how much data you want to store in a computer and when to lose or retrieve these data.
Limitations of computer
1. Sometime the failure in devices and programs can produce unreliable information.
2. Computer is a dull machine. It doesn’t have intelligence on it.
3. It cannot operate without human involvement.
4. Computers lack emotions.
Advantages and Disadvantages of computer
Advantages
a. Computers are always accurate and reliable than human.
b. They are faster than human in calculations.
c. They never feel exhausted and tired like human being.
d. They can perform complicated and difficult works which are hard for us.
e. They are versatile i.e. master in all types of work and fields like education, hospital, banks, etc.
f. It is used for communication between many peoples.
Disadvantages
a. They cannot operate without batteries or electricity.
b. Failure in devices and wrong information by users makes it unreliable.
c. It is an expensive device.
d. They can be used for computer crimes like hacking, sending viruses, etc.
Applications of Computer
Business :
A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which has made it an integrated part in all business organizations. Computer is used in business organizations for −
Payroll calculations
Budgeting
Sales analysis
Financial forecasting
Managing employee database
Maintenance of stocks, etc. Banking
Today, banking is almost totally dependent on computers.
Banks provide the following facilities −
Online accounting facility, which includes checking current balance, making deposits and overdrafts, checking interest charges, shares, and trustee records.
ATM machines which are completely automated are making it even easier for customers to deal with banks.
Insurance :
Insurance companies are keeping all records up-to-date with the help of computers. Insurance companies, finance houses, and stock booking firms are widely using computers for their concerns. Insurance companies are maintaining a database of all clients with information showing −
Procedure to continue with policies
Starting date of the policies
Next due installment of a policy
Maturity date
Interests due
Survival benefits
Bonus
Education:
The computer helps in providing a lot of facilities in the education system.
The computer provides a tool in the education system known as CBE (Computer Based Education).
CBE involves control, delivery, and evaluation of learning.
Computer education is rapidly increasing the graph of number of computer students.
There are a number of methods in which educational institutions can use a computer to educate the students.
It is used to prepare a database about performance of a student and analysis is carried out on this basis. Marketing In marketing, uses of the computer are following −
Advertising − With computers, advertising professionals create art and graphics, write and revise copy, and print and disseminate ads with the goal of selling more products.
Home Shopping − Home shopping has been made possible through the use of computerized catalogs that provide access to product information and permit direct entry of orders to be filled by the customers.
Healthcare :
Computers have become an important part in hospitals, labs, and dispensaries. They are being used in hospitals to keep the record of patients and medicines. It is also used in scanning and diagnosing different diseases. ECG, EEG, ultrasounds and CT scans, etc. are also done by computerized machines. Following are some major fields of health care in which computers are used.
Diagnostic System − Computers are used to collect data and identify the cause of illness.
Lab-diagnostic System − All tests can be done and the reports are prepared by computer.
Patient Monitoring System − These are used to check the patient's signs for abnormality such as in Cardiac Arrest, ECG, etc.
Pharma Information System − Computer is used to check drug labels, expiry dates, harmful side effects, etc.
Surgery − Nowadays, computers are also used in performing surgery. Engineering Design Computers are widely used for engineering purpose.
One of the major areas is CAD (Computer Aided Design) that provides creation and modification of images. Some of the fields are −
Structural Engineering − requires stress and strain analysis for design of ships, buildings, budgets, airplanes, etc.
Industrial Engineering − Computers deal with design, implementation, and improvement of integrated systems of people, materials, and equipment.
Architectural Engineering − Computers help in planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings.
Military Computers are largely used in defense. Modern tanks, missiles, weapons, etc. Military also employs computerized control systems. Some military areas where a computer has been used are −
Missile Control
Military Communication
Military Operation and Planning
Smart Weapons
Communication:
Communication is a way to convey a message, an idea, a picture, or speech that is received and understood clearly and correctly by the person for whom it is meant. Some main areas in this category are −
E-mail
Chatting
Usenet
FTP
Telnet
Video-conferencing
Government:
Computers play an important role in government services. Some major fields in this category are −
Budgets
Sales tax department
Income tax department
Computation of male/female ratio
Computerization of voters lists
Computerization of PAN card
Weather forecasting
Components of Computer
All types of computers follow the same basic logical structure and perform the following five basic operations for converting raw input data into information useful to their users.
Input Unit:
This unit contains devices with the help of which we enter data into the computer. This unit creates a link between the user and the computer. The input devices translate the information into a form understandable by the computer.
CPU (Central Processing Unit):
CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results, and instructions (program). It controls the operation of all parts of the computer. CPU itself has the following three components −
ALU (Arithmetic Logic Unit)
Memory Unit
Control Unit
Memory or Storage Unit:
This unit can store instructions, data, and intermediate results. This unit supplies information to other units of the computer when needed. It is also known as internal storage unit or the main memory or the primary storage or Random Access Memory (RAM). Its size affects speed, power, and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of the memory unit are −
It stores all the data and the instructions required for processing. It stores intermediate results of processing.
It stores the final results of processing before these results are released to an output device.
All inputs and outputs are transmitted through the main memory
Control Unit:
This unit controls the operations of all parts of the computer but does not carry out any actual data processing operations. Functions of this unit are −
It is responsible for controlling the transfer of data and instructions among other units of a computer.
It manages and coordinates all the units of the computer.
It obtains the instructions from the memory, interprets them, and directs the operation of the computer.
It communicates with Input/Output devices for transfer of data or results from storage.
It does not process or store data.
ALU (Arithmetic Logic Unit)
This unit consists of two subsections namely,
Arithmetic Section
Logic Section
Arithmetic Section
Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication, and division. All complex operations are done by making repetitive use of the above operations.
Logic Section
Function of logic section is to perform logic operations such as comparing, selecting, matching, and merging of data.
Output Unit
The output unit consists of devices with the help of which we get the information from the computer. This unit is a link between the computer and the users. Output devices translate the computer's output into a form understandable by the users.
History of computer
The computer, which is one of the most advanced discoveries of mankind, has got a long history. Around 3000 years before the birth of Jesus Christ, there were no any kinds of number system. So, people had to remember a lot of information. They felt the need to count the things. Then they started counting using their fingers. But the limited number of fingers had made it difficult for them to remember more facts. So, they used stones for counting or they made scratches on wall or tied knots in a rope. The history of computer is classified on the basis of age as follows:
1) Age of Mechanical Calculators
2) Age of Electromechanical Computers
3) Age of Electronic Computers
1) Age of Mechanical Calculators
a. Abacus:
It is manual calculating device. Basically an abacus consists of wires having pebbles or beads. The frame consists of two parts upper & lower. The upper part is called ‘heaven’ whereas lower part is called ‘earth’. The heaven consists of two beads whereas the earth part consists of five beads to each wire. The value of a bead on heaven part is five & one in earth part. Each abacus consists of eleven wires. Its exact origin is unknown. It may have originated in china, Egypt or Greece.
b. Pascal’s Calculator:
In 1642, French mathematician Blaise Pascal invented the first real calculating machine that could add and subtract numbers quickly, which was named as Pascal’s Calculator or Pascaline. It consists of numbered toothed wheels, each wheel having numbers from 0 to 9. A complete turning of first Wheel causes the 2nd wheel to move the next number. It has a simple monitor to see the result, too. Calculation including addition and subtraction was possible up to 8 digits, which was a great achievement at that time. The disadvantage of this machine was that it could not carry out multiplication and divisions.
c. Babbage’s Difference and Analytical engine:
In 1822, a professor of mathematics, Charles Babbage developed a machine called Difference engine in Cambridge University. It was made to calculate various mathematical function and logarithmic tables. Difference machine was intended to be steam powered, fully automatic, even to the printing of the resulting tables and commanded by a fixed instruction program. While working on the difference table, in 1833, he developed the new idea to build an Analytical Engine, which was to become a real ancestor of the modern day computer. That’s why he is known as “father of computer”. The analytical machine would operate on words of 50 digits and was able to store 1000 such numbers. The instructions for the machine were to be stored on punched cards like on Jacquard loom. He wanted to input data with the help of punched card and output (result) to be printed on copper plates. Babbage’s analytical engine and modern day computer are similar in their structure. But unfortunately, due to the lack of time and equipment’s, he was unable to complete this machine, so the world had to wait for another hundred years. Fig: Analytical Engine (Left) and Difference Engine (Right).
d. Lady Augusta Ada Lovelace:
After the death of Babbage, an English mathematician, Ada Lovelace, a long-time supporter of Babbage was successful in discovering some of the key elements of programming and program design. She got the idea of loop in the program. Not only this, she made the first program to be used in Babbage’s machine. So she is called “the first programmer”. To honor her contribution, the programming language used in American defense was named as ‘ADA’.
e. Hollerith’s machine:
In 1887, an American statistician, Herman Hollerith constructed a tabulating machine, to compute the statistics of 1890 US census. He used the punched cards to store data, with the holes representing data values. This machine can read 200 punched cards per minute. So, Hollerith’s punched cards method become very popular and widely used. In 1896, he established the Tabulating Machine Company to make and sell his invention. Later in 1923, this firm merged with other companies to form the IBM Corporation, which is the most popular and biggest company in computer manufacturing.
2) Age of Electromechanical Computers
f. Mark–I:
In 1937, Harvard professor, Howard Aiken, constructed an electromechanical computer named Mark-I (also known as Automatic Sequence Controlled Calculator), which could perform according to pre-programmed instruction automatically. Thus it is also called the first computer. It was based on Charles Babbage’s principle after 100 years of his death. Although it was very huge with dimension 51 ft. long, 8 ft. height and 3ft. wide using 18,000 vacuum tubes (electronic) with 7 lakhs 50 thousands parts, it was the milestone in history of computer. In 1944, Howard Aiken modified Mark-I and invented Mark-II, which used 19000 valves.
g. ABC (Atanasoff Berry Computer):
In 1938, John Atanasoff and Clifford Berry designed ABC (Atanasoff Berry Computer) for solving systems of simultaneous equation. It used 18000 valves and other 45 valves for internal logic and capacitors for storage of electrical charges. It used punched cards as secondary storage. 3) Age of Electronic Computers
h. John Von Neumann:
In 1944, Hungarian mathematician, Jon von Neumann gave the ideas: Computer instruction as well as the data being manipulated could be stored internally in the machine. So he is called the “father of stored program”. Before that, program required for the computer were integrated and written permanently in chips, so modification of program was not possible. But after Neumann, such programs were stored inside computer in some storage media, so modification was easy and flexible.
i. ENIAC (Electronic Numerical Integrator and Calculator):
In 1946, J. Presper Eckert and John W. Mauchly developed ENIAC. At that time ENIAC was the largest single electronic apparatus in the world. It was a large-scale, general-purpose digital electronic computer built from 17468 vacuum tubes. It was the first and last computer, which used decimal number system instead of binary system.
j. EDSAC (Electronic Delay Storage Automatic Computer):
It was invented by Maurice Wilkes in 1949. It also used vacuum tubes. Although started after EDVAC, it was completed before EDVAC. So, it became the first stored program computer.
k. EDVAC (Electronic Discrete Variable Automatic Computer):
It was developed by J. P. Eckert and J. Mauchly in 1952. Although started before, it was completed after EDSAC. It also used vacuum tubes and some internal storage.
l. UNIVAC (Universal Automatic Computer):
It was developed by J. P. Eckert and J. Mauchly in 1961. It was the first computer manufactured for commercial use and general purpose digital computer. Before this, all the computers were either for defenses or census.
Generations of Computer
Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to distinguish between varying hardware technologies. Nowadays, generation includes both hardware and software, which together make up an entire computer system. Following are the main five generations of computers. S.No Generation & Description
1 First Generation
The period of first generation: 1946-1959. Vacuum tube based.
2 Second Generation The period of second generation: 1959-1965. Transistor based.
3 Third Generation The period of third generation: 1965-1971. Integrated Circuit based.
4 Fourth Generation The period of fourth generation: 1971-1980. VLSI microprocessor based.
5 Fifth Generation The period of fifth generation: 1980-onwards. ULSI microprocessor based.
FIRST GENERATION
The computer, using vacuum tubes or valves as memory devices, are called first generation computers. Vacuum tubes are the devices in which a stream of electrons is controlled by electric and magnetic fields. Because, a vacuum must be provided in the form of an evacuated enclosure in which the electrons can move without collisions with gas molecules, these devices were called vacuum tubes. Lee De Forest invented it in 1908.
Characteristics:
1. Very big size and slower than other generation
2. They produced large amount of heat and prone to frequent hardware failure
3. Punch cards were used as secondary storage.
4. Machine level programming used.
5. Cost was very high and not available for commercial use.
6. Computing time is milliseconds Examples: Mark-I, EDVAC (Electronic Discrete Variable Computer), EDSAC (Electronic Delay Storage Automatic Computer), UNIVAC (Universal Automatic computer).
SECOND GENERATION
Second generation of the computer started after the invention of transistors. John Bardeen, Walter Brattain and William Shockley invented the transistor in 1947 at Bell Laboratory. There are two kinds of transistors, the bipolar transistor (also called the junction transistor) and the field effect transistor (FET). All computers, which use transistors as memory device, are categorized as second-generation computer.
Characteristics:
1. Transistors were smaller, faster, occupied less space and higher reliable compared to vacuum tubes. One transistor can do the tasks of 1,000 vacuum tubes.
2. Transistors required less electricity and emitted less heat than vacuum tubes.
3. Magnetic cores were developed for primary storage and magnetic tape and magnetic disk for secondary storage.
4. Second-generation computer replaced machine language with assembly language (abbreviated or mnemonic form) to replace long difficult binary codes for giving instructions.
5. High level languages such as COBOL (Common Business Oriented Language) and FORTRAN (Formula Translator) came in common use during this time.
6. The operating speed was increased up to the microseconds range. Examples: The examples of the second-generation computers are IBM 1401, IBM 1600, 7070, 7080, 7080, and ICL 1950/10 and Honey well 400 series.
THIRD GENERATION
The third generation computers replaced transistors with “Integrated circuits (IC)” popularly known as chips. An IC is an electronic circuit with a large number of components (many transistors, resistors and capacitors) built on a small silicon chip. The third generation computer use SSI (Small Scale Integration) and MSI (Medium Scale Integration) circuits for internal operations.
Characteristics:
1. Using ICs proved to be highly reliable, relatively inexpensive and faster.
2. Less human labor was required at assembly stage.
3. Operation speed increased beyond nanoseconds.
4. Computers became portable. They were smaller in size but had high memory.
5. The computer used programming languages such as Pascal and FORTRAN. Example: IBM 360 series, IBM 370 series, ICL 1900 series, ICL 2900, UNIVAC 9000
FOURTH GENERATION
The fourth generation computer use LSI (large Scale Integration) and VLSI (Very large Scale Integration) circuits for internal operations. VLSI has squeezed hundreds of LSI (1000 transistors) onto a single chip.
Characteristics:
1. Highly accurate and totally reliable.
2. Operation speed increased beyond Picoseconds and MIPS (Millions of Instruction per Seconds)
3. This chip reduced the physical size of the computer and increased their power.
4. Magnetic and optical storage devices. Examples: IBM PC, Apple/ Macintosh, Wang Laser, Letron etc.
FIFTH GENERATION (FUTURE GENERATION)
The fifth generation computer will use AI (Artificial Intelligence) and be based on advances in silicon technology, i.e. Gallium Arsenide (GaAs) termed as super- conductor or bio- chips. Scientists are now at work on these computers.
Characteristics:
1. They will be able to understand natural language, speak command, capacity to see their surrounding and will have thinking power called Artificial Intelligence (AI).
2. In contrast to present DIPS/LIPS (Data/Logic Information Processing System), the 5th generation computer will have KIPS (knowledge Information Processing System)
3. It will support parallel processing in full fledge.
Examples: There are different programs under way to develop fifth generation computer. ICOT program in Japan. MCC and DARPA project of USA. Alvey project of UK. The famous 5th generation computer is fictional HAL9000.
Classification of computers on the basis of size, purpose and technology.
On the basis of Size
1. Super Computers:
The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, nuclear energy research and petroleum exploration. Supercomputers are used by universities, government agencies, and large businesses. ANURAG is also an Indian super computer, other super computers are Cray-1, Titan, etc.
Advantages:
a. Solve bigger problems.
b. Run more problems in shorter time.
c. May save money.
Disadvantages:
a. Can be expensive.
b. Takes up a lot of space.
c. May only be good for specific applications.
2. Mainframe Computers:
These are also large in size. Both the super and mainframe computer are high speed computers performing billions of calculations per second. Mainframe computers on the other hand can support thousands of users at a time and it is used for data processing in large organization for information and data base management. But they are expensive and they generate a lot of heat. Mainframes are used by banks and many business to update inventory etc.
• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where many users need access to shared data and programs.
• Mainframes are also used as e-commerce servers, handling transactions over the Internet.
Modern mainframes Computers
1. IBM zSeries
2. System z9
3. System z10 servers
Advantages:
a. Huge Memory.
b. High speed compared to volume of data.
c. High security.
Disadvantages:
a. Cost of hardware: Normal persons can’t afford to have their own mainframe.
b. Special Operating System/Software.
c. Intense Space Occupied.
3. Mini Computers
Compare to mainframe these are mid-range computers, small in size and more compact and less expensive. They are designed for computerization of data, scientific research, industrial process, data collection and telephone switches. Minicomputers are multiprocessing system and can support upto 200 user at a time but the power of processing is not as great as the mainframe and supercomputers. Time-sharing, batch processing and online processing is available on these mid-range computers. Examples of Minicomputers
1. IBM System/3
2. Honeywell 200 3. TI-990
Mini Computers are smaller than mainframe, general purpose computers, and give computing power without adding the prohibitive expenses associated with larger systems. It is generally easier to use.
• Minicomputers usually have multiple terminals.
• Minicomputers may be used as network servers and Internet servers.
These are small version of mainframe computers designed to support more than one user at a time but many take up to (200) users at a time. It is not portable and it is expensive and it generates a lot of heat.
4. Micro Computers:
These are latest technology in computer to reduce the size of computer hence, the development of personal computer (PC3) indicating that an individual can now have computer at home and small offices. They are durable, cheap, and fast and generate less heat.
The following are the types of microcomputers:
i. Desktop Computers
ii. Laptop Computers
iii. Notebook Computers
iv. Palmtop Computers
i. Desktop Computer: A computer designed to fit comfortably on top of a desk, typically with the monitor sitting on top of the computer. Desktop model computers are broad and low, whereas tower model computers are narrow and tall. Because of their shape, desktop model computers are generally limited to three internal mass storage devices. Desktop models designed to be very small are sometimes referred to as slim line models.
ii. Laptop
Portable and compact personal computer with the same capabilities as a desktop computer. Laptop computers have an L-shape design and the screen can be lowered and closed to allow for easy transportation of the machine. The primary feature that attracts users to laptops over desktops is their portability. Laptop computers provide users the ability to run the machine using an internal battery or an outside power adapter.
iii. Notebook Computers
A notebook is an extremely lightweight personal computer. Note book computers typically weigh less than six pounds and are small enough to fit easily in a briefcase. Notebook computers use a variety of techniques, known as flat-panel technologies, to produce a lightweight and non-bulky display screen. In terms of computing power, modern notebook computers are nearly equivalent to personal computers. They have the same CPUs, memory capacity and disk drives. However, all this power in a small package is expensive. Notebook computers come with battery packs that enable you to run them without plugging them in. However, the batteries need to be recharged every few hours.
iv. Palmtop Computers:
These are very small computers designed to be operated on the palm like mobile phone, calculator, organizer etc. This type of computer is among the smallest size of computer.
According to Purpose:
a. General Purpose Computers:
A‘General Purpose Computer’ is a machine that is capable of carrying out some general data processing under program control. Refers to computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program.
b. Special Purpose Computers:
A computer that is designed to operate on a restricted class of problems. Special purpose computers are used to obtain patient diagnostic information.
On the basis of technology
1. Digital Computers:
Computers that uses binary digits to display discrete information is called digital computer. Information is in discrete form. It displays information in the form of text, graphics and pictures. The speed of digital computer is fast in nature. It is more accurate than analog computers. Digital computers are used for general purposes. It is easy to read and write. It doesn’t produce sound and it is used for programming.
2. Analogue Computers:
A Computer that uses analog signal to display information is called analog computer. Information is produced in continuous form and displayed in the form of curves. It is used to measure continuous physical quantity like current flow, temperature, heart bit, blood pressure etc. Analog computers are slower than digital computers. Accuracy is not always 100 %. Analog computers are used on special purposes and it is not used for programming.
3. Hybrid Computers:
A hybrid computer is a type of computer that is designed to provide the features and functions that are found by both the digital and the analog computers. A hybrid computer system offers a much cost effective method that is used to perform complex simulations.
On the basis of model
On the basis of model computer is classified as:
XT (Extended / Extra Technology) Computer
The computers that use 8086, 8088 microprocessor are called XT computers. The time periods for this computer are from 1975 - 1982. XT computers have processing speed of 4.77 MHz and are comparatively slow in speed. These processors are of 4, 8 or 16 bits of word length.
AT (Advanced Technology) Computer
With the development of 80286 microprocessor AT computer were introduced in the field of computers. The processors are of 8, 16, 32 or 64 bits of word length. The computers using Pentium I, Pentium pro & Pentium II are the examples of AT computers. The time periods for these computers are from 1982 - 1995. These computers can run any type of soft wares including text based as well as graphical base and processor speed of these computers is up to 233 MHz.
PS/2 (Personal System / 2) ComputerIBM started manufacturing next model of computer since 1990. This model is called PS? 2 computers. Most of the computers manufactured after 1990 including laptop, belongs to this model. These computers are refinement of AT computers. These computers can run almost all software & programs.
4. On the Basis of Brand
Computer has two world wide brands:
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. IBM PC is the largest computer manufacturing company establishing USA. The computer manufactures by IBM PC or branded computer. Personal Computer (PC) is the most important type of micro computer system. The micro computer manufactures by IBM Company are called IBM PC. These computers are reliable, durable and have better quality but they are costly.
Apple/Macintosh Computer
All the computers manufacture by apple cooperation, a leading computers manufacturing computer of USA are known as apple/Macintosh computers. The Apple series of micro computers was developed by Steve Wozniak & Steve Jobs in 1976. This used 8-bit microprocessor chips. These computers use their own software and hardware. They are totally different than that of IBM computers, In terms of both hardware and software. For e.g. software developed for apple computer can't run or IBM computers and vice-versa. Similarly, floppy disk formatting in IBM computer can't be recognized by apple Macintosh computer and vice-versa. It is popularly used in desktop publishing (DTP) houses as they provide better quality of graphic output.
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6. No Feeling: - It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.
7. No IQ: - Computer is a dumb machine and it cannot do any work without instruction from the user. It performs the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in what sequence. So a computer cannot take its own decision as you can.
8. Power of Remembering: - Computer has the power of storing any amount of information or data. Any information can be stored and recalled as long as you require it, for any numbers of years. It depends entirely upon you how much data you want to store in a computer and when to lose or retrieve these data.
Limitations of computer
1. Sometime the failure in devices and programs can produce unreliable information.
2. Computer is a dull machine. It doesn’t have intelligence on it.
3. It cannot operate without human involvement.
4. Computers lack emotions.
Advantages and Disadvantages of computer
Advantages
a. Computers are always accurate and reliable than human.
b. They are faster than human in calculations.
c. They never feel exhausted and tired like human being.
d. They can perform complicated and difficult works which are hard for us.
e. They are versatile i.e. master in all types of work and fields like education, hospital, banks, etc.
f. It is used for communication between many peoples.
Disadvantages
a. They cannot operate without batteries or electricity.
b. Failure in devices and wrong information by users makes it unreliable.
c. It is an expensive device.
d. They can be used for computer crimes like hacking, sending viruses, etc.
Applications of Computer
Business :
A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which has made it an integrated part in all business organizations. Computer is used in business organizations for −
Payroll calculations
Budgeting
Sales analysis
Financial forecasting
Managing employee database
Maintenance of stocks, etc. Banking
Today, banking is almost totally dependent on computers.
Banks provide the following facilities −
Online accounting facility, which includes checking current balance, making deposits and overdrafts, checking interest charges, shares, and trustee records.
ATM machines which are completely automated are making it even easier for customers to deal with banks.
Insurance :
Insurance companies are keeping all records up-to-date with the help of computers. Insurance companies, finance houses, and stock booking firms are widely using computers for their concerns. Insurance companies are maintaining a database of all clients with information showing −
Procedure to continue with policies
Starting date of the policies
Next due installment of a policy
Maturity date
Interests due
Survival benefits
Bonus
Education:
The computer helps in providing a lot of facilities in the education system.
The computer provides a tool in the education system known as CBE (Computer Based Education).
CBE involves control, delivery, and evaluation of learning.
Computer education is rapidly increasing the graph of number of computer students.
There are a number of methods in which educational institutions can use a computer to educate the students.
It is used to prepare a database about performance of a student and analysis is carried out on this basis. Marketing In marketing, uses of the computer are following −
Advertising − With computers, advertising professionals create art and graphics, write and revise copy, and print and disseminate ads with the goal of selling more products.
Home Shopping − Home shopping has been made possible through the use of computerized catalogs that provide access to product information and permit direct entry of orders to be filled by the customers.
Healthcare :
Computers have become an important part in hospitals, labs, and dispensaries. They are being used in hospitals to keep the record of patients and medicines. It is also used in scanning and diagnosing different diseases. ECG, EEG, ultrasounds and CT scans, etc. are also done by computerized machines. Following are some major fields of health care in which computers are used.
Diagnostic System − Computers are used to collect data and identify the cause of illness.
Lab-diagnostic System − All tests can be done and the reports are prepared by computer.
Patient Monitoring System − These are used to check the patient's signs for abnormality such as in Cardiac Arrest, ECG, etc.
Pharma Information System − Computer is used to check drug labels, expiry dates, harmful side effects, etc.
Surgery − Nowadays, computers are also used in performing surgery. Engineering Design Computers are widely used for engineering purpose.
One of the major areas is CAD (Computer Aided Design) that provides creation and modification of images. Some of the fields are −
Structural Engineering − requires stress and strain analysis for design of ships, buildings, budgets, airplanes, etc.
Industrial Engineering − Computers deal with design, implementation, and improvement of integrated systems of people, materials, and equipment.
Architectural Engineering − Computers help in planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings.
Military Computers are largely used in defense. Modern tanks, missiles, weapons, etc. Military also employs computerized control systems. Some military areas where a computer has been used are −
Missile Control
Military Communication
Military Operation and Planning
Smart Weapons
Communication:
Communication is a way to convey a message, an idea, a picture, or speech that is received and understood clearly and correctly by the person for whom it is meant. Some main areas in this category are −
Chatting
Usenet
FTP
Telnet
Video-conferencing
Government:
Computers play an important role in government services. Some major fields in this category are −
Budgets
Sales tax department
Income tax department
Computation of male/female ratio
Computerization of voters lists
Computerization of PAN card
Weather forecasting
Components of Computer
All types of computers follow the same basic logical structure and perform the following five basic operations for converting raw input data into information useful to their users.
Input Unit:
This unit contains devices with the help of which we enter data into the computer. This unit creates a link between the user and the computer. The input devices translate the information into a form understandable by the computer.
CPU (Central Processing Unit):
CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results, and instructions (program). It controls the operation of all parts of the computer. CPU itself has the following three components −
ALU (Arithmetic Logic Unit)
Memory Unit
Control Unit
Memory or Storage Unit:
This unit can store instructions, data, and intermediate results. This unit supplies information to other units of the computer when needed. It is also known as internal storage unit or the main memory or the primary storage or Random Access Memory (RAM). Its size affects speed, power, and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of the memory unit are −
It stores all the data and the instructions required for processing. It stores intermediate results of processing.
It stores the final results of processing before these results are released to an output device.
All inputs and outputs are transmitted through the main memory
Control Unit:
This unit controls the operations of all parts of the computer but does not carry out any actual data processing operations. Functions of this unit are −
It is responsible for controlling the transfer of data and instructions among other units of a computer.
It manages and coordinates all the units of the computer.
It obtains the instructions from the memory, interprets them, and directs the operation of the computer.
It communicates with Input/Output devices for transfer of data or results from storage.
It does not process or store data.
ALU (Arithmetic Logic Unit)
This unit consists of two subsections namely,
Arithmetic Section
Logic Section
Arithmetic Section
Function of arithmetic section is to perform arithmetic operations like addition, subtraction, multiplication, and division. All complex operations are done by making repetitive use of the above operations.
Logic Section
Function of logic section is to perform logic operations such as comparing, selecting, matching, and merging of data.
Output Unit
The output unit consists of devices with the help of which we get the information from the computer. This unit is a link between the computer and the users. Output devices translate the computer's output into a form understandable by the users.
History of computer
The computer, which is one of the most advanced discoveries of mankind, has got a long history. Around 3000 years before the birth of Jesus Christ, there were no any kinds of number system. So, people had to remember a lot of information. They felt the need to count the things. Then they started counting using their fingers. But the limited number of fingers had made it difficult for them to remember more facts. So, they used stones for counting or they made scratches on wall or tied knots in a rope. The history of computer is classified on the basis of age as follows:
1) Age of Mechanical Calculators
2) Age of Electromechanical Computers
3) Age of Electronic Computers
1) Age of Mechanical Calculators
a. Abacus:
It is manual calculating device. Basically an abacus consists of wires having pebbles or beads. The frame consists of two parts upper & lower. The upper part is called ‘heaven’ whereas lower part is called ‘earth’. The heaven consists of two beads whereas the earth part consists of five beads to each wire. The value of a bead on heaven part is five & one in earth part. Each abacus consists of eleven wires. Its exact origin is unknown. It may have originated in china, Egypt or Greece.
b. Pascal’s Calculator:
In 1642, French mathematician Blaise Pascal invented the first real calculating machine that could add and subtract numbers quickly, which was named as Pascal’s Calculator or Pascaline. It consists of numbered toothed wheels, each wheel having numbers from 0 to 9. A complete turning of first Wheel causes the 2nd wheel to move the next number. It has a simple monitor to see the result, too. Calculation including addition and subtraction was possible up to 8 digits, which was a great achievement at that time. The disadvantage of this machine was that it could not carry out multiplication and divisions.
c. Babbage’s Difference and Analytical engine:
In 1822, a professor of mathematics, Charles Babbage developed a machine called Difference engine in Cambridge University. It was made to calculate various mathematical function and logarithmic tables. Difference machine was intended to be steam powered, fully automatic, even to the printing of the resulting tables and commanded by a fixed instruction program. While working on the difference table, in 1833, he developed the new idea to build an Analytical Engine, which was to become a real ancestor of the modern day computer. That’s why he is known as “father of computer”. The analytical machine would operate on words of 50 digits and was able to store 1000 such numbers. The instructions for the machine were to be stored on punched cards like on Jacquard loom. He wanted to input data with the help of punched card and output (result) to be printed on copper plates. Babbage’s analytical engine and modern day computer are similar in their structure. But unfortunately, due to the lack of time and equipment’s, he was unable to complete this machine, so the world had to wait for another hundred years. Fig: Analytical Engine (Left) and Difference Engine (Right).
d. Lady Augusta Ada Lovelace:
After the death of Babbage, an English mathematician, Ada Lovelace, a long-time supporter of Babbage was successful in discovering some of the key elements of programming and program design. She got the idea of loop in the program. Not only this, she made the first program to be used in Babbage’s machine. So she is called “the first programmer”. To honor her contribution, the programming language used in American defense was named as ‘ADA’.
e. Hollerith’s machine:
In 1887, an American statistician, Herman Hollerith constructed a tabulating machine, to compute the statistics of 1890 US census. He used the punched cards to store data, with the holes representing data values. This machine can read 200 punched cards per minute. So, Hollerith’s punched cards method become very popular and widely used. In 1896, he established the Tabulating Machine Company to make and sell his invention. Later in 1923, this firm merged with other companies to form the IBM Corporation, which is the most popular and biggest company in computer manufacturing.
2) Age of Electromechanical Computers
f. Mark–I:
In 1937, Harvard professor, Howard Aiken, constructed an electromechanical computer named Mark-I (also known as Automatic Sequence Controlled Calculator), which could perform according to pre-programmed instruction automatically. Thus it is also called the first computer. It was based on Charles Babbage’s principle after 100 years of his death. Although it was very huge with dimension 51 ft. long, 8 ft. height and 3ft. wide using 18,000 vacuum tubes (electronic) with 7 lakhs 50 thousands parts, it was the milestone in history of computer. In 1944, Howard Aiken modified Mark-I and invented Mark-II, which used 19000 valves.
g. ABC (Atanasoff Berry Computer):
In 1938, John Atanasoff and Clifford Berry designed ABC (Atanasoff Berry Computer) for solving systems of simultaneous equation. It used 18000 valves and other 45 valves for internal logic and capacitors for storage of electrical charges. It used punched cards as secondary storage. 3) Age of Electronic Computers
h. John Von Neumann:
In 1944, Hungarian mathematician, Jon von Neumann gave the ideas: Computer instruction as well as the data being manipulated could be stored internally in the machine. So he is called the “father of stored program”. Before that, program required for the computer were integrated and written permanently in chips, so modification of program was not possible. But after Neumann, such programs were stored inside computer in some storage media, so modification was easy and flexible.
i. ENIAC (Electronic Numerical Integrator and Calculator):
In 1946, J. Presper Eckert and John W. Mauchly developed ENIAC. At that time ENIAC was the largest single electronic apparatus in the world. It was a large-scale, general-purpose digital electronic computer built from 17468 vacuum tubes. It was the first and last computer, which used decimal number system instead of binary system.
j. EDSAC (Electronic Delay Storage Automatic Computer):
It was invented by Maurice Wilkes in 1949. It also used vacuum tubes. Although started after EDVAC, it was completed before EDVAC. So, it became the first stored program computer.
k. EDVAC (Electronic Discrete Variable Automatic Computer):
It was developed by J. P. Eckert and J. Mauchly in 1952. Although started before, it was completed after EDSAC. It also used vacuum tubes and some internal storage.
l. UNIVAC (Universal Automatic Computer):
It was developed by J. P. Eckert and J. Mauchly in 1961. It was the first computer manufactured for commercial use and general purpose digital computer. Before this, all the computers were either for defenses or census.
Generations of Computer
Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to distinguish between varying hardware technologies. Nowadays, generation includes both hardware and software, which together make up an entire computer system. Following are the main five generations of computers. S.No Generation & Description
1 First Generation
The period of first generation: 1946-1959. Vacuum tube based.
2 Second Generation The period of second generation: 1959-1965. Transistor based.
3 Third Generation The period of third generation: 1965-1971. Integrated Circuit based.
4 Fourth Generation The period of fourth generation: 1971-1980. VLSI microprocessor based.
5 Fifth Generation The period of fifth generation: 1980-onwards. ULSI microprocessor based.
FIRST GENERATION
The computer, using vacuum tubes or valves as memory devices, are called first generation computers. Vacuum tubes are the devices in which a stream of electrons is controlled by electric and magnetic fields. Because, a vacuum must be provided in the form of an evacuated enclosure in which the electrons can move without collisions with gas molecules, these devices were called vacuum tubes. Lee De Forest invented it in 1908.
Characteristics:
1. Very big size and slower than other generation
2. They produced large amount of heat and prone to frequent hardware failure
3. Punch cards were used as secondary storage.
4. Machine level programming used.
5. Cost was very high and not available for commercial use.
6. Computing time is milliseconds Examples: Mark-I, EDVAC (Electronic Discrete Variable Computer), EDSAC (Electronic Delay Storage Automatic Computer), UNIVAC (Universal Automatic computer).
SECOND GENERATION
Second generation of the computer started after the invention of transistors. John Bardeen, Walter Brattain and William Shockley invented the transistor in 1947 at Bell Laboratory. There are two kinds of transistors, the bipolar transistor (also called the junction transistor) and the field effect transistor (FET). All computers, which use transistors as memory device, are categorized as second-generation computer.
Characteristics:
1. Transistors were smaller, faster, occupied less space and higher reliable compared to vacuum tubes. One transistor can do the tasks of 1,000 vacuum tubes.
2. Transistors required less electricity and emitted less heat than vacuum tubes.
3. Magnetic cores were developed for primary storage and magnetic tape and magnetic disk for secondary storage.
4. Second-generation computer replaced machine language with assembly language (abbreviated or mnemonic form) to replace long difficult binary codes for giving instructions.
5. High level languages such as COBOL (Common Business Oriented Language) and FORTRAN (Formula Translator) came in common use during this time.
6. The operating speed was increased up to the microseconds range. Examples: The examples of the second-generation computers are IBM 1401, IBM 1600, 7070, 7080, 7080, and ICL 1950/10 and Honey well 400 series.
THIRD GENERATION
The third generation computers replaced transistors with “Integrated circuits (IC)” popularly known as chips. An IC is an electronic circuit with a large number of components (many transistors, resistors and capacitors) built on a small silicon chip. The third generation computer use SSI (Small Scale Integration) and MSI (Medium Scale Integration) circuits for internal operations.
Characteristics:
1. Using ICs proved to be highly reliable, relatively inexpensive and faster.
2. Less human labor was required at assembly stage.
3. Operation speed increased beyond nanoseconds.
4. Computers became portable. They were smaller in size but had high memory.
5. The computer used programming languages such as Pascal and FORTRAN. Example: IBM 360 series, IBM 370 series, ICL 1900 series, ICL 2900, UNIVAC 9000
FOURTH GENERATION
The fourth generation computer use LSI (large Scale Integration) and VLSI (Very large Scale Integration) circuits for internal operations. VLSI has squeezed hundreds of LSI (1000 transistors) onto a single chip.
Characteristics:
1. Highly accurate and totally reliable.
2. Operation speed increased beyond Picoseconds and MIPS (Millions of Instruction per Seconds)
3. This chip reduced the physical size of the computer and increased their power.
4. Magnetic and optical storage devices. Examples: IBM PC, Apple/ Macintosh, Wang Laser, Letron etc.
FIFTH GENERATION (FUTURE GENERATION)
The fifth generation computer will use AI (Artificial Intelligence) and be based on advances in silicon technology, i.e. Gallium Arsenide (GaAs) termed as super- conductor or bio- chips. Scientists are now at work on these computers.
Characteristics:
1. They will be able to understand natural language, speak command, capacity to see their surrounding and will have thinking power called Artificial Intelligence (AI).
2. In contrast to present DIPS/LIPS (Data/Logic Information Processing System), the 5th generation computer will have KIPS (knowledge Information Processing System)
3. It will support parallel processing in full fledge.
Examples: There are different programs under way to develop fifth generation computer. ICOT program in Japan. MCC and DARPA project of USA. Alvey project of UK. The famous 5th generation computer is fictional HAL9000.
Classification of computers on the basis of size, purpose and technology.
On the basis of Size
1. Super Computers:
The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, nuclear energy research and petroleum exploration. Supercomputers are used by universities, government agencies, and large businesses. ANURAG is also an Indian super computer, other super computers are Cray-1, Titan, etc.
Advantages:
a. Solve bigger problems.
b. Run more problems in shorter time.
c. May save money.
Disadvantages:
a. Can be expensive.
b. Takes up a lot of space.
c. May only be good for specific applications.
2. Mainframe Computers:
These are also large in size. Both the super and mainframe computer are high speed computers performing billions of calculations per second. Mainframe computers on the other hand can support thousands of users at a time and it is used for data processing in large organization for information and data base management. But they are expensive and they generate a lot of heat. Mainframes are used by banks and many business to update inventory etc.
• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where many users need access to shared data and programs.
• Mainframes are also used as e-commerce servers, handling transactions over the Internet.
Modern mainframes Computers
1. IBM zSeries
2. System z9
3. System z10 servers
Advantages:
a. Huge Memory.
b. High speed compared to volume of data.
c. High security.
Disadvantages:
a. Cost of hardware: Normal persons can’t afford to have their own mainframe.
b. Special Operating System/Software.
c. Intense Space Occupied.
3. Mini Computers
Compare to mainframe these are mid-range computers, small in size and more compact and less expensive. They are designed for computerization of data, scientific research, industrial process, data collection and telephone switches. Minicomputers are multiprocessing system and can support upto 200 user at a time but the power of processing is not as great as the mainframe and supercomputers. Time-sharing, batch processing and online processing is available on these mid-range computers. Examples of Minicomputers
1. IBM System/3
2. Honeywell 200 3. TI-990
Mini Computers are smaller than mainframe, general purpose computers, and give computing power without adding the prohibitive expenses associated with larger systems. It is generally easier to use.
• Minicomputers usually have multiple terminals.
• Minicomputers may be used as network servers and Internet servers.
These are small version of mainframe computers designed to support more than one user at a time but many take up to (200) users at a time. It is not portable and it is expensive and it generates a lot of heat.
4. Micro Computers:
These are latest technology in computer to reduce the size of computer hence, the development of personal computer (PC3) indicating that an individual can now have computer at home and small offices. They are durable, cheap, and fast and generate less heat.
The following are the types of microcomputers:
i. Desktop Computers
ii. Laptop Computers
iii. Notebook Computers
iv. Palmtop Computers
i. Desktop Computer: A computer designed to fit comfortably on top of a desk, typically with the monitor sitting on top of the computer. Desktop model computers are broad and low, whereas tower model computers are narrow and tall. Because of their shape, desktop model computers are generally limited to three internal mass storage devices. Desktop models designed to be very small are sometimes referred to as slim line models.
ii. Laptop
Portable and compact personal computer with the same capabilities as a desktop computer. Laptop computers have an L-shape design and the screen can be lowered and closed to allow for easy transportation of the machine. The primary feature that attracts users to laptops over desktops is their portability. Laptop computers provide users the ability to run the machine using an internal battery or an outside power adapter.
iii. Notebook Computers
A notebook is an extremely lightweight personal computer. Note book computers typically weigh less than six pounds and are small enough to fit easily in a briefcase. Notebook computers use a variety of techniques, known as flat-panel technologies, to produce a lightweight and non-bulky display screen. In terms of computing power, modern notebook computers are nearly equivalent to personal computers. They have the same CPUs, memory capacity and disk drives. However, all this power in a small package is expensive. Notebook computers come with battery packs that enable you to run them without plugging them in. However, the batteries need to be recharged every few hours.
iv. Palmtop Computers:
These are very small computers designed to be operated on the palm like mobile phone, calculator, organizer etc. This type of computer is among the smallest size of computer.
According to Purpose:
a. General Purpose Computers:
A‘General Purpose Computer’ is a machine that is capable of carrying out some general data processing under program control. Refers to computers that follow instructions, thus virtually all computers from micro to mainframe are general purpose. Even computers in toys, games and single-function devices follow instructions in their built-in program.
b. Special Purpose Computers:
A computer that is designed to operate on a restricted class of problems. Special purpose computers are used to obtain patient diagnostic information.
On the basis of technology
1. Digital Computers:
Computers that uses binary digits to display discrete information is called digital computer. Information is in discrete form. It displays information in the form of text, graphics and pictures. The speed of digital computer is fast in nature. It is more accurate than analog computers. Digital computers are used for general purposes. It is easy to read and write. It doesn’t produce sound and it is used for programming.
2. Analogue Computers:
A Computer that uses analog signal to display information is called analog computer. Information is produced in continuous form and displayed in the form of curves. It is used to measure continuous physical quantity like current flow, temperature, heart bit, blood pressure etc. Analog computers are slower than digital computers. Accuracy is not always 100 %. Analog computers are used on special purposes and it is not used for programming.
3. Hybrid Computers:
A hybrid computer is a type of computer that is designed to provide the features and functions that are found by both the digital and the analog computers. A hybrid computer system offers a much cost effective method that is used to perform complex simulations.
On the basis of model
On the basis of model computer is classified as:
XT (Extended / Extra Technology) Computer
The computers that use 8086, 8088 microprocessor are called XT computers. The time periods for this computer are from 1975 - 1982. XT computers have processing speed of 4.77 MHz and are comparatively slow in speed. These processors are of 4, 8 or 16 bits of word length.
AT (Advanced Technology) Computer
With the development of 80286 microprocessor AT computer were introduced in the field of computers. The processors are of 8, 16, 32 or 64 bits of word length. The computers using Pentium I, Pentium pro & Pentium II are the examples of AT computers. The time periods for these computers are from 1982 - 1995. These computers can run any type of soft wares including text based as well as graphical base and processor speed of these computers is up to 233 MHz.
PS/2 (Personal System / 2) ComputerIBM started manufacturing next model of computer since 1990. This model is called PS? 2 computers. Most of the computers manufactured after 1990 including laptop, belongs to this model. These computers are refinement of AT computers. These computers can run almost all software & programs.
4. On the Basis of Brand
Computer has two world wide brands:
IBM PC
The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. IBM PC is the largest computer manufacturing company establishing USA. The computer manufactures by IBM PC or branded computer. Personal Computer (PC) is the most important type of micro computer system. The micro computer manufactures by IBM Company are called IBM PC. These computers are reliable, durable and have better quality but they are costly.
Apple/Macintosh Computer
All the computers manufacture by apple cooperation, a leading computers manufacturing computer of USA are known as apple/Macintosh computers. The Apple series of micro computers was developed by Steve Wozniak & Steve Jobs in 1976. This used 8-bit microprocessor chips. These computers use their own software and hardware. They are totally different than that of IBM computers, In terms of both hardware and software. For e.g. software developed for apple computer can't run or IBM computers and vice-versa. Similarly, floppy disk formatting in IBM computer can't be recognized by apple Macintosh computer and vice-versa. It is popularly used in desktop publishing (DTP) houses as they provide better quality of graphic output.
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