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Introduction
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:
- Age of Mechanical Calculators
- Age of Electromechanical Computers
- 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.
Fig: Old Abacus.
Fig: Modern Abacus.
Unit – 1 Introduction to Computer
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.
Pascal‘s Pascaline.
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 equipments, he was unable to complete this machine,
so the world had to wait for another hundred years.
Fig: Difference Engine
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 Computer
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.
Fig: ENIAC
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.
Fig: UNIVAC
Over View of Generation of Computer
In 1962, scientists decided to classify computer into different classes according to the device technology and system architecture. The computers are classified into five groups. These groups are called generation of computer. The classification, their time period and memory device are given below:
Generation Time Duration Electronic Device Used
First Generation 1940 - 1956 Vacuum tubes or valves
Second Generation 1956 – 1963 Transistors
Third Generation 1963 - 1971 Integrated Circuits (ICs)
Fourth Generation 1971 - till now VLSI or Microprocessor
Fifth Generation Present and Beyond Bio-chips, superconductors, Artificial Intelligence
1. First Generation:
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts. The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.
5. Fifth Generation:
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.
Types of Computer
The computers are classified on the basis of size, work, brand and model. They are listed as below:-
1. On the basis of SIZE
- Micro Computer
- Mini Computer
- Mainframe Computer
- Super Computer
2. On the basis of WORK
- Analog Computer
- Digital Computer
- Hybrid Computer
3. On the basis of BRAND
- IBM Computer (IBM PC and IBM Compatible)
- Apple/Macintosh Computer
4. On the basis of MODEL
- XT Computer
- AT Computer
- PS/2 Computer 1. On the basis of size
Super Computers
Super computers are the most powerful and fastest computers among digital computers.
These computers are capable of handing huge amounts of calculations that are beyond
human capabilities. They can perform trillions of instructions per second (TIPS).
Some of the today‘s super computers have the computing capability equal to that of
40,000 microcomputers.
These computers cost in 15 – 20 million-dollar range (most expensive). They are mostly
used in weather forecasting, scientific research, human genome mapping, modeling
complex process like nuclear fusion and nuclear fission, satellite launching, etc.
They need large space and temperature controlled room.
Example: CRAY X-MP/24 NEC-500, PARAM, ANURAG etc.
Mainframe Computers
Mainframe computer is a very large and powerful computing system.
It is a general-purpose computer system designed for large-scale data processing.
Very large in size with approximate an area of 1000 sq. ft.
It can supports more than 100 terminals.
They are suitable for big organizations, banks, and industries etc.
They can be used in networking systems.
Some popular mainframes are IBM 1401, ICL 2950/10, ICL 39, and CYBER 170.
Mini computers
Also called as midrange computers since its capability is somewhere between those of
mainframes and microcomputers.
Minicomputers are similar to the mainframe computers but they are comparatively small
and less expensive.
These are the medium sized computers.
They can support 50 terminal
They require area of 100 sq. ft.
These computers are useful for small business organizations, industries universities etc.
Example: Prime 9755, VAX 7500, HCL, MAGNUM etc.
Micro computers
Also called as Personal Computer
A computer, which is based on microprocessor, is called microcomputer.
It is a small, low cost, digital computer.
It requires small space, can be placed on a table or even kept inside a briefcase.
These computers have central processing unit on a single chip.
They are mainly used in offices, homes, schools, shops, stores etc.
Examples: IBM PC, Apple/Macintosh computer etc.
The microcomputers in non-portable categories are:
a) Desktop Computer
b) Workstation Computer
c) Network Computer
The microcomputers in portable categories are:
a) Notebook computers
b) Personal digital Assistance (PDA)
c) Tablet PC
- Some of the analog devices are thermometer, barometer, speedometer, ammeter etc.
- Example of analog computer is ―Plesley‖
Digital computer
- The computer which accepts discrete data (discontinuous data) is known as digital computer.
- Digital computers are mostly used for general purpose.
- Digital computers are faster than analog computer and more accurate.
- It has large memory capacity.
- Example, IBM PC, IBM Compatible, Apple / Macintosh etc
Differences between Digital Computer and Analog Computer:
Digital Computer Analog Computer
1. It works upon discrete data. 1. It works upon continuous data.
2. It operates by counting and adding. 2. It operates by measuring.
3. Faster than analog computer. 3. Slower than digital computer.
4. Its accuracy is high. 4. Its accuracy is low
5. Results are obtained after complete
computation.
5. Output is continuous.
6. It calculates 6. It compares and measures.
7. It is multipurpose in nature 7. It is used for special purposes
Different Types of Digital Computer:
General-purpose computer
It is the one that can work on different types of programs input to it and thus be used in countless
application, i.e., these computers are designed to do wide range of information processing tasks,
from scientific to commercial file processing. It can be used to prepare sales report, banking
system, payroll etc.
Special purpose computer
They are designed to perform a specific task. The programs to carry out the task are permanently
stored in the computer memory. These types of computer work efficiently but such computers
are not versatile [can not be used in various field].
Hybrid Computer
A computer, which has a combined feature of both analog and digital computers, is called hybrid
computer. It can perform the tasks of an analog computer as well as digital computer. It can
transfer data from analog to digital and vice-versa. It has high Cost. Here are two functional
examples:
During the launching of rockets, the analog computers measure the speed of the rocket,
temperature and pressure of atmosphere. These measurements are then converted into
digital signals and supplied to the digital computer to analyze the data for taking
appropriate steps on launching.
In hospital, analog devices measure the temperature and blood pressure of patients. Then
these measurements are converted into digital signal and fed to the digital computer that
monitors the patient‘s vital signs.
3. On the basis of Brand
IBM PC
IBM PC is a microcomputer produced by IBM Company. It is a leading company for the market
of mainframe and PCs. It uses the processors, multimedia devices and some other hardware parts
developed by some other companies like Intel but use the principal of its own. So all the
computer developed by IBM Company are called IBM computers.
IBM Compatible
IBM Compatible can use hardware and software designed for the IBM PC. The internal
architecture of IBM compatible is similar to IBM PC. So they are called duplicate computers.
Examples are: Epson, Acer etc.
Apple/Macintosh
Apple Corporation was established in1970 AD in USA. Its computers are called
Apple/Macintosh (Mac) computers. The internal architecture of these computers is totally
different from that of IBM. They have their own software.
4. On the basis of Model
XT Computers XT (extra or extended Technology) computers are old technology computers with much slower processing speed (not more than 4.77MHz). Advance GUI based software like windows can‘t be run in these computers. Everything was based on text-based system. Serial number of processors was like 8080, 8086, and 8088. I/O devices were not flexible and faster.
AT Computers AT (Advanced Technology) computers are the new technology computers. They are faster in processing (more than 2GHz) and can run any type of software whether that is text based or GUI based. Serial number of processors is 80286, 80386, and 80486, Pentium Series. I/O devices are interactive, flexible and faster.
PS/2 Computers Actually, these are not totally different model of computers but are refinement of AT computers. These models were built after 1990s and mostly used in laptop computers. OS/2 operating system was used at the beginning but the now a days, windows operating system is in leading.
