The document provides an introduction to computers, including definitions, comparisons to human abilities and limitations, and classifications. It defines a computer as an electronic device that can perform mathematical, logical and graphical manipulations by receiving input, processing data according to instructions, and providing output. Computers are classified by their processing type (analog, digital, hybrid), purpose (special purpose, general purpose), and physical attributes (mainframes, supercomputers, mini computers, microcomputers). The document also briefly discusses the history of computing from the abacus to modern generations of computers.

1. Chapter 1
Introduction to Computer

2. Definitions of Computer
Computer is an electronic device that can perform activities that involve
 Mathematical,
 Logical and graphical manipulations
It performs the following three operations in sequence
 It receives data & instructions from the input device
 Processes the data as per instructions
 Provides the result (output) in a desired form
According to artificial intelligence computer is
 Computer is similar to human being, but without thinking power

3. Computers vs. Human Beings
Human Computer
 Can Think  Cannot think by itself
 Gets Mental Tiredness  Never gets Tiredness
 May do mistake  Can’t do mistake by itself
 Has limited speed  Very High Speed
 Has limited Memory
 Accuracy may be missing
 More Amount of memory
 Never missing
Ability of a Human to do anything a computer can do but a computer cannot do everything a human can do

4. Cont.
Operations Performed by a Computer Corresponding Actions Performed by a Human
 Hold instruction in internal storage  Remember a set of instructions
 Read data in machine readable form  Read data in written or printed form and memorize it or file it.
 Perform arithmetic Computations  Can perform arithmetic operations
 Make comparisons  Can make comparisons
 Retrieve any data from internal memory or secondary storage  Remember data or retrieve data from file
 Output the results on an output device  Speak or Write the result on paper

5. Characteristics of Computer
 High speed
 the ability to perform routine tasks at a greater speed
 Accuracy
 the ability to perform tasks in a way that ensures accuracy
 Storage
 computers can store large amount of information
 Automation
 computers can be instructed to perform complex tasks automatically
 Diligence
 computers can perform the same task repeatedly & with the same accuracy without getting tired.

6. Cont.
Versatility
 computers are flexible to perform both simple and complex tasks
Cost effectiveness
 computers reduce the amount of paper work and human effort, thereby reducing costs.

7. Limitation of computers
Computers need clear & complete instructions to perform a task accurately
Computers cannot think
Computers cannot learn by experience
 Why we Use Computers?
 computer can save your time and money,
 increase your productivity, and process information with speed and accuracy.
 Store and process large amount of information with high speed and accuracy
 Transmit information across continents via communication channels
 Perform complex mathematical computations and make comparisons
 Monitor ongoing industrial operations

8. Application Areas of computer
 Accounting
 Payroll preparation
 General Shops
 Small calculations like Billing
 Airlines and Railways
 Reservation of Tickets
 Hospital
 To store patient information
 Education
 Educational tutorials

9. Types of Computers
Their differences depend on different categories of characteristics
Classification by the method of operation (processing)
 Computers are classified by the type of data they are designed to process
Classification by purpose of application
 Computers are classified by the way they are designed to solve problem
Classification by physical capacity, price, size, and performance
 Computers are classified by their capacity and prize

10. Classification by the method of operation
Analog Computers
 operate by measuring
 They deal with continues variables, they don’t compete directly with numbers
 they operate by measuring physical magnitude such as pressure, temperature, voltage, current and etc.
 use analog signals for calculating and transmitting data
 Electrical signals on a telephone line are nothing but analog data representing the original voice
Examples
 Thermometer
 Voltmeter

11. Cont.
Digital Computers
 The word digital is derived from the
word “digit”.
 The word digit simply means numeral
 deal with discrete variables
 they operate by counting rather than
measuring
 They operate directly up on numbers
(or digits) that represent numbers,
letters, or other special symbols
 use digital signals to calculate and
transmit data
 The digital signal has only two states in
which it can be represented.
 They are ON and OFF or HIGH and
LOW or 1 and 0
 The result obtained from the digital
computer is more accurate when
compared to the analog computers.
 Examples
 Abacus and desk & pocket computers

12. Hybrid computers
 Combination of analog and digital computers
 processes the information by
 collecting input data with analog method,
 converts it into digital quantities,
 processes the digital values and
 converts the output from digital to analog form
 examples In hospital insensitive-care unit
 analog devices measure a patient’s heart function, temperature and other vital signs.
 These measurements converted into numbers and supplied to a digital component in the system.
 This component is used to monitor the patient’s vital signs and to send an immediate signal to the nurse’s station if any
abnormal readings are detected.

13. Classification by purpose of application
Special purpose computers
 Designed to perform one specific task.
 Instructions is built into, or permanently stored in the machine.
 Specialization results in the given task being performed very quickly and efficiently.
 It is inflexible and cannot be easily used to perform other operations.
 Past, it was expensive.
 Now-a-days, for example, new cars have such devices installed to monitor and control fuel, ignition and
other system.
 Some of the areas where these computers are being used are – soil testing, drip irrigation, medical
scanning, traffic signals, spacecraft, rocket technology etc.…

14. Cont.
Most analog computers are special purpose computers.
Examples
 The public telephone box
 Traffic control system
 Ticket machines (used in grocery, super market etc.)
 Pocket-calculators.
 Counters etc.

15. General purpose computers
is one that has the ability to store different programs of instructions.
Performs a variety of operations through the use of “store program concept”.
It is designed to do a wide variety of jobs rather than perform a specific activity.
It is also called personal computers (PC’s).
Examples
 Micro computers
 Mini computers
 workstation
 Super computers etc.

16. Classification by physical capacity, price,
size, and performance
This classification is for general purpose computer
Mainframe computers
 The word mainframe refers to mean the “Central Processor”
 used by multinational companies or by companies have many branches
 banks, airlines, insurance
 They are used in applications like weather forecasting, space applications etc.
 they support a large number of terminals for use by a variety of users simultaneously, but they are
expensive
 Smaller than in size and capacity, lower in speed & memory capacity than the super computers

17. Cont.
The older ones used punched card for data input
Computers are more powerful in processing, faster in speed, have large
memory, and very expensive when compared to the mini and microcomputers
Their size varies depending on how many concurrent users they are serving – from
a few hundreds to thousands
when used in networks and has the capacity to support many powerful peripheral
devices

18. Super computers
Are the largest, fastest, most expensive and very powerful type of computer
They have
 speed of hundreds of millions of operation per second,
 a primary memory capacity of about 80 million characters, and
 a secondary memory of capacity of about 20 times its primary memory
They are multi-user systems in intercontinental range
They can carry out enormously complex scientific calculations
They are used to process huge amount of data and are commonly used in
 space technology centers, meteorology stations, astronomical observatories, inter-continental communications,
and airline organizations and so on.

19. Cont.
They occupy specially designed air-conditioned rooms
are often used for research and to process complex scientific applications like
 weather forecasting,
 oil exploration,
 aircraft design,
 mathematical research etc.
Unlike microcomputers, which generally have only one CPU, super computers have
hundreds of processors.
CRAY-I is an example of super computer.

20. Microcomputers
It is the most widely used type of computers.
They are single users, can fit on desktops, are
of varying capacity and easy to handle.
sometimes referred as personal computers.
They have video display unit for output
purpose.
Data is entered through the keyboard and by
the help of floppy disk.
Computers that can either fit next to a desk
(called the Desktop) or can be carried around
(called the Laptop and Notebook).
use microprocessor as its important device.
Microprocessor is a chip used to perform
arithmetic and logical operations.
These computers can be used either as a
standalone machine or connected to a
network.
Microcomputers are used for general
purpose business applications such as
 invoicing,
 accounting etc.

21. Mini computers
It has relatively lower speed, can handle
multi-users, and is smaller in size than the
mainframe computers.
They use terminals for inputs and output.
Mini computers are used in small
organizations.
Are bigger in size, faster in speed, have
more memory capacity and expensive
when compared to the microcomputers.
Minicomputers can be used for general
purpose applications and as a server for
small networks.
These computers are relatively small but
expensive computer with somewhat
limited input and output capabilities.
Minicomputers use large hard-disk units as
online secondary storage.
It can serve multi-users simultaneously.

22. History of computer and generations of
computer
History of computer
Abacus
 emerged about 5,000 years ago in Asia Minor
and is still in use today
 may be considered the first computer
Generations of computer
 People have been processing data and
information since prehistoric times.
 The development of the computer that
revolutionized information processing.
ENIAC
 Stands for Electronic Numerical Integrator
and Computer/Calculator
 The first large scale electronic computer
 the grand parent of today’s hand held
machines
 Became operational in 1946

23. Cont.
contained approximately 18000 light bulb size electronic vacuum tubes,
weighed 30 tons and occupied about 1500 square feet of floor space.
computers have been developed through four so called generations or stages
each characterized by
 smaller size,
 more powerful and
 less expensive than its predecessor.
Computer professionals do not agree on exact dates or specifics
Actually there are five generations

24. Major characteristics that distinguish these
generations are :-
Dominant type of electronic circuit elements used.
Major secondary storage media used.
Computer language used.
Types or characteristic of operating system used.
Memory access time (a time to store or retrieve a word or data from memory).
Computer generations are usually categorized by
 dramatic improvement in the hardware,
 typically tenfold or better increases in speed and reliability.

25. FIRST GENERATION (1944 – 1958)
Manufactured using vacuum tubes.
unreliable as the vacuum tubes failed very frequently.
very huge in size, produced enormous amount of heat, very slow and very, very expensive.
ENIAC and UNIVAC (Universal Automatic Computer) were the examples
Punched cards were the main source of inputs
were used for internal storage.
They operate in a speed of milliseconds (thousands of a second)
could handle more than 10,000 additions each second.
Most applications were scientific calculations.

26. SECOND GENERATION (1959 – 1963)
 Manufactured using transistor.
 Transistor is
 an electronic switching device that alternatively allows or
does not allow electronic signals
 smaller than vacuum tube.
 consumed less power and produced less heat when
compared to the vacuum tubes.
 smaller in size, more reliable, and considerably faster than
first generation of computers.
 Magnetic cores and disk packs were introduced as storage
devices.
 Programming languages like BASIC, FORTRAN,
COBOL, etc. were used.
 operate in microseconds (millionths of a second) with
more than 200,000 additions possible each second.
 Business applications become more common place, with
large data files stored on magnetic tape and disk.
 The most widely used second generations were
 Examples
 IBM 1620 –small scientific computers
 High level languages COBOL and FORTRAN were
introduced during this period.
 Batch operating systems are used that permitted rapid
processing of magnetic tape files.

27. THIRD GENERATION (1964 – 1970)
 Manufactured using Integrated Chips(IC)
 Integrated Circuit is a complete circuit packed
with hundreds of transistors and other electronic
components on a small silicon chip.
 The size got reduced with improved reliability and
speed.
 The usage of RAM (Random Access Memory)
and magnetic disks as the storage media became
wide spread.
 It was characterized by solid-state logic and
integrated circuit (IC).
 Computer storage switched from magnetic cores
to integrated circuit boards that provide
modularity (expandable storage) and compatibility
(interchangeable equipment).
 Software become more important with
sophisticated operating systems, improved
programming languages, and new input/output
methods such as optical scanning and plotters.
 Example
 IBM system /360 was the dominant
 IBM 1130

28. FOURTH GENERATION (1970S)
Manufactured using Large scale integrated circuit.
The computers main memory capacity increased, the cost got decreased and speed also
increased
Software applications like
 Word Processing,
 Electronic Spreadsheets, Database Management Programs, Painting and Drawing programs,
It has greatly expanded storage capabilities and improved circuitry.
Computer memory operates at speeds of Nano-seconds (billionths of a second)
with large computers capable of adding 15 million numbers per second.

29. FIFTH GENERATION
 They are under development.
 Function with the Artificial Intelligence provided to it.
 Due to the artificial intelligence the computer will have
 the ability to learn by itself,
 can reason and
 make decision with the knowledge it possess.
 These computers will have:
 Intelligent processors, i.e., processors which can draw inferences.
 Users will also be able to interact with them in natural languages such as English, Amharic, Afaan Oromo
etc.