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1. INTRODUCTION
TO COMPUTERS
UNIT ONE
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2. Computer:
What is computer?
 is a general purpose, electronic and programmable machine that
processes information automatically in accordance with the
instruction that you provide it.
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3. Data
 Are raw facts about an entity.
 Entities are things such as objects, people, observations, events.
 Data are representations of facts.
 They are raw materials for information and they are subjected to
further processing.
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4. Information:
 is the out put element of a data processing system.
 It is a refined and processed data.
 Information is a processed and organized data that man can
understand and get knowledge out of it.
 It tells people something they do not already know.
 It is a function of data and processing.
 It deal with the past.
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5. Knowledge:
 Is the confident understanding of subject, potentially with the
ability to use for a specific purpose.
 It’s source is learning or experience.
 It is dynamic as it lives within us.
 Knowledge deals with the present.
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6. Wisdom
 is the ultimate (final) level of understanding.
 Is the ability to make decision.
 As with knowledge, wisdom operates within us.
 it need to be communicated with others.
 Dealing with the future.
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7. Data processing:
 Is the process of converting data into information.
 The following are basic data processing activities.
 Data collection: involves getting data from the origin to the system.
 Data recording: the process of expressing data in a form that is
recognizable by either a person or a machine.
 Data classification: a process of categorizing all items of data
according to common characteristics and features.
 Data sorting: the arrangement of data items in a desired sequence.
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8. Data processing…
 Data store: retaining the data for future reference.
 Retrieving data: refers to finding a specific stored data.
 Summarizing data: is the process of condensing data.
 Data communication: distributions of information to the
specific end users.
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9. Sources of information
 Sources of information are generally categorized as:
Documentary source of information
Non documentary source of information
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10. Documentary source of information
 Depending on their originality and their proximity to the source
or origin it may again categorize as:
 Primary
 Secondary or
 Tertiary
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11. Primary Sources:
 Original material that has not been interpreted or analyzed.
 They present information in its original form,
 neither interpreted nor condensed nor evaluated.
 It present original thinking;
 For example, suppose there had been a car accident. The
description of the accident which a witness gives to the police is
a primary source.
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12. Cont.
 Examples: sets of data, such as
Interviews
 Meetings
Conferences
experimental research results
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13. Secondary Sources:
 Created from primary source of information,
 It interpreting original material.
 usually has been modified, selected, or rearranged for a specific
purpose or audience.
 They represent someone else's thinking.
 Examples: References,
Textbooks,
Review articles,
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14. Tertiary Material:
 Acts as a tool in understanding and locating information.
 Twice removed from the original works which list primary and
secondary resources in a specific subject area
 show you how to use, secondary (and sometimes primary)
sources.
Examples: Databases,
Dictionaries,
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15. Generations of Computers
Generation Circuit
element
Storage
device
Access
time
language Operating
system
1 st Vacuum
tube
Punched card Milli sec 10 -3 Machine Operating
controlled
2 nd transistor Magnetic tape Micro sec 10-6 HLL(COMBO
L
&FORTRAN)
BATCH
3 rd IC Magnetic disc 100 micro sec 10-7 Structured
language
Time sharing
4 th vlsic Magnetic disc,
optical disk
Nano sec 10-9 Appln
oriented
virtual
5 th AI Natural
language
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16. Types of computers
 Computer are classified according to
Method of operation(processing)
Purpose
size of memory, shapes, size, and capabilities
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17. Classification by Method of operation (processing)
 ANALOG COMPUTER: They deal with continues signal.
It operates by measuring. RATHER THAN COUNT.
Used in scientific research center, hospital and flight center.
Example: thermometer temp, voltmeter voltage ….
 DIGITAL COMPUTER: They deal with discrete signal.
They operate by counting rather than measuring.
On 1 and off 0
High accurate and fast than ANALOG COMPUTER:
Example: general purpose computer and desk
 HYBRID COMPUTER: Combination of BOTH Computer.
Collect analog data, convert to digital quantity, process the digital
value and convert the output from digital to analog form.
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18. Classification by purpose
1. Special purpose computer: designed to solve a single type of
problem/ TASK.
 Most analog computers are SPC
Example public telephone box, traffic control system, calculator
General purpose computer: designed to solve more than one type
of problem.
 D/t program store on memory
Example: Mini Computer
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19. Based on size of memory, shapes, size, and capabilities
 Micro computers
 Minicomputers
 Mainframe computers
 Super computers
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20. Microcomputer:
 They are single user computer.
 It is at the lowest end of the computer range in terms of speed and
storage capacity.
 Its CPU is a microprocessor.
 The most common microcomputer is a personal computer (PC).
 The PC supports a number of input and output devices.
 a collection of computers connected together so that they can
exchange data.
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21. Common types of pc
 Palm top computer: small size /Palm
Perform certain function such as calc, phone books..
Use pen for input
Also called hand held computer
 Laptop comp: called notebook computer.
 Desktop computer: have sub divided part.
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22. Minicomputer:
 This is designed to support more than one user at a time.
 It possesses large storage capacity and operates at a high speed
than a microcomputer.
 It is used in multi-user system.
 This type of computer is generally used for processing large
volume of data in an organization.
 They are also used as servers in Local Area Networks (LAN).
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23. Mainframe Computers:
 Took their name from the big metal cabinet or “frame” that was
originally required to house the CPU.
 They require special air conditioning.
 They have large memories and can serve many different users for
different functions at different locations.
 Main frame’s OS allows a number of people to use its CPU
simultaneously through a technique called multi programming.
 Mainframes are huge, multi-user systems
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24. Super Computer:
 This is the fastest and most expensive machines.
 It has high processing speed compared to other computers.
 They also have multiprocessing technique.
 It is built by interconnecting hundreds of microprocessors.
 It is mainly used for weather forecasting, biomedical research,
aircraft design and other areas of science and technology.
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25. Characteristics of Computers
 Automatic:
 a machine is said to be automatic if it works by itself without
human intervention.
 Computers are automatic machines because once started on a job,
they carry on until the job is finished, normally without any human
assistance.
 Speed:
 a computer is a very fast device.
 Performing several billion operations per micro/ nano/ Pico second.
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26. Characteristics of Computers…
 Storage:
 it has a capability to store a very large amount of data
 Also used for fast retrieve and process of information.
 Accuracy:
 It produce accurate/exactly correct output.
 Errors can occur in a computer due to human rather than
technological weakness,
 that is due to inexact thinking by the programmer or due to incorrect
input data referred to as garbage in garbage out or GIGO.
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27. Characteristics of Computers…
 Diligence:
 unlike human beings, a computer is free from repetitiveness,
tiredness, lack of concentration, etc.
 Versatility:
 a computer is capable of performing varieties/more than one of tasks
at a time.
 No IQ:
 performs these tasks with unthinkable speed and accuracy.
 It possesses no intelligence of its IQ is zero.
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28. Data Representation
 Elements inside modern computers have only two possible states:
on and off.
 Therefore every data and instruction inside computers is
represented using two symbols 0 and 1. For example, you see a
sentence as a collection of letters, but the computer sees each
letter as a collection of 0’s and 1’s.
 Computers use the binary number system to represent numbers.
This system uses only two digits: 0 and 1.
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29. Bits, Bytes
BIT
 It is the smallest unit
 It a contraction of binary digit
 It is a single element-on (1) or off (0)
 ON-high voltage
 OFF-low voltage
BYTE
 It is the basic unit of information
 1 byte = 8 bits
 The smallest usable unit of measure for memory is the byte – the
amount of memory required to hold one character.
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30. Coding Schemes
 ASCII
Uses one 8 bit byte
28 = 256 possible combinations or characters
 EBCDIC
Uses one 8 bit byte
28 =256 possible combinations or characters
Used primarily on IBM-compatible mainframes
Unicode
Uses two 8 bit bytes (16 bits)
216 = 65,536 possible combinations or characters
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31. Internal units of a computer and their functions
 A CPU: is known as the brain or the core of the computer, it
controls the processing of the computer.
 Screen : is something you know, you are looking into it now. The
screen allows us to see inside the computers processing.
 Power supply: The power supply supplies all the computer
components with electricity.
 Fans: The fans are added to prevent the computer from over
heating.
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32. Internal units of a computer and their functions….
 Mother board: connects all the components in the computer.
 RAM (Random accessing memory): is the main memory of the
computer and is fond in the mother board.
 NIC (network interface card): Allows the computer to connect to
the internet.
 FDD (floppy disk drive): A drive that can read or write on a
removable magnetically coated floppy disk. It is a type of storage
medium and back up device.
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33. Internal units of a computer and their functions …..
 HDD (Hard disk drive): A drive that can run on a magnetically
coated platter, that spins at high speed. There can be more than
one in a platter in the hard drive. While the platter is rotating the
magnetic head reads the data stored on it.
 Optical drives: There are two types of optical drives, the DVD
drive is a built in DVD player. DVD players allow the computer
to read DVD’s and show their data. The other optical drive is a
CD-ROM drive, it allows the computer to run CD-ROM’s.
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