Computer Fundamental

Saturday, July 13,
2013
1Prof.(Dr.) Anand K. Tripathi

Computer
Fundamentals
Saturday, July 13, 2013 2Prof.(Dr.) Anand K. Tripathi

Q. What is a Computer?
Ans. The term computer is derived
from the word ‘to compute’ and
therefore, can literally, be applied to
any calculating device. However the
term computer has come to mean as
electronic computing device with
certain characteristics e.g. high
speed, memory, stored program etc.
Saturday, July 13,
2013

• In simple terms, the computer can be
defined as an electronic data
processing machine. It receives data
as input, processes the data, i.e.
performs arithmetic and logical
operation on the same time and
produces output in the desired form
on output device as per the
instruction coded in the program.
Saturday, July 13,
2013

• The processing function of the
computer is directed by the stored
program, a set of coded instructions
stored in the memory unit, which
guides the sequence of steps to be
followed during processing.
Saturday, July 13,
2013

Q. Define Computer?
Ans. Computer system is made of two
major components: Hardware and
Software. Computer hardware is
physical equipment .The software is
the collection of programs
(instructions) that allows the hardware
to do its job. Figure depicts the
computer system.
Saturday, July 13,
2013

Q. What are the applications of
Computers?
Ans-The applicability of compute is in
all the department of life .Some of
them is as follows:
1. Weather forecasting
2. Management of organization
3. Entertainment
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2013

4. CAD/CAM
5. E-mail
6. Scientific and education works
7. Advertisements
8. Medical
9. Database processing and word.
10. Sports activity
Saturday, July 13,
2013

Q. WHAT ARE THE COMPONENTS OF
A COMPUTER?
Basically a computer consists of the
following three units.
Input Unit
Central Processing Unit
Output Unit
The input and output units are usually
abbreviated to I/O devices and the
Central Processing Unit as C.P.U.
Saturday, July 13,
2013

Q. State the functions performed by
the above stated units.
The above stated units namely
Input unit, Output unit, and the
Central processing unit
perform the following
functions.
Saturday, July 13,
2013

1) Input Unit. This unit serves as
communication channel between user
and the computer. All the instructions
and data are fed to the computer
through this unit. This unit consists of
several devices called input devices.
- Input device accepts instructions and
data from the input unit
Saturday, July 13,
2013

(2) Central Processing Unit (C.P.U.). This
unit is called heart and nerve centre of
a Computer. The C.P.U. performs the
following functions.
Controls and coordinates the working
of all the parts of a computer.
The input data is manipulated by the
C.P.U. according to the instructions
given by the user. This set of
instructions is known as a program or
a computer program or Receives
instructions and data from the input
unit.
Saturday, July 13,
2013

Stores instructions and data in its
primary memory. These instructions
and data remain in its memory up to
the time as required.
Processes the data according to the
instructions.
The CPU consists of three units:
A) C.U. (Control Unit)
B) Primary Memory
C) A L U (Arithmetical Logical Unit )
Saturday, July 13,
2013

A) C.U. (Control Unit):
Control Unit is also known as the big
boss of CPU or nerve centre of a
computer system.
-It controls and co-ordinates the
functioning of all other units of a
computer.
-It is responsible for fetching or
executing or running all the
instructions and data from the main
memory to the A.L.U. and it’s vice
versa.
Saturday, July 13,
2013

- Once the data is processed, this
unit issues proper command (in
the form of electrical signals or
pulses) for the transfer back of this
processed data along with feeded
data (if required) to the main
memory.
-It also controls the input-output
devices and the secondary storage
devices too.
Saturday, July 13,
2013

B) The Primary Memory Unit: The Memory
Unit, as its name suggests stores all the
instructions and data and is also called the
Primary Storage Section/Memory or the
Main Memory or the Immediate Access
Memory (IAS).
-Data and instructions entered into the main
memory are held there until needed to be
processed.
-Similarly the results of action taken on data
are held at primary memory until they
required for out put.
Saturday, July 13,
2013

-The ideal memory is one which is
large enough to store all the
information and from which the
information can be retrieved as fast
as required. However the design
limitations of main/primary memory is
that it forces to store only a limited
amount of information in the form of
instructions and data that are needed
immediately.
Saturday, July 13,
2013

-The remaining bulk of information is
stored in Secondary Storage
Devices also called Auxiliary
Memory. The other commonly used
names for this auxiliary memory are
External Memory or Backing
Storage.
-This external memory consists of
magnetic tapes or floppy disks, the
later being more common.
Saturday, July 13,
2013

-Compared to main memory this
memory is quite slow and does not
form a part of C.P.U.
-A memory is said to be faster if it takes
lesser time to retrieve information
from it.
Inside a Computer a primary memory
is divided into two parts:
a) ROM (Read Only Memory)
b) RAM (Random Access Memory)
Saturday, July 13,
2013

a) ROM (Read Only Memory)
-ROM stands for Read Only
Memory. It is permanent in nature
and stores of information in the
form of built in programs which
ultimately activates the computer
to test whether all the parts or
devices are available or attached
or working properly.
Saturday, July 13,
2013

- The information stored in this part
of memory is of permanent in
nature means information or data
stored in this part can not be
erased or lost even though the
power supply is off, or switched off
hence it is Non Volatile Memory
-This part of memory is machine
dependent.
Saturday, July 13,
2013

b) RAM (Random Access Memory)
-The other part of the Main
Memory/Primary memory is known
as RAM. - It stands for Random
Access Memory. In this unit, the
instructions and data are received
through input device with respect
to CU and are stored in this part of
memory.
-
Saturday, July 13,
2013

RAM contains the information as
long as power supply is on. All the
information stored in this part of
memory is lost or erased when
power supply is switched off.
Hence this Volatile Memory.
-This part of memory is user
dependent.
Saturday, July 13,
2013

3) Arithmetic Logic Unit (ALU): This unit
itself consists of two units which are as
follows:
1) Automatic Unit: Which performs the
arithmetical operations on to feeded
data?
2) Logical Unit: which performs the
logical operations on to feeded data.
-As the data comes to this unit relevant
unit of these two automatically activates
for doing operation.
Saturday, July 13,
2013

- The basic operations of the type
addition, subtraction, multiplication,
and division are known as arithmetic
operations.
- A logical operation simply means the
comparisons of two data numbers or
two sets of alphabetic characters.
Saturday, July 13,
2013

3) Output Unit Communicates
the results of data processing to the
user. These results are
communicated through the output
devices or
- Results along with along feeded data
(if required) are sent from main
memory to an output device which
displays results in user readable form
or
Saturday, July 13,
2013

Once the data is processed, the
output unit converts it into a form
which can be understood by the
user easily as sent by the memory
with respect or order or
instructions issued by the CU or
- Output unit serves as a link
between the computer and the user
which displays the results along
with feeded data.
Saturday, July 13,
2013

• Some names of output devices.
1.Character Printer 9. OCR
2.Line Printer 10.OMR
3.Dot Matrix Printer 11.
MICR etc
4.Visual Display Unit
5.Plotter
6.Optical Printer
7.Laser Printer
8. Audio Response Unit
Saturday, July 13,
2013

- These three operations (of CU,
Memory, and ALU) together
are also known as Electronic
Data Processing cycle
popularly called as EDP cycle.
The Fig. given below
illustrates an EDP Cycle.
Saturday, July 13,
2013

Working of Computer or CPU:
1) As we feed the data by the input device, it
goes to primary memory storage section
(e.g. RAM) first with respect to CU (Control
Unit).
2) From Memory Storage Section data goes
to ALU (Arithmetical Logical Unit), where it
is executed and result comes back to
memory again at the same memory location
or address along with the feeded data.
3) Now from memory it goes to output device
like screen or printer to display.
This is known as working of CPU.
Saturday, July 13,
2013

Q. What is a secondary storage device?
Ans. The ideal memory of a computer system is
one which is large enough to store all the
information and this information could be
retrieved from it in as short time as possible.
The design limitations of memory unit limit the
size of the computer memory. So the bulk of
information which cannot be stored in the main
storage or primary storage is stored on
external storage devices like magnetic tapes,
floppy disks and magnetic drums, CD etc.
These external devices are also known as
Auxiliary memory, backing storage or
External memory or secondary storage
device.
Saturday, July 13,
2013

• Q. What is the difference between Data and
Information?
• Generally in our day to day usage the words data
and information are commonly used to mean one
and the same thing. But in scientific and business
applications the word data stands for facts relating
to business and scientific investigations. For
computational purposes, data is regarded as a fact
on which a program or set of instructions acts to
make it more meaningful, this data in the more
meaningful form is known as information or we
can say that data when organized into more useful
form by manipulations is called information. Payroll
is an example of data and information. Every
organization has to pay salary to its employees for
which records about employees are to be
maintained.
Saturday, July 13,
2013

The record of each employee consists of
his name, address, identity number,
basic pay, details of allowances. This
record along with the data like leave
taken if any, overtime hours, income tax
deduction etc. is fed to the computer
system. After processing of this data by
the computer, the output that is obtained
is the salary slip of the employee. Now
the salary slip in computer language will
be known as information and facts or
data on which this salary calculation is
based is called data. Figure-4 depicts the
data and information
Saturday, July 13,
2013

Q. What is analog computer and
what are its uses.
Ans. The analog computer operates by
measuring the physical items rather than
by counting.
Analog computers measure the physical
quantities.
-These computers produces us appropriate
results.
-Ex. 1. Thermometer
2. Speedometer
3. Pressure meter etc.
Saturday, July 13,
2013

-Uses: Analog computers
are used mainly for
scientific and
engineering purposes
because they deal with
quantities that vary
constantly .They give
only approximate results.
Saturday, July 13,
2013

Q. What is Digital Computer and what
are its uses?
- Digital Computer is used for
mathematical and logical operation.
- These computers provide us 99.9%
accurate results .Mostly it give
100 % accurate results.
Exp. 1. Calculator
2. Personnel Computer
3. Digital Watch etc.
Saturday, July 13,
2013

Uses: Scientific purpose
digital computer can be
fixed permanently in the
machine i.e. processors
are installed in auto
mobile to control fuel,
breaking system etc .
Saturday, July 13,
2013

Q. What is the most important
characteristic of a digital
computer?
Ans. The most important characteristic
of a digital computer is that it is a
general purpose device capable of
being used in a number of different
applications. By changing the stored
program, the same machine can be
used to implement totally for different
takes.Saturday, July 13,
2013

Q. How will you differentiate between
an analog computer and a digital
computer?
Ans. The analog computer processes work
electronically by analog. It uses an
analog for each variable and produced
analog as output. It, thus, measures
continuously. It does not produce number
but produces its results in the form of
graph. It is more efficient in continuous
calculations. Digital computer performs
calculations by counting and thus counts
discretely. It is most versatile machine.
Saturday, July 13,
2013

• The analog computer accepts variable
electrical signals (analog values) as inputs,
and its output is also in the form of analog
electrical signals.
• Digital computer operators on inputs which
are on-off type (being digits 0 or 1) and its
output is also in form of on-off signal.
Analog computer operates by measuring
analog signals whereas digital computers
are based on counting operation.
• Most of the computers available today are
digital computers and therefore term
computer usually stands for digital
computers
Saturday, July 13,
2013

Q. What is Hybrid Computer?
Ans. The combination of analog and
digital computer is known as hybrid
computer.
Ex. Analog devices measure a patient
vital sign like temperature, heart
function etc.
-Any fluctuations can thus be noticed
immediately.
Saturday, July 13,
2013

• -As a hybrid computer is combination of both
analog and digital computers i.e. a part of
processing is done on analog computer and a
part on digital computer. A hybrid computer
combines the best characteristic of both analog
and digital computers. It provides greater
precision than can be attained with analog
computers, greater control and speed than is
possible with digital computers. It can accept
input data in both analog and digital form.
• Uses: It is used for simulation applications, MAT
LAB purpose etc.
Saturday, July 13,
2013

Q What is the input to a computer?
The input to the computer consists of
two kinds of information, the program
and the data. The program is the set
of instruction which the computer is to
carry out, and the data is the
information on which these
instructions are to operate.
Saturday, July 13,
2013

Q. What are the four basic operations
performed by a computer?
Ans. The four basic operations performed
by a computer are:
1. To exchange information with the out
side word via I/O devices.
2. To transfer data internally within the
CPU.
3. To perform the basic arithmetical
operations.
4. To perform the Boolean operations.
Saturday, July 13,
2013

Q. Distinguish between mainframe
computers, mini computers and micro
computers.
Ans. MAIN FRAME COMPUTERS: The
advancement of technology has made it
quite difficult to draw a line of
demarcation between large mini-
computers and small main frame
computers. The design of mainframe
computers is similar to that of the mini
computers; however the following
characteristics of main frame computers
are worth noting.
Saturday, July 13,
2013

i)These are big general purpose
computers.
These are capable of handling all
kinds of
problems whether scientific or
commercial.
Saturday, July 13,
2013

(ii) These have large storage
capacities of millions of
words. For example, IBM 370
can store up to 10 Mega
words (1 mega-word = 1
million words) in its main
memory
Saturday, July 13,
2013

(iii) The main frame computers have
a large
number of backing storage devices
attached
to them.
(iv) These computer can accept and
transfer
data from I/O devices at the rate of
millions of bytes (One byte = 8
bits) per second.
Saturday, July 13,
2013

(v)The main frame computers
can accept all
types of high level languages.
(vi)The word length in these
computers is quite
large usually 32 to 64 bits.
Saturday, July 13,
2013

(vii) The cost of these computers
depending upon the facilities
required varies from 1 crore to 10
crores of rupees.
(viii) These computers can
support a large number
of terminals say up to 100 or more.
• The examples of mainframe
computers are IBM 360/370, ICL
1900/2900, and DEC 10.
Saturday, July 13,
2013

• 2. MINI COMPUTERS. The mini
computers have following
characteristics.
(i) These computers are also general
purpose computers but have a
smaller size central processing unit.
(ii)These have lower storage capacity.
For example, a mini computer PDP-
11 can store up to 2 Mega words.
Saturday, July 13,
2013

iii) Mini Computers in general have
hard disks
for backing stores. Some mini-
computers may
use magnetic tapes for this purpose.
(iv) These computers can accept and
transfer
data from I/O devices at the
maximum speed
of 4 million bytes per second.
Saturday, July 13,
2013

(v)These mini computers accept all types of
high level languages.
(vi)The word length in these computer is
comparatively smaller, usually 12 to 32 bits.
(vii)The cost of these computers varies from
6 lakhs to 25 lakhs of rupees.
(viii)These computers can support up to a
maximum
of 20 terminals. The examples of mini
computers are PDP-11, Vase Range and
Micro
Galaxy etc.
Saturday, July 13,
2013

3. MICRO COMPUTERS. The micro
computers have the following
characteristics.
(i) These computers have C.P.U. on a
single chip.
(ii)These have low storage capacity up
to a
maximum of 10 kilo words (1 kilo
word = 1000 words).
Saturday, July 13,
2013

(iii)These computers can accept and
transfer data from I/O devices at the
maximum speed of 5 lakhs bytes/sec.
(iv)These computers have a display
unit as a cathode ray tube attached to
them.
(v)These computers accept high level
languages BASIC, PASCAL,
FORTRAN and PL/1 and PL/M.
The commonly used language on
these computers is BASIC.Saturday, July 13,
2013

(vi) The maximum word length in these
computers is 16: bits. However most of
these computers use-bits words.
(vii) These computers are quite
inexpensive. The cost usually varies from
2 lakhs to 6 lakhs rupees. Personal
Computers in these categories have very
low costs up to a few thousands rupees.
This factor has made the micro-
computers a household item. The
examples of micro computers have been
discussed in previous sections.
Saturday, July 13,
2013

Computer Fundamental

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