Computer Notes MFS Booklet Class 9th.compressed

IX-Computer Chapter # 3 Page # 101

(iii) Hand-held Scanners:

Hand-held scanners are most frequently used with microcomputers. It is
very small in size. Handheld scanners are less expensive, but require a steady
hand to get a clear image. These scanners are-easy to use, but sometimes they
are limited to scan a wide picture.

Q No.6 what is the difference between impact and Non-impact printers?
(2011)

DIFFERENCE B·ETWEEN IMPACT AND NON-IMPACT PRINTERS

Impact Printer Non-Impact Printer

1. It uses striking method. 1. It uses sensing method.

2. I t is noisy printer. 2. It is quiet printer.

3. It does not produce a very fine 3. It produces very fine quality of
quality of output. output.

4. It is cheap in cost. 4. It is expensive in cost.

5. Printing quality is fix. Or low 5. Printing quality is high.(font size is
(font size is standard) not standard)

6. Impact Printer can produce copies 6. They cannot produce carbon copies.
carbon.

Q No.7 which device is used as an input device as well as output
device? Define it in detail

Disk drive and CD writer are input and output devices. When these
devices are used to read some data from it, they fall in the category of input
devices, while during writing, data onto the disk they will be considered as
output devices. The most commonly used I/O devices are listed below.
CD-ROM, Hard Disk, Floppy Disk etc.

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8. Fill in the blanks.
a. Keyboard and Mouse are the two most common input
devices.
b. GUI stands for Graphical User Interface.
c. CRT and LCD are the two basic types of monitors.
d. Scanner is an input device to read images as inputs.
e. Resolution is a characteristic of monitors that effects on the
sharpness on an image.
f. Dot Pitch is a characteristic of monitors that effects on the
sharpness on an image.
g. CD-ROM is the abbreviation of compact Disk Read Only
Memory.

9. Choose correct answer.

I. The purpose of input device is __________.

a. Pass information b. Filtration of information

c. Pass information directly to CPU

ii. The mouse is a primary input device but lacks the ability to easily

Transmit ___________________ information.

a. Graphical b. Numerical

c. Alpha numerical d. Textual

iii. The following are the input devices

a. Keyboard, Mouse, Scanner, Flatbed scanner

b. Keyboard, Mouse scanner. Flatbed plotter

c. Hand-held scanner, Drum plotter, M ice, Joystick.

IV. Laser primer and ink-jet printers are examples of _______________.

a. impact printers b. Line printers

b. Drum printers d. None of above

V. Plotters can be generally divided into

_____________________categories, namely_____________________

a. Two, Pen plotters and Electrostatic plotters

b. Four, Pen. Electrostatic, Drum and Flatbed plotter

c. Three, Pen. Electrostatic and Flatbed plotters.

vi. The CD-writer performance is measured in -

_____________________unit.

a. DPI b. Y. c. Bytes d. X

vii. Screen output is known as ________________________

a. Software b. Livewire c. Softcopy d. Hardcopy

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Viii. Where engineering applications are used and precision is mandatory,

we use___________________ for printing.

a. Laser printer b. Electrostatic plotter c. Pen plotter

ix. Printer resolution is usually measured in _______.

a. Data per inch b. Characters per inch c. Dots per inch

10. Choose the-correct statement - True or False.

i. A keyboard is a secondary text input device.

a. True .b. False

ii. The function of trackball is same as-joystick.

a. True .b. False

iii. A sheet-fed scanner can be used to scan pages in books or magazines.

a. True .b. False

iv. The light pen is only used for engineering applications?

a. True .b. False

v. LCD stands for Liquid Crystal Display.

a. True .b. False

vi. The screen output is known as software.

a. True .b. False

vii. A machine-readable form of corresponding hardcopy is software.

a. True .b. False

viii. Plotter is used for general purpose printing.

a. True .b. False

ix. DPI stands for data per inch.

a. True .b. False

QUESTIONS FROM PAST PAPERS:
YEAR 2014:

Section "A" (Multiple Choice Questions) - (MCQs) (No Questions)
Section B (Short -Answer Questions)

Q No.16 Define Keyboard.

Section "C" (Detailed-Answer Questions)

Q.17 (a) Define printer and describe its types.

Section "A" YEAR 2013: * Five types
(v) (Multiple Choice Questions) - (MCQs)
Plotters cab be generally divided into:
(iv) * Two types * Three types * Four types
Impact Printer is an example of:
* Drum Printer * Dot-matrix Printer
* Daisy wheel Printer *All of these

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(ix ) The screen output which is intangible and temporary refer to:
* Softcopy * Hardcopy * Source code *All of these

Se tio B" (Short -Answer Questions)

Q.4 what is an output device rite down the capabilities of Monitor.

Q.13. Which device is used as an input as well as an Outpu?

Section "C" (Detailed-Answer Questions)
Q.I7 What is a Plotter? Write down the different kinds of plotters
and their functions.

YEAR 2012:

Section "A" (Multiple Choice Questions) - (MCQs)
(ii)
The device mostly used for computer or video games:
(v)
* Mouse * Light pen * Trackball *Joystick

Impact Printer is an example of:

* Drum Printer * Dot-matrix Printer

* Daisy wheel Printer *Printer

Section "B" (Short -Answer Questions)
Q.3 Define dual purpose device with examples?
Q.5 Differentiate between Hard copy and Soft copy.

Q.14 Define Printer and write its kinds.

Section "C" (Detailed-Answer Questions)

Q.16(b) What is an input Device? Write down the characteristics of it.

YEAR 2011:

Section "A" (Multiple Choice Questions) -(MCQs)
(iii)
The Screen output which is intangible and temporary refers to:
(v)
* Softcopy * Hardcopy

* Source Cole * Object Code

LCD stands for ____________.

* Light Code Digit * Liquid Crystal Display

* Light Colour Display * None of them

Section "B" (Short -Answer Questions)
QA Define Keyboard and write down the names of its parts.

Section "C" (Detailed-Answer Questions)

Q.17(b) What is a Printer. Describe Impact and Non-Impact Printer.

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YEAR 2010: * Five types
Section "A" (Multiple Choice, Questions) - (MCQs)
(iv) Plotters can be generally divided into:

* Two types * Three types * Four types

(vii) LCD stands for:

* Light Code Digit * Liquid Crystal Display

* List Code Digit * Light Colour Display

Section "B" (Short -Answer Questions (No Questions)
Section "C" (Detailed-Answer Questions)

Q.5(b) What is a Monitor? Define various types of monitor in detail.

Section "A" YEAR 2009:
(viii)
(Multiple Choice Questions) - (MCQs)

____________ is the characteristic of a monitor that affects the

sharpness of an image:
*Net pitch *Patch pitch * Do t pit h *None of the above

Section "B" (Short -Answer r Questions)

Q.2(iv) Define as input device and describe mouse Or Light pen.

(vii) Define a Monitor and state its types.
(xii) Define as impact Printer and a Non-Impact Printer. Give

example

Section "C" (Detailed-Answer Questions) (NO Question)
MULTIPLE CHOICE QUESTIONS (MCQs)

(1) The permanent document/output on a paper is called
(a) Hardware (b) Software
(c) Softcopy (d) Hardcopy

(2) The devices through which we enter the data into the computer are

known as_______ devices.

(a) Output (b) Storage

(c)Input (d) I/O(Input / Output)

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(3) The Keyboard and Mouse are_________ devices.

(a) Output (b) Storage

(c) Input (d) Non of the above

(4) The output result in printed form is known as______ __________.
(a) Hardware (b) Software
(c) Softcopy (d) Hardcopy

(5) __________printers print by striking the ribbon against the paper .

(a) Ink-jet (b)LASER
(c)THERMAL d Do t Mat i

(6) The printer which makes the noise during printing is known as

______printer.

(a) Ink-jet (b) LASER
(c) THERMAL d Do t Mat i

(7) Dot matrix and Daisy wheel printers are the type of _____
printer.
(a)Impact (b)Non impact
(c) THERMAL (d) Non of the above

(8) A blinking cell on the display screen is known as _______.
(a)Cursor (b) Pixel
(c)pointer (d) Non of the above

(9) In the ______ printer as electronic beam passing through the character
and then their image produce on the paper.
(a) Ink-jet (b) LASER
(c) Pointer (d) Non of the above

(10) ________is a random access device.

(a)Magnetic Tape (b) Magnetic Disk

(c)paper tape (d) Non of the above

(11) _________device are used to read information.
(a) Output (b) Input
(c) Storage (d) Non of the above

(12) Keyboard is an/a ____device.
(a) Output (b) Input
(c) Dual purpose (d) Storage

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(13) Light pen and Joystick are_____ device.

(a) Output (b) Input
(c) Dual purpose (d) Non of the above

(14) ___________is similar to a Mouse.

(a) .Joystick (b) Track ball

(e) Keyboard (d) None of the above

(15) Plotter is an/a___________ device

(a) Input (b) Output

(e) Dual purpose (d) None of the above

(16) Monitor is an/a ___________device.

(a) Input (b) Output

(e) Dual purpose (d) None of the above·

(17) Printer is an/a___________device.

(a) Input (b) Output

(e) Dual purpose (d) None of the above

(18) To save the data and programs permanently, we use devices.

(a) Secondary storage (b) Backing storage

(c) Auxiliary storage (d) All of the above'

(19) ______printers make noise during printing.

(a) Ink-jet (b) Laser

(c) Dot-matrix (d) None of the above

(20) The keyboard and the-monitor together are called __________.

(a) Console device (b) Input device

(c) Output device (d) None of the above

(21) _____printer directs a high-velocity stream of ink towards the paper.
(a) Thermal (b) Ink Jet
(e) Laser (d) None of the above

(22) Thermal printer and Laser printer are the types of printer,

(a) Impact (b) Non Impact

(e) Line (d) None of the above

(23) The____ printer IS a solid cylindrical drum upon which character are
embossed
(a) Cylinder (b) Drum
(e) Chain (d) None of the above

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(24) Drum printer and Wheel printer are the example of printers.

(a) Non impact (b) Impact

(c) Live (d) None of the above

(25) _______printer print one complete line at a time. '

(a) Laser (b) Ink-jet

(e) Dot Matrix (d) None of the above

(26) The shape of a printer wheel resembles the petals of daisy flower,

therefore, it is named as _________printer.

(a) Dot Matrix (b) Chain

(c) Daisy wheel (d) None of the above

(27) In the __ printer each character is formed with the series of dots

(a) Ink-jet (b) Laser

(c) Dot matrix (d) none of the above,

(28) _____ printer print one character at a time,
(a) Daisy wheel (b) Dot Matrix
(e) Character (d) Line

(29) There are two types of printers, which are known as____ and______.
(a) Line and serial (b) Character and line
(e) Dot Matrix and serial (d) Impact and Non-Impact

(30) Printer and plotter are the most popular _____ device.
(a) Output (b) input (c) Storage (d) All of the above

(31) The keyboard and mouse are______devices,

(a) Input / Output (b) Input (c) Output (d) All-of the above

(32) The monitor and printer are devices.
(a) Input (b) Output
(c) Storage (d) All of the above

(33) Is a printing device which is used for engineering designing.

(a) Pen plotter (b) Printer

(c) Scanner (d) None of the above

(34) An input device, which is used to read the numeric and alphabetic
characters form the printed documents is known as____________.
(a) Speaker (b) Microphone
(c) Keyboard (d) None of the above

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(35) The output result in video visual form is known as,____________.
(a) Software (b) Hardware (c) Softcopy (d) Hardcopy

(36) _________is an ,input device to read images as input.
(a) Printer (b) Plotter (c) Scanner (d) Light pen

(37) Trackball is a pointing device like________.
(a) Mouse (b) Light pen
(c) Joystick (d) None of the above

(38) The three main components of computer are_____________.

(a) Tape, CPU, Printer (b) Disk, CPU, Keyboard

(c) Printer, CPU, Monitor (d) Input, CPU, output devices

(e) None of above

(39) An Impact printer_________.
(a) Is slow than a non-impact printer (b) Is a noisy printer
(c) Can make-carbon copies (d) Is a hardcopy output device
(e) All of the above

(40) A dot-matrix printer_________.

(a) Is an input device (b) Is an impact printer

(c) Is a non-impact printer (d) which prints one line at a time

(e) None of the above

(41) Keyboard is a device that_____________.
(a) Is used to supervise the operations of the computer
(b) Is used for entering data to the computer
(c) Is used for low volume input and output
(d) None of the above,

(42) Plotters can be generally divided into_________.
(2010)
(a) Two types (b) Three types
(c) Four types (d) Five Types

(43) LCD stands for _________________. (2011, 2010)

(a) Light code Digit (b) Liquid colour Display

(c) Light colour Display (d) Liquid crystal Display

(44) A plotter is___________. (b) An impact device
(a) A storage device (d) An Output device
(c) A character printer

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(45) Multiple choice examination answer sheets can be evaluated

automatically by:

(a) Magnetic tape reader (b) Optical mark reader

(c) Magnetic ink character reader (d) Optical character reader

(e) All of the above

(46) Magnetic ink characters are______________.
(a) Easily read by a person
(b) Too few in number to constitute a general recoding medium
(c) Used to bank check
(d) All of the above

(47) The purpose of input device is to_____________.
(a) Pass information (b) Filtration if information
(c)Pass information directly to CPU (d) All of the above

(48) The mouse is a primary input device, but lacks the ability to easily

transmit___________ information

(a)Graphical (b) Numerical (c) Alpha numerical

(d)Textual . (d) None of above

(49) Computer-is electronic device that accepts data instructions

as_____________ process the data (according to the given instructions)

and produce information as__________.

(a) Output Input (b) Input output

(c) Stores Output (d) None of the above

(50) _________devices are used to take data from user and supply it to the
computer.
(a) Input (b) Output
(c) Storage (d) None of the above

(51) ________printer prints text with combinations of Dots from characters.

(a) Line (b) Daisy wheel

(c}Dot matrix (d) None of them

(52) ________ IS the characteristic of a monitor that effects the sharpness of

an image.

(a) Net Pitch (b) Path Pitch

(c)Dot Pitch (d) None of the above

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(53) The Screen output which is intangible and temporary refer to:

(2011)

(a) Softcopy (b) Hardcopy (c) Source Code (d) Objective Code

(54) The program directly related to the computer hardware controlling and

utilizing them is known as: (2011)

(a) System Software (b) Operating System

(c) Application Software (d) Special Purpose Software

(55) The device mostly used for computer or video games: (2012)
(a) Mouse (b) Light-Pen (c) Track-Ball (d) Joystick

(56) Output-displayed on screen is called____________.
(a) Soft Copy (b) Software (c) Live ware (d) Hard Copy

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CHAPTER-4
STORAGE DEVICES

CLASS-IX

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STORAGE DEVICES 4

4.1 Storage

4.1.1 Primary Storage / Main Memory

4.1.2 Backing Storage Devices.
4.1.2.1 Sequential Access Devices.
4.1.2.2 Random Access Devices.
Main Use of Backing Storage

4.2 COMS (Complementary Metal-Oxide Semi Conductor)
4.3 Units of Memory

4.4 Punch Cards.
4.5 Magnetic Tape.
4.6 Cassettes.
4.7 Magnetic Disk.
4.7.1 Floppy Disk.
4.7.2 Hard Disk.

4.8 Compact Disk.
4.9 Write-able Compact Disk.
4.10 Peripheral Devices.

DIFFERENCES:

1. Magnetic Tape and Magnetic; Disc
2. Sequential Access Devices and Random Access Device
3. SIMM and DIMM
4. DRAM and SRAM

1.11 Exercises

4.12 Multiple Choice Questions (MCQs)

4.1 STORAGE MEMORY:

It is possible for a computer to function with just processing, memory,
input and output devices. To be really useful, however, it also needs a place to
keep program files and related data when it is not using them. The purpose of
storage memory is to hold data.

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Types of Storage Device Memory:

There are two types of storage.
(l) Primary storage or main memory.
(2) Secondary storage or backing storage.

4.1.1 Primary Storage Main Memory Functions Purpose:(2011, 2009)
(Importance of Primary Memory):
Every computer has a main memory where data and instructions which

are currently being processing are storage main memory is wholly electronic,
fast and reliable. Program is loaded into memory and run from memory. Its
nearness to the rest of the central processing unit (CPU).

 TYPES OF MAIN MEMORY:

Computer's main memory is further divided into the following:

1. Random Access Memory ( RAM)
2. Read Only Memory (ROM).

(1) ROM (Read Only Memory):- (2012)

Rom stands for Read only Memory. The progress and data stored on
Rom are Permanent and cannot be changed. When the computer is switched
off, the contents Rom are not lost. This sort of memory, which isn't wiped clean
when the computer is turned off, is called non-volatile, memory.

Types of ROM: (2012)

There are several types of ROM:-

(a) PROM (Programmable Read - Only Memory):-

A Read-Only Memory (ROM) chip pro grained at the factory for use with
given computer. The alternative to PROM is a ROM chip In which the
information expressed in the actual design of the circuits internal to the chip.

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(b) EPROM (Erasable Programmable Read-Only Memory):-

A Read-only memory (ROM) chip that can be programmed and
programmed. The eras-ability of EPROM chip matters to computer
manufactures, which often find that they need to reprogram, ROM chip
containing bugs. PROM chips, which cannot reprogrammed; must be discarded
when a programming error is discovered.

(c) EEPROM (Electrically Erasable Programmable Read Only Memory):
An EEPROM is a special type of PROM that can be erased by exposing

it to an electrical charge. Like EPROM, after erasing data you can reuse it.

2- RAM (Random Access Memory):- (2008)

RAM stands for Random Access Memory. RAM is the computer's
working memory where it stores the programs and data that are being used at
a given time. The contents of RAM can be changed because it only stores
programs and data temporarily when the computer is turned off the contents
of RAM are lost. This sort of memory which is wiped clean when the computer
is turned off is called volatile memory.

 Types of RAM:

There are two basic types of RAM:
1. DRAM (Dynamic RAM). 2. SRAM (Static RAM).

 DRAM:-

DRAM stands for Dynamic Random Access Memory. Dynamic RAM
chips hold data for a very short time. Dynamic RAM needs to be refreshed
thousands of times per second. It is the most common type of RAM. DRAM is
slower than SRAM.

 SRAM:-

SRAM stands for Static Random Access Memory. Static RAM chips hold
data until the power turned off. Static RAM does not need to be refreshed,
which makes it faster but it is also more expensive than DRAM. Both types of
RAM are volatile. SRAM is faster than DRAM.

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DIFFERENCES BETWEEN DRAM AND SRAM (2010)

DRAM SRAM

1) DRAM stands for Dynamic 1) SRAM stands for Static Random

Random Access Memory. Access Memory.

2) DRAM needs to be refreshed 2) SRAM does not need to be
thousands of time per second. refreshed.

3) DRAM is slower than SRAM. 3) SRAM is faster than DRAM.

4) This RAM is expensive in cost. 4) SRAM is more expensive in cost.

5) DRAM chips holds data for a very 5) SRAMS chips hold data until the

short time. power turned off

 SIMM (Single In-line Memory Module):-

A Plug in memory module containing all the chips needed to add

256k or 1M of Random Access Memory to the computer.

RAM Chips are installed on a small circuit board. These RAM) chips
are wired together to form a single module of large memory called (SIMMs).
SIMM· has contact terminals on its one side. It can easily be plugged into the
Mother board. A SIMM have chips with 30 or 72 pins. SIMM hold from 8 MB
to 64MB of RAM.

 DIMM, (Dual In- Line Memory Modules):-

SIMM were popular by PC users in 1980s but has now been replaced by

DIMMs. DIMMs have been developed installing many RAM chips. DIMMs

provides larger capacity as compared to SIMMs. DIMMs have wider data bus

and thus have higher rate of data transfer. DIMM have 168 Pins. A DIMM can

hold from 8 MB to 256 MB of RAM.

DIFFERENCES BETVEEN SIMM AND DIMM

SIMM DIMM

I) SIMM stands for Single in line 1) DIMM stands for Dual ln line
Memory Modules. Memory Modules.

2) A SIMM has chip with 30 or 72 pins; 2) DIMM has 168 pins.

3) SIMM holds from 8M.B. to 64M.R 3) A DIMM can hold from 8M.B to
256M.B.

4) SIMMs provides small capacity as 4) DIMM provides large capacity as
compare to DIMM. compare to SIMM s.

5) SIMM have lower rate of data 5) DIMM has wider data bus, thus has
transfer as compare to DIMM higher rate of data transfer.

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4.3 UNITS OF MEMORY:-

BIT:-

In the binary system, each 0 or 1 is called a bit. Which is short for binary digit.

BYTE:-

To represent letters, numbers, or special characters such as ! or *, bits are
combined into groups. A group of 8 bits is called a byte.

KILOBYTE:-

A kilobyte (K, KB) is about 1000 bytes. (Actually, it's precisely 1024 bytes but
the figure is commonly rounded). The kilobyte was a common unit of measure
for memory or secondary storage capacity on older computers. 1KB equal
about ½ page of text.

MEGABYTE:-

A megabyte (M, MB) is about 1 million bytes (1, 048576 bytes). Measure of
micro computer primary storage capacity today are expressed in megabytes.
1MB equals about 500 pages of text.

GIGABYTE:-

A gigabyte (G, GB) is about 1 billion bytes (1,073,741,824 bytes).

TERABYTE:-

A terabyte (T, TB) represents about 1 trillion bytes 1,009,511,627,776 bytes).

PET ABYTE:

A pet a byte (P, PB) represent about 1 quadrillion bytes (1,048,576 gigabytes):

4.1.2 SECONDARY STORAGE DEVICES:

These devices are sometimes called as Backing Storage Devices,
Secondary Storage Devices External Storage Devices and Auxiliary Storage
devices. As compared to primary or main memory, it has much larger capacity.
Secondary storage devices are virtually unlimited in size and-much cheaper than
main memory.

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Need TQ Use Secondary/Backing Storage Devices:

The computer's memory is limited in size, is needed as a working space
for the, current program and only retains information on a temporary basis.
However, computer may often works on vast amount of data and Backing
Storage Devices are used to retain the data on a permanent basis. There are
two methods used to access the information from these storage devices and
they are classified as:

1 ) Sequential Access Device 2) Random Access Device

4.1 .2.1 SEQUENTIAL ACCESS DEVICE:

The storage devices, which use the sequential access method,

is called sequential access device. The information on a sequential access

device can only be considered in the same sequence in which it is stored.

Most commonly used Sequential Access Devices are punched cards, paper

tapes and magnetic tapes.

4.1.2.2 RANDOM ACCESS DEVICE:

The' storage devices, which are used random access method
to retrieve the information is called Random Access Devices. These devices
access the individual information or record in the direct or immediate
manner. Most commonly used Random Access Devices are Magnetic Disk,
Floppy Disk, Hard Disk and Compact disk.

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DIFFERENCES BIW SEQUENTIAL AND RANDOM ACCESS DEVICES:

SEQUENTIAL ACCESS DEVICE RANDOM ACCESS DEVICE

1) Sequential access devices are 1) Random-access devices· are those

those in which we can access the in which we can access the data

data serially. directly.

2) These devices provide slow 2) These devices provide the fast

communication. communication.

3) It is time consuming. 3) It is time saving

4) Examples of Sequential access 4) Examples of Random access

devices are Punch card and devices are Floppy disk Hard disk

Magnetic tape. and Optical disk.

5) It is cheap in cost 5) It is costly as' compare Sequential

Access.

4.4 PUNCH CARDS:

They are used for giving data and instructions to computers. Holes

are punched into a special card that has 80 columns to store data or

instructions. Punched cards are not much in use presently. There are special

devices for punching holes into and reading details from the cards. The card

punch is used to punch holes that marks data or instructions on a punched

card. The CARD READER reads the details-from a card for the computer.

 Advantages of punch card:

1. Punch cards are fairly inexpensive
2. Data entry using Hollerith cards is relatively fast, modem card readers

can easily read 600 cards per minute.
3. Punch card can be stored and reread if the need arises.
4. Errors found in cards cannot be corrected or remove, but the card

containing we error can be replaced without affecting the rest of tile
deck.

 Disadvantages of punch card:

1. Punch cards are larger in comparison to the amount of data they can
contain storage requires a great deal of space.

2. The system still involves a form of keyboard entry; the keypunch
machine merely a method of converting key presses to holes punched in
the card.

3. Anything that might make additional holes in the card must be avoided.
Any additional holes may be read as data or may corrupt other data.

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4.5 MAGNETIC TAPE:

The magnetic tape reel is about
10 inch in diameter' and contains up to 2400
feet (370 m) of tape 0.5inch wide. The tape
is a plastic material coated with a magnetic.
Oxide, spots can. be magnetized to indicate
1 or 0. The spots are arranged in nine tracks
of channel as a parity check. Magnetic tape
is a MASS STORAGE device, even though
information can only be accessed serially or
accessed sequentially, magnetic tape is very
widely used frequently. Tape is ideal for this
purpose as it is cheap and the transfer rate
to and from the computer's main memory is
relatively fast.

 Advantages of magnetic tape:

 It is cheaper than magnetic disk.
 It is very 'compact and easy to transport.
 A standard reel can hold 10 million or more characters.

 Disadvantages of magnetic tape:

 Random or direct access to files is not possible.
 Individual records cannot be modified updated.
• Tape has a limited shelf life (about 2 years) for reliable results.

 Data is Organized on Magnetic Tape:

Data on tape is processed, i.e. read or recorded, a block at a time. These
data blocks may contain one or more records are separated by inter block
gaps.(Typically 1/2 inch to 2/4 inch) to allow the tape to speed up and slow
down at the beginning and end of each block.

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4.6 CASSETTES:

These are similar in principle to magnetic tape but much smaller (the

same size as an audio cassette). The main uses include the storage of games,

etc., on home computers and as a medium for transferring data to mainframe

computers from point-of-sale (POS) and bank cash point terminals. The

cassette is too slow for many purposes.

4.7 MAGNETIC DISK:

A round, flat, thin circular metal plate coated on both side with a

magnetic material that is rotated in order to read or write data is called

magnetic disk. It is just similar to a LP gramophone record. Information stored

or retrieves randomly from disk. So it is too fast. Now magnetic disks are the

most popular medium for direct access secondary storage in two shapes, for

microcomputers.

 Types of Magnetic Disk:

There are two types of Magnetic Disk.
1. Floppy disk (Diskette or removable disk).
2. Hard disk (fined or non-movable disk).

4.7.1 FLOPPY DISK:

Floppy disk is a small removable storage device: This is a single, flexible
disk intended for microcomputers. Early floppy disks were 8-inch in diameter,
followed by the 5.25-inch disk, which is now most common. The 3.5inch disk
is steadily taking over and is likely to be the standard.

The principles of the floppy disk are similar to the hard Disk except that
the disk consists of only two surfaces. Each surface has nine sectors with 512
bytes per sector. Various formats are available but an 80 tracks double-sided
disk is common, storing , 720K of data. The latest 3.5 inch disks can hold 1.44
megabytes of data (1440K).

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 Capacity of Floppy Disk:

The capacity of each surface = 80 x 9 x 512 bytes.
For a double-side disk:
Capacity = 2 x 80 x 9 x 5.12
= 73 7280 bytes
I K = 1024 bytes

Therefore disk capacity = 737280/ 1024 =
720 K

IBM disk capacities
Single sided Double

sided

40 tracks 180K 360K

80 tracks 360K 720K

8 Inch Floppy Disk:

The original size of flexible disk is enclosed in an 8 inch square

Jacket, and the actual disk bas a diameter of 7.88 inch. The recording surface is
a 100 inch thin Layer of magnetic oxide on a 0.003 inch thick polyester

substrate. Standard track spacing is 48 per inch.

5.25 Inch Floppy Disk:

Inch floppy disk is known as "Mini Floppy Disk". These are also

made of flexible plastic material. Whose lining is coated with ferrite. These are

also enclosed in a plastic jacket. These are cheapest storage floppies, these are

available in different storage capacities to increase the disk capacity,

manufacture now supply two side double-track density disks.

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Characteristics of 5.25 Inch Floppy Disk

Side Tracks Sectors Capacity
180 KB
1 40 9 360 KB
1.2MB
2 40 9

2 80 1

3.5 Inch Floppy Disk:

These floppy disks are known as "Micro Floppy Disk". The actual disk is

also made of flexible plastic material but it is enclosed in a hard plastic cover.

When this disk is inserted in the disk drive then head-slot shutter opens

automatically. These floppies are available in two densities which are known as

high density disk and low density disk.

Characteristics of 3.5 Inch Floppy Disk

Side Tracks Sectors Capacity
2 80 9 720 KB
80 18 1.44 KB
2(HD)

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 The Parts of a floppy Disk:

An outer hard plastic cover and inner woven cloth liners protect a round

plastic disk coated with a magnetic material. When the disk is put into a disk

drive a metal shutter slides back to reveal its surface. A small plastic write-

protect tab can be clicked back to reveal a hole in the outer cover. When this

tab is clicked back the disk becomes write- protected. This means that no data

can be added to or removed from the disk.

1. Centering Hole:
Disk drive mechanism locks into hole to spin the diskette.

2. Indexing Hole:
Disk drive. locks here to find the starting sector for each track on the
diskette.

3. Access Hole:
The head of disk drive comes in contact with the magnetic surface
through this cutout. The head move back and forth in this opening, from
track to track.

4. Notch:
There is a write protect notch, writing on the diskette means, adding

information to the disk the notch is uncovered one can write on the disk,

if the notch is covered, the disk is protected against writing.

DIFFERENCES BETWEEN MAGNETIC DISK AND MAGNETIC TAPE

MAGNETIC DISK MAGNETIC TAPE

1. Magnetic Disk is a random access 1. Magnetic Tape is a sequential

device. access device

2. A magnetic disk is a Mylar or 2. Magnetic Tape is a one half of one

Metallic Platter. fourth inch ribbon of Mylar coated

with thin layer of iron-oxide

material.

3. It has faster data access speed. 3. It has slow data access speed.

4. It is used to hold more data in a 4. It is used to hold data in a large

smaller space. space.

5. It is costly. 5. It is cheap in cost.

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INSIDE THE HARD DISK

4.7.2 HARD DISK:

A hard disk is a magnetic random access device on which we can
store computer data. A hard disk is a circular metal disk coated' magnetic
material and usually sealed in a hard disk drive inside the computer. Some hard
disk drives are not permanently fixed inside the computer but are removable.
Data stored on a hard disk Can be accessed much more quickly than data
stored on a floppy disk. Hard disks can store much more data than a floppy
disk. A typical hard disk inside a personal computer can hold several gigabyte of
data.

4.8 COMPACT DISK (Optical Disk):

CD-ROM stands for Compact Disk Read Only Memory A CD-ROM
looks just like an ordinary compact disk, CD-ROMs can store approximately
650 megabytes of data, which is four hundred times more data than an
ordinary 3.5 inch floppy disk. CD-ROM disks come with information already
on them and are read only. This means that the information on a CD-ROM
cannot be erased or changed, and no new information can be saved.

When a compact disk is manufactured a laser burns small
depressions called pits into its surface. A CD-ROM drive reads data from a
disk by shining laser light onto its surface as it spins around. A sensor in the
drive detects the amount of light that is reflected back from the disk's
surface. No light is reflected back from the disk's surface.

No light is reflected back from areas where there are no pits. These
are given the binary value 1. This is how data is stored on the surface of a
CD-ROM as a binary pattern of s and s.

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4. 9 WRITEABLE COMPACT DISKS:

Write-able compact disks are supplied blank and can have data put

onto them using a special read/write CD drives. There are two main types of

Write-able compact disk WORM (Write-Once, Read-May) disks which can

have data written to them just once and Magneto-Optical disks which can

have data written to them any number of times just like a hard disk.

 Advantages of disk drives (For all types of Backing Storage):
 Access is fast for saving and retrieving files.
 Very large amounts of data can be stored in small space, compared

with traditional files, i.e. on paper.
 Direct or random access permits files to be accessed immediately

without reading through other files.
 The disk surface can be used repeatedly by overwriting new data.
 Sophisticated "housekeeping" operations are possible, e.g. delete files,

update records, rename files, catalogue files, etc.

 Disadvantages:

 The disk drive units themselves are expensive compared with
alternative methods.

 Computer programs to handle certain types of random access disk
files are more complex than programs for alternative forms of
storage (e.g. sequential files on tape).

4.1 0 PERIPHERAL DEVICES:

A device, such as a printer or disk drive, connected and controlled by a

computer' but external to the computer's Central Processing Unit (CPU).

The components attached to a CPU are also called peripherals they are

not necessarily a part of the computer but are often essential for its successful

operation. They usually have a special purpose.

TYPES OF PERIPHERAL DEVICES:
 Input devices:

The mouse, keyboard, joystick, scanner, track ball etc. are all input

peripherals.

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 Output devices:

Monitors, printers, plotters etc. are all output peripherals.

 Secondary Storage devices:

Sequential Access (Magnetic tape drive): using a reel-to-reel and

cassette tape . Random Access (Magnetic disk drive): using floppy

disks, hard disks and CD- ROM.

4.11 EXERCISE:

Q No.1 Define various types of ROM?

 ROM (Read Only Memory):

Rom stands for Read only Memory. The progress and data

stored on Rom are Permanent and cannot be changed. When the computer is

switched off, the contents of Rom are not lost. This sort of memory, which

isn't wiped clean when the computer is turned off, is called non-volatile

memory

There are several types of ROM:

(a) PROM (Programmable Read - Only Memory):
A Read-Only Memory (ROM) chip programmed at the factory for use

with given computer. The alternative to PROM is a ROM chip in which the

information expressed in the actual design of the circuits internal to the chip.

(b) EPROM (Erasable Programmable Read-Only Memory):

A Read-only memory (ROM) chip that can be programmed and
reprogrammed. The eras-ability of EPROM chip matters to computer
manufactures; which often find that they need to reprogram, ROM chip
containing bugs. PROM chips, which cannot be reprogrammed, must be
discarded when a programming error is discovered.

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(c) EEPROM (Electrically Erasable Programmable Read
Only Memory):

An EEPROM is a special type of PROM that can be erased by exposing it

to an electrical charge. Like EPROM, after erasing data you can reuse it

Q No.2 What is the difference between Dynamic and Static RAM?

DYNAMIC RAM (DRAM) STATIC RAM (SRAM)

1) DRAM stands for Dynamic 1) SRAM stands for Static Random

Random Access Memory. Access Memory

2) DRAM needs to be refreshed 2) SRAM dose not needs to be

thousands of time per second. refreshed

3) It is slower and cheaper than 3) SRAM is faster and expensive

SRAM than DRAM

4) DRAM chips holds data for a very 4) SRAMS chips hold data until the

short time. power turned off.

Q No.3 Define: (2010)
(a) Floppy Diskette (b) Hard Disk (c) Magnetic Tape

(a) Floppy Disk:

This is a single, flexible disk intended for microcomputers, Early floppy
disks were 8-inch in diameter, followed by the 5.25-inch disk, which is now
most common. The 3.5-inch disk is steadily taking over and is likely to be the
standard. The principles of the floppy disk are similar to the Hard Disk except
that the disk consists of only two surfaces. Various formats are available but
an 80 track double sided disk is common, storing 720K of data. The latest
3.5-inch disks can hold 1.44 megabytes of data (1 440K).

(b) Hard Disk:

A hard disk is a circular metal disk coated magnetic material and
usually sealed in a hard disk drive inside the computer. Some hard disk drives
are not permanently fixed inside the computer but are removable. Data
stored on a hard disk can be accessed much· more quickly than data stored on
a floppy disk. A typical hard disk inside a personal computer can hold several
gigabytes of data.

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(c) Magnetic Tape:

The magnetic tape reel is about 10 inch in diameter and, contains up to
2400 feet (370 m) of tape 0.5 inch wide. The tape is. a plastic material coated
with a magnetic oxide, spots can be magnetized to, indicate a 10,a0.. The
spots are arranged in. nine tracks of channel as a parity check Magnetic tape is
a MASS STORAGE device, even though information can only be accessed
serially or accessed sequentially, magnetic tape is very widely used frequently.

Q No.4 What is the difference .between SIMM and DIMM?

SIMM DIMM

1) SIMM stand for Single Inline 1) DIMM stand for Dual Inline

Memory Modules. Memory Modules.

2) A SIMM has chip with 30 or 72 2) DIMM has 168 pins.

pins.

3) It can hold from 8M.B to 64 M.B 3) It can hold from 8M.B to 256

of RAM. M.B

4) SIMM provide small capacity as 4) DIMM provide Large capacity as

compare to DIMM. compare to SIMMs.

5) SIMM have lower rate of data 5) DIMM has wider data bus, thus

transfer as compare to DIMM. has higher rate of data transfer.

Q No.5 Fill in the blanks.
i. RAM is a volatile memory.
ii. The programs stored in ROM are called Firmware.
iii. The smallest accessible unit of computer memory is byte.
iv. 1K Byte = 1024 Bytes.
v. All the programs must be copied into volatile (RAM) memory
before execution.
vi. Magnetic Tape is a storage device that stores data serially.
vii. CD stands for Compact Disk
viii. Inter Block Gap separates logical blocks in a magnetic tape.

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Q No.6 Choose correct answer.
i.
ii RAM is _________memory.
iii.
iv. a. Volatile b. Non-volatile
v.
vi. c. Permanent d. None of the above

vii. ________ is a pre-programmed memory.
viii.
ix. a. Static RAM (b) Dynamic RAM

c. SIMM and DIMM both (d). None of the above

Irregular data can be accessed on magnetic tape_____________.

a. Randomly b. Serially

c. Use indexing (d). None of the above

LBA stands for___________.(2014)

a. Logical block address b. Logical buffer area

c. None of the above

Auxiliary storage is a_________ memory.

a. Primary b Non-volatile c. Temporary

The read write heads of a hard disk drive, floppy disk drive and

tape drive contain electromagnets.

a. The above statements is true

b. The above statements needs Little correction

c. The above statement is a false statement

d. Information is not sufficient

Each byte is the combination of_________________ small unit

called bits.

a. Sixteen b Ten c. Eighteen d Eight

Each box of memory has_________ address.

a Alterable b Unique c. Two

Smallest unit of the memory is________.

a. Nibble b Bit c. 0 to 1 d Byte

Q No.7 Choose the correct statement - True and False.
i. From magnetic tape one can access data randomly.
a. True b. False

ii. There are two basic types of RAM, dynamic and primary.
a. True b. False

iii. Static RAM does not need to be refreshed, which makes it
faster and cheaper.
a. True b. False

iv. RAM always retains the data it holds, even when the computer is
turned off.
a. True b. False

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v. PROM, EPROM and EEPROM are types of SIMM.
a. True b. False

vi. RAM is an external storage.
a. True b. False

vii. SDRAM stands for Synchronous data random access memory.
a. True b. False

viii. A group of four bits makes two nibbles.
a. True b. False

ix. RPM stands for Rotation Per Mile.
a. True b. False

x. The smallest accessible unit of memory is byte
a. True b. False

QUESTIONS FROM- PAST PAPERS:
YEAR 2014:

Section "A" (Multiple Choice Questions) - (MCQs)

Q.1 (i) LBA sands for:
(x)
(xiii) * Logical block address * Logical buffer area

* Logical block area * None of these

4 bites =:

* I byte * Half byte * Nibble

* None of these

The range of months in date commands is:

* 16000 * 16384 * 10000 *256

Section "B" (Short -Answer Questions) (No Questions)
Section "C"
(Detailed-Answer Questions) (No Questions)
Section" A"
Q No.1 (i) YEAR 2013:

(iv) (Multiple Choice Questions) - (MCQs)

The other name of Fixed Disk is:

* Hard Disk * Optical Disk * Floppy Disk * All the above

Pre-programmed memory is:

* SRAM * DRAM * DIMM * None of the

(viii) ROM has special programs called:

* Firmware * Live wares *Hardware * Software

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Section "B" (Short -Answer Questions) (No Questions)

Section "C" (Detailed-Answer Questions) (No Questions)

YEAR 2012:

Section "A" (Multiple Choice Questions) - (MCQs)

Q.1(vi) The process of creating sectors and tracks on disk is known as:

* Booting * Tracking * Formatting *Listing

(vii) In computer term 16KB means:

* 16000 *16384 *1000 *256

(viii) ROM has special programs called:

* Firmware * Live ware *Hardware *software

(ix) The other name of fixed disk is:

* Hard Disk * Optical Disk*Floppy *All of these

Section "B" (Short -Answer Questions)
Q.2 Define ROM and name its types.

Section "C" (Detailed-Answer Questions) (No Questions)
YEAR 2011:

Sect inn "i" (Multiple Choice Questions) - (MCQs)

Q.l (iv) Hard disk is a _________storage device:

* Volatile * Permanent * Primary *None of them

(xiii) The program stored in ROM is also called:
* Software * Live ware * Firmware *Hardware

Section "B" (Short -Answer Questions)
Q.5 Describe functions of Primary Memory.

Section "C" (Detailed-Answer Questions) (No Questions)

YEAR 2010:

Section" A" (Multiple Choice Questions) - (MCQs)

Q.1 (iii). Pre-programmed memory is:

* SRAM * DRAM *DIMM *None of them

(viii) Non-volatile memory is:

* ROM * Cache Memory *RAM *All of them

(ix) An eight bit sequence is called a:

* World * Cell *Nibble *Byte

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Section "B" (Short -Answer Questions)

Q.2(ii) What is the difference between SRAM and DRAM?

Section "C" (Detailed-Answer Questions)

Q.4(b). Write notes on Floppy disk, Hard disk and Magnetic tape.

YEAR 2009:

Section "A" (Multiple Choice Questions) - (MCQs) (No Questions)

Section "8" (Short -Answer Questions) (No Questions)

Section "C" (Detailed-Answer Questions) (No Questions)

MULTIPLE CHOICE QUESTIONS (MCQs)

(1) ___________ is the volatile memory for temporary storage of

data/program.

(a)RAM (b) ROM (c)PROM (d)All of the above.

(2) ___________ Bit = 1 Byte.

(a)4 (b)2 (c)7 (d)8

(3) ___________Bytes =1 KB

(a)8 (b)1 (c)1024 (d) None of the above.

(4) ___________ memory is that type of memory which dose not lose the

information stored when the power is turned off.

(a)RAM (b)ROM (c)Register (d) None of the
above.

(5) In computer terms 65KB means_______ bytes.

(a)Kilo (b)Mega (c)Tera (d)Giga

(6) __________is a volatile memory.

(a) ROM (b)RAM (c)PROM (d) None of the above.

(7) Secondary Storage Devices are also called_________.

(a)Backing storage (b)External storage (c)Internal storage (d) None of
the above.

(8) Magnetic Tape is a _____________.

(a)Sequential Access (b)Random Access (c) Internal storage (d) None
of the above

(9) 1 Kilobyte is equal to _____ bytes.

(a) 1024 (b)8 (c)16 (d) 4

(10) Magnetic_______ is a Random access medium/ device.

(a)Disk (b)Drum (c)Tape (d) None of the above

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(11) The program stored in ROM is also called:

(a)Software (b) Live ware (c) Firmware (d) Hardware

(12) One byte is the combination of________ bits.

(a)2 (b)4 (c) 8 (d) None of the above

(13) _______ is the slowest and cheapest form of memory.

(a) DIMM (b) SIMM (c) ROM (d) None of the above

(14) A 3.5" high density floppy disk can store_________.

(a) 720 KB of data (b) 1.22 MB of data

(c) 1.44 MB of data (d) None of them

(15) Hard disk is coated with ______material and read/write head transfer

data to it magnetically.

(a) Plastic (b) Magnetic (e) Iron (d) None of the above

(16) ROM is____________.

(a) Non-Volatile memory (b) Non-Changeable

(c) Memory where information provided by manufacturer

(d) All of them

(17) Magnetic tape_________________.

(a) Cost less than magnetic disk (b) Is slow access

(c) Stores data in the serial or sequential manner (d) All of them

(18) The spiral tracks on a CD-ROM holds approximately ________of data.

(a) 450mb (b) 650mb, (c) 590mb (d) None of the above

(19 ) Hard disks are rigid aluminum or glass disk about_________ inches in
diameter in a personal computer.

(a) 3.5 (b) 5.5 (c) 4.5 (d) 8

(20) A hard disk/drive unit comes with a set rotation speed varying from

__________to____________ rpm.

(a) 3500"': 6200 rpm (b) 4500 - 7200 rpm (c) 4000 - 6500 rpm

(21) The magnetic tape is divided into_____________.

(a) Logical blocks (b) Tracks and sectors

(c) Intent block gap (d)None of these

(22) It is considered that future computer will standardize on_________.

(a) SIMM (b) DIMM (e) PROM

(23) PROM is an abbreviation of____________.

(a) Paragraph Reference Only Memory

(b) Programmable Read Only Memory

(c) predefined Read Only Memory

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(24) ___________ is the smallest and non addressable unit of memory.
(25)
(a) BIT (b) Nibble (c) Byte (d) Kilo byte
(26)
SIMMs usually come in memory chip multiples of
(27)
_______________MB
(28)
(a) Five (b) Six (c) Four (d) None of them
(29)
_________________)memory is that type of memory which does not
(30)
(31) lose the information stored when the
(32)
power "is turned OFF.
(33)
(34) (a) ROM (b) SRAM (e) RAM (d) DRAM
(35)
(36) A set of bit consider as a unit. normally consisting of 8 bits is known

(37) as__________.
(38)
(39) (a) Byte (b) Nibble (e) Word (d) None of the above

___________________RAM needs to be refreshed thousands of

times per second.

(a) Static (b) Dynamic static (e) Dynamic (d) None of them

Secondary storage is also called____________.

(a) Internal storage (b) Main storage

(e) Auxiliary storage (d) None of them

Pre programmed memory is____________.

(a) SRAM (b) DRAM (c) DIMM (d) None of them

An eight bit sequence is called a ____________.

(a) Word (b) Cell (e) Nipple (d) Byte

The method of is complement arithmetic is commonly used in

computer to handle___________. (2009)

(a) Positive number (b) Negative number

(c) Equal number (d) Binary number

Computer can recognize a total of _____different characters.(2009)

(a) 275 (b) 255 (c) 235 (d) 256

Hard disk is a _________storage device. (2011)

(a) Volatile (b) Permanent (e) Primary (d) None of them

The other name of fixed disk is: (2012)

(a) Hard Disk (b) Optical Disk (e) Floppy Disk (d) All of these

The speed of CD-Rom is measured in x and lx is equal to ______KBs

per second

(a) 150 (b) 128 (e) 1024 (d) 100

The Process of creating sectors and tracks on disk is known as:

(a) Booting (b) Tracking (e) Formatting (d)Listing

ROM has special programs called:

(a) Firmware (b) Live ware (c)Hardware (d)Software

Bits=_____________.(2014)

(a) 1 byte (b) Half byte (c) Nibble (d)None of these

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CHAPTER-5

DATA REPRESENTATION

CLASS-IX

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DATA REPRESENTATION

5.1 HOW DOES THE COMPUTER REPRESENT THE DATA?
5.2 A CONCEPT OF DATA AND INFORMATION
5.3 DATA
5.4 NUMBER SYSTEM
5.5 CONVERSIONS OF NUMBER SYSTEM
5.6 ARITHMETIC OPERATIONS IN BINARY
5.7 CODES USED IN COMPUTER
5.8 EXERCISE
5.9 MANIPLE CHOICE QUESTIONS (MCQS)

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5.1 HOW DOES A COMPUTER REPRESENT THE DATA?

To discuss how the computer processes the data. We should first
have to understand of the form in which the data is stored in the computer's
memory. There are two basic types of data, which are stored and.
processed by the computer. They are characters and numbers. But in a
computer everything is in number. Numbers are numbers, letters are
numbers, punctuation marks are numbers, sounds and pictures are
numbers, even the computers own instructions are numbers. This might
seem very strange to you as you have seen the series of words, sentences
and numbers on them.

These characters and numbers are assigned different values by the
computers. Now the output from the computer, must be in the form that is
understood by the users. Thus the computer translates those values into [he
form understandable by the users, which is again natural language consisting
of numbers and characters. This constitutes EXTERNAL DATA
REPRESENTATION. On the other hand, the values: are used by the computer
to store and process the data is INTERNAL DA TA REPRESENTATION.

In computer however all the data has to be converted in to electrical
switches. A switch has only two states they are "ON" or "OFF". As they take
only two numeric symbols, they are said to function in base 2 which is
known as Binary System (BI means Two in Latin).

5.2 A CONCEPT OF DATA AND INFORMATION:

The computer works on data. The words data and information are
often used interchangeably. There is an important distinction between
them. Data is the words numbers and graphics that describe people events
things or ideas. Data becomes information when it is arranged in a form that
is meaningful.

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A representation of facts, concepts or instructions suitable for
communication, interpretation or processing by humans or machines is
called Data. In short "DATA" mean collection of raw facts. When these facts
are arranged in a suitable manner they provide some information. For
example, AMMAR reach Islamabad 200 hrs. Karachi tomorrow is a data
which can be arranged in a number of way. When this data is arranged as
given below:

AMMAR will reach Karachi from Islamabad at 200 hrs by tomorrow.
This arranged data conveys a message, is called Information.

5.3 DATA:

The word DATA is derived from Latin language. It is plural of Datum.
(But Data is usually used as a singular term). As ·we know that the data is the
collection of raw facts and figures therefore, we need symbols for their
representation. These symbols may be letters words or figures such as 3
Books, 6 students. 20th march, 100 Watts PK- 429. Each data item conveys
certain meanings.

 Types of Data:

In computers data items can be classified in to the following two types.

1. Numeric Data 2. Character Data

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(1) NUMERIC DATA:

Numeric Data contains discrete numbers only such as 20, 345, 8.25, -

45, -16.2 etc. Numeric data can be classified into two types:

(i) Integer Data (ii) Real Data

(i) Integer Data:

Integer Data consists of positive or negative whole numbers including
zero. For example: +5, +8, -32 are integers

(ii) Real Data:

Real data contains numbers which may be fractions or incremental
including integer. For example: 2/7, 13.4, 0.14 etc. are representatives of
real numbers. Real data is further divided into two types.

(a) Fixed-point Data (b) Floating-point data

(a) Fixed Point Data:-

Fixed point data may include digits (0-9), decimal point, and +-/ sign.

For example, percentage of marks, weight etc. (-42.002,0.05, +426.8 etc) .

(b) Floating Point Data:-

Floating point data may include digits (0-9), decimal point, +/- sign
and letters "'0", "d", "E", e ; etc. For example, speed of light, mass of
atomic particle etc.

(1.602 X 10-19 (Charge of electron in coulomb)).

2. CHARACTER DATA:

Character data falls into two groups.

(i) String (ii) Graphical Data

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i) String Data:
String data consists of the sequence of characters. Characters may be

English alphabets, numbers or space. The space which separates two words,

is also a character. The string data is further divided into two types:

(a) Alphanumeric Data (b) Alphabetic Data

(a) Alpha-Numeric Data:

Alphanumeric data contains a combination. of numerals and letters
of alphabets including special characters such as #, %, '?, *, + etc. For
example 1432, B/29 PK I02, Practical Centre, B-14 Block# 1 etc.

(b ) Alphabetic Data:

Alphabetic data includes all the uppercase and lowercase letters of
alphabets and combination such as A, B, C, Z, a, b, c z. MCB, AASHIR,
PAKISTAN etc.

ii) Graphical Data: It is possible that pictures, charts and maps can be
treated as data; The scanner is normally used to enter this type of data.
The common use of Graphical data is found in the National. Identity
card The photographs and thumb impression are scanned and stored in
the computer to identify a person.

Differentiate between Data and Information (2014)

Date Information

1) Un-processed information is called 1) Processed form of data is called
Data. information.

2).Raw facts and figures are called Data. 2) Organized and meaningful data is
called information.

3) We cannot take decision on data. 3) We can take any decision on
information.

4) Example, Each student is test score is 4) The class average score or the
one piece of Data. school's average score is the
information that can be concluded
from the give data.

5) Data is the computer's language. Information is our translation of this
language.

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5.4 Number System:

Since early times different number systems have been used. By number
system, we mean using a base for counting. Digital computers are the machines
which respond numbers. All the data and instructions must therefore be
represented in a numeral format. 'Thus number systems are very important to
understand because a computer understands numbers only. The binary
number system has been found to be the most natural and efficient system for
modern digital machines.

TYPES OF NUMBERSYSTEM:

(1) The Decimal Number System (DECl Means 10)

The decimal number system consists of 10 digits (from 0 to 9). The
values of each digit in a number depends upon the following: The face
value of the digit, i.e. the digit itself. The base of the system. The
position of the digit in the number.

Example:

Let us consider a decimal number 642. The position of digits 2,4 and
6are at and unit, tens and at hundredth places respectively, Thus 542 can be
written as Hundreds (102) Ten (101) Unit (100) (position value)

Solution:

642 = 6 42

= 600 + 40 + 2

=6 x 100 + 4 x 10 + 2
642 = 6 x 102 + 4 x 101 + 2 x 100

(2) The Binary Number System :
The ON/OFF positions of electronic switches in a digital computers

correspond to binary digits 0 or l. In binary number system any number can be
expressed by the digits, 0 and 1 only. The place or position value of each digit,
in a binary number, is twice the place-value of the digits on its right.

 In binary system 1 corresponds to 2° = 1 in decimal system.
 In binary system 10 corresponds to 21 = 2 in decimal system.
 In binary system 100 corresponds to 22 = 4 in decimal system.
 In binary system 1000 corresponds to 23 = 8 in decimal system.

And so on.

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Example:

Convert binary numbers (1 10101)2 into its decimal equivalent.

25 24 23 22 21 20

32 16 8 4 2 1
(110101)2=1 1 0 1 0 1 -------------> (Place Value)
(110101)2=1x32 + 1x16 +0x8 +1x4 +0x2 +1x1
(110101)2=32 +16 +0 +4 +0 +1
(110101)2=(53)10

(3) The-Octal Number System (OCT Means 8):
The Octal Number system consists of 8digits (0, 1, 2, 3,4, 5, 6 and 7). In

this number system, the base is 8. Each digit position in octal number system
represents a power of eight. The numbers next to 7 will be 10, 11. ..... 17, 20,
21.... 27, 30 and soon.

Example:

Convert an octal number (246)8 into its decimal equivalent.

Solution:
82 81 80

64 8 1 (positions Value)

(246)8 = 2 4 6

= 2x64 + 4x8 + 6x1

= 128 + 32 + 6

(246)8 = (166)10

(4) The Hexadecimal Number System (HEXA means 16 and DEC means 10)
The Hexadecimal number system consists of 16 digits (0,1………9, A, B. C. D,

E and F) The alphabets A, B, C, D, E and F are used to represent decimal
numbers 10, 11, 12. 13, 14 and 15 respectively. In this number system the base
is 16.

Example:

Convert Hexadecimal number (2B5)16, into its decimal equivalent.

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Solution:
162 161 16°
256 16 1 <------------ (Position Value)
2 B5

= 2 x 256 + 11 x 16 + 5 x 1
= 512 + 176 + 5

(2B5)16 = (693)10

5.5 CONVERSIONS OF NUMBER SYSTEM:

All the number systems discussed above can inter-converted to one
other. The set of rules to convert them are discussed below:
Decimal to other Number systems.

The decimal number system can be converted into other number systems
by using either of two methods given below:

Power Method:

(a) Written the powers of the radix till it is less than the number to be
converted

(b) Subtracting the highest number, which is obtained by raising the
powers of the radix from the number? This is to be converted.

(c) Obtaining the remainder say R.
(d) Subtracting the next highest number from this remainder.
(e) Repeating the process till remainder is zero.
(f) Now multiplying the powers, which have been used with one and

multiplying the powers by zero which have not been used.

Remainder Method:

This is the method commonly used for the conversions from decimal

number system to the binary number system. The conversion is carried out

in the following order divide the given number (decimal system) by the

radix of the proposed system (in which the number has to be converted).

Note down the remainder.

Now the quotient will again be divided by the radix and the remainder will
be noted down.

The procedure goes on till zero comes as quotient.

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Fractions:

We have already discussed the remainder and the power methods to
convert the decimal numbers to binary numbers. Now the fractional
decimal numbers can be converted to binary numbers by following the
steps given below.
1. Multiply the radix of the proposed system with fraction to be

converted.
2. Note clown the resulting integer (if any) otherwise put down zero in

that place.
3. Repeat the multiplication with the resulting fraction.
4. Keep repeating the procedure till the fraction vanishes or you

encounter the recursive.

Decimal into Binary Conversion:

Example:

1. By using Power Method:

(i) (220)10
Radix of the binary system = 2

Power of radix which are less than 220

2' 2
22 4
23 8
24 16
25 32
26 64
27 128

220
-128 -----------------------------------> 27=1x27
92
-64 -------------------------------------> 26=1x26
28
-16 -------------------------------------> 24=1x24
12
-8 --------------------------------------> 23=1x23
4
-4 --------------------------------------> 22=1x22
0
1x27 -------------------------------------- 1
1x26-------------------------------------- 1
0x25-------------------------------------- 0
1x24-------------------------------------- 1
1x23-------------------------------------- 1
1x22-------------------------------------- 1
0x21-------------------------------------- 0
0x20-------------------------------------- 0
Thus the binary equivalent of (220)10 is (1010100010)2

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(ii) (674)10

Radix of the binary system = 2

21 ow 2
22 .4
23 8
24 16
25 32
26 64
27 128
28 256
29 512

674 29 = 1x29

-512

162
-128 27 = 12x7

34
-32 25 = 1x25

2
-2 21 = 1x21

0

Ix29 1
0x25 0

lx27 1
0x25 0
lx25 1
0x24 0
0x23 0
0x22 0
lx21 1

0x2° - 0

Thus the binary equivalent of (674)10 is (1010100010)2
By using Remainder method:

(i) 22010

2 220

2 110 0

2 55 0
2 21 1
2 13 1

2 61

2 30

11

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While writing the binary equivalent the digits are taken from bottom to top (as
indicated by arrow). The binary equivalent in the above example is
(11011100)2

(ii) 67410

2 674
2 337 0

2 168 1
2 84 0
2 42 0
2 21 0
2 10 1
2 50
2 21

10

Thus binary equivalent of (674)10 is (1010 100010)2

Fractions:

Converting (0.40) to binary form

Radix = 2 Fractions Integer

OAOx2 = 0.80 0

0.80x2 =1.60 1

0.60x2 = 1.20 1

0.20x2 = OAO 0

OAOx2 = 0.80 0

Thus binary equivalent of 0.4010 = (0.01 100 ..)2

(12.25)

Radix = 2

Integer part = 12

Using remainder method:

2 12

26 0
0
23 1

1

Thus binary equivalent of (12) 10 is (1100) 2
Fraction part = 0.25

Fraction Integer

O.2Sx2 = 0.50 0

0.50x2 = 1.00 1

The binary equivalent of (O.25)10 is (01) 2

Thus the binary equivalent of (12.25) 10 is (100.10) 2

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Decimal to Octal:
1. Integer:
(98)10
Radix = 8

8 92 2
8 12 4
1
Thus octal equivalent of(98) 10 is (142) 8 7
423 4
2. Fraction: 52 0
8
• (423.03125) 10 1

Integer part = 423

8
8
8

Thus the octal equivalent of (423) 10 is (1047) 8
Fraction part = 0.03125

Fraction:

0.3125 x 8 = 0.250
0.250 x 8 =2.00
That is (0.03125)10 = (0.02) 8
Thus the octal equivalent of (423 .03125) 10 =(1047.02) 8
Decimal to Hexadecimal:

Integer:

(8234) 10

16 8234
16 514 10 10 = A

16 32 2
20

Thus the hexadecimal equivalent of(8234)10 is (202A)16
Fraction

(0.225) 10

Fraction Integer

0.225 x 16 = 3.6 0.6 3

0.6 x 16 = 9.6 0.6 9

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Thus the Hexadecimal equivalent of (0.225) 10 is (39)16
Binary System to Other Number Systems:
Binary to Decimal Number System:
Binary number can be converted to decimal number system by multiplying
each binary digit with its respective position weight and then adding all the
results.

Examples: 27 = 128
1. (10.100011)2

1X

0 x 26 = 0
1 x 25 = 32

0 x 24 = 0
0 x 23 = 0

0 x 22 = 0

1 x 21 = 2
1 x 20 = 1

2.(1101)2 23 163
1x =8

1 x 22 =4

0 x 21 =0

1 x 20 =1

13

 Binary to Decimal (Fraction):

The binary fractions are converted to the decimal number systems by
multiplying each digit by their respective position weights (that is the negative
powers of the base 2) and then adding them together.

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Example:

(1011.11011)2
Consider the inter part first:

1 x 23 =8

0 x 22 =0

1 x 21 =2
1 X 20 =1

11

Consider the fraction part now:
Fraction = (0.11011)2
= 1 x 2-1 + 1 x 2-2 + 0 x 2-3 + 1 x 2-4 x 1x2-5
= 1/2 + 0 + 1/16 +1/32
= (0.84375)10
Thus the decimal equivalent of (1011.1 1011)2 is (11.84375)10
Binary into Octal Number System:
Binary numbers can be converted to octal number system by two methods:

1. By converting the Binary number first into the Decimal number system
and then converting the number so obtained into octal number system.

2. By grouping three Binary digits to produce a single Octal number
proceeding from least significant bit to most significant bit.

Examples:

1. Integer:
(110100101)2
First converting the above binary number to the decimal equivalent by
multiplying .each digit with its respective position weight:

110100101
28 27 26 25 24 23 22 21 20

256 128 0 32 0 0 4 0 1

= 256 + 128 + 0 + 32 + 0 + 0 + 4 + 0 + 1

=421

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