PIXELES CLASSES
BCA & MCA (IGNOU)
Course Code
Course Title
: BCS-011
: Computer Basics and PC Software
Assignment Number
: BCA (I)/011/Assignment/ 2015
15 October, 2015 (For July 2015 Session) April, 2016 (For January 2016 Session)
1. (Covers Block 1)
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(7×4=28 Marks)
(a) What are the functions of various operational units of a computer system? What is
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von Neumann Architecture? How can you relate von Neumann architecture to an actual
computer? Explain with the help of an example configuration. (4 Marks)
Ans:
“A computer is an electronic device that accepts data, processes it and returns processed
information (Result)”. It works on the principle of input, process and output.
Input
Process
Output
Main Functional Unit:
CPU: - it is the brain of any computer system. It is just like brain that takes all major
decisions, makes all sorts of calculations, functions and controlling the operations.

The Arithmetic Logical Unit: - it is an important component of the CPU, which carry
the actual execution of the instructions.

The control unit: it determines the sequence in which computer programs and
instructions are executed. It acts like the supervisor seeing that things are done in
proper fashion

A von Neumann machine has single path between the main memory and control unit.
This feature is known as bottleneck.
Structure of von-Neumann computer machine & Function
John Von Neumann architecture a design model for the modern computers, which has central
processing unit (CPU), and the concept of memory used for storing both data and instructions.
All computers have memory, an I/O system, arithmetic logic unit (ALU) and control unit (CU).
(Structure of Von-Neumann Machine)
Features of von-Neumann
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
CPU consists of ALU and CU.

Program and data are stored in the same memory unit.

A von Neumann machine has unique memory address of each location.

A von Neumann machine has only a single path between main memory and control unit
this feature is called bottleneck.

Serial processing system

Input /output system

Main memory system
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(b) Compare and contrast the characteristics and/or organisation of the following:
(i) DRAM Vs. SRAM
Ans: Static RAM (or SRAM)

Static RAMs retain stored information for long time as the power supply is on.

Static RAMs are costly and consume more power. Static RAMs have a higher speed
than dynamic RAMs.

Static Ram is faster and so is used in cache memory.

SRAM does not need to be refreshed.
Dynamic RAM (or DRAM)

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Dynamic RAM loses its stored information in a very short time even the power supply is
on.

Dynamic RAMs are cheaper and consume less power

Dynamic RAM is cheaper and so is used for main memory.

Dynamic RAM requires the data to be refreshed periodically.
(ii) Access time on Magnetic disks Vs. access time on Magnetic tapes
Ans:
Magnetic disks:-It provides random access. This means that a file can be accessed from any
location directly. The total access time for a disk is equal to the seek time plus the latency time.
The average access time for most disk systems is usually between 10 to 100 milliseconds.
Magnetic tapes: - A file or some particular information stored on a magnetic tape cannot be
accessed directly on random basis as is possible in the case of hard-disks or floppy disks.
These devices are slower, but due to their low cost, they are still widely used for massive data
warehouse and other business storage requirements.
(iii) Pen Drive Vs. CD-RW
Ans:-
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Pen Drive is available as a very convenient and flexible data storage medium which
can store up to 256 GB data. It can be used for the same purposes as floppy-disks or CDROMs. Pen Drives are a smaller, faster, durable and more reliable storage medium.
CD-R (compact-disk recordable) is another optical disk technology. The user can record (write) PIXELES Classes
their own data once on a CD with a CD-R disk drive unit. After this recording user can read the Page | 3
data as many times as desired.
(iv) ROM Vs. PROM (4 Marks)
Ans:
ROM: it is read only semiconductor memory. It is designed for the purpose for reading only. It is
non-volatile; means it does not lose their contents on power failure. It is written only once at the
time of manufacture. It is used by system program only. There are various varieties of ROM:PROM: it stands for programmable ROM. it is also non-volatile. It is written (programmed) only
once by special writing device.

It is possible for a user to customize a system by storing own program in a PROM chip.

Once a program has been written on to a PROM chip, the recorded information cannot
be changed i.e., the PROM becomes a ROM and it is only possible to read the stored
information.

PROM is also a non-volatile memory. It stored information remains even if power is
switched off.

The basic difference between PROM and a ROM is that a PROM is manufactured as
blank memory, whereas a ROM is programmed during the manufacturing process.
(c) Convert the following numbers as stated
(i) Decimal 79.005125 to binary
(ii) Decimal 3267 to hexadecimal
(iii) Character A and z to ASCII and Unicode Hexadecimal FA6B to binary
(4 Marks)
(d) What is an instruction? What are its components? What is the role of an instruction
in a computer? Explain with the help of an example. Where does the instruction reside at
the time of execution? (4 Marks)
Ans:
An instruction specifies the operation performed by CPU. An instruction tells the processor what
task is to be performed and what micro operations need to be completed to perform the task.
Every instruction is comprised of two parts: opcode and operands.

The opcode specifies the operation to be performed
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Operands provide the data on which the operation is to be performed.
Example
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Page | 4
Instructions are stored in CPU register during operation.
(e) A 2.5 inch diameter disk has 8 platters with each platter having two data recording
surfaces, each platter on disk has 4084 tracks, each track has 400 sectors and one
sector can store 1 MB of data. Calculate the storage capacity of this disk in Bytes. If this
disk has a seek time of 2 milli-seconds and rotates at the speed of 6000 rpm, find the
Access time for the disk. Make suitable assumptions, if any.(4 Marks).
Ans:
Surface m=8X2=16
Track (t)=4048
Sector per track (p)=400
Byte per sector (s)=1MB X 1024 X 102 bytes
Capacity =mtps
=16 X 4048 X 400 X 1MB X 1024 X 1024 bytes
Access time= seesk time + latency time
Latency time = (1/(RPM/60))*0.5
=(1/(6000/60))*0.5
=(1/100)*0.5*1000 ms
=5ms
Access time =2ms +5ms=7ms
(f) What are the uses of various components of motherboard of a computer? List at least
four output devices and ports to which these devices can be connected. Explain the
characteristics of these output devices and ports.(4 Marks)
Ans:
Motherboard holds some of the most important components of the computer system. It acts as
a base for these components. It is also known as system board, main board etc. In a typical
computer microprocessor, main memory and other components are connected to the
motherboard. Motherboard also provides connectors for several other devices.
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ATX Power Connector: Advanced Technology Extended (ATX) power connector is
used to connect computer’s power supply to motherboard.

AGP Slot: Accelerated Graphics Ports (AGP) is a point-to point channel which is
used to attach a video card to a motherboard.

CD-in header: At this CD drive is plugged in or connected. FDD Header: Floppy Disk
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Drive (FDD) header is used for Floppy drive. Now this slot is obsolete because floppy
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disks are outdated.

HDD Headers: Hard Disk Drive header is used for connecting to hard disk.

PCI Slots: It is used for connecting the PCI (Peripheral component interconnect)
card.

USB Headers: It is a group of pins to which an internal USB cable can be attached to
provide extra USB ports. These ports are used for attaching external/auxiliary devices
such as pen drive, printer etc.
4
(g) What are the uses of following Software?
(i) Data compression utility:- - Data compression is the process in which information is
encoded with lesser bits in compare to the original representation. Data compression is very
useful, as it reduces the size of the file so it consumes fewer resources like disk space.
(ii) Media Player: - It is one of the other common examples of application software. It is an
application which is used to play multimedia files. Most of the media players can play both audio
and video files.
(iii) Disk Defragmenter:- it is used to rearrange the files and unused space on the hard disks
that program run faster.
(iv) Disk checker:- Disk Checkers are used to check the integrity of the hard disk and Pen
Drive/ Flash Drive. CHKDSK is a command which is used for this purpose. This command
can be used on a computer running Windows operating system. It fixes the logical file system
errors found in the disk/drive.
(4 Marks)
2. (Covers Block 2)
(7×4=28 Marks)
(a) Why do you need virus detection software? What are their drawbacks? What are the
techniques to identify a virus? Explain the importance of backup for a computer system.
(4 Marks)
Ans:
Computer viruses are software programs that are deliberately designed to interfere with
computer operation; record, corrupt, or delete data; or spread themselves to other computers
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and throughout the Internet. Virus Scanning Software is utility programs designed to protect
your computer from computer viruses, worms and Trojan horses.

Antivirus software can impair a computer’s performance. Active anti-virus programs can
cause conflicts with other programs.

Most popular anti-virus programs are not very effective against new viruses.
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
Slow down the system.
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Techniques

Signature based detection: This is the most common method. It compares the
contents of the infected file to a known pattern of data. Because viruses can embed
themselves in existing files, the entire file is searched.

Heuristic-based detection: This method is primarily used to identify unknown
viruses by looking for malicious code or variations of such code.

File emulation: This is another heuristic approach in which the infected program
is run in a virtual environment and the actions it performs are recorded. The
actions are analyzed to check for any malicious actions and carry out disinfection
actions accordingly.
Backup
Backup refers to making copies of data so that these additional copies may be used to
restore the original after a data loss event. All types of data could be backed up like
pictures, word documents, files, executables or an entire database. The main purpose is to
recover data in the event of data loss or data getting corrupt. Other purpose could be to
recover historical data.
(b) Consider that you have to run several computer programs simultaneously on a
computer. Each program takes input from a file and output information on a printer. How
does different components of an Operating system (like memory management, I/O
management, Process management, file system and user interface) will help in execution
of these programs.
(4 Marks)
Ans:
Process Management.
A process is a program under the execution. It is the job, which is currently being executed by
processor (CPU). OS manages process of jobs.
Memory Management
OS take-cares of memory allocation and de-allocation of main memory to various processes. It
allocates the memory space in main memory and secondary memory to store the system
program, user program and data.
Input Output Management
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OS co-ordinates the various input and output devices such as terminals, printers, disk drives,
tape drives. It controls I/O Devices.
File management
As we know, data are stored in a file and files are stored in a device. All operation related to file
are managed by operating system such as data storage, data retrieval, updatation, deletion andPIXELES Classes
Page | 7
other activities.
Scheduling Management
Operating system establishes process priority for the task execution.
Security Management
Operating system provides data security and data integrity. That is, it protects data and
programs stored in computer from unauthorized access.
(c)
Explain the differences between procedural programming and object oriented
programming with the help of one example program of each.(4 Marks)
Ans:
OO programming
 Modular Design: - OOP provides modular approach to design a program that can be
compiled separated and run together in a software, it increase the productivity of
programmers.
 Simple interface: it provides simple and easily understandable interface design of programs.
 Flexible: Software built on objects oriented programming can be flexible in adapting to
different situations because interaction between objects does not affect the internal working
of objects.
 Reusable: OOP provides facility to reuse of code using inheritance.
 Maintainable: Objects are separate entities, which can be maintained separately allowing
fixing of bugs or any other change easily.
Procedure programming

It is based on the principle of building a program from logical structures.

It provides divide and conquer method to reduce complexity.

It provides clear flow of control.

Modules can be reused.

Easy to learn.

It doesn’t provide information hiding.

If any changes made in a program may reflect other part of program.
(d) Draw a flow chart of a program that adds N odd numbers starting from 1. The value
of N should be input by the user.(4 Marks)
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Ans:-
We are teaching IGNOU’s BCA & MCA
Students
Why join us?
 Regular Classes
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(e) List the elements of a programming language. Explain the terms data type,
expression, assignment; and logical, relational and equality operators with the help of an
example each.
(4 Marks)
Data Types
Here you are going to explain basic data type:Char
It stores a single character by default and reserved 1 byte memory space. For Example Ch=’S’,
here ch is a variable name that is holding a character ‘s’. Single character quoted by single
quote and more than one character quoted by inverted commas like “pixeles” that is called
string. Store more than one character you need to declare size as flows.
Char s [10]
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Now you can input more than one character, upto 10 characters including NULL into the
variable s.
Character constant declares as
const char emp=‘t’
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Integer
This is the numeric data type that accepts number without fraction ranges between –32768 toPage | 9
32767 to be stored. It occupied 2 bytes memory space.
For example:int x=234, y=567;
Constant integer declared as const int x=56;
Float
It is also numeric data type. It can store floating-point values; a number has a precision of only 6
digits. Float variable allocates 4 bytes of memory space.
For Example- float x=34.878677
Double
It is also numeric data type. It can store double floating-point values these number have a
precision of 16 to 18 digits. Double variable allocates 8 bytes of memory space.
double x=134.4500000000000000
Float and double constant
const float pie=3.142857
Expression: Collection of operators and operands is known as expression. For example:
2+5*(6+4)
Logical operator:
it is used to evaluate conditional expression. There are four types of it-.
AND – evaluates true if both condition are true otherwise false.
OR - evaluates true if any condition is true otherwise false.
NOT – Evaluates true if condition is false.
XOR - evaluates true if one condition is true and other is false.
For example:
10>5 AND 7<9 =‘true’
10>5 OR 12<9 = ‘true’
NOT(10>5) = ‘false’
10>5 XOR 37<9 =‘true’
Arithmetical Operators:-
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This operator performs an arithmetic (numeric) operation such as +,-,*, / or % is called
arithmetic operator. It requires two or more operands. So these operators are called binary
operators.
Operator
Meaning
Example
Answer
+
Addition
6+3
9
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-
Subtraction
6-3
3
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*
Multiplication
6*3
18
/
Division
6/3
2
%
Modulo
5%2
1
Relational Operators:- This operator is used to check the relation between two values .All
relational operators are binary operators and it require two operands. When relation is false
then it returns zero otherwise non zero.
Operator
Meaning
Example
==
Equal to
3==3
!=
Not equal to
3!=5
>
Greater than
4>2
<
Less than
3<5
>=
Greater than equal to
4>=4
<=
Less than Equal to
7<=7
(f) What are the phases of project development in which project management software
can help. Explain with the help of examples.
(4 Marks)
Ans:Typical development phases of a project are:
o
Project initiation stage
o
Project planning or design stage
o
Project implementation stage
o
Project monitoring and controlling systems
o
Project completion stage.
Software project management is used to maintain following things in Software project:
Scheduling

Calculating critical path

Providing information

Timesheet Management
Example
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Microsoft Office Project
One of the most widely used software for Project Management used all over the world is MS
Project. It is used for planning, managing and organizing resources for all kinds of projects. It
uses a powerful scheduling engine to help align different projects and tasks with available
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resources.
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(g) Explain the following with the help of an example/diagram, if needed:
(i) Development Model for Open Source Software
Ans:The Open
source
development model is a collaborative model. It anticipates the
participation of many developers in the development of a single product or
module. Example: The most popular open source utility used by the gatekeeper is
the Concurrent Versioning System (CVS), which is licensed under GPL.
(ii) Tools for program development
Ans:- A programming tool or software development tool is a program or application that
software developers use to create, debug, maintain, or otherwise support other
programs and applications. The most basic tools are a source code editor and a
compiler or interpreter, which are used ubiquitously and continuously.
iii) Use of functions and Macros
Ans:
Excel has builtin functions like IF, AND, OR, SUM which you use in your worksheet.
Functions can invoke other functions to return a value.
A stored series of commands and functions that can be run to perform a specific task or
tasks. In Excel a macro could be a complete program. Macros may be run from a
toolbar button, or menu, from a shape in the workbook, or from another macro.
(iv) Database and Database Management system (4 Marks)
Ans:Database is used to organize information into data in the form of tables. For
example, a table with student’s data. Different tables are joined together on the basis of
relationships.
Database management is software that is used to manage database. It allows creating,
updating, selecting and deleting operation on database.
3. (Covers Block 3)
(6×4=24 Marks)
(a) Explain the characteristics of any two guided and any two unguided channels for
data transmission. (4 Marks)
Ans:
Guided media
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Twisted pair cable. - It consists of two insulated copper wires, typically about 1mm thick. It is
generally used in local telephone communication. It is also used for digital data communication
over the short distance upto 1 km. unshielded twisted pairs are used to connect computing
devices. Data transferred rates are usually 1-2 megabytes per second.

It is easily available.
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
Low cost
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
Used for analog and digital data transmission

Easily breakable

Easily picks the noise
Co- axial cable: - it consists of a stiff copper wire as the core, surrounded by an insulating
material. The insulator is encased by a mesh conductor. The outer mesh conductor is covered
by the plastic. The signal is transmitted through the inner copper wire(copper core).

It is used for digital and analog transmission

It is used for longer distance

Higher data transfer rate (100 mbps)

Difficult to connect to network device

It requires connector.
Radio Waves
Electromagnetic waves ranging in frequencies between 3 Kilo-Hertz and 1 Giga-Hertz are
normally called radio waves. Radio waves are easy to generate and can travel long distances
and can penetrate buildings easily, therefore widely used for communication.
Microwaves
Electromagnetic waves ranging from 1 to 300 Gigahertz are called microwaves. Microwaves are
unidirectional that is the sending and receiving antennas need to be aligned.
(b) Four branch offices of an organisation are located in four major cities of a vast
country. Explain the characteristics of the network that will be needed for every branch
office. The entire four branch offices network should also be connected by another
network. Explain the characteristics of this network also.
(4 Marks)
Ans:
LAN is used for every office branch.
Characteristics

All connected devices share the transmission media

Small area covered.

Data transfer rate are high

Low cost of setting.
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
Shared the hardware resources

Each device can work standalone or in network
WAN: - As per question four cities in vast country, so, we can assume distance exist among the
cities is more than 50 km. Thus Wan is more suitable for that.
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Characteristics

It generally covers large distances (states, countries, continents).

Communication medium used are satellite, public telephone networks that are
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connected by routers.

Routers forward packets from one to another on a route from the sender to the receiver.
(c) What is Internet? What are the major protocols used on Internet? What is an IP
address? How can an IP address be related to a web address? Explain with the help of
an example.(4 Marks)
Ans:
Internet is a big network of networks. Some common Protocols used in internet are:
Telnet, FTP, SMTP,RTP

TCP, UDP

IP, ICMP, IGMP
IPv4 address is a series of four numbers separated by dots (.). The four numbers ranges
between 0 and 255. So IPv4 address takes only 4-bytes (or 32-bits) of computer memory.
Example: IP address: 152.108.10.7
Each 32 bit IP address consists of two components:
Network Identifier (Net ID) – which identifies one of the Networks that is a part of
Internet.

Device Identifier (Device ID) – which identifies a specific device within the identified
Net-ID.
How IP address works with web address.

Suppose we want to open www.pixelesindia.com.

The Web browser tries to resolve the IP address of the website www.pixelesindia.com
by the information available in its own cache memory. If web server does not have the
information about IP address stored in its cache, it requests the IP address from Domain
Name System (DNS) servers. The DNS server tells the browser about the IP address of
the website.

Once the web browser knows the IP address of the website, it then requests the web
page (index.html) from the web server.
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The web server responds by sending back the requested web page. If the requested
page does not exist then it will send back the appropriate error message.

web browser receives the page from the web server and displays it as per the display
requirements of the web page.
(d) What are the different features of a browser? If you want to perform Net banking
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what precautions will you take before performing a transaction?
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Ans:
Features of browser:

Address bar

Navigation button

Stop Button

Tabbed browsing

Bookmark button

Integrated Search
Net banking what precautions

Use a personal firewall and anti-virus software.

Automatic termination of your connection.

Use a personal firewall and anti-virus software.

Avoid clicking through emails.

Access your accounts from a secure location.

Always log out when you are done.

Keep your operating system and browser up-to-date with the latest security patches.
Install these only from a trusted web site.
(e) Describe the process of creating a web email account. What are the different
components of a mail message? Explain with the help of a diagram. (4 Marks)
Ans: Do yourself.
(f) Explain the following in the context of Internet and its applications, giving their
features and uses:
(i) Wiki
Ans:
Wiki’s are a powerful tool for creating collaborative knowledge resources created by the
community. A wiki is a page or collection of Web pages designed to create and edit contents.
Wiki supports hyperlinks and has simple text syntax for creating new pages. Wiki’s are also
used to create websites, to enhance the features of community websites and for knowledge
management.
(ii) Collaboration
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Ans:Collaboration is defined as an act or process of working together on a project or some
intellectual activity. Each collaborative project has several social, political, ethical and technical
issues that are to be addresses at the start of the project itself. Collaboration involves both
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collaborative. Today, you may find a number of research papers co-authored by many peoplePage | 15
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