Download AFS 611 COMPUTER APPLICATIONS CAT I A56/78111/2012

AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
QUESTION ONE
a) Computer is an electronic device that is capable of performing calculations (i.e.
computations) and making logical decisions at very high speed.
Some of the uses of computers in our society include;
 Education and research;
Computers are being used to disseminate information from the tutors/lecturers through the
use of laptops and overhead projectors. They also play an important role in collecting and
analyzing information (data) during research work. Through the computers, researchers
access the internet and obtain loads of vital information. Computers are also being used in
open distance learning where the students access training materials and information without
physically being present at the training institutions and at the same time interacting with the
tutors/lecturers through e-mail.
 Government institutions;
Computers play a major role in the improvement and efficiency of service delivery to the
people. For instance, computers help in record keeping reducing the episodes of information
disappearing like in the judiciary, pensions and lands departments. Computers have also
ensured accurate capturing of bio-data particulars of the people through the introduction of
biometric voter registration. Last but not least, computers have enabled the government to
accelerate the processes such as passport application, personal identification number (PIN)
registration, provision of e-pay slips to her employees, remittance of taxes to the revenue
authority, payment of utility bills like water, electricity, telephone etc.
 Communication institutions;
The telecommunication industry heavily depends on the computers which play a vital role at
the exchanges. The mobile telephony industry also relies on the computer to connect the
phone calls made by millions of mobile phone users. Computers also play a significant role
in transport sector where they make it possible to do online booking, reservation and
payment of tickets.
 Employment;
The computing industry worldwide provides employment opportunities to many people,
amounting to over 60% in some countries e.g. Singapore.
 Multimedia applications;
Multimedia is currently used exclusively in business presentations, training, information
distribution, point of sale terminals, education/learning, photo albums, reference books etc.
b) The five generations of computer in terms of technology are;
 First generation computers e.g. ENIAC (Electronic Numerical Integrator And Computer).
 Second generation computers e.g. IBM 1620.
 Third generation computers e.g. IBM-360.
 Fourth generation computers e.g. the present day personal computers (PCs).
 Fifth generation computers e.g. supercomputer.
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
c) A computer bus is a set of wires that carry special information to and from the central
processing unit (CPU).
The three types computer buses are;
 Address bus - this bus carries address given by the CPU from one unit to another in the
computer.
 Data bus - this bus carries data from one unit to another. It is a bi-directional bus and that
is the data can be carried in both directions.
 Control signal - this bus carries control signal from the arithmetic logical unit (ALU) to
the memory and from the memory to the ALU and then to the output unit.
d) The following are the functions of a UPS (Uninterrupted Power Supply);
 Provides power for some time after blackout has occurred enabling backing up of data
not yet saved.
 Continues to provide power to equipment during line sags.
 Absorbs relatively small power surges.
 Smoothens out noisy power sources.
 Automatic shutdown of equipment during long power outages.
 Monitoring and logging of the status of the power supply.
 Displays the voltage/current draw of the equipment.
 Restarts the equipment after a long power outage.
 Displays the voltage currently on the line.
 Provides alarms on certain error conditions.
 Provides short circuit protection to the equipment.
e) Microprocessor operating cycle:
The microprocessor is a multipurpose, programmable device that accepts digital data as input
and processes it according to instructions stored in its memory and provides results as output.
The microprocessor contains the arithmetic and logic unit (ALU) and the control unit (CU)
for a microcomputer. It is connected to memory and input-output devices via buses which
carry information between the units. The ALU handles all mathematical calculations and
logical comparisons. It takes commands from the CU and executes them, storing the results
back into the memory. These four steps i.e. fetching, decoding, execution and storage are
referred to as the machine cycle of a computer. The memory is described as a digital
processing system which can store the data.
It takes the command from the CU and executes them, storing the results back into the memory.
These four steps (fetch, decode, execute and store) are referred to as the machine cycle of a
computer.
Input
ALU
Output
CU
(CPU)
Memory
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
f) Kinds of memories in the computer;
 Random Access Memory (RAM) - This is a primary storage and is referred to as RAM since
it is possible to randomly select and use any location of the memory to directly store data.
The storage of data and instructions inside primary memory is temporary and it disappears
from RAM immediately there is a power failure. These kinds of memories that lose their
contents on failure of power are known as volatile memories.
 Read Only Memory (ROM) - The ROM stores some standard processing programs supplied
by the manufacturer to operate the personal computer. The ROM can only be read by the
CPU and cannot be changed. The basic input/output program that examines and initializes
the various equipment attached to the personal computer (PC) when the switch is made on is
stored in the ROM. Storage of programs and data in the ROM is permanent and is not lost on
power failure. These kinds of memories that do not lose their contents on failure of power are
known as non-volatile memories.
 Programmable Read Only Memory (PROM) - This type of primary memory allows for
storage of programs and once the programs have been written, they cannot be changed and
remain intact even if the power is switched off. The programs or instructions written in
PROM therefore cannot be erased or changed.
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
QUESTION TWO
a) Types of human computer interface (HCI);
 Graphical user interfaces
 Web-based user interfaces
 Command line interfaces
 Touch user interfaces
Features that make HCI user friendly;
 Design of a user interface - This affects the amount of effort the user must expend to
provide input for the system and to interpret the output of the system, and how much
effort it takes to learn how to do this.
 Usability - is the degree to which the design of a particular user interface takes into
account the human psychology and physiology of the users, and makes the process of
using the system effective, efficient and satisfying.
 Attractive - screen arrangements i.e. colours, typefaces (font and sizes), graphics
elements, all impact on the look of the interface.
 Forgiving - users should be able to recover easily from mistakes users should be able to
get on line help easily.
 Customizable - the user should be able to tweak the interface to his or her own habits e.g.
ability to size or move windows, design icons and tools, design desktop patterns.
 Transparent - this implies predictability i.e. the interface should provide choices that are
logical and reflect how users are likely to react to situations.
 Safe - e.g. the pilot of a jumbo jet.
b) A computer network refers to an interconnection of various computers located at different
places. In networking, two or more computers are linked together with a medium and data
communication devices. The computer that provides resources to other computers in a
network is called a server, while the individual computers which access the shared resources
are known as workstations or nodes.
Networking is necessary in the ICT world because of the following;
 Sharing of information/data.
 Sharing of resources e.g. printers.
c) Star topology is a network topology where a number of workstations (or nodes) are directly
linked to a central node, which controls all the activities of the nodes. Any communication
between the station must pass through the central node. There is a bi-directional
communication between the various nodes. Some of the advantages of the star topology are;
 It offers flexibility of adding or deleting of workstations from the network.
 Breakdown of one station does not affect any other device on the network.
The major disadvantage of star topology is that the failure of the central node disables
communication throughout the entire network.
Workstation 1
Workstation 3
Central Node
Workstation 2
Workstation 4
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
d) Functions of the following;
 Repeaters - These are electronic devices that receive signals and retransmit them it at a
higher level or higher power, or onto the other side of an obstruction, so that the signals
can cover longer distances.
 Bridges - Network bridges are network devices that connect more than one network
segment to allow the networks to communicate independently as separate networks.
 Routers - These are devices that forward data packets between computer networks
thereby creating overlay interworks.
 Gateway - This a network point that acts as an entrance to another network.
e) Services offered by the internet
 Communication services (E-mail): This is sending a message electronically over the
internet from the sender to the receiver.
 Remote access: The internet allow computer users to connect to other computers and
information stores easily, wherever they may be accessed across the world.
 File sharing: A file can be e-mailed by the internet using an attachment in the e-mail. A
computer file can also be put on to a shared location on a shared network so that people
using the network have access to it.
 Streaming media: Radio and television broadcasters provide internet feeds of their live
audio and video streams.
 Voice telephony: VoIP means voice over IP where IP refers to internet protocol that
underlies all internet communication. This began as an optional two-way voice extension
on some instant messaging systems. This has become easy to use and is much cheaper or
even free that normal calls especially for long distances.
f) Transmission media refer to technical devices that employ the material substances to transmit
or guide waves and the transmission of networks.
The following are examples of transmission media;
 Wire pairs: These are commonly used in local telephone communication and for short
distance digital data communication. They are normally made up of copper and the pair
of wires is twisted together. Data transmission speed is normally 9,600 bits per second in
a distance of 100 meters.
 Coaxial cables: These are groups of specially wrapped and insulated wires that are able to
transfer data at a higher rate. They consist of central copper wire surrounded by an
insulation over which copper mesh is placed. They are used for long distance telephone
lines and local area network for their noise immunity and faster data transfer.
 Microwave: This system uses very high frequency radio signals to transmit data through
space. The transmitter and receiver of a microwave system should be in line of sight
because the radio signal cannot bend. With microwave very long distance transmission is
not possible. In order to overcome the problem of line of sight and power amplification of
weak signal, repeaters are used at intervals of 25 to 30 kilometers between the
transmitting and receiving ends.
 Communication satellites: This is a microwave relay station placed in outer space e.g.
INSAT-1B that is accessible from anywhere in India. Here, microwave signals are
transmitted from a transmitter on earth to the satellite at space. The satellite amplifies the
weak signal and transmits it back to the receiver. The main advantage of satellite
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
communication is that it is a single microwave relay station visible from any point of a
very large area thereby eliminating the use of repeaters. The data transmission rate is 16
gigabytes per second. They are mostly used to link big metropolitan cities.
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
QUESTION THREE
a)
User
Application
Operating System
Hardware
An operating system (OS) is a collection of software that manages computer hardware
resources and provides common services for computer programs. The OS is a vital
component of the system software in a computer system. Application programs usually
require an operating system to function.
For hardware functions such as input and output and memory allocation, the OS acts as an
intermediary between programs and the computer hardware, although the application code is
usually executed directly by the hardware and will frequently make a system call to an OS
function or be interrupted by it.
b) A high level language is a simple language that use English and mathematical symbols like
+, -, %, / etc for its program construction. They are problem oriented because their
instructions are suitable for solving a particular problem.
The following are the three popular third generation languages;
 COBOL (Common Business Oriented Language): This language is mostly suited for
business language where there is very little processing of huge output.
 FORTRAN (Formula Translation): This language is for scientific application.
 BASIC (Beginners All-purpose Symbolic Instruction Code):
c) Data: Refers to a collection of raw facts that become information after processing by the
computer.
Information: Refers to a processed data.
Data processing : Refers to any process that uses a computer to enter data and summarize,
analyze or otherwise convert data into usable information.
d) Utility software is a system software that is designed to help analyze, configure, optimize or
maintain a computer.
Examples of Utility software include; anti-virus, archive and backup.
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
e) A spreadsheet is an interactive computer application program for organization and analysis of
information in tabular form. Spreadsheets are developed as computerized simulations on
paper accounting worksheets.
Features of spreadsheets that are used in financial modeling
 Rows and columns
 Cell formatting
 Cell merging
 Copy paste and cut
 Multiple worksheets
 Graphs and charts
 Inserting/deleting columns and rows
 Mathematical functions
 Mathematical formulas
f) Conversion of 459 to binary system;
2
2
2
2
2
2
2
2
2
1
1
0
1
0
0
1
1
1
459
229
114
57
28
14
7
3
1
111001011
Therefore 459 in binary system in 111001011
g)
Conversion of 11100111 to decimal system;
List of the elements of the digits;
128
64
32
16
8
4
2
1
1
1
1
0
0
1
1
1
____________________________________________________
128 + 64 + 32 + 0
+ 0
+ 4
Hence 11100111 in decimal system is 231
+ 2
+ 1
= 231
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
QUESTION FOUR
a) Important Ergonomics in computer architecture design;
 Physical ergonomics: This is concerned with the human anatomy and some of the
anthropometric, physiological and bio-mechanical characteristics as they relate to
physical activity
 Cognitive ergonomics: This is concerned with the mental processes such as perception,
memory, reasoning and motor response as they affect interactions among humans and
other elements of the system.
 Organizational ergonomics: This is concerned with the optimization of socio-technical
systems, including their organizational structures, policies and processes.
 Environmental ergonomics: This is concerned with human interaction with the
environment
b) Computer virus is a computer program that replicates itself and spread form one computer to
another.
Sources of computer viruses include;
 Downloadable programs
 Cracked software
 E-mail attachments
 Internet
 Booting from compact disk (CD)
c) How an infected computer can be cleaned;
 Backup files that you know are safe onto a disk or other external media source if
possible. Do not use system restore since when you create a restore point the virus file's
are also backed up.
 Turn off the system restore and delete all of the restore points. That way you make sure
you move the virus, it will be off your computer.
 Download free and anti-virus and anti-spyware software on non-infected PC and then put
the files on a disk and bring to the infected PC
 After installing your anti-spyware and anti-virus software, update them and run a scan
them. Make sure you write down the name of the infection it finds before you remove
them.
 Restart your computer in safe mode. Use the F5 or F8 keys depending on which operating
system you are running.
 Repeat the scanning step to make your PC is clean.
d) Two methods of starting and quitting application program in Linux operating system;
Method One:
To start word program;
 Boot the machine
 Go to the menu on the task bar
 Open all applications
 Open for instance office.org word to open word
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
 Go to the title bar and open a new document
To quit
 Save the document
 Then quit
Method Two:
To open word program;
 Boot the machine
 Go to the menu on the task bar
 Open terminal
 Type open office.org word on the command line
 Then press enter
To quit;
 Type log out on the command line
e) Types of software interfaces;
 Macintosh/Mac
 Windows/PC
 Linux ubuntu
 Linux kabuntu
f) How to perform the following using spreadsheet;
Regression;
 Enter the data into the spreadsheet that you are evaluating.
 Open the regression analysis tool.
 Define your input, Y range.
 Repeat the previous step for the input, X range.
 Designate where output will appear.
 Click OK and the summary of your regression will appear where designated.
Anova;
 Feed the file FEED_ANOVA or enter the data into an excel datasheet.
 In Excel 2003 or earlier versions, pull down "Tools" to "Data Analysis". In Excel 2007,
click Data and then Data Analysis.
 Select Anova: Single Factor.
 In the dialogue box, enter the input range that corresponds to the data column and click
OK. Check the option "Label in First Row".
T-test
 Feed the data into an Excel datasheet.
 Click Data then Data Analysis.
 Select t-test: Two samples assuming equal variance.
AFS 611
COMPUTER APPLICATIONS CAT I
A56/78111/2012
 Then click OK and enter cells for Variable range 1, cells for variable range 2, and a free
cell for output range.
 Then click OK and the printout appears.