1993 - 2003 cxc_pastpapers with solutions

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INFORMATION TECHNOLOGY THEORY (1993)

Question 1

(a) Using appropriate examples, explain the difference between discrete and continuous data.(b) Define the terms ‘hard copy’ and ‘soft copy’.

Solution

(a) Discrete data represent data that permit only certain values (there are gaps between the possible values)

Discrete data is countable.

ith continuous data given any two different values in an interval it is possible to find a value that falls between them. !ontinuous data is measurable.

"xample# $.$ pound or %$.$ degree !elsius.

(b) &ard copy ' relatively permanent form of output that can be read immediately or stored forlater use, such

as output on paper. oft copy transient (temporary) output, example, information displayed on a screen (monitor) or output

from a spea*er.

Question 2

(a) +ist -U functions of an operating system.

(b) (i) /ive -0" benefit to the user of customwritten software.(ii) /ive -0" benefit to the user of generalpurpose software.

(c) hat do the abbreviations ‘-1’ and ‘12!’ stands for3 Describe a situation in which"4!& is used.

Solution (a) 4n operating system does any of the following#(i) !ontrols program execution (ii) !ontrols input and output (iii) 1anages data and file storage(iv) 4ssigns different tas*s to the !5U (v) 5rovides security and control

(b) (i) !ustomwritten software meets the specific need(s) of the user (ii) /eneralpurpose software can be used by many different users

(!) 12! 1agnetic 2n* !haracter ecognition U" reads data prerecorded on che6ues and deposits slips with a special ferriteimpregnated in* that

can be magneti7ed.

-1 -ptical 1ar* eader U" 2t is used in educational institutions for scoring examinations.

Question 3

Describe, using an appropriately labeled diagram, how a computer can be used to maintain the temperature ofli6uid between 8$9 and :$9!.



Solution

ignal to turn heater up;down ;off

Question

(a) 2dentify any <- industries and, for "4!&, state how the use of the computer hasresulted in either a

change of procedures for two =obs or made the =obs obsolete.

(b) 0ame -U =obs which have been created by the computer industry.

olution(a) (i) !ar 1anufacturing 2ndustry

!ars are being assembled y computer controlled robots instead of manual labour producing better

6uality output.

(ii) !hemical industry !omputers are used in the preparation of dangerous gases replacing the human factor.

(b) <he computer industry has created#

(i) 5rogrammers (ii) oftware "ngineers (iii) !omputer -perators (iv) Data "ntry -perators

Question !

(a) Define "4!& of the following terms as it applies to data transmission#

(i) >oice band(ii) implex(iii) &alf duplex

(b) (i) what is meant by ‘data integrity’3 (ii) tate <- examples where a lac* of data integrity can causes loss, inconvenience or embarrassment.

Solution

(a) (i) >oice band has a bandwidth of %,999 and can transmit data at speeds in the range of ?99to @9,999

bits per second.

(ii) implex are communication lines that permit data flow in only one direction. (iii)Duplex are communication lines that permit data traffic in both directions but only in one direction at

a time.

(b) (i) Data integrity refers to techni6ues which protect a database against invalid alteration ordestruction.

(ii) a. 4ltering a personAs age, instead of an age value of @: an age value of %: is entered.

!omputer ater &eater &eat to digital

converter



b. 2nput wrong information about a person in a medical history file, example, saying that the personhas cancer instead of saying he;she has a common cold.

Question "

(a) hat is a ‘videotext’ system3(b) Describe <- distinct uses of videotext systems.(c) 0ame <- distinct effects that videotext systems can have on the traditional 5ost -ffice

Solution

(a) >ideotext is an information service in which data is transmitted over television cables or

telephone linesand displayed on a television or computer screen in the home.

(b) >ideotext systems are used for#(i) 4dvertising a product(ii) ending warning messages to users about dangerous weather.

(c) >ideotext systems#(i) educe the number of persons using the postal system.(ii) educe the paper flood caused by the traditional postal system.

Question #(a) 2n 4!22 !B code, the letters of the alphabet are stored using consecutive codes. 2f ‘C’ is

represented by@9999@9, what is the representation of ‘/’3

(b) /ive the binary value of %@9 E @@9@

Solution

(a) / is five ($) spaces to the right of C<he binary value for $ is @9@.<he binary representation of / is#

@ 9 9 9 9 @ 9E @ 9 @B @ 9 9 9 @ @ @

(b) <he binary value for % is @9@@@

@ 9 @ @ @ E @ @ 9 @ @ 9 9 @ 9 9

Question $

rite a pseudocode algorithm to read a set of positive integers (terminated by 9) and print their aversge aswell as the largest of the set.

Solution

0umcount B 9 um B 9 +argest B 9



2nput 0umber

hile 0umber not e6ual to 9 do um B um E 0umber

0umcount B 0umcount E @ 2f 0umber F +argest +argest B 0umber "ndif

2nput number "ndwhile4verage B um divide by 0umcount5rint um, +argest

Question 9

rite a pseudocode algorithm to print a conversion table from miles to *ilometers. <he table ranges from $ to@99 miles in steps of $ (@ mile B @.?@ *ilometers).

Solution

5rint G12+" H2+-1"<"I

5rint GB B B B B B B B BI

2nitials B $

hile initial JB @99 do

5rint initial initial K@.?@ 2nitial E $ "ndwhile

Question 1%

rite a pseudocode algorithm to read a positive integer 0 followed by 0 integers. or these 0 integers, thealgorithm must count and print the number of 7ero and non7ero values.

Solution

input 0 !-U0< B 9 0-0!-U0< B 9 L"-!-U0< B 9 repeat

input 0U1C"

if 0U1C" B 9 L"-!-U0< B L"-!-U0< E @ endif

if 0U1C" not e6ual to 9 0-0!-U0< B 0-0!-U0< E @ endif



!-U0< B !-U0< E @ until !-U0< B 0

INFORMATION TECHNOLOGY THEORY (199)

Question 1

Describe <- functions of "4!& of the following components of a computer#(i) !ontrol unit (ii) 4rithmetic;+ogic Unit (iii) 1ain memory

Solution

(i) T&e 'ontol nit *oes +n, o- t&e -ollo.in/0 reads and interprets program instruction directs the operation of the internal processor component controls the flow of programs and data in and out of primary memory controls the flow of information to and from l;- devices.

(ii)T&e Ait&eti'Lo/i' nit0

performs all arithmetic operations performs logical operations stores the data which can be immediately processed by the program instructions.

(iii) T&e M+in Meo, stores program instructions prior to execution stores the data which can be immediately processed by the program instruction stores information temporarily after processing is complete.

Question 2

tate -0" advantage and -0" disadvantage of the first item over the second item in "4!& of the following pairs#

(a) (i) !haracter printer (ii) +ine 5rinter (b) (i) 1icrofilm output (ii) 5rinted output(c) (i) 1agnetic tape (ii) 1agnetic hard dis* (d) (i) -ptical dis* (ii) 1agnetic hard dis*

Solution

(a) 4dvantage !haracter printer is cheaper than a line printer Disadvantage !haracter printed is slower than a line printer

(b) 4dvantage ' 1icrofilm output can store much more information in a smaller space than printedoutput.

Disadvantage ' 1icrofilm is more expensive than printed output; 1icrofilm needs special e6uipment to read the information, printed output does not.

(c) 4dvantage 1agnetic tape is cheaper than magnetic hard dis* ; 1agnetic tape has a larger capacity

than magnetic hard dis*. Disadvantage ' lower access to date;recordsecords cannot be updated in place

(d) 4dvantage -ptical dis* has a larger capacity than magnetic hard dis* -ptical dis* can retain data longer than magnetic hard dis* -ptical dis* is "4D -0+M therefore information cannot be tampered with

Disadvantage-ptical dis* is slower, more expensive than magnetic hard dis*



-ptical dis* is "4D -0+M

Question 3

(a) "xplain briefly "4!& of the following terms (i) Cistable device (ii) /igabyte (iii) -perating system (iv) Car code

(b) (i) hat is an ‘expert system’(ii) 0ame -0" area in which expert systems are used

(iii) /ive -0" advantage and one disadvantage of using an expert system in the area named at (ii)above.

Solution

(a) (i) Cistable devices are devices capable of assuming either one of two stable states, for example alight switch is a bistable device, it can either be on or off.

(ii) /igabyte is @,999,999,999 bytes or @9: bytes.(iii) -perating system is a set of programs used for controlling the operations of a computer system.

(iv) Car !ode is a series of parallel light and dar* lines representing a code placed on a product foridentifying that product.

(b) (i) 4n ‘expert system’ is a program that reproduces the *nowledge and thought processes of humanexperts in certain well defined fields.(ii) 4reas of application ' any -0" of the following#

1edicine# diagnosis of infections blood diseases, prescription of medicine /eology# search for mineral deposits !hemistry# identifying molecular structure of compounds

(iii) advantages does not display biased =udgments does not =ump to conclusions on the face of contrary evidence

systematically considers all possible alternatives

disadvantages not good at =udgment re6uiring common sense cannot adapt easily to new rules and concepts cannot reason across disciplines

Question

"ach regional office of Namaican ood !rop 1ar*eting 4gency uses a system of hardware, software andcommunication channels that connects hardware devices to provide its computing services. 2nformation iscollected at the regional offices and at the end of the day it is transferred to a mainframe computer at the headoffice in Hingston. 4t nights, this mainframe at head office collates the information and transfers it to theregional offices using different rules established to govern the way data is transmitted in the particularnetwor*. 4part from providing up 'todate information to users through its regional offices, the system allowsusers access to the information at their own homes. &owever, to utili7e this facility users must subscribe to its

special service which allows them to send and receive messages to;from other users. <he cost of this facility isaffordable to the average homeuser since the subscription fee is small and the only other capital cost is the price of a device which convert digital signals into analog signals and vice versa.

tate the proper te'&ni'+l tes for "4!& of the -U underlined phrases in the above passage.

Solution

(i) +ocal 4rea 0etwor*



(ii) 5rotocol(iii) Culletin Coard of "lectronic 1ail(iv) 1odem

Question !

(a) Describe <- =obs "4!& of the following#(i) ystem 4nalyst(ii) !omputer -perator (iii) Database 4dministrator

(b) tate <- ways in which a computer can be used by a teacher in his;her =ob.

(c) tate <- ways in which the computer is beneficial to the ban*ing industry.

Solution

+ (i) A s,ste An+l,st *oes +n, o- t&e -ollo.in/0

5erforms feasibility studies derives information system, re6uirements;specifications designs information systems performs system reviews

(ii) A Co4ute O4e+to *oes +n, o- t&e -ollo.in/0

prepares e6uipment to run =obs mounts and removes tapes, dis*s and dis*ettes monitor operations during the running of each =ob

(iii) A 5+t+6+se A*inist+to *oes +n, o- t&e -ollo.in/0

designs a database creates a database maintains a database coordinates discussion between user groups

b. A te+'&e '+n use t&e 'o4ute to *o +n, o- t&e -ollo.in/0

develop course wor* store students’ records use G!omputer 4ides 2nstructionI software

teach students to use the computer mar* scripts

c. T&e 'o4ute is 6ene-i'i+l to t&e 6+n7in/ in*ust,8 6e'+use it0

provides management with useful information for running the ban* *eeps records of transactions by customers

provides electronic funds transfer provides automated teller services

Question "

(a) or "4!& of -1,-! and 12!, give an application in which that technology is fre6uently used.

(b) Data security’ refers to the protection of data from destruction or corruption. tate <&"" measures which can be employed to ensure data security.



Solution

(a) OMR reading of solutions to multiple choice 6uestions OCR converts a printed document to machinereadable form so that it could be edited on a

!omputer MICR used by ban*s for reading information on che6ues

(') To ensue *+t+ se'uit, one +,0

use fireproof cabinets for storing tapes and dis*s perform bac* up and recovery procedures properly

implement a password system to prevent unauthori7ed access use anti virus software use software features to restrict access to certain records.

Question #

(a) 2n a certain character coding system, each character occupies seven (O) bites and the lettersof the alphabet

4re assigned consecutive codes. 2f ‘1P is represented by @9@999@, what is the representation of ‘&’3

(b) hat is the value of Q 2 the following e6uations3 $@9 Q B @@@@@

Solution(a) H B 1$R&is consecutive spaces to the left of 1S M : @9@999@ B 8@RDecimal valueS

H : 8@$ B O? B @99@@99 RCinary >alueS

(b) $@9 'Q B @@@@@B %@ RDecimal >alueS Q B $ %@ B @ B @9@9@ RCinary >alueS

Question $

(a) hat is the purpose of formatting or initiali7ing a dis*ette3

(b) hat is the ma=or interfacing device for(i) a command language interface3

(ii) a graphical user interface3

(b) "xplain briefly -0" distinguishing feature of "4!& interface mentioned in part(ii)

Solution

(a) -ne formats a dis*ette to place electronic mar*s on the surfsce of the dis*ette so thatdata can be written to and read from their specific ‘addresses.’

(b) (i) <he *eyboard is the ma=or interfacing device for a command language interface.(ii) <he mouse is the ma=or interfacing device for a graphical user interface.

(!) Using a command language interface (!+2), the user ‘points’ to a picture (or icon) of a data file or program or a selection from a menu and activates the program or selection by clic*ing the pointing devices (usually mouse).

Question 9



end if print f, gstop

Solution

(a) read !-" 2f !-"F B 89 then

printG4I

"lse if !-" F B ?$ then print GCI "lse if core F B $9 then

printG!I "lse printGI "ndif

(') T&e -ollo.in/ is 4inte* 6, t&e +l/oit& .&en n ; !0

,%,$,%,$



199!

Question 1

(a) +ist <- benefits of !omputer 4ided Design and Draughting.

(b) 0ame <&"" peripheral devices which are used in !omputer 4ided 1anufacturing butwhich are not

!ommonly used in an office.

( !) tate a measure which can be adopted a minimi7e data and;or program corruption or loss in the event of a hard dis* failure.

(c) hat is software piracy3

Solution

(a) !omputer 4ided Design and Draughting provides#i. improved accuracy and legibility of engineering drawingii. ease of ma*ing alterations to designs leading to increased productivityPiii. decreased time for developing blue printsP

iv. increased detailPv. simulation;cost estimation facilities

(b) i. ensors ii. obots (robotic arms) iii. /uided pallets

(c ) !opy files unto bac*up devise on a regular basis and in the evet of a hard dis* failure recovery isaccomplished by replacing the damaged and lost files on the hard dis* by the last copy of the filesfrom the bac*up device.

(d) oftware piracy is the illegal copying of program(s).

Question 2

Draw a labeled diagram showing the main component of a computer system, indicating clearly the direction inwhich data flow.

Solution

Question 3

205U<

D">2!"

!5U -U<5U<

D">2!"

C4!H20/<-4/"



(a) !onvert the decimal number $$ to its binary e6uipment.(b) !onvert the binary number @9@@9@9 to its decimal e6uipment.(c) 4dd the binary numbers @@9@9 and @99@@.(d) <he 4!22 code for the letter & has a decimal e6uivalent O. hat is the 4!22 code

for the letter 5.

Solution

(a)

$$@9 B @@9@@@

(b)

@ 9 @ @ 9 @ 9

?

$

%

@

9

@9@@9@9 B? E E %E @Rignoring columns with 9S B :9@9

(c) @ @ 9@ @ 9

E @ 9 9 @ @

@ 9 @ @ 9 @

(e) pB O E8 B 89 B@9@9999 RCinary e6uivalentS

Question

hen a program ma*es a read re6uest to the hard dis*, the device which reads data from the dis* ismoved along a radius to the particular concentric circle on with the data is stored. hen the relevant part of the concentric circle of the dis* arrives under the device which reads the data, the data is readand stored in a special area of memory from which it could be accessed.

tate the proper te'&ni'+l tes for "4!& of the -U underlined phrase in the passage above.

Solution

(i) read;write head (ii) trac* (iii) sector (iv) buffer

Question !

$$O@%?%@9

@@@9@@



(a) 2dentify -U measures to secure data.(b) tate <- advantage and <- disadvantages of normal mail over electronic mail.

Solution

(a) -ne can secure data by#

(i) encryption (ii) virus protection (iii) password (iv) physical access restriction

(b) advantages(i) parcel can be sent(ii) sent to more people (people without computer

disadvantages(i) mail could be lost(ii) mail ta*es a longer time

Question "

(a) +ist -U ways in which medical personnel may use information technology intheir =obs.

(b) tate <- =ob functions of "4!& of the following computer personnel#

(i) 0etwor* manager (ii) Database administrator

Solution

(a) 1edical personnel may use information technology for#(i) toring patient records (ii) expert system

(iii) &ealth education (iv) monitoring patients

(b) (i) 4 networ* 1anager does any of the following# tarts up and shuts down the networ*

grants access privileges monitors use of the networ* and other shareable resurces liaise with other networ* re# connectivity

(ii) 4 database administrator# grants access to data ma*es modification to database structure

Question #

(a) Nohn receives computer hardware from a friend who lives in the United tates of 4merica, but the software is missing. &e, therefore, decided to purchase the

necessary software. 2n order for his system to run he reali7ed that he would haveto purchase software to manage the resources of the computer as well assoftware which could provide for his particular needs. or both types ofsoftware he had a choice of two styles of interfaceP one which was commanddriven or the other which provides screen listings with options from which theuser could select appropriate functions. ome software provides user interfaceswhich display small graphic images that can be selected when the function theyrepresented is re6uired. ince Nohn intended to use the computer in his family



business, he had a choice of ac6uiring software written especially for his business or general purpose software. &e noted, however, that if he purchasedgeneral purpose software, that he would have to do some modification to allowit to meet his specific need.

tate the proper te'&ni'+l tes for "4!& of the 2Q underlined passages.

(b) tate <- functions of an operating system.

Solution(a) (i) system software (ii) application software (iii) 1enus (iv) 2!-0

(v) customwritten software (vi) customi7ation

(b) T.o -un'tions o- +n O4e+tin/ S,ste +e0

(i) input;output control (ii) file and dis* management

Question $

hat is printed by the following algorithm3

U1 B 9

0 B 9 &2+" 0J %9 D- U1 B U1 E 0 520< 0, U1 0B 0 E % "0D&2+"

Solution

9, 9,%,%,?,?:,:,:8

Question 9(a) Define the following#(i) ource(ii) -b=ect(iii) !ompiler

(b) Draw a labeled diagram to illustrate the relationship between source code, ob=ect code andcompiler.

(c) rite a pseudocode algorithm to read in <&"" numbers and print the highest and lowest number.

Solution

(a) (i) ource code is program written in a programming language(ii) -b=ect code machine language, program produced by a computer (iii) 4 compiler is a computer program which converts a program in a high level

programming language to machine code.

(b)



(b) read 4,C,!

2f ((4BC) and (4B!)) then 5rint G0umbers are e6ualendif if 4FC then

+4/"< B 4 14++"< B Celse +4/"< B C 14++"<B4endif

if !F+4/"< then +4/"< B !if !J14++"< then 14++"< B !

print +4/"< print +4/"<

Question 1%

<he following data represents some sample score obtained by students in a test# $ , , O, @9, 9, ?, 9, @, 9, :, 8, :::

::: is the dummy value which terminates the data. rite pseudocode algorithm to readany data in the above format, and print the number of students scoring 9 and the numberscoring @9.

Solution

L"-!-U0< B 9 <"0!-U0< B 9

2nput 0U1C"

while 0U1C" not e6ual ::: do

if 0U1C" B 9 then

L"-!-U0< E@ endif

2f 0U1C" B @9 then <"0!-U0< E @ endif

ead 0U1C"

-U!" !-D"

!-152+" -CN"!< !-D"



endwhile

print G0U1C" of students scoring 9I, L"-!-U0< print G0U1C" of students scoring @9I, <"0!-U0<

199"

Question 1

tate -0" difference between "4!& of the following#

(a) !ommandline interface and graphical user interface(b) 2mpact printers and nonimpact printers(c) !haracter printers and line printers(d) /eneral purpose software pac*age and speciali7ed software pac*age(e) implex and duplex transmission

Solution

(a) (i) 2nterfacing device for commandline driven interface is the *eyboard while that for graphical

user interface is the mouse.

(b) (i) 2mpact printers can produce multiple carbon copies of a document while nonimpact cannot. (ii) 2mpact printers are more expensive than character printers.

(c ) (i) +ine printers are faster than character printers. (ii) +ine printers are more expensive than character printers.

(d) (i) /eneral purpose software pac*age can be used to perform a wide variety of tas*s while speciali7ed software pac*age cannot.

(e) (i) Duplex transmits data in both directions, while simplex transmits data in one direction only.

Question 2

(a) !onvert the decimal number $O@9 to a binary number.

(b) !onvert the binary number @@9@@@9@ to decimal number

(c ) "xplain the term ‘parity’ as it relates to the coding of characters.

(d) 4dd the binary numbers @@9@9@ and @9@@@9

Solution

(a)

$O8@ O % @

9

@99@@@



$O@9 B @@@99@

(b)

@ @ 9 @ @ @ 9 @O ? $ % @ 9

@@9@@@9@ B O E ? E E % E E 9 B @@9

( c) 5arity is used as a chec*ing system or dummy value within the coding of character. 2t is used to detect whether the transmission or coding of data is complete or accurate.

(d) @ @ 9 @ 9 @

E @ 9 @ @ @ 9

@ @ 9 9 9 @ @

Question 3

0ame the hardware component that performs "4!& of the following functions#

(a) tores programs and data that are currently being used by the !5U(b) 5erforms the logical operations within the !5UV tores programs and data that are not currently being used by the !5U(d) 1odulates and demodulates signals(e) eads from dis*s(f) Directs internal operations within the !5U

(g) 4llows users to move the cursor

Solution

(a) 41 (andom 4ccess 1emory)(b) 4+U (4rithmetic ; +ogic Unit)

(c ) econdary torage (e.g. Dis*ettes, magnetics tapes, etc)(d) 1-D"1(e) ead;rite &ead(f) !U (control Unit)

(g) 2nput Device (Heyboard, 1ouse etc.)

Question

<he statistic Department holds confidential information on the citi7ens of a country since its databasesare online and are connected to the telephone company via a modem, any person with a computer anda modem can potentially access from the databases. -utdated data are usually stored at other locations.

(a) tate -0" method which can be used to prevent an unauthori7ed user from accessing data stored



in the databases.(b) tate <- methods which can be used to prevent users from accessing data from files to which

they do not have access.(c) tate -0" potential danger that may exist when legitimate users within the tatistics Department

import data into the department’s computer.(d) tate <- strategies to protect the archived data from physical damage.

Solution

(a) 5assword 5rotection(b) (i) 5assword 5rotection (ii) Data encryption(c) >irus infection(d) tore archive data away from the elements (wind, rain etc)

Question !

(a) <he increase in the level of computeri7ation in offices, together with the decrease in cost and theavailability of data communication services have created new ways of conducting business. omeemployees now have an opportunity to perform their wor* from home by a process *nown as

‘telecommuting.’

(i) tate <- items of hardware that an employee must have if he;she is telecommuting.(ii) tate -0" advantage to the employee of telecommuting.(iii) tate -0" disadvantage to the employee of telecommuting.

(b) <he owner of a larger department store in the city center is planning to offer telemar*etingservices to the general public. !urrently, his retaining business customers are encouraged to

browse in the store. <hey are normally offered assistance by the sales cler*. 2f a customer issatisfied with a particular item, he;she ta*es the item to the cashier where the customer must pay incash. 4fter the transaction is completed, the customer must ta*e away the item(s) purchased.

(i) tate <- additional services that the owner should offer so that he could introducetelemar*eting .

(ii) tate -0" change that the owner must ma*e in the operation of his business so that hecould introduce telemar*eting.

(iii) tate -0" reason why a customer might still choose to visit the store to ma*e a purchaseeven though the cusromer might have to travel a long distance to get to the store.

Solution

(a) i. 1odem , ax machine, eduction in travel expenses;fuel consumption wor*ing men and women would be able to spend more time with their families.

ii. <he wor*er might miss out on promotion opportunities at central head6uarters.

(b) i. &ome delivery of items purchased ubscrption maga7ines advertising products tocustomers.



ii. Use of electronic fund transfer instead of cash payment for goods bought.iii. <o examine products being bought.

Question "

(a) tate <&"" functions that are li*ely to be computeri7ed when the Coard of Directors of

a private local ban* with several branches has decided to computeri7e its operations.

(i) tate <- new =ob positions that would be created in the ban*.(ii) tate -0" additional service that the ban* would now be able to provide.

Solution

(a) (i) ecord*eeping, payroll, billing and ordering of drugs and supplies(ii) 4utomating the recording of patient histories(iii) 1onitoring critically ill patients in surgery and intensive care units(iv) ecording and analy7ing the result of health screening examination to help detect

diseases that might otherwise go unnoticed.(v) ecording and interpreting the results of electrocardiograms ("!/s)

(b) (i) 5rogrammers , Database admistrator (ii) "< ("lectronic und <ransfer) , 4<1 (4utomated <eller 1achines)

Question #

(a) <he customer cience teacher in a secondary school is attempting to convince the!hemistry teacher to use !omputer 4ided +earning (!4+) software in the teaching of!hemistry.

i) tate <- benefits that the !omputer cience teacher could cite to convince the

chemistry teacher.

ii) tate <- obstacles that would prevent the chemistry teacher from using the computer in teaching.

Solution

(a) (i) !omputers could be used to stimulate experiments eliminating the use of dangerouschemicals.

low students could learn at their own pace.

(ii) <eacher not computer literate +arge class si7e !ost of computer hardware and software.

Question $

(a) !opy the following trace table in your solution boo*let.



< M Y =

1

2 $

!omplete the following trace table for the following algorithm, given that the number is the input value.

ead Q or 1 B @ to Q do M B Q ' 1 L B $KM1 "nd

5rint L

(b) hat is printed by the algorithm3

Solution

(a)

(b)

Question 9

(a) rite an algorithm which prompts the user to enter the price of an item and which!alculates and prints the new price after a discount of @W.

(b) rite an algorithm to read in <- numbers into 4 and C. <he algorithm should storethe smaller in 4 and the larger in C, and print 4 and C.

Solution

(a) 2nput 52!" 0"52!" B 52!" E (52!" K 9.@)

5rint 0"52!" (b) 2nput 4

2nput C2f 4 B C then print G0umbers are e6ualI endif 2f 4 F C ! B C C B 4

Q 1 M L @ % @

8

%

@

9



4 B !"ndif5rint 4, C

Question 9

rite an algorithm to read "+">"0 numbers, find their average and print it. <healgorithm should also print the number of times the number ? occurs in the data.

or example, given the input data#

8 ? : ? $ ? @9 O 9 @?

<he algorithm should print O as the average and % as the number of times ? occurs.

Solution

U1 B 9 2Q!-U0< B 9

or !-U0< B @ to @@ do

2nput 0U1C"

U1 B U1 B 0U1C" 2f 0U1C" B ?

2Q!-U0< B 2Q!-U0< E @ "ndif

"nddo4>"4/" B U1 divide by @@

5rint 4>"4/", 2Q!-U0<

199#

Question 1(a) 0ame a type of device which produces a human readable copy.(b) 0ame a type of device which produces a machine readable copy.(c) 0ame a type of device that accepts data in human readable form.

Solution

(a) 5rinter , 5lotter(b) Dis* Drive(c) Heyboard

Question 2

<he wide variety of input devices and media is a ma=or factor which adds to the flexibility andversatility of computer systems. <he use of a (i) device which allows users to move around imageon the monitor by the shifting of a lever on the device has made computer games very popular. 2nsupermar*ets, there are (ii) devices which allow a cashier to *ey in data on sales and this data isautomatically transmitted to a computer for processing. <here also (iii) devices that are capable ofreading pencil mar*s on an examination script thereby allowing the test to be scored automatically.<he use of (iv) devices to read in images allow pictures and logos to be incorporated in adocument.



tate the technical names for "4!& of the devices numbered (i) ' (iv) in the passage above.5lease use the numbering indicated in the passage to identify your solutions.

Solution

(i) Noystic* (ii) 5oint of ale terminals (iii) -ptical 1ar* eaders (iv) canner

Question 3

(a) !onvert the decimal number 8% to its binary e6uivalent.(b) !onvert the binary number @@99@@9@ to its decimal e6uivalent.(c) 4dd the two binary numbers @@9@ and @99@9@.(d) "xplain the difference between discrete and continuous data.

Solution

(a) 8%@9 B @9@99@@

(b)

@ @ 9 9 @ @ 9 @

O ? $ % @ 9

@@99@@9@ B O E ? E % E E 9

B @8 E ? E 8 E E @ B 9$@9

(!) @ @ 9 @

E @ @ 9 @ 9 @

@ @ 9 9 @ 9

(d) ee @::% Xuestion @ (a).

Question

(4) tate <&"" ways in which a teacher would use a computer in his or her =ob.

(C) tate <- ways in which a =ournalist would use a computer in his or her =ob.

(!) 4 large company has decided to computeri7e the functions of its &umanesource (5ersonnel) Department. <he computer department has been giventhe responsibility for completing the tas*.

(D) 0ame -U categories of personnel from the !omputer Department that the !omputerDepartment 1anager must assign to the tas*, stating clearly -0" function of "4!& category.

Solution

(4) (i) <o store students records



(ii) <o use ‘!omputer 4ided 2nstruction’ to aid in teaching(iii) <o mar* scripts

(C) (i) <o research a topic using the internet(ii) <o creates articles

(!) >ERSONNEL FNCTION

(i) 5rogrammers rites programs that solves specific problems (ii) Data "ntry !ler*s se 7e,ent, *e?i'es to ente +. *+t+ into +'&ine

e+*+6le -o+t (iii) Database 4dministrator !reates and controls the use of an organi7ation’s database. (iv) ystems 4nalysts <he analyst interacts with various users of a computer systems

and with programmers to help analy7e, design and implementthe new computer system.

Question !

(4) Describe briefly an application in which a robot (or robotic arm) is used inindustry, tarting clearly -0" function that the robot performs.

(C) tate <- advantages of using the robot (or robotic arm) over using a manual method

in the application described in part (a) above.

(!) tate -0" advantage to the customer of telemar*eting.

(D) tate -0" disadvantage to a customer of telemar*eting.

(") tate -0" advantage and -0" disadvantage of teleconferencing.

Solution

(4) obotic arms are used in the manufacturing of motor vehicles. -ne function that the robotic

arm serves is to spray the motor cars with a uniform coat of paint.

(C) i. <he robot does not miss ii. 2t wastes less than half as much paint as a human painter does. iii. <hey are not affected by the dangerous fumes or heat, therefore they do not get sic*.

(!) <he customer does not have to travel long distances to ac6uire a product.

(D) <he customer is unable to examine the product closely before purchase.

(") 4dvantage# <he customer can see their friends or relatives anywhere on the globe while

pea*ing to them.

Disadvantage# <he cost of the e6uipment and service are high.

Question "

(4 T C) St+te T@O 4o6les .&i'& .oul* +ise -o t&e s&+in/ o- *+t+ in t&e 'o4+n,



(!) hat is ‘data encryption3’(D) tate <- methods, other than data encryption, used to secure data.(") "xplain the difference between the role of an applications programmer and that of a systems

programmer in an organi7ation.

Solution

(4) Cecause it is ta*ing away from the creator of the program the right to earn from his or hercreation.

(C) i. <he integrity of the data is at ris* seeing that anybody can modify it ii. <here is no privacy

(!) Data encryption is the scrambling of data to render it unintelligible to an unauthori7edrecipient.

(D) i. 5assword protectionii. +oc* away the dis*s and computers when they are not in use.

(") 4n 455+2!4<2-0 5-/411" writes programs that solve specific problems for users.4 M<"1 5-/411" creates and maintains operating systems, monitors database

programs, and so forth.

Question #

(4) hat is meant by the term ‘protocol3’(C) "xplain the difference between the following terms# (i) Upload and download (ii) &alfduplex and duplex (iii) +ocal area networ* and wide area networ* (iv) "lectronic mail and bulletin board

Solution

(4) 4 GprotocolI is a formal set of rules that govern how communication or exchange of datata*es place over a networ*.

(C) i. U5Y+-4D is the process of reading data from a user’s computer storage and sending itto another computer via communication channel. D-0+-4D is the process whereby

programs or data are transferred via communication channels, from a computer andstored on a media located at the user site.

ii. &4+ Duplex is transmission system that allows data to be transmitted in one directionat a time. <hat is, the system can transmit and receive data but not at the same time.DU5+"Q is a transmission system that allows data to be transmitted in both direction at

the same time. <his system is sometimes called U++DU5+"Q.

iii. 4 local area networ* is the lin*ing of computers or terminals in the same building orsite so that they can communicate. <his communication usually ta*es place alongcables. 4 2D" 4"4 0"<-H is the lin*ing of computer or terminals over a widegeographical area in order to facilitate communication system using telephone lines,

satellites, microwave transmission or any other medium that facilitates long distancecommunication.



iv. "lectronic 1ail is mail or messages transmitted electronically by computers via communication channels. 2t is usual for such messages to be held in a central store

for retrieval at the user’s convenience. 4 Culletin Coard is an electronic e6uivalent of a conventional bulletin board. 2t is used as part of a communication networ* where users

can post messages, read messages posted by other users, communicate with the systemoperator and upload or download programs.

Question $ hat is printed by the following algorithm3

!-U0< B @ Q B

hile !-U0< J $ D- Q B Q E print !-U0<, Q !-U0< B !-U0< E $ endwhile

Solution

CONT < >RINTE5

@ @,

? ?, ?

@@ ? @@, 8

@? 8 @?, @9

@ @9 @,@

? @

<he following is printed#@, , ?, ?, @@, 8, @?, @9, @, @

Question 9

(4) "xplain the difference between a high level programming language and a machinelevel language.

(!) "xplain the difference between an interpreter and a compiler.

(D) rite a pseudocode algorithm to read two numbers and print the lower value.

Solution

(4) 4n HIGH LEEL >ROGRAMMING LANGAGE is one that is more intelligible tohuman beings and, before it can be understood by the machine it has to be converted to aform that the machine can understand. MACHINE LANGAGE consists of data andinstruction as coded binary digits, 9s and @s. 0o translation is necessary for the computerto understand this language.



(C) INTER>RETERS translate highlevel language statements one at a time, executing eachstep immediately after it has been translated. 0o permanent ob=ect program is generatedPeach time a source program statement is encountered, it is reinterpreted. COM>ILERS

translate the entire source code (all statements) to its ob=ect code before execution ta*es place. 4 permanent ob=ect program is generated. henever changes are made to the sourcecode, the program has to be recompiled for the changes to ta*e effect.

(!) read 4read C

if 4BC <&"0 520< G0umbers are e6ualIendif

if 4JC print 4else print Cendif

Question <he following data represents some sample data of the number of children in severalfamilies.

@ % $ 9 ? O % $ 9 :::

::: is the dummy value which terminates the data. rite the pseudocode algorithm read in

any data in the above format, and print

(4) <he number of families with no childrenP and(C) <he largest number of children existing in any family

Solution

read 0U1C 9!-U0< B 9 &2/&"< B 0U1C

while 0U1C JF ::: D- if 0U1C B 9 <&"0 9!-U0< B 9!-U0< E @ endif

if 0U1C F &2/&"< &2/&"< B 0U1C endif



read 0U1C

endwhile

print Gnumber of families with no children BI, %CONT

print G largest number children BI, HIGHEST

199$

Question 1

(4) Define the term ‘protocol’ as it relates to data communication. (C) Digital transmission can occur in three ways# (i) Data can be transmitted in one direction only. (ii) Data can be transmitted in both directions but only in one direction at a time. (iii) Data can be transmitted in both directions simultaneously.

tate the correct technical term for "4!& of the transmission methods above.

(!) (i) 0ame type of networ* that would be suitable for lin*ing all the computers in a building.

(ii) tate -0" advantage of lin*ing the computers in this way.

Solution

(4) 5rotocol is a set of rules that govern the communication of data between a terminal and acomputer or between computers.

(C) Digital transmission can occur in the following three ways# i. 215+"Q ii. &4+ DU5+"Q iii. U++ DU5+"Q

(!) (i) +ocal 4rea 0etwor* (+40) would be the most suitable for lin*ing computers in a building.

(ii) 4dvantages of lin*ing the computers in this way are# the computer e6uipment e.g. printers, can be shared by several users hence reduction

in cost.

2nstead of buying many software program for each 5!, the software can be installedonto the main computer and the users access this computer. 1emos and otherteaching materials can also be done using this method.

Question 2hen a program ma*es a read re6uest to the dis* drive, the component which reads data from thedis* is moved along a radius to the particular concentric circle on which the data are stored. henthe relevant part of the concentric circle of the dis* arrives under the component, which reads thedata, the data are read and stored in a special area of memory from which they could be accessed.

tate the proper technical term for each of the -U underlined phrases in the passage above.



Solution

<he proper technical terms for each of the four underlined phrases are#i. ead;rite headii. <rac* iii. ector iv. Cuffer

Question 3

1atch the following applications with the most appropriate input device.

455+2!4<2-0 205U< D">2!"

5ointofsale optical mar* reader /ames *eyboard4rchitectural design magnetic in* character recognition1ultiplechoice examination microphone5ublishing pads and tablets!he6ue processing barcode reader +anguage processing =oystic* 5reparing letters scanner

Solution

455+2!4<2-0 205U< D">2!"

5ointofsale barcode reader /ames =oystic* 4rchitectural design pads and tablets1ultiplechoice examination optical mar* reader 5ublishing scanner !he6ue processing magnetic in* character recognition

+anguage processing microphone5reparing letters *eyboard

Question

(4) Define the term ‘resolution’ as it applies to a graphic display.

(C) /ive <&"" examples of input devices that can read data directly from sourcedocument.

(!) /ive <- advantages of using devices that can read data directly from sourcedocuments.

Solution

(4) esolution refers to how clear an image is seen on the screen. 2n other words,



image clarity.

(C) "xamples of inputdevices that can be read directly from source documents are# i. barcode readers

ii. mar* and character readers iii. image scanners

(!) <wo advantages for using devices that read data directly from source documents are#

i. 5rocessing of data is faster and therefore saves time ii. <he method reduces the error produced when data is being entered.

Question !

(4) hat is a computer virus3

(C) tate <- measures that could be implemented in order to prevent a computer virusfrom infecting a computer.

(!) 2dentify <- ways in which a person could be affected by the misuse of personalinformation, which has been stored in a data ban*.

(D) 2dentify <- ways by which personal information, stored in data ban*, may becomeinaccurate.

Solution

(4) 4 computer virus is a program that attaches itself to other programs or files and thenreplicates itself in such a way that it corrupts and destroys data.

(C) 1easures that could be implemented are# i. use of 4nti>irus programs e.g. 0-<-0 4nti>irus 5rogram ii. do not share dis*ettes

iii.avoid downloading information from Culletin Coard ervices that do not chec* forviruses regularly

(!) ays in which a person could be affected by the misuse of personal information are#

!an result in discrimination if personal information is not *ept confidential. or e.g. ifconfidential medical records are seen by the wrong persons, such as prospective employers, then itcan lead to discrimination.

ii.2f unauthori7ed persons can access the data ban*, then they can change pertinent information about the individual thereby creating a wrong identity.

(D) ays in which personal information, stored in a data ban*, may become inaccurate are#

i. hen the data ban* is not updated regularly. 2f there should be a change of address and thedatabase in not updated, then the information about that individual becomes inaccurate

ii. !orruption of data by virus



iii. 2f the data ban* is not properly protected, then unauthori7ed persons can access and changeinformation in it.

Question "

(4) !onvert 8O@9 to its binary e6uivalent.

(C) 4dd the two binary numbers @@9@9@ and @@@9@, giving your solution in binary form.

(!) /ive the C!D representation of $:@9

(D) /ive the C!D representation of $:@9

Solution

(4)

8O @

% @

@ @

@9 9

$ @

9 @ @

9

8O@9 B@9@9@@@

(C)

@ @ 9 @ 9 @

E @ @ @ 9 @

@ 9 @ 9 9 @ 9

(!)

$ : 9@9@ @99@

$:@9 B 9@9@ @99@ in C!D representation (D) !onvert ($:) using the two’s complement method#

$:@9 B 9@9@ @99@ in C!D

$:@9 B @9@@ 9@9@ @99@ 20 C!D Rthe @9@@ attached to the left represent the negative signS

Question #

(4) !D-1s are used extensively in the field of education. <ate <&"" features ofeducational software on !D-1s that ma*e them useful for educational purposes.

(C) or "4!& of the following, state <- ways in which information <echnology can assistemployees in the performance of their =obs#



i. +aw enforcement ii. 1edicine iii. "ntertainment

Solution

(4) <hree features of educational software on !D-1s are#

i. !Ds have a large storage capacity (at least $ gigabytes). <herefore they can hold a lot of

information

ii. Cecause it is ead -nly, information cannot be altered or erased. 4s a result, mischievousstudents are unable to change any information

iii. !Ds can record sound along with information. <he sounds and images are clearer and sharperthen if recorded on another medium e.g. a dis*ette.

(C) <wo ways information <echnology can assist the following employees in their =obs are#

L+. en-o'eent

i. tore information about criminals. <his information includes, fingerprints, photograph, offencesto date and all other relevant information. ith the entrance of the person’s name or fingerprint,all relevant information about the person are available.

ii. <rac* delin6uent traffic offenders. ith the input of license number all traffic offencescommitted by a person are made available.

Me*i'ine

i. Diagnosis systems that collect data and analy7e the data to diagnose the illnesses.

ii. oftware that records and maintains patients record in databases

Entet+inenti. ith the aid of computer technology a musician is now able to compose a song on the computer

ii. 1usical notes and sounds of different instruments can be stored and combined to give a pleasantsound to the ear.

Question $

(4) rite a structured algorithm to read in <- numbers and print the higher value.

(C) rite a structured algorithm to interchange the values in <- variables 4 and C.

Solution

(4) read 0U1C@ read 0U1C

if 0U1C@ B 0U1 then5rint Gnumbers are e6ualI

endifif 0U1C@F0U1C then



5rint 0U1C@ else 5rint 0U1C endif

(C)ead 4

ead C ! B 4

4 B C C B !

Question 9

(4) !opy and complete the trace table below for the following algorithm.

Q B $ H B @9 U1 B $ hile umJO$ do U1 B U1 E H

5rint H HB H E Q "ndwhile 5rint U1

Q H U1 $ @9 9 $$ $

(!) hat is printed by the algorithm3

Solution

(4)Q H U1 520<

$ @9 $ @9 $ @$ $$ @$ $ 9 O9 9

$ $ :9

(C) <he following values of H would be printed# @9, @$, and 9.

Question 1%

rite a structured algorithm to read the names and scores of fifteen students in a class. <healgorithm must print name of the students and his;her grade which is determined according to thegrading scale below. <he algorithm must also calculated and print the average score for the class.



/4D20/ !4+"

!-" /4D" 89 or more 4 ?$ or more but less than 89 C $9 or more but less than ?$ ! +ess than $9

Solution<-<!-" B 9

or !-U0< B @ to @$ Do ead 041" ead !-" <-<!-" B <-<!-" E !-" 2f !-" F B 89 then

/4D" B ‘4’ "lsif !-" F B ?$ and !-" J 89 then /4D" B ‘C’

"lsif !-" F B $9 and !-" J ?$ then

/4D" B ‘!’ "lse /4D" B ‘’ "ndif 5rint 041", /4D" "ndfor

4>"4/" B <-<!-";@$ 5rint 4>"4/"

1999

Question 1

4 computer consists of several hardware devices and software components. <he *eyboard, mouseand printer are all peripheral devices connected to the systems unit. <he systems unit comprises of a!entral 5rocessing Unit (!5U) and a component, (4), that holds the data and programs that arecurrently being used. <he !5U in turn, consists of two components. -ne component, (C),directs theinternal operations within the !5UP and the other component, (!), is responsible for themanipulation of data. 2n addition,, there is another storage component, (D),which stores data and programs that are not currently being used by the !5U.

tate the component that performs "4!& of the functions named 4 to D and underlined above.

Solution

<he components are#

4. andom 4ccess 1emory (41) C. !ontrol Unit (!U) !. 4rithmetic;+ogic Unit (4+U) D. econdary torage



Question 2

1atch "4!& characteristic, listed 4 to & below with the 1-< approximate device. rite the letter (4,C, etc) to represent the characteristic and next to "4!& letter write the name of the device thatmatches it.

CHARACTERISTIC 5EICE

4. 1odulates and demodulates signals 5lotter C. 4ccepts voice inputs Heyboard

!. 4llow users to input architectural plans 1odemD. eads in graphics data /raphics tablet". Used for printing architectural plans 1icrophone. Used for entering text documents Carcode reader/. etrieves pricing data from grocery items Noystic* &. Used to move the cursor canner

Solution

CHARACTERISTIC 5EICE

4. 1odulates and demodulates signals 1odem

C. 4ccepts voice inputs 1icrophone!. 4llow users to input architectural plans canner D. eads in graphics data /raphics tablet". Used for printing architectural plans 5lotter . Used for entering text documents Heyboard/. etrieves pricing data from grocery items Carcode reader &. Used to move the cursor Noystic*

Question 3

(4) tate <&"" functions of an operating system.

(C) 2dentify the type of processing mode that would be suited for the following applications# i. 1onthly payroll ii. <ransactions at an 4utomatic <eller 1achine iii. 5rocessing electricity bills

Solution

(4) <hree functions of an operating system are# (i) 2t manages the sharing of internal memory among multiple applications

(ii) 2t handles input and output and from attached hardware devices, such as hard dis*s printersand dialup ports.

(iii) 2t provides security and control.

(C) (i) Catch processing(ii) eal time processing(iii) <ransaction processing system

Question

(4) +ist <&"" ways in which a teacher can use computers in the classrooms.



(C) uggest <- reasons why computers may 0-< be used in classroom.

(!) tate <- advantages of using computers in the classroom.

Solution

(4)<hree ways in which a teacher can use computers in classroom are#

i. to teach students to use the computer ii. to mar* scripts

iii. to use ‘!omputer 4ided 2nstruction’ softwareiv. to store student’s records

(C) <- reason computers may not be used in the classroom are# i. not all students are computer literate

ii. the cost of computers and related software are still too expensive for some schools. 2ii. 0ot all teachers are computer literate

(!) <- advantages of using the computer in the classroom are# i. students can learn at their own pace using ‘!omputer 4ided 2nstruction’ software. ii. teachers can spend more time with wea*er students while the faster students wor* with the

computer.

Question !

(a) !onvert the decimal number :9@9 to a binary number.(b) !onvert the binary number @@9@@ to a decimal(c) 4dd the two binary numbers @@9@ and @9@9@, giving your solution as a binary number.(d) Determine the C!D representation of 8O@9

Solution (4)

:9@9 B @9@@9@9

(C)

@ @ 9 @ @

:9 9

$ @

9

@@ @

$ @ 9

@ @

9



5lotter 5rints maps and architectural drawings 1odem 2nternet use and electronic mail 1agnetic 2n*character reader Can*ing, to read che6ue numbers

encoded at the bottom of the che6uesQuestion #

(a) 2n order to secure its data, a company uses the following method for encrypting text#

4 letter is replaced by, five letters later in alphabetical order. or example, the letter G4I is replaced by GI, GCI is replaced by G/I and so on. 0ote that the letter G4I is considered to follow the letter

GLI.

(i) hat would the word G"4MI be stored as 3(ii) hat is the meaning of the following text3 0+<M0M

(C) (i) hat is the purpose of a password3 (ii) hat is meant by the term ‘archiving’3

(iii) ithin many organi7ations, data on personnel are stored in a central location fromwhich

various departments can access relevant information. <4<" <&"" problems that mayarise because of the sharing of this type of data.

Solution

(a) i. "4M would be stored as NQQD ii. 0+<M0M means 2/-<2<

(b) i. 4 password is a special code, word or symbol that is re6uired to access a computersystem.

ii. 4rchiving is the storage of data no longer in use on tape or other durable mass storage media for long term storage or bac*up. iii. <hree problems that can occur are#

data can become incorrect or erased by deliberate tampering or human error

unauthori7ed persons could access the data for personal gain

violation of individual’s privacy

Question $

5rograms are written with the general purpose of solving problems. &owever, it is unli*ely that a program will run completely errorfree on the first attempt. <he process whereby a program ischec*ed to ensure that it does what it was designed for is important in the development of the program. <here are two main types of errors that can occur# one type of error occurs when the programmer fails to properly thin* through the solution to the problem and the other occurs when the programmer does not ade6uately *now the rules of the programming language. 2t is good practice to perform a manual trace on the program, using approximately selected input values, which chec*s

each segment of the program.

tate the proper technical term of "4!& of the underlined phrases labeled 4 to "

Solution

4. Des* chec*ing or dry runningC. +ogical error !. tructured wal*through



D. <est data

Question 9

(a) D2""0!" B 92nput 4, C2f 4JBC then D2""0!" B 4Celse D2""0!" B C4

endif print D2""0!"

what is printed by the algorithm above if the input values are the following3

(i) 9 %9 (ii) @99 @99 (iii) $9 @9

(b) rite a structured algorithm to prompt the user to input two values which are then stored in 4and C. <he algorithm must divide 4 by C and print the result. <he algorithm must *eep prompting for the second number as long as the user enters 9 (Lero) for the second number.

Solution

(a) (i) @9 (ii) 9 (iii) 9 (b) 5rint G"nter two valuesI 2nput 4,C

hile C B 9 do 2nput C

"ndwhile

esult B 4;C 5rint esult

Question 1%

(i) rite a structured algorithm which prompts a user to enter an integer value which is then storedin a variable 0. <he algorithm must then print each integer from @ to 0 and its correspondings6uare. "ach output line must show the integer and its s6uare. Mou may assume that the userwould enter an integer value .

(ii) 1odify the algorithm in (i) to determine the sum of all the s6uares. 5rint this sum if it is less than or e6ual to @999. -therwise, print the following message#

THE SM IS GREATER THAN ONE THOSAN5Solution

5rint G"nter >alueI 2nput 0 or !ounter B @ to 0 do 5rint !ounter,!ounterK!ounter "ndfor



um B 9 5rinter G"nter >alueI 2nput 0 or !ounter B @ to 0 do

5rinter !ounter, !ounterK!ounter um B um E !ounterK!ounter "ndfor

2f um J B @999 5rint um

"lse 5rint G<&" U1 2 /"4<" <&40 -0" <&-U40DI "ndif

2%%%

Question 1

/ive -0" similarity and -0" difference between "4!& of the following pairs#(a) -1 and 4(b) -1 and "5-1(c) &ard Dis* and loppy Dis*

(d) 5rimary torage and econdary torage(e) ystem software and 4pplication software

Solution

(a) Siil+it,0 -1 and 41 are both memory chips 5i--een'e0 41 is volatile and -1 is not

(b) Siil+it,0 2nformation on the -1 and "5-1 chips is only for the computer to use 5i--een'e0 2nformation on the -1 chip is permanently stored, information on "5-1 can be

erased and new instructions written to it.(c) Siil+it,0 Data stored on loppy Dis* and &ard Dis* can be accessed without reading any other

data item first(D4D). 5i--een'e0 loppy Dis*s are removable, &ard Dis*s cannot be easily moved from place to place.

(d) Siil+it,0 <hey store data for processing. 5i--een'e0 5rimary storage is volatile, and secondary storage is not.

(e) Siil+it,0 Coth are instructions carried out by the computer5i--een'e0 4pplication software is used by end user to solve specific user problems while

ystem software is used by the computer to manage its activities.Question 2

(a) /ive brief explanations for "4!& of the following terms#

(i) ordsi7e (ii) Cuffer (iii) 1icrofilm (iv) Candwith (v) ide area networ*

(b)(i) hat is electronic eavesdropping3

(ii) hat is software piracy3 (iv) tate <- ways in which software piracy may be controlled.



Solution

(a) (i) <he number of bits that is handed by the computer as a unit.<he unit could represent aninstruction or data element.

(ii) <emporary storage area for data. <he purpose of the buffer is to act as holding area fordata that has been processed by the !5U and waiting to be transmitted to a device, thus

freeing the !5U to continue its processing function.

(iii) 4 high resolution film on which photographic records are *ept of documents or othermaterial, in greatly reduced si7e. <o read the information a special optical viewer must

be used to enlarge the information on the microfilm for viewing.

(iv) <he amount of data that can be sent through a networ* connection, measured in bits per second (bps)

(v) 4 networ* in which computers are connected to each other over a long distance, usingtelephone lines and satellite communications.

(b) (i) +in*ing into telecommunication channels to access information.

(ii) oftware piracy is the illegal copying of software. (iii) oftware piracy can be controlled by the following methods# the use of passwords that allow only authori7ed persons to access and use software.

etting up laws which punish persons who engage in software piracy.

Question 3

riting a program to solve a problem.

Cefore writing a program in high level language, it is advisable to write an algorithm that solves the problem. <his algorithm can be written in pseudocode and tested thoroughly for logic errors.5erform a dryrun of the algorithm using a wide variety of test data to ensure that your algorithm

wor*s for all possible cases. 0ext, convert your algorithm to the high level language. !ompile your program and correct any syntax errors which you may have. un your program an use the same setof test data you used for the dryrun, if you get the same results, your program is wor*ing correctly.

"xplain the meanings of "4!& of the underlined terms.

Soution

Hi/& le?el l+n/u+/e is one that is more intelligible to human beings and, before it

can be understood by the machine it has to be converted to a form that the ! machinecan understand.

>seu*o'o*e is a form of representation used to provide an outline description of the

specification for a software module. Lo/i' eos are errors that occur when the programmer fails to properly thin*

through the solution to a program. 4 *,un is the execution of a program for purposes of chec*ing that the program behaves correctly rather than for producinguseful results.



<o 'o4ile a program is to translate the entire source code (all statements) to its

ob=ect code before execution ta*es place. S,nt+B eos occur when the programmer does not ade6uately *now the rules of

the programming language.Question

<he 2nsure 0ow 2nsurance !ompany has its head office in Cridgetown, Carbados, <he company hasone computer, on which it stores all company data. <he company handles a lot of confidential clientdata. "ach client is assigned to a particular agent. Mou do not want agents to see confidentialinformation about other agent’s clients.

(a) &ow can you prevent agents from viewing one another confidential files3

(b) tate <- precautionary measures which can be ta*en to ensure that in the case of a fire, allclient data is preserved.

Solution

(a) 4gents can be prevented from viewing each other’s files by giving each agent a password that

can be used to view their file only, preventing others from doing so.

(b) <- precautionary measures are#

the use of fire proof cabinets to store data copy all documents and store them in a building away from yhe present location of

the business.

Question !

(a) hat is GteleconferencingI(b) tate <- advantages of teleconferencing.(c) tate -U hardware re6uirements for teleconferencing.

Solution

(a) Tele'on-een'in/ is the means by which participants are able to conduct

interactive electronicmeetings between one or more distant locations.

(b) <- advantages of teleconferencing are# <he cost for traveling is reduced as participants can remain where they are, not

traveling long distances. <he time for traveling is reduced.

(c) our hardware re6uirements for teleconferencing are# <elephone

1odem

pea*ers 1icrophone

Question "

(a) (i) tate -0" advantage of machine language over a high level language. (ii) tate <- advantages of a high level language over machine language.

(b) tate <&"" advantages of computer networ*s.



(c) e convert an integer in its C!D representation by#

@. !onverting each digit in the integer to its binary value using a four bit coding scheme.. Noining the four bit representation of each bit in the same order as the integer%. if the integer is negative attach @9@@ to the left of the bit string to indicate that the number

is negative or @9@9 to the left of the bit string to indicate that the number is positive.

(d)

? $ @9@@ 9@@9 9@9@

<he C!D value of ?$ is @9@@9@@99@9@

Question $

(a) rite an algorithm which reads three values, a,b and c and prints the largest of allthree

(b) <his part is based on the algorithm given below.

set 4 to %

set C to $set U1 to @while 4JB$9 do 4B 4EC CB CE4 U1B U1 E C"ndwhile5rint U1top

Using the algorithm above

(i) copy and complete the trace table which follows#

A SM

% $ @(ii) tate what is printed by the algorithm

Solution

"4D a "4D b "4D c

2f a B b and a B c then 5rint G0umbers are e6ualI "ndif

2f a F B b then+argest B a

"lse



+argest B b "ndif

2f c FB largest then+argest B c

"ndif

5rint largest.

(b) i.4 C U1

% $ @

8 @% @

@ % 8

$$ 8: @%O

ii. @%O

Question 9

rite an algorithm to read a positive integer 0 and find the average of all even numbers between @

and 0 inclusive. 5erform any necessary validates.

Solution

ead 0 if 0 J B 9 then print G2nvalid "ntryI else U1 B 9 0U1 B 9 !-U0< B 9 while U1 J B (0@) do

U1 B U1 E !-U0< B !-U0< E @ endwhile ">"04>/ B U1;!-U0< endif Question 1%

rite an algorithm to read the names of @9 items and their price and print the name of the item withthe highest price. 4ssume that no items have the same price. Data is supplied in the form# 2tem @, price @, price , etc

Solution

read itemread pricehprice B pricehitem B itemfor !-U0<" B @ to : do read item



read price if price F hprice then hprice B price

hitem B item endif endfor print G&ighest item with highest priceI, hitem

2%%1

Question 1

(a) ortrans was the first third generation language. hat are the features distinguishing the thirdgeneration from the first T second generation3

(b) /ive the meaning of the followingP i. +ogic ii. <est data

iii. ource code iv. >ariable

(c) hat are the responsibilities of the !hief 5rogrammer3

Solution

(a) <he features distinguishing the third 'generation languages from the first and secondgenerations are#

<hird generation language uses words, sentences and mathematical formulas, while

first generation uses ones and 7eros. second generation language uses assemblylanguage.

<hird generation language has a special way of organi7ation program instructions

*nown as a syntax.

<hird generation language in comparison to first and second generation languages iseasier for human to understand.

(b) Lo/i' eo 4n error caused by a mista*e in programming instructions. 4 logic

error causes a program to operate wrongly or produce incorrect results but does notstop the program from wor*ing.

Test *+t+ ' 4pproximately selected input data for testing computer systems to ensure

that it fulfills the purpose for which it was created. Sou'e 'o*e ource code is a program written in a high level programming

language.

+i+6le ' 4 named storage location in memory where data is stored temporarilyduring program execution and whose content constantly changes.

(c) <he responsibilities of the !hief 5rogrammer are# @. coordinates programming tas*s among programmers . leads and guides programming pro=ects %. writes computer programsQuestion 2



rite down what "4!& of the following abbreviations stand for, and what is the purpose of "4!&of the components listed3

(a) 5-1(b) !5U(c) 4+U(d) 41

Solution

(a) >ROM programmable ead -nly 1emory ' has no data on it when first manufactured. !omputer manufactures then place the information on the chip, and when this is

done the chip becomes read only.(b) C> !entral 5rocessing Unitthis is where all processing ta*es place. 2t interprets and

executes program instructions as well as, communicates with input, output andstorage devices.

(c) AL 4rithmetic and +ogic Unit 'performs all arithmetic operations

all logical operations stores the data which can be immediately processed by the program

2nstructions.

(d) RAM andom 4ccess 1emory# stores program instructions prior to execution stores the data which can be immediately processed by the program

instructions. stores information temporarily after processing is complete. Question 3

(a) "xplain the difference between data and information.

(b) "xplain the following terms(i) U5+-4D

(ii) 40

(b) hich of the following are of serialaccess type3(i) 1icrofilm(ii) 1icrofiche(iii) eeltoreel tape(iv) !artridge tape

Solution

(a) <he difference between data and information is#Data is raw, unprocessed fact. 2nformation is processed or interpreted data that can be used.

(b) (i) >LOA5 <he transfer of files from one computer to a mainframe or a server via anetwor* such as the internet. (ii) @AN ide 4rea 0etwor*, group of networ*s connected over a large geographic

area such as city, country or continent.(c) <he following storage media are serial access#

(iii) eeltoreel tape (iv) !artridge tape



Question

(a) -utline the <&"" main functions of a computer’s operating system

(b) &ow does a ‘pulldown menu’ help you in completing your tas* more easily3(c) /ive the 1-< important advantage of primary storage over secondary storage.(d) /ive the 1-< important advantage of dis* storage over tape storage.(e) 2n using dis*ettes, one precaution is G*eep dis*ettes away from magnetic

fields.I/ive <&"" further precautions in the use of dis*ettes to store files.

Solution(a) <&"" main functions of the computer’s operating system are#

(i) !ontrols program execution(ii) &andles input and output to and from attached hardware devices(iii) 1anages data and file storage(iv) 4ssigns different tas*s to the !5U

(b) 4 pull down menu helps in completing tas*s more easily by providing the user with a list of user friendly commands, that can be executed by simply clic*ing the command.

(b) <he access time for primary storage is faster than that of secondary storage

(c) Dis* storage allows 6uic*er retrieval of data because it is direct access media.

(e) <&"" further precautions in handling dis*ettes are# (i) Do not bend the dis*ette (ii) 0ever touch the recording surface of the dis*ette (iii) Heep the dis*ette away from heat surfaces (iv) Do not remove or insert dis*ette if the drive light is on (v) Do not write on dis*ette except with soft tip pen

Question !

(a) hich print output devices is best suited for printing an architectural drawing of the frontview of a new building, and why3

(b) 4 dot matrix printer is producing very faded output. /ive -0" li*ely reason for this problem, and explain what must be done to remedy it.

(c) "xplain the operation of the light pen.

(d) /ive -0" similarity and -0" difference between -! and 12!.

Solution

(a) <he printer output device that is best suited for printing an architectural drawing ofthe frontview of new building is a plotter. 4 plotter produces large si7ed documents by using special

mechanism to draw lines that constitute a document.

(b) 2f a dot matrix printer is producing very faded output it could be that the in* on theribbon is finishing and the ribbon needs to be rein*ed or replaced.



(c) 4 light pen detects the presence and absence of light on a surface. <his information sent to thecomputer that interprets it.

(c) -0" similarity and -0" difference between -! and 12! operation is that

imilarity ' both read and convert text into electrical signals that are converted to character by the computer.

DifferenceZ<he 12! reads only magneti7es or magnetic characters.

Question "

(a) 4 certain computer uses an unsigned binary floating point representation for positive real numbers.<he mantissa is an 8bit normali7ed fraction and the exponent is an 8bit, two’s complement integer

2n a particular case, the mantissa is @99@99@@ and the exponent is 99@@99@@. what is the number being represented3

(b) !onvert the binary number 9@9@9@9@ to decimal number

(c) !onvert the decimal number O (seven) to a binary number.

Solution

(a) <he number being represented is@.@99@99@@K 99@@99@@

B@.@99@99@@K $@

B(@K9 E @K @ E @K E @K O E @K 8)K$@

B(@K8 E @KO E @K E @K @ E @K 9)K% B ($?E@8E@?EE@)K%

B 9% K %

(b) <he decimal value of 9@9@9@9@ is#

9 @ 9 @ 9 @ 9 @@8 ? % @? 8 @

? E @? E E @ B 8?

(c) <he binary value of the decimal number O is#

O @

% @

@ @

9

99999@@@

Question #

(a) <he use of information for strategic purposes can sometimes involve a violation of ethics. /ive<- ways in which this statement is true.

(b) 2n dealing with computer security, explain -0" advantage of software restrictions compared with



physical restrictions.

(c)hat is ‘telecommuting’3 what ma=or development has contributed to ma*ing telecommuting aeasible option3

Solution

(a) <- ways in which the statement is true is# i. !ustomer information is distributed or sold without their *nowledge to individual;company who use

the information for strategic purposes.

ii. 2nvasion of privacy by the monitoring of electronic mails of millions of customer whose data arestored in private and public databases. <hen using the information gathered to assist in strategic planning of product output.

(b) oftware restriction prevents access of information in any location. 5hysical restriction =ust prevents physical contact with the software. 2f the barrier is bro*en, the information may beacessessed.

(c) <elecommuting is wor*ing at home by sending information (via phone, fax and computer) from

home to the office. <he ma=or developments that have contributed to ma*ing telecommutinga feasible option are# (i) <elephone (ii) 1odem (iii) <he 2nternet (iv) ax 1achine

Question $

<he following terms relate to memory and data storage. /ive the meaning and purpose of "4!&

(a) Cac*ing up(b) ead;rite head(c) 4ddress

(d) 4ccess timeSolution

elation to memory and storage#(a) +'7in/ u4 <he routine activity of duplicating computer files or database on

secondarysecondary storage media. <his is done to preserve information in the case of data destruction because of e6uipment failure or other catastrophe.

(b) Re+*@ite &e+* 4 read;write head is the device that reads data from and writesdata ontoa

storage medium in magnetic pattern.

(c) A**ess 4 uni6ue number that references a location in computer memory.

(c) A''ess tie the time for the read;write head to move to the correct trac* plus thetime for

half a complete rotation of the dis* platter.

Question 9



!onsider the following#

205U< Q,M,LM B Q E MQ B Q ' MM B Q E M2 Q F M <&"0 L B QML

"+" LB QEMEL"0D2520< Q,M,L

hat is printed by the algorithm if the input is#

(a) @,@,@3(b) @,,%3

Solution

(a)

Q M L@ @ @

@ @

@

t&e -ollo.in/ is 4inte*0 18181

(b)

Q M L

@ %

% @

T&e -ollo.in/ is 4inte*0 28182

Question 1%

4 certain account at a ban* earns compound interest on a yearly basis, and has no deposits orwithdrawals. <he balance after a year is given by the formula#

<his year’s CalanceB +ast Mear’s Calance K( @ E 2nterest ate), where 2nterest ate is given as adecimal fraction.( for example, $W must be entered as 9.$)

rite a structured algorithm to do the following#

(a) e6uest the user to provide the interest rate as a decimal, the number of years tocompute interest

for and the starting balance.(b) ead in the interest rate , and the value 0 which is the number of years to

compute interest for.



(c) ead in the starting balance.

(d) !ompute and display the balance, including the interest, after 0 years have passed

Solution

5rint G"nter the interest rateI

ead ()5rint G"nter the number of years to computer interest forIead (0)5rint G"nter the starting balanceIead (+astYMearYCalance)

or counter B @ to 0 do

<hisYMearYCalance B +astYMearYCalance K(@ E ) +astYMearY Calance B <hisYyearYCalance

"ndfor

5rint G<he balance after #I,0, Gyears is # G,<hisYMearYCalance5rint G<he interest rate# G,

2%%2

Question

(a) 0ame the <- main component of the central 5rocessing Unit.(b) or the two component named in part (a),discuss their 1420 functions.(c) /ive -0" difference between 5-1 and "5-1

(d) hat is ‘halfduplex transmission’Solution

(a) <he <- main component of the !entral 5rocessing Unit are#2. <he !ontrol Unit

22. <he 4rithmetic ;+ogic Unit (4+U)

(b) <heir 1420 functions are#T&e Contol nit

eads and interprets program instruction

Directs the operation of the internal processor component

!ontrols the flow of programs and data in and out of primary memory

!ontrols the flow of information to and from 2;- devicesT&e Ait&eti'Lo/i'+l nit (AL)

5erforms all arithmetic operations

5erforms logical operations

tores the data which can be immediately processed by the program instructions

(c) -0" difference between 5-1 and "5-1 is that once an instruction iswritten on a 5-1 chip it cannot be erased. "5-1, on the other hand , can



be programmed electronically at any time and can be erased with ultra violetlight.

(d) &alfduplex transmission is the transmission of data on only one direction atany given time.

Question 2

(a) you have saved a file on dis*ette. Mou later find that although you see the filelisted, you cannot

open the file from the dis*ette. /ive -0" possible cause for this problem

(b) -ne of the things done in high level format is the creation of a ile 4llocation<able. hat is the

purpose of the ile 4llocation <able3

(c) "xplain how a fixedhead system on a hard dis* unit can reduce the access timefor the device.

(d) ith reference to a hard dis* arrangement, give the difference between a trac* and a cylinder.

(d) 4 hard dis* system has six dis* surfaces, with one moving head for eachsurface. 4 certain trac*

has ten sectors forming a ring, each sector carrying [ Hbyte. &ow many

i) bytes are there in each [ Hbyte sector3ii) Hbytes are there in the entire cylinder3

Solution

(a) <he Dis*ette may have damaged sectors.

(b) <he file allocation table (4<)# +ists all of the clusters available on a dis*

Heeps trac* of which clusters belong to which file as files may be scattered all over a

dis* +ocates each cluster and determines whether it is damaged in use or available for use

(!) 4ccess time is e6ual to the time for the read;write head to move to the correct trac* plus the timefor half a complete rotation of the dis* platter. ith a fixed head system the time to locate thetrac* is eliminated because each trac* has it own read;write head.

(e) <he difference between a trac* and a cylinder is that a trac* is a circular ring onone side of the

dis*, while a cylinder is a set of corresponding trac*s running vertically through the dis* pac*.

(")

2. [ Hbyte B@9; bytes B $@ bytes22. @9K .$K? B%9Hbytes per cylinder

Question 3



(a) 4n old %9 pin memory module (211) was capable of providing one byte at a timeto the !5U. 4 % bit machine would re6uire four of these to wor* together in asingle ban*. "xplain why is this so.

(b) 2ntegers are good for representing discrete data. eal numbers and floating pointvalues are good for representing continuous data. "xplain these statements.

Solution

(a) @ Cyte B 8 Cits

% Cits is therefore e6ual to %;8 B Cytes.our of the old %9pin memory module ( 211) would be needed because each representsone byte of data.

(b) 2ntegers are whole numbers and do not have a decimal part , discrete data vary indistinct

steps and is therefore suitably represented by integers. eal numbers and floating pointvalue do not vary in distinct steps but change smoothly and continuously over a range.<hey are therefore used to represent continuous data, that is, data that is related to a scaleof measurements where there is always an additional data point between any two ad=acent points.

Question

(a) "xplain why magnetic tape is a serial access medium.(b) "xplain why a floppy dis* is considered a direct access medium.(c)hat is 1icrofilm3

Solution

(a) 4 magnetic tape is a serial access medium because all data between the persent position of the read;write head and the re6uired data has to be passed over the data can be accessed.

(b) 4 floppy dis* is considered a direct access medium because it allows re6uired data to beaccessed directly without reading any other data item first

(c) 4 high resolution film on which photographic records are *ept of documents or othermaterial, in greatly reduced si7e. <o read the information a special optical viewer must beused to enlarge the information on the microfilm for viewing.

Question !

(a) /ive two applications for the use of -ptical 1ar* eader (-1).(b) /ive two meanings of the abbreviation -!.(c) "xplain why a monitor screen specified as G @9K O?8I is expected to give a clearer

picture than one specified as G ?9K89I



(d) /ive one advantage and one disadvantage of a touch as compared to the use of the mouse. (e) /ive the difference between G custom softwareI and G customi7e software.I

Solutions

(a) 4pplication for -1 includes the following#2. <he mar*ing of multiple choice papers

22. <o read information collected on mar*et research 6uestionnaires222. 2n supermar*et for reordering stoc*.

(b) <wo meanings for the abbreviation -! are -ptical !haracter ecognition and-ptical !haracter eader.

(c)<he monitor screen of G @9K O?8I has more dots or pixels per inch and is thereforeable to produce more detailed images and thus gives a clearer picture than the G?9K

89I screen.

(d) 4dvantages# re6uires less eye and hand coordination does not re6uire the fine movements of using a mouse

re6uires less des* space

Disadvantages# fingers are bigger than cursors and therefore each option re6uiresmore screen space.

may become tiring if a lot of options have to be selected.

(e) !ustom software is software specially created to serve the needs of a specific2ndividual or company. !ustomi7ed software is general software that can be modified by thecustomer to better serve his personal needs

Question "

(a) Using an 8 bit binary representation, give the binary representation for the decimal number @9

one’s complement representation for the decimal number negative @9

two’s complement representation for the decimal number negative @9

sign and magnitude representation for the decimal number negative @9



(b) Using even parity with an 8 bit data byte, where the leftmost bit is to be used as the parity bit,which of the following are valid bit patterns3 99999999

999999@@

999999@9

@999999@

Solution

(i)

@9 9

$ @

9

@ @

9

@9@9 B 9999@9@9

(ii) <he one’s complement representation for the decimal number negative @9 is# @@@@9@9@R we change all the ones to 7eroes and all the 7eroes to ones

(iii) <he two’s complement representation fot the decimal number negative @9 is#@@@@9@9@

E@ @@@@9@@9

(iv) ign and magnitude representation for the decimal number negative @9 is# @@@@@9@9@

(b) 2 >alid 2i >alid 2ii 2nvalid 2v >alid

Question #

(a) 1r. N’s basic computer system has a monitor, *eyboard, system unit, mouse andmodem. /ive two additional devices that would enhance each of the following#i. /ame 5laying

ii. <eleconferencingiii. 5resenting a report



manually.

Question 9

(a) 4 large company offers free transportation or a transport allowance to its employees.

or this purpose it has prepared a list of the names and addresses of employees. 2n thoseareas with many persons needing a transport, the company provides transportation.

i. Cesides name and addresses, -ne of the other item of information that might be desirable in this case .

ii. "xplain one way in which the information here might be misused.

(c) 4 foreign university *eeps records of past students performance on a computer database.<he entired building is destroyed by fire, along with the records. /ive two methods thatmight have been used to allow the record *eeping to continue.

Solution

(a) i. Cesides name and addresses, one other item of information that might be desirable inthis case is the person telephone number or email address.ii. -ne way in which the information collected here may be misused is if the individual’s personal information is use for other purpose than that which it was intended without the person’s permission.

(b) @. use of a fire proof cabinet . use of a UC lash Drive; !D Curner; <ape Drive to create copies the data that isstored in a safe off site place.

Question 1%

(a) "xplain the term ‘electronic eavesdropping.’(b) 2n the case of an encrypt file, what is the purpose of a password3(c) /ive two typical responsibilities of a networ* manager.

Solution

(a) "lectronic eavesdropping is the intentional surveillance of data voice, data, fax, email,mobile telephones etc, often for dishonest purposes.

(b) 2n the case of an encrypted file, the purpose of a password is to grant access to decryptedthe file to authori7ed persons.(c) @. 1onitor the networ*’s performance

. <rouble shooting of problems encountered by the users of the networ* %. <o grant access rights to employees.



Question 11

rite an algorithm or program to read in two numbers and find the average of thenumbers.

Solution

ead 0umb @ead 0umb 4verageB ( 0umb@ E 0umb );

Question 12

rite an algorithm to read the names and prices of @99 items, and print the names ofthose items with price being lee than fifty dollars.

Solution

or counter B @ to @99 do begin ead item 0ame ead 5rice 2f 5rice J $9.99 then 5rint 2tem 0ame "nd 2f "nd or

Question 13 4 concert organi7er wants to charge different entrance prices as follows#

1ales over the age of fifteen pay \$9. emales over fifteen years old pay \9. emalesfifteen years old or younger must pay \9, males firteen and under pay \%9. 0o personunder two is allowed. rite a program or algorithm to read the name, age and sex of each patron, and for each person, to print out the names and entrance fee. <he program muststop when it encounters a person named G"0D.I

Solution

ead nameead ageead sex

hile nameJF G"0DI Do Cegin2f ageF@$ and sex B G 1aleI then



5rint name 5rintI\$9.99I

"nd 2f 2f 4ge F @$ and sex B GemalesI then

5rint name 5rint G\9.99I

"nd 2f

2f ageJB @$ and age FB and sex B G 1alesI then5rint name5rint G\%9.99I"nd 22f age JB @$ and age FB and sex BIemalesI then 5rint name 5rintI \9.99I"nd 2f 2 age J

5rint G 5ersons under two years of age not allowedI

"nd 2f ead name ead age ead sex"ndwhile

Question 1

(a) !opy and complete the following trace table, for the algorithm.

Q M L

@ %

<he algorithm#QB @M BL B %L B LE QQ B LQM B LEM

L B MLM B MQL

5rint Q, M,L hat is finally printed by the algorithm3



Solution

(a)

Q M L 5rinted@ % %,@,

% ?

@

(c) <he following is printed by the algorithm#%,@,

2%%3

Question 1

(a) +ist <- advantages of secondary storage for long term storage of data, as compare to using the computer’s main memory.

(b). i. 2dentify <- input devices that are regularly used at pointofale <erminals, and brieflydescribe how they function.

ii. +ist <- locations at which pointofale <erminals are helpful.

(c) "xplain the difference between ‘data’ and ‘information’

(d) tate one similarity in the operation of -ptical 1ar* eaders and barcodes.

Solution

(a) i. econdary storage is nonvolatile and therefore more permanentii. +arger amounts of data maybe stored using secondary storage than the main memory.

iii. econdary storage is less li*ely to be lost by virus attac*s and therefore more secure.

(b) i. +'o*e Re+*e <he barcode reader contains a scanning device that scans theinformation contained on the barcode of a product and sends it to the computer. <he

barcode reader contains a decoder that analy7es this information before it is sent to thecomputer.

De,6o+* 2nformation is sent to the !5U by pressing the *eys on the *eyboard the pressing of the *ey generates a code that represents the character associated with the *ey.<he code is sent to the !5U for processing.



Ce*it*e6it '+* e+*e <he reader pic*s up the information contained on themagnetic strip on the bac* of the card and sends it to the computer.

ii.+ocations at which pointofsale terminals are helpful are#

estaurants /as tation upermar*ets !lothes tore(c) Data is raw facts and figures collected by an individual or organi7ation. 2nformation isdefined as data that have been processed and analy7ed in a formal, intelligent way.

(d) Coth detect the presence or absence of a mar*.

Question 2

(a) 4 computer user suspects that the laser printers toner cartridge is about to run out.uggest -0" way in which the user can tell whether or not the toner is about to finish.

(b) 2n handling dis*ettes, one precaution is G*eep dis*ettes away from li6uidsI. /ive<&"" further precautions to be ta*en in the handling of dis*ettes.

(c) <apes storage involves Gerial 4ccessI. Criefly, explain the meaning of the term ‘erialaccess’, highlighting and disadvantage that this *ind of access may have.

Solution

(a) @. -ne way in which the user can tell whether or not the toner is about to finish is tonote the print 6uality of the printer. +aser printers have high print 6uality therefore, ifthe prints is faded one can conclude that the toner is about to finish.

OR

. <he status of the toner cartridge will be displayed on the computer screen or for some printers on the printer’s display screen.

(b) i. Heep dis*ettes away from magnetic fields such as telephones or electric motors.ii.Do not expose dis*ettes to direct sunlight for prolonged periods.iii.Don’t insert or remove a dis*ette from a dis* drive if the Gdrive activesI light is on.

(c) erial 4ccess involves writing to or reading information from a storage device inse6uential order. <he disadvantage of this *ind of access is the high access time as alldata occurs before the re6uired data has to be read.

Question 3

!omplete the following paragraphs, using the terms supplied in the listing below. +2< -<"1 (some orall may be used)# +it&eti' +n* lo/i' unit8 6+'7in/ stoe8 'ontol unit8

',lin*es8 &e+*s8 inten+l eo,8 4o/+8 se'tos8 t+'7s

(a) 2n order to execute a (A) which is stored on the computer, the computer must readthe instructions from its () into its (C) the (5) then pic* each

instruction in turn, passing any mathematical or logic operations over the (E) until theentire se6uence is completed.

(b) <he data stored on a high density % [ inch dis*ette is arranged in 89 circular (F) formingrings on the surface of the dis* each ring is divided into @8 (G) having [ *bytes each ahard dis* has multiple surfaces. <he corresponding rings on those surfaces are directly above and below each other, -n a hard dis*s, these rings, one above the other, are said to form (H)



(a) 2n order to execute a (A)>o/+ which is stored on the computer, the computer must readthe instructions from its ()6+'7in/ stoe into its (C)Inten+l Meo,. <he (5)'ontol unit then pic*s each instruction in turn, passing any mathematical or logic operations over to the(E)+it&eti' +n* lo/i' unit until the entire se6uence is completed.

(b) <he data stored on a high density % [ inch dis*ette is arranged in 89 circular (F)t+'7s forming rings on the surface of the dis* each ring is divided into @8 (G)se'tos having [ *byte

each. 4 hard dis* has multiple surfaces. <he corresponding rings those surfaces are directlyabove and below each other. -n a hard dis*, these rings, one above the other, are said to form(H)C,lin*es.

Question

(a) ith regard to data storage, what is the difference between a byte and a word3

(b) "xplain the difference between odd parity and even parity.

(c) ith respect to information being read from a hard dis*, what is the purpose of a CU"3

(d) uggest -0" use for which a D>D is more suitable than !D.

(e) <he information contained in -1 (ead -nly 1emory) cannot be changed. hat is the purpose of the -13

Solution

(a) ith regard to data storage, a byte for micro computer represents eight bits used to store orrepresent a single character. 4 word is usually a multiple of bytes. or example bytes (@?bits), bytes (%bits) or 8 bytes (bits).

(b) E?en >+it, 2f a character or number is stored as a pattern of bits that contains an oddnumber of ones, a @ Kthe parity bit) is added to ma*e the number of ones an even number. henthe bit not even, an error is reported and the bit pattern declared corrupt. O** >+it, imilar to "ven 5arity in that if a bit pattern contains an even number of onesthe parity bit ma*es it odd with the same results at the receiving end.

(c) A u--e is an internal memory area used for temporary storage of data read from a hard dis*during data retrieved operation.

(d) -ne use for which a D>D is more suitable than a !D is for storing movies.

(e) <he information contained in -1 (ead -nly 1emory) cannot be changed. <he purpose ofthe -1 is to store instructions and data permanently. -1 is typically used to store things thatwill never change for the life of the computer, such as low level portions of an operating system.

Question !

(a) "xplain briefly what is meant by Gthe resolution of visual display unitI.



(b) hat is i. 5ointtopoint transmission ii. 4 voice response unit iii. 4 bulletin Coard.

Solution

(a) <he resolution of a visual display unit is the number of pixels or dots hori7ontally andvertically on a monitor screen and corresponds to the clarity and sharpness of the image that theunit is able to display. <he denser the array of dots the better the resolution.

(b) i. >ointto>oint t+nsission is communication between two designed stations only.

ii. A oi'e es4onse unit a type of voice synthesis that forms sentences by lin*ing pre recorded words from a database.

iii.A ulletin o+* is a central online community similar to a wall mounted bulletin boardthat, allow uses in computer networ* to exchange information via a centrali7ed message

database.

Question "

<he eightbit representation of the decimal number $ is 999@@99@.(a) hat is the two’s complement representation of 0"/4<2>" $3

(b) hat are the sign and magnitude representations of 0"/4<2>" $3

(c) hat is the decimal e6uivalent of 99@@9@@@3

(d) <he 4!22 representation of ‘&’ is 9@99@999.

hat is the 4!22 representation of ‘D’3

Solution

(a) <he one complement of 999@@99@ is@@@99@@9

<he two’s complement of 999@@99@ is @@@99@@9 E @

@@@99@@@ (b) <he sign and magnitude representation of 0"/4<2>" $3 is#

@999@@99@ (c) <he decimal e6uivalent of 99@@9@@@ is

9 9 @ @ 9 @ @ @

@8 ? % @? 8 @

% E @? E E E @ B $$



(d) DB & R D is \ consecutive spaces to the lift of &S &B 9@99@999 BO DB O B ?8 ?8B 9@999@99

DB 9@999@99

Question #

<he list below contains hardware and software aspects of interface. <hese are hardware aspects#+ist the hardware.

(a) !ommand line (b) <ouch creen (c) 2cons (d) 5ulldown menus (e) tart button (f)tatus bar

Solution

<ouch creen

Question $

(a) &ow can an Gexpert systemI be of value to a doctor3

(b) +ist <- obstacles to be overcome before naturallanguage programming could become part of everyday life.

(c) G obots replace humansI. /ive <- advantages and <- disadvantages of using robots.

(d) uggest <- ways in which a high school student could benefit from using a newsgroup.

Solution

(a) 4n G"xpert system G can be of value to a doctor by assisting the doctor in obtaining asecond opinion on a diagnosis or providing the doctor with additional ideas relating to thesymptoms.

(b) i. Developing of natural language to understand the many dialects of the "nglish+anguage is needed. ii. /etting the computer to GunderstandI the semantic meaning of a phrase or a sentenceand to lin* the concepts in a meaningful way.

(c) 4dvantages.@. educed production time . educed wastage of material due to human error caused by fatigue or

interruptions.

Disadvantages @. &uman labour is placed causing unemployment.

. +ess investment in human labour leading to increased poverty amonguns*illed wor*ers.

(d) i. <o get information needed for research ii. broader perspective on a sub=ect can be gained. iii. haring of *nowledge with others.

Question 9



"xplain what is(a) 2nternet elay !hat(b) 4 synthesi7er (c) >ideotext(d) 4 web browser (e) 4rchiving

Solution

(+) Intenet Rel+, C&+t (2!) is a multi!hannel !hat system that is run on a computer

networ*. 2t gives people all over the world the ability to tal* (type) to each one othe inreal time each user has a nic*name and converses with other users either in private oron a channel (chat room)

(6) S,nt&esie is an electronic musical instrument designed to produce artificiallygenerated sound, using techni6ues such as additive, subtractive, 1, 5hysicalmodeling synthesis, or phrase distortion.

(') i*eoteBt communication service that is lin*ed to an adopted television receiver or a personal computer by telephone lines, cable television facilities, or the li*e. 2t allowsa user to retrieve and display alphanumeric and pictorial information at home.

(*) @e6 6o.se software programs that help one navigate the web and access. <ext,graphics, hyperlin*s, audio, video, and other multimedia. Crowser wor* by

GtranslatingI or GinterpretingI hypertext mar*up language (&<1+) the codeembedded in web pages that tells them how to loo*. Crowsers read this code anddisplay the web page accordingly

(e) A'&i?in/ is a system that allows all email messages passing through a server to besecurely archived or stored, either on the same machine or to a secure off sitelocation. 4rchiving provides the ability to store all message passing through a /1server to a specific archive (or store). <his archive can either be local to the mailserver, or more normally at a secure off site location

Question 1%

(a) hat is the difference between a web page and a website3(b) +ist <&"" responsibilities of a systems analyst.

(c) i. Criefly explain the difference between data integrity and data securityii. -utline -0" method of ensuring the integrity of the data.

Solution

(+)<he difference between a web page and a website is basically about 6uantity. 4 single webdocument (an &<1+ file) is considered a web page. /roups of web pages constitute a website.

(6) i. designing information systems. ii. performing feasibility studies iii. performing system reviews.

(') i. data integrity is the property that data meets a prior expectation of 6uality and accuracyfrom capture the use. Data security, however, is the protection of data from unauthori7ed( accidental or intentional) modification, destruction, or disclosure. ii. -ne method of ensuringthe integrity of the data is to employ parity chec*ing in the encoding and transmission of data.

E?en >+it, 2f a frame contains an odd number of ones, a @ (the parity bit) is added to ma*e the number of ones an even number. hen the frame is received, if the number of

ones is not even, an error is reported and the frame declared corrupt.



O** >+it, similar to even parity in that if a frame contains an even number of ones the parity bit ma*es it odd with the same results at the receiving end.

Question 11

rite an algorithm using pseudocode to do the following se6uence at ts*s#(a) ead in the values of two numbers(b) ind the product of the two numbers(c) ind the sum of the two numbers

(d) !hec* whether the product is bigger than the sum.2f the product is bigger, it must print a message to say so, and if the product is not bigger it must print a message saying that the product is not bigger.

Solution

(a) "4D 0umb@"4D 0umb

(b) 5rod B 0umb @K 0umb

(c) um B 0umb E 0umb

(d) 2f 5rodFum then begin5rint G<he 5roduct is CiggerI

"ndif 2f um B 5rod the begin 5rint G 5roduct is not biggerI"ndif 2f um B 5rod the begin 5rint G 5roduct and sum is e6ualI"ndif.

Question 12rite an algorithm to find the sum of 1 numbers where the user supplies the value of 1 andtypes in the numbers, in response to the prompts generated by the program.

Solution

um B 9ead B 1or counter B @ to 1 do 5rint G"nter 0umberI ead 0umb um B um E 0umb

"ndfor

Question 13

!onsider the following routine# 205U< Q, M L B Q K Q E M K M 520< G <he sum of s6uare isP GLor "4!& of the first two lines of code, write a comment to indicate what the code does.



Solution

+ine @ ead or accepts value that are stored in the variables Q and M+ine 6uare the value in Q and s6uare the value in M and odd the two s6uares and store the

result in L+ine % -utput the phrase G the sum of s6uare is G, followed by the value in L

Question 1

(a) &ow is ob=ect code obtained from source code3(b) Criefly explain the difference between source code and ob=ect code.

Solution

(a) <he -b=ect !ode is obtained from the source code by compilation or interpretation ofthe

source code.

(b) <he ource !ode is the program written (coded) in an high level language by thecomputer

programs.

<he ob=ect code is the machine language version of the source coded that is created by thecompiler or the interpreter.

!ompiler

2nterpreter

Question 1!

!onsider the following code

205U< 4,C D- 4 B 4 E C C B C ' @ +--5 &2+" CF9 520< 4,C.

Using a trace table, or other wise, determine the values printed in the final statement, when theinput value of 4 and C are (a) @, (b) %,

Solution

(a) 4 C 520<"D

@ ,9

% @

9

, 9 is printed.

-U!" !-D" -CN"!< !-D"



(b)

4 C 520<"D

% @% , 9

O %

@9

@ @

@% 9

@%, 9 is printed

Question 1"rite a program in basic, 54!4+ or another specified language (0-< pseudocode) to do thefollowing#

i. 4nnounce (with a printed statement) that it will find the volumes of sets of boxes.

ii. 4s* how many boxes there areiii. or each box, as* for the length, width, and height.iv. !ompute the volume of "4!& box. 2f the values of length, width and height

are all greater than 7ero, then print the volume.v. hen finished with all the boxes, print the message# Golumes have been

foundI.

Solution

5rogram volume (2nput, -utput)P>ar >ol, length, idth, &eight# ealP 0YofYCoxes, counter# 2ntegerPCegin rite2n (G<his program will calculate the volume of a set of boxesI). rite2n (G"nter the number of boxes in the setI)P ead (0YofYCoxes)P or counter# B @ to 0YofYCoxes do begin

rite (G"nter the length of the box#)Pead2n (width)P rite (G"nter the height of the box#)Pead2n (&eight)P >ol# B +ength K idth K &eightP 2f >olF9 then rite2n (G>olume of boxes#, G>ol# $#)P"ndPrite2nPrite2nPrite2n (G>olumes have been foundI)P"nd.

1993 - 2003 cxc_pastpapers with solutions

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