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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 thepossible values)

Discrete data is countable.

ith continuous data given any two different values in an interval it is possible to find a value that fallsbetween 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$9and :$9!.

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Solution

ignal to turn heater up;down ;off

Question

(a) 2dentify any oice band(ii) implex(iii) &alf duplex

(b) (i) what is meant by data integrity3 (ii) tate 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.

!omputerater&eater &eat to digital

converter

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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 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 isrepresented by

@9999@9, what is the representation of /3

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

Solution

(a) / is five ($) spaces to the right of C

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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.

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

INFORMATION TECHNOLOGY THEORY (199)

Question 1

Describe

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-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 a

light 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.

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

Question !

(a) Describe

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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 MICRused by ban*s for reading information on che6ues

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

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

implement a password system to prevent unauthori7ed accessuse 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) bits 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 QB @@@@@

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)

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(a) rite an algorithm to interchange the value in two () variables 4TC.

(b) rite an algorithm to read the names and ages of ten (@9) people and print the name of theoldest

person. 4ssume that there are no persons of the same age. Data is supplied in the following form#name, age, name, age etc.

Solution

(a) ! B 4

4 B CC B !

(b) -+D4/" B 9or = B @to @9 ead 041", 4/" 2f 4/"F -+D4/" then -+D4/" B 4/" -+D5"-0 B 041" "ndif"ndfor

5rint G

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end ifprint 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

,%,$,%,$

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199!

Question 1

(a) +ist

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(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)

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Solution

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

Question !

(a) 2dentify -U measures to secure data.(b) tate

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software 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 familybusiness, he had a choice of ac6uiring software written especially for hisbusiness or general purpose software. &e noted, however, that if he purchasedgeneral purpose software, that he would have to do some modification to allow

it to meet his specific need.

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

(b) tate

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(iii) 4 compiler is a computer program which converts a program in a high levelprogramming language to machine code.

(b)

(b) read 4,C,!

2f ((4BC) and (4B!)) then 5rint G0umbers are e6ualendifif 4FC then

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

14++"

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2f 0U1C" B @9 then

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(a)

$O@9 B @@@99@

(b)

@ @ 9 @ @ @ 9 @

O ? $ % @ 9

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

$O8@ O % @ 9

@99@@@

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(e) ead;rite &ead(f) !U (control Unit)(g) 2nput Device (Heyboard, 1ouse etc.)

Question

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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.

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(b) rite an algorithm to read in "0 numbers, find their average and print it.

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(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

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Question

(4) tate

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(C) i.

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

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@, , ?, ?, @@, 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*esplace. 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

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Solution

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

while 0U1C JF ::: D- if 0U1C B 9

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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 reductionin 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

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Question

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

(C) /ive

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(!) 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 aboutthe 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@9to 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

(!)

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$ : 9@9@ @99@

$:@9B 9@9@ @99@ in C!D representation(D) !onvert ($:) using the twos 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.

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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

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Solution

(4)Q H U1 520alueI 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

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Solution

(a) Siil+it,0-1 and 41 are both memory chips 5i--een'e041 is volatile and -1 is not

(b) Siil+it,02nformation 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,0Data stored on loppy Dis* and &ard Dis* can be accessed without reading any other

data item first(D4D).

5i--een'e0loppy Dis*s are removable, &ard Dis*s cannot be easily moved from place to place.

(d) Siil+it,0

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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 theproblem. seu*o'o*eis a form of representation used to provide an outline description of the

specification for a software module.

Lo/i' eosare errors that occur when the programmer fails to properly thin*through the solution to a program. 4 *,unis the execution of a program forpurposes of chec*ing that the program behaves correctly rather than for producinguseful results.

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Question !

(a) hat is GteleconferencingI(b) tate

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9

@ 9

? 9

% @

@ @

9

::@9B @@999@@

(b)

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

@ 9 @ 9 9 9 9

Con?etin/ 1%1%%%% to *e'i+l -o

@ 9 @ 9 9 9 9

? $ % @ 9

B ?E B ? E @?B 89@9

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

(d)

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

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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

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(a)

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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) LOA5

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(e)

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@.@99@99@@K 99@@99@@

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

B(@K9E @K @E @K E @K OE @K 8)K$@

B(@K8E @KOE @K E @K @E @K 9)K%B ($?E@8E@?EE@)K%

B 9% K %

(b)

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(i)

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@ @

@

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.

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5rint G

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

Solution

(a)

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(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 canbe 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.

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

Question #

(a) 1r. Ns 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.

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(a) /ive two reasons why someone might =oin the newsgroup(b) "xplain the ma=or difference between internet relay chat and electronic mail(c) /ive the meaning of the following abbreviations, and for each case, explain the

purpose#2 &

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(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 individualspersonal information is use for other purpose than that which it was intended without thepersons permission.

(b) @. use of a fire proof cabinet . use of a UC lash Drive; !D Curner;

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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 eachpatron, and for each person, to print out the names and entrance fee.

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ead name ead age ead sex"ndwhile

Question 1

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

Q M L@ %

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(a) +ist

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(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

.

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

(e) +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--eis 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)

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database.

Question "

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(b) +ist

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(*) @e6 6o.sesoftware programs that help one navigate the web and access. +it, 2f a frame contains an odd number of ones, a @ (the parity bit) is added to ma*e thenumber 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 mustprint a message saying that the product is not bigger.

Solution

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

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

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(c) um B 0umb E 0umb

(d) 2f 5rodFum then begin5rint G

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(b)

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iv. !ompute the volume of "4!& box. 2f the values of length, width and heightare all greater than 7ero, then print the volume.

v. hen finished with all the boxes, print the message# Golumes have beenfoundI.

Solution

5rogram volume (2nput, -utput)P>ar >ol, length, idth, &eight# ealP

0YofYCoxes, counter# 2ntegerPCegin rite2n (Golumes have been foundI)P"nd.