as student book answers

8/13/2019 As Student Book Answers

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Student book answers

1.1............................................................................................................................................6End of topic questions..........................................................................................................6

Exam practice questions......................................................................................................6

1.2............................................................................................................................................6

Activities..............................................................................................................................6

End of topic questions..........................................................................................................9

Exam practice questions....................................................................................................10

1.3..........................................................................................................................................11

Activities............................................................................................................................11


1.4..........................................................................................................................................16

Activities............................................................................................................................16

End of topic questions........................................................................................................16


2.1..........................................................................................................................................21


2.5..........................................................................................................................................21


2.6..........................................................................................................................................22

Activities............................................................................................................................22


3.1..........................................................................................................................................23End of topic questions........................................................................................................23


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3.2..........................................................................................................................................24

Activities............................................................................................................................24


4.1..........................................................................................................................................27



4.2..........................................................................................................................................28

End of topic questions........................................................................................................285.1..........................................................................................................................................30

Activities ...........................................................................................................................30

! 0000 1001..........................................................................................................................30

c! 0001 0011..........................................................................................................................30

d! 0001 1100..........................................................................................................................30

e! 0100 1100..........................................................................................................................30

f! 1000 0001...........................................................................................................................30

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! ...........................................................................................................................................30

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c!............................................................................................................................................30a .............................................................................................................................................32

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 1


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"1...........................................................................................................................................32

"2...........................................................................................................................................32


5.2..........................................................................................................................................35

Activities............................................................................................................................35

End of topic questions .......................................................................................................36


5.3..........................................................................................................................................37

End of topic questions .......................................................................................................37


5.4..........................................................................................................................................39

End of topic questions........................................................................................................39Exam practice questions....................................................................................................39

a! #$e samp%in& rate' t$e numer of its avai%a%e to represent eac$ samp%e (samp%in&

reso%ution...............................................................................................................................39

! Editin& out noise)*ron& notes or c$an&in& sounds to &et a specia% affects' sound can e

stored)transmitted di&ita%%+' ..................................................................................................40

c! ,+nt$esisin& sound means creatin& sounds ased on an interna% definition of t$e sounds

to e p%a+ed and not a di&ita% recordin& of t$e actua% sound *aves. #$e pitc$- timre *$ic$

instrument sound! and duration of eac$ required note ma/in& up t$e sound is read from a

fi%e and t$e note- its pitc$- timre and duration &enerated from e%ectronic circuits capa%e of

&eneratin& individua% notes....................................................................................................40

i! Ana%o&ue sound! is converted into di&ita% )) discrete va%ues' ei&$t of ana%o&ue *ave! samp%ed at re&u%ar interva%s'

ei&$t)va%ue represented + a numer)inar+ code)inar+ pattern'...............................40

ii! i&ita%(to(Ana%o&ue converter' ....................................................................................40

! ,ound samp%ed re&u%ar%+- samp%e $ei&$ts measured- $ei&$ts coded in inar+- inar+

va%ues stored .........................................................................................................................40

6.1..........................................................................................................................................40


7.1..........................................................................................................................................41


0.............................................................................................................................................41

1.............................................................................................................................................411.............................................................................................................................................41

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1.............................................................................................................................................410.............................................................................................................................................42

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1.............................................................................................................................................42

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1.............................................................................................................................................42

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1.............................................................................................................................................420.............................................................................................................................................42

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1.............................................................................................................................................42

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1.............................................................................................................................................421.............................................................................................................................................42

0.............................................................................................................................................42

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0.............................................................................................................................................42

0.............................................................................................................................................42

0.............................................................................................................................................42

1.............................................................................................................................................42

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0.............................................................................................................................................42

1.............................................................................................................................................42

1.............................................................................................................................................42



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1.............................................................................................................................................42

0.............................................................................................................................................42


7.2..........................................................................................................................................49


7.3..........................................................................................................................................53



8.1..........................................................................................................................................58


opies of a printed invoice or receipt are required at t$e time of printin&. #$is can e

ac$ieved + usin& mu%ti(part stationar+ in t$e printer and caronised paper........................59

or securit+ reasons- e.&. distriution of numers requires t$at printin& of a pin ta/es

p%ace *$i%st t$e paper is inside a sea%ed enve%ope. #$is is possi%e + usin& caronisedsea%ed enve%opes containin& a sin&%e s$eet of paper..............................................................60

a! A trac/ is one of t$e concentric rin&s on a surface of a ma&netic dis/ p%atter................60

! A sector is a sudivision of a trac/.................................................................................60

c! A dis/ %oc/ is t$e sma%%est unit of transfer et*een a computer and a dis/..................60

d! A %oc/ address comprises a surface address- a trac/ address and a sector address. Eac$

surface- trac/ on a surface and sector on a trac/ is numered sequentia%%+ startin& at ero..60

ata is *ritten to a (: disc usin& disc(masterin& mac$iner+ t$at impresses pits into a

continuous spira% trac/ across t$e surface of a ref%ective meta% %a+er. A pit encodes inar+

it 0 and t$e asence of a pit encodes inar+ it 1. A data it is read + focusin& a %aser

eam onto a point in t$e ref%ective meta% %a+er *$ere t$e pits are impressed. :ore %i&$t is

ref%ected from t$e meta% surface at points on t$e spira% trac/ *$ic$ are not pitted t$an frompoints *$ic$ are. #$e intensit+ of ref%ection is detected and converted into an e%ectrica%

equiva%ent *$ic$ is t$en di&itised so t$at it can e stored and processed + computer........60

a! (; A *rite once- read man+ time optica% disc ompact isc! capa%e of recordin&

aout 600(700 : A *rite and read man+ times optica% disc ompact isc! capa%e of

recordin& aout 600(700 :


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! E(mai% c%ients use t$e ost ffice rotoco% version 3 3!- an app%ication(%a+er

protoco%- to retrieve e(mai% from an e(mai% ox on a remote mai% server over a #)

connection. #$e server $o%ds incomin& mai% unti% t$e user connects and requests t$e mai%

usin& 3............................................................................................................................67

d! #e%net is a usefu% text(ased protoco% t$at can e used to;...............................................67

A te%net c%ient connects to port 23 of a te%net server on t$e remote mac$ine a%%o*in& t$e

c%ient to mana&e t$e remote mac$ine- i.e. to create fi%es or fo%ders- to de%ete fi%es or fo%ders-

to open fi%es for vie*in&- etc.- as if t$e remote mac$ine *as t$e user@s o*n %oca% mac$ine.

...............................................................................................................................................68

e! +pertext #ransfer rotoco% over ,ecure ,oc/et a+er ## over ,, or ##,! is a

=e protoco% deve%oped + etscape t$at encr+pts and decr+pts user pa&e requests as *e%%

as t$e pa&es t$at are returned + t$e =e server. ##, uses a ,ecure ,oc/et a+er ,,!

eneat$ t$e ## app%ication %a+er. ##, uses port 443 instead of ## port 80 in its

interactions *it$ #). ##, is *ide%+ used on t$e =e for securit+(sensitivecommunication- suc$ as pa+ment transactions and corporate %o&ons....................................68


9.2..........................................................................................................................................70



10.1........................................................................................................................................73



AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 !


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1.1

End of topic questions

ComputationQ1 omputation is t$e act or process of ca%cu%atin& or determinin& somet$in& + mat$ematica%- %o&ica%

or interactive met$ods.

Q2 Bomputin& is no more aout computers t$an astronom+ is aout te%escopes.C

Q3 omputai%it+ refers to *$at can and cannot e computed.

Q4 omputin& is t$e stud+ of natura% and artificia% information processes.

Q5 Artificia% nte%%i&ence is a ranc$ of computin& t$at studies t$e use of computers to perform.

computationa% processes norma%%+ associated *it$ t$e $uman inte%%ect.

Programming, abstraction and automationQ6 An a%&orit$m is a description- independent of an+ computer pro&rammin& %an&ua&e- of a process

for ac$ievin& some tas/. t is a step(+(step procedure for so%vin& a pro%em.

Q7 #$e purpose of an a%&orit$m is to communicate a computation to $umans not to computers.

Q8 #$e+ are not t$e same t$in&. An a%&orit$m is meant to e independent of an+ pro&rammin&

%an&ua&e and is aimed at descriin& to a $uman not a mac$ine $o* to so%ve a pro%em.

Q9o.

Q10

a) Astraction > $o* to communicate comp%ex ideas simp%+ and $o* to decompose pro%ems

%o&ica%%+.

ii) Automation > $o* to automate an a%&orit$m.

Exam practice questions

Q1 1

i! #$e stud+ of natura% and artificia% information processes.

ii! #$e act or process of ca%cu%atin& or determinin& somet$in& + mat$ematica%- %o&ica% or

interactive met$ods.

iii!A measure of *$at can and cannot e computed.

1.2

Activities

Page 9 - Define the boundaries#a/e t$e midd%e fi%%ed &%ass and pour its contents into t$e midd%e empt+ &%ass

Assumption; #$e contents of t$e &%asses $ad to remain unc$an&ed or t$at t$e &%asses cou%d

on%+ e rearran&ed.

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 "


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:essa&e; +ou need to ta/e time to c%arif+ t$e ru%es)constraints)oundaries.

Page 10 - atera! thin"ing pu##!esomeo and Du%iet are &o%dfis$. #$e+ died *$en t$eir o*% fe%% to t$e f%oor and s$attered

%eavin& a trai% of ro/en &%ass and *ater.

#$e man is a d*arf and is una%e to reac$ t$e %ift utton for t$e ei&$teent$ f%oor *$en

ascendin& t$e %ift. f course- if it $as een rainin& in t$e mornin& t$e man *i%% $ave $is

umre%%a *it$ $im *$ic$ $e uses to press t$e %ift utton to t$e ei&$teent$ f%oor.

Page 11 - $nterpreting a hierarch% chart

=2# 9

=ac $

=2# ac 1

=2%# ac& 1

= = 2# %# ac& 3 1 or 2

= 2# %# ac&

2a 2or

= 2 22

or 1

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 '


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Page 11 - &odu!e chart

Page 1' - (tep)ise refinement0 Calculate Sum and Average of two Numbers

0.1 Get two numbers

0.1.1 Read(No1)

0.1.1 Read(No2)

0.2 Sum two numbers

0.2.1 Sum (No1 + No2

0. !"nd Average

0..1 Average (Sum # 2

0.$ %"s&la' Sum

0.$.1 r"te()Sum )* Sum)

0. %"s&la' Average

0..1 r"te()Average )* Average)

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 $

Stages o*+ro#lemSolving

,nderstandingthe +ro#lem

-e*ining the+ro#lem

-e*ining.oundaries

+lanning aSolution

Carr/ing out a+lan o* Action

Topdon-esign

Stepisee*inement


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Page 1* - +ierarch% chart for triang!e prob!em


nderstanding the prob!emQ1 Apro%emis a &iven *$ere it is not immediate%+ ovious $o* to reac$ t$e &oa%.

Q2 ro%em so%vin& invo%ves movin& from an initia% state- t$e &iven-to a desired state- t$e &oa%- usin&

a set of resources- possi%+ constrained- to $e%p reac$ t$e &oa%.

Q3 nderstandin& a pro%em means turnin& an i%%(defined pro%em into a *e%%(defined pro%em stated

c%ear%+ and unami&uous%+.

Defining the prob!emQ4

iv!Fivens

v! esources and constraints

vi!Foa%

vii!*ners$ip

Q5 *ners$ip is not made c%ear.

Q6 #$ese are ru%es- re&u%ations and &uide%ines for *$at +ou are a%%o*ed to do in so%vin& a particu%ar

pro%em.

Q7 t ena%es a pro%em definition to e made c%earer + esta%is$in& t$e facts and ru%es and definin&

t$e oundaries of pro%em so%vin&!.


Calculate/potenuse

4et #5 cCalculate S6rt

%#27 c2&8utput

/potenuse

Calculate #2 Calculate c2


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Defining boundariesQ8 efinin& oundaries to a pro%em means esta%is$in& t$e %imits or ru%es aout *$at can and cannot

e done. #$ese %imits are a t+pe of constraint.

Q9 #ime- avai%a%e equipment and soft*are resource(t+pe constraints!.

Q10 atera% t$in/in& a%%o*s an i%%(defined pro%em to e transformed into a *e%%(defined pro%em.

atera% t$in/in& can e used to c$a%%en&e assumptions- esta%is$ facts and ru%es and define t$e

oundaries of pro%em so%vin&.

Q11 atera% t$in/in& is used;

viii! #o add facts to t$ose started *it$ + as/in& questions.

ix! #o separate *$at is esta%is$ed from *$at $asn@t een esta%is$ed ut $as unconscious%+ een

assumed. ne *a+ to do t$is is + c%osin& +our e+es and picturin& t$e scene descried. #$en

focusin& on a%% t$e detai%s of t$is picture *$ic$ *ere not actua%%+ &iven ecause t$ese are a%%

assumptions.

x! #o ma/e ne* proposed facts from matc$in& to&et$er ot$er facts.

P!anning a so!utionQ12

xi! =$at strate&ies *i%% +ou app%+G

xii!=$at resources *i%% +ou useG

xiii! o* *i%% +ou use t$e resourcesG

xiv! n *$at order *i%% +ou use t$e resourcesG

xv!Are +our resources adequate for t$e tas/G

Q13 A moduleis a se%f(contained entit+ t$at resu%ts *$en a pro%em is divided into su(pro%ems'

eac$ modu%e corresponds to a su(pro%em.

Q14

xvi! #op(do*n desi&nmeans rea/in& a pro%em do*n into sma%%er pro%ems ca%%ed su(

pro%ems *$ic$ are easier to *or/ on.

xvii! Stepwise refinementis t$e process of rea/in& a pro%em do*n t$rou&$ successive

steps into sma%%er pro%ems.

Q15 A structure tableis an indented- numered %ist of steps produced + t$e process of step*ise

refinement.

Q16

Level 0 Travel *rom London to anchester

Level 1

1: ;oin 1 at ;1

2: Sitch *rom 1 at ;19 onto the " in direction o* .irmingham

3: Leave " at

?8n an/ topic@ means that the initial state is not clearl/ de*ined: hat are the topicsBThese are not clearl/ de*ined:



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?Compose poetr/@ is too vague a goal state: o ill the s/stem no that it hascreated poetr/B

hat are the rulesDguidelines governing the poetr/ creation process: Can the/ #especi*iedB hat length should each poem have5 *or eEampleB Ft ill #e ver/ di**icult tospeci*/ these rules:

-oes this student have su**icient noledge and sill to create such a s/stemB Theanser is liel/ to #e no:

1.3

Activities

Page 1 . (tates of a !iftift at &round f%oor and &round f%oor doors c%osin&

ift at &round f%oor and &round f%oor doors c%osed

ift at &round f%oor and &round f%oor doors openin&

ift at &round f%oor and &round f%oor doors open

ift at first f%oor and first f%oor doors c%osin&

ift at first f%oor and first f%oor doors c%osed

ift at first f%oor and first f%oor doors openin&

ift at first f%oor and first f%oor doors open

ift at second f%oor and second f%oor doors c%osin&

ift at second f%oor and second f%oor doors c%osed

ift at second f%oor and second f%oor doors openin&

ift at second f%oor and second f%oor doors open

ift trave%%in& up et*een &round and first f%oor

ift trave%%in& up et*een first and second f%oor

ift trave%%in& do*n et*een second and first f%oor

ift trave%%in& do*n et*een first and &round f%oor

ift stuc/ et*een &round f%oor and first f%oor

ift stuc/ et*een first and second f%oor

Page 1 . ift inputs and outputs


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1 2 ules or condition options!

" means "es# $ means false

$o

onditions H I 6 J J J J

J K 7 J J J J

L M 3 J J J J

Actions utput

NassN

% % % % %

utput

Nai%N

% % %


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inite state machinesQ1 ero or more @s

or

an even numer of a@s

or

ero or more @s fo%%o*ed + an even numer of a@s fo%%o*ed + ero or more @s

or

ero or more @s fo%%o*ed + an odd numer of a@s fo%%o*ed + one or more @s fo%%o*ed + an

odd numer of a@s fo%%o*ed + ero or more @s.

Q2 omination %oc/ state transition dia&ram;


Loced Girst-igit

Second -igit

,nloced

An/thing #ut 9

An/thing #ut !

9 ! "

An/thing #ut "


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omination %oc/ state transition ta%e;

2 &nput 3 'urrent State 4 $e(t state

9 oc/ed irst i&it

An+t$in& ut 9 oc/ed oc/ed

5 irst i&it ,econd i&it

An+t$in& ut 5 irst i&it irst i&it

6 ,econd i&it n%oc/ed

An+t$in& ut 6 ,econd i&it ,econd i&it

Q3 ,tate transition dia&ram;

Q4 ecision ta%e;

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 1!

3 4 ule or condition

options! " means "es#

$ means $o

onditions H I 6 J J

J K 7 J J

Actions utput OassO % % %

utput Oai%O %

S0

S1

Start

05 0

15 null

05 0050

S2

S3

15 null 15 1

05 0

15 0


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1i. A


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Q3 An a%&orit$m descries $o* to so%ve some pro%em ut an ans*er cannot e produced

automatica%%+ from t$e a%&orit$m a%one- it can e manua%%+ t$ou&$. o*ever- some a%&orit$ms

*ou%d ta/e far too %on& to execute manua%%+ + a $uman. #$erefore- an a%&orit$m needs to e

expressed as a computer pro&ram and t$e computer pro&ram executed automatica%%+ to otain aresu%t.

Q4

b) P fi%% saucepan *it$ *ater from co%d tap

ii)+lace egg in saucepan

iii)+lace saucepan on ho#

iv)eat ater to #oiling point

v)educe heat to simmering

vi)Start cloc

vii)Sitch o** heat a*ter to minutes

viii)emove egg *rom saucepan

P!anning an a!gorithmQ5

i! ,equence > consecutive steps or &roups of steps processed one after anot$er in t$e order t$at

t$e+ arise.

ii! ,e%ection > a decision(ma/in& step.

iii!epetition or iteration > a step or sequence of steps t$at are repeated unti% some condition is

satisfied or *$i%e some condition is satisfied.Q6

iv! emove *$ee% *it$ f%at t+re from ic+c%e

v! emove inner tue from *$ee%

vi! ind puncture

vii!atc$ puncture

viii! it inner tue ac/ onto *$ee%

ix! nf%ate t+re

x! it *$ee% ac/ onto ic+c%e

,tep 1 refinement

1.1 ,%ac/en *$ee% nuts unti% *$ee% %oose

1.2 ,%ac/en ra/e ca%iper

1.3 emove *$ee%

,tep 2 refinement

2.1 App%+ first t+re %ever to t+re and %oc/ to a spo/e

2.2 App%+ second t+re %ever and ease t+re over rim a%% *a+ round

2.3 emove inner tue

,tep 2.3 refinement

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 1'


18/76

2.3.1 emove rin& nut from inner tue adapter

2.3.2 us$)pu%% adapter t$rou&$ $o%e for adapter in rim unti% it

no %on&er proQects out t$rou&$ rim

2.3.3 emove inner tue

,tep 3 refinement

3.1 ump some air into inner tue

3.2 %ace inner tue in o*% of *ater

3.3 oo/ for escapin& air

,tep 4 refinement

4.1 Arade ruer in area around puncture

4.2 App%+ a %a+er of ruer so%ution t$e sie of t$e patc$ around

puncture area

4.3 ress patc$ firm%+ onto area around puncture

,teps 5 and 7 are refined as *e%% to e t$e reverse of 2 and 1 respective%+

Q71. epeat nti% a%% c$airs stac/ed

,tep 1 refined

1.1 epeat nti% no more c$airs

1.2 f next c$air stac/ K 6

#$en stac/ c$air

1.3 f next c$air stac/ M 6 #$en p%ace c$air on ne* stac/

Computer-base prob!em so!vingQ8

xi! dentif+ t$e pro%em inputs

xii!dentif+ t$e pro%em outputs

xiii! etermine t$e varia%es

xiv! erive t$e a%&orit$m t$at transforms inputs into outputs

Q9 Assi&nmentis an operation t$at assi&ns a va%ue to a varia%e

Q10 .

ro%em inputs; #$ree numers

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 1$


19/76

ro%em utput; ar&est numer

ro%em varia%es; x- +- - ar&est

A%&orit$m;

Input x, y, z

Largest x

If y > Largest

Then Largest y

If z > Largest

Then Largest z

Output Largest

Expressing a!gorithmsQ11

n esult

0

2 2

6 8

34 42

12 54

0 54

Q12

xv!,tructured En&%is$

nput - c

a%cu%ate ,quare root of squared p%us c squared

utput resu%t

xvi! seudocode

nput - c

a R ,qrtS T cSc!

utput a



20/76

Q13


5

i! ,e%ection- sequence

ii! ,tructured En&%is$ is a ver+ %imited- $i&$%+ restricted suset of t$e En&%is$ %an&ua&e.

seudocode is simi%ar to rea% pro&rammin& code ut it is not rea% pro&rammin& code.iii!

( + esult utput

0 0

3 1 3

7 2 10

6 3 16

8 4 24 6.0

6 (t+pe pro%em


Loop

No

Hesn I 0

Result , Result + n

Result , 0

4=T n

+ut esult


21/76

7 o

2.1


ariab!esQ1 %a+er1#ota%oints

Q2ext%a+erumer

Q3umerforrectAns*ers

Q4 #ota%umerf"uestions

Q5umerf"uestions#ried

Assignment statementQ1umerf=ron&Ans*ers ;M umerf"uestions#ried ( umerforrectAns*ers

Q2 ercenta&eorrect ;M umerforrectAn*ers ) umerf"uestions#ried S 100

Q3 ercenta&e#ried ;M umerf"uestions#ried ) #ota%umerf"uestions S 100

Q4umerf5oundotes ;M Amount ? 5

2.5


Q1 Advanta&es of named constants; easier to understand pro&ram code- easier to c$an&e if t$e va%ue

c$an&es.

Q2 i) =$+ are procedures used; to &ive a set of statements a name- to avoid repeatin& code as t$e

same procedure can e ca%%ed man+ times from different parts of t$e pro&ram.

ii)+arameters are used to pass data ithin programs in and out o* procedures or*unctions:

Q3 i)F%oa% varia%es in t$e &iven code are; ame- ours- atefa+.

#$e %oca% varia%e in t$e &iven code is; #ota%.

ii)+rocedures and *unctions are sel*contained i* the/ do not use an/ glo#al varia#les:The/ onl/ use local varia#les and parameters:

iii) ro&ram u&s ma+ e introduced + usin& &%oa% varia%es ecause %oca% and &%oa% varia%es

*it$ t$e same name cou%d e misidentified and as a side(effect of executin& a procedure a

&%oa% varia%e cou%d c$an&e its va%ue.



22/76

2.6

Activities

Page 21 . Distance arra%Q1

a: -istance #eteen 8E*ord and anchester are held in -istanceJ152K and alsoin -istance J251K

#: -istance #eteen anchester and London are held in -istanceJ051K andalso in -istance J150K

Q2

a: -istance #eteen 8E*ord and anchester

#: -istance #eteen anchester and 8E*ord

c: -istanceJ05K is out o* #ounds

d: -istanceJ050K re*ers to distance #eteen London and London5 so notrelevant

Page 2' . (tudent arra%Q1 ,tudentU5V.ame contains


23/76

#: F* e


24/76

3.2

Activities

Page 9* . 3ubb!e sortQ1

vii! 78 is in its fina% p%ace after t$e first pass.

viii! 56 is in its fina% p%ace after t$e second pass.

Q2

ix! 98 is in its fina% p%ace after t$e first pass.x! 78 is in its fina% p%ace after t$e second pass.


inear (earchQ1

a)#race ta%e;

.lementSou*/t ound /is.lement

arr+ 1 a%se

2

3

4

5 #rue

b)#race ta%e;

.lementSou*/t ound /is.lement

Doe 1 a%se

2

3

4

5

6

7

8



25/76

9

ThisElement is no* &reater t$an t$e maximum numer of arra+ e%ements and t$e a%&orit$m stops*it$out findin& Doe.

$ooreSwaps .lement 1 2 3 4 5 6 7

#rue 96 59 74 32 27 64 23

a%se 1 59 96

2 74 96

3 32 96

4 27 96

5 64 96

6 23 96

#rue

1

a%se 2 32 74

3 27 74

4 64 74

5 23 74

#rue

a%se 1 32 59

2 27 59

3

4 23 64

#rue

a%se 1 27 32

2

3 23 59

#rue

1

a%se 2 23 32

3

4

5

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 2!


26/76

6

#rue

a%se 1 23 27

#rue

Q2

Function Search (List: array Of String; Max: Integer;

ElementSought: String): Integer;

Var

ThisElement : Integer;

Found : Boolean;

Begin

ThisElement := 1;

Found := False; Repeat

If List[ThisElement] = ElementSought

Then Found := True

Else ThisElement := ThisElement + 1;

Until (Found = True) Or (ThisElement > Max);

If Found

Then Result := ThisElement

Else Result := -1;

End;

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 2"


27/76

Ei&

,tr emp

istU1V U2V U3V U4V U5V U6V U7V U8V U9V U10V

43 25 37 81 18 70 64 96 52 4

1 43 25 43

2 43 37 43

3

4 81 18 81

5 81 70 81

6 81 64 81

7

8 96 52 96

9 96 4 96

10

xii! Control *i%% pass to t$e instruction after Endwhile

xiii! List[1]*i%% e 25

List[9]*i%% e 81

List[10]*i%% e 96

4.1


a!idation chec"sQ1 ?a%idation c$ec/ for date of irt$ in a Qo app%ication; ran&e c$ec/.

Q2 ?a%idation c$ec/ for a an/ account numer; c$ec/ di&it.

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 2'


28/76

Exam practice questionsQ1 ouse;presence c$ec/ ecause a va%ue in t$is fie%d is compu%sor+

ostode;ormat c$ec/ ecause t$e fie%d $as a specific pattern of c$aracters

atef


29/76

Exam Practice Questions

Q1 a

+ ( &nde( esult

3 2 1

( 5 0 ( ( (

1 2 1 ( ( 1

0 1 2 0

1 0 3 1

bonverts an inte&er into its inar+ equiva%ent

Q2 a

( + esult

5 3 1

5 2 5

5 1 25

5 0 125

ba%cu%ates x+

Q3 a

$ew ast ,tr alues

1 2 3 4 5

6 3 1 4 7 9

2

2 9

1 7

6



30/76

! nserts a va%ue into t$e arra+ at t$e correct position so t$e arra+ remains a sorted %ist!

5.1

Activities

3inar% to decima!a) inar+ 0100 is denar+ 4.

b) inar+ 0101 is denar+ 5.

c) inar+ 1010 is denar+ 10.

d) inar+ 01000010 is denar+ 66.e) inar+ 01011001 is denar+ 89.

Denar% to binar%Q1 enar+ 227 is inar+ 11100011.

Q2

)a 0000 0011.

b)0000 1001.

c)0001 0011.

d)0001 1100.

e)0100 1100.

f)1000 0001.

3inar% additionQ1 a)

0101 in denar+; 5

T 0010 T 2

0111 7

b)

01101010 106

T 01000011 T 67

10101101 173

c)

01010101 85T 01111110 T 126



31/76

11010011 211

Q2 01010111

T 10101001

100000000

#$is causes overf%o*- an extra it *ou%d e required to store t$e resu%t.

3inar% mu!tip!ication - chec" the ru!es101 mu%tip%ied + 2; 1010

n denar+; 5 x 2 M 10

110 mu%tip%ied + 2; 1100

n denar+; 6 x 2 M 12

1001 mu%tip%ied + 2; 10010

n denar+ 9 x 2 M 18

10101 mu%tip%ied + 2; 101010

n denar+ 21 x 2 M 42

1100 mu%tip%ied + 2; 11000n denar+ 12 x 2 M 24

1000 mu%tip%ied + 2; 10000

n denar+ 8 x 2 M 16



32/76

3inar% mu!tip!ication

a

0101 5

x 0010 x 2

01010 10

b

01001010 74

x 00000011 x 3

10010100 210

T 01001010 T 12

11011110 222

c

01000001 65

x 00000110 x 6

100000100 360

T 010000010 T 30

110000110 390

3inar% subtraction

Q1

00011001 in denar+; 25

11100111 ( 25

00011100 28

1!00000011 3

Q2

00010111 in denar+; 23

11101001 ( 23

01111011 123

1!01100100 100



33/76

Page 105 . Denar% to t)o6s comp!ementa) 11111011

b) 11110110

c) 11101100

d) 00000101

Page 102 . 4)o6s comp!ement to denar%a) (86

b) (127

c) (1

d) 23

3inar% to denar% and hexadecima!

1 a)0110 1101 is denar+ 109b) 6 in $exadecima%

2 1111 1110 1110 1101 1101 1010 1101

E E A

Page 10/ . Denar% to binar% and hexadecima!126 01111110 in inar+- and 7E in $exadecima%


3inar% numbersQ1

a! 11111111 M denar+ 255 M28 (1

! 11111111 11111111 M denar+ 65-535 M 216 (1

c! 11111111 11111111 11111111 11111111 M 429-4967-295 M denar+ 232 (1

d! 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111

M denar+ 264 (1

Q2 8

Q3 0 or 1

Q4 00010100 20 T 00001010 T 10

00011110 30

Q5 0101 5

x 0110 x 6

010100 30

001010

011110



34/76

7egative numbers

Q6 (128

Q7 00001001 in denar+; 9

11110111 ( 9

00001011 11

1!00000010 2

Q8 00010001 in denar+; 17

11101111 ( 17

00001111 15

11111110 (2

Q9 01100000 in denar+; 96 00101000 in denar+; 40

10111111 (96 11011000 (40

10111111 ( 96

11011000 ( 40

1!10010111 ( 136 overf%o*X

+exadecima! numbersQ10


35/76

i! 000000000101.1000 is denar+ 5.5

ii! 000000000011.0010 is denar+ 3.125

Q14

i! %ar&est positive numer; 011111111111.1111

ii! sma%%est positive numer; 000000000000.0001

Q15

ar&est positive numer; 0111.1111 M denar+ 7.9375.

ifference et*een t*o consecutive va%ues is 0.0625.

recision can e improved + usin& more its after t$e inar+ point- ut t$en t$e ran&e of numers

is reduced for a &iven numer of its.


Q1 95; 01011111(73; 10110111

22 1!00010110

53; 00110101

(75 10110101

53 00110101

T75 01001011

128 10000000 verf%o*. #$is represents (128

Q2a! enar+ 1032 is inar+ 0000 0100 0000 1000

! n $exadecima%; 0 4 0 8

Q3

a! enar+ 1026.75 is inar+ 010000000010.1100

! n $exadecima%; 4 0 2

Q4


36/76

Q2 7 its &ive 127 different patterns

ut 6 its *ou%d on%+ &ive 63 patterns- so not enou&$!.

Parit%Q1

a! 00100001

! 01010011

c! 11000011

d! 11001001

Q2 c! e! and &! contain an error since t$eir numer of 1(its is even

Parit% bit errorf on%+ one parit+ it is different to *$at it s$ou%d e- t$e error *as in t$e parit+ it- and

t$erefore t$e data its are correct. #$e parit+ its are a%% stripped out an+*a+.


A(C$$Q1 A, code for t$e c$aracter Y5@ is 53.

Q2 ,torin& t$e c$aracters Y35@ in a 2(+te *ord; 00110011 00110101

Q3 ,torin& t$e inte&er 35 in a 2(+te *ord; 00000000 00100011

Q4 #$e numeric difference et*een a di&it and its pure inar+ equiva%ent is 48.

nicodeQ5 65-535 different c$aracters can e coded usin& 16 its.

Q6 nicode for Z is 00AE in $exadecima%.

nicode for [ is 221E in $exadecima%.

nicode for \ is 20A in $exadecima%.

Q7 nicode for A is 0041 in $exadecima%- *$ic$ is 65 in decima% t$e same as A, codeX!.

Error chec"ing and correctionQ8 f one it did not &et transmitted correct%+.

Q9 After transmission t$e parit+ is ca%cu%ated + addin& a%% t$e 1(its. f t$e parit+ is no* different- an

error must $ave occurred.

Q10 ammin& code can detect a sin&%e error in a *ord and correct it.Q11 t provides a &ood a%ance et*een error correction and error detection.

Q12 A Fra+ code counter to&&%es on%+ one it at a time- *$ereas a pure inar+ counter ma+ to&&%e

mu%tip%e its.

Q13 Fra+ code counters use $a%f t$e e%ectrica% po*er of an equiva%ent inar+ counter.


Q1

a) 7(it inar+ A, code for Y


37/76

Q2

a!

i! 7(it A, code for Y?@ is 1010110

ii! 11010110

!

i! Y@

ii! YD@

Q3

i! 4

ii! nicode

Q4

i! #$e numer of 1(its inc%udin& t$e parit+ it compute to an even numer.

ii! #$e tota% numer of 1@s is ca%cu%ated efore transmission. A 0 or a 1 is added to t$e 7(it code

so t$at t$e tota% numer of 1(its computer to an even numer. #$e numer of 1(its is re(

ca%cu%ated after t$e +te is received. An odd numer of 1(its indicates an error.Q5 00110011 10110111

#$e parit+ it is set *$en t$e c$aracter is first &enerated. #$e parit+ it is adQusted to ma/e t$e

numer of 1(its even. #$e numer of 1(its is re(ca%cu%ated + t$e receiver. f t$e parit+ is no*

odd- an error $as occurred.

Q6 #$e parit+ it is set *$en t$e c$aracter is first &enerated. #$e parit+ it is adQusted to ma/e t$e

numer of 1(its even. #$e numer of 1(its is re(ca%cu%ated + t$e receiver. f t$e parit+ is no*

odd- an error $as occurred.

Q7

i! 53

ii! 00110010 00110101

ote; no reference to parit+ *as made in t$is question.

5.3


3itmap raphicsQ1 A pixe% is t$e sma%%est addressa%e area or sma%%est so%id %oc/ of co%our of an ima&e.

Q2 A itmap is created *$en t$e pixe%s of an ima&e are mapped to positions in memor+ t$at storeinar+ codes representin& t$e co%our of eac$ pixe%.

Q3 #$e reso%ution of a ? screen; a quantit+ expressed as t$e numer of pixe%s per ro* + t$e

numer of pixe%s per co%umn. #$e reso%ution of an ima&e; a quantit+ expressed as t$e numer of

dots)pixe%s per inc$ or centimetre.

Q4 o%our dept$ descries t$e numer of its used to represent t$e co%our of a sin&%e pixe% in a

itmapped ima&e.

Q5 i%e sie M 1024 x 768 x 3 +tes M 23556096 +tes M 23556096)1024 ]< M 23004 ]


38/76

Q7 n vector &rap$ics representation on%+ data for eac$ &eometric e%ement *i%% e stored *$i%st a

itmap stores data for ever+ pixe%. #$ere are man+ more pixe%s t$an &eometric e%ements in a &eometric

dia&ram.

Q8 A dra*in& %ist is t$e %ist of dra*in& commands t$at recreate a vector &rap$ic.

Q9 ,ie- direction- t$ic/ness- s$adin&- font sie- t+peface.

Q10 =$en a itmap is sca%ed- t$e pixe%s en%ar&e. As t$e ma&nification increases- t$e pixe%s can

ecome visi%e- %eadin& to a staircase effect. ?ector &rap$ics avoid suc$ distortion *$en ma&nified

ecause sca%in& is app%ied to a %ineNs endpoints ta/in& into account t$e c$an&e in %ine t$ic/ness in a *a+

t$at avoids creatin& a staircase effect. #$e sca%in& is &eometric ecause vector &rap$ics dea% *it$

oQects not pixe%s. ?ector &rap$ics are defined + t$e re%ative positions of oQects in a t$ree(

dimensiona% or t*o(dimensiona% coordinate s+stem. f +ou increase t$e sie of t$e coordinate s+stem-

t$e dra*in& increases in sie. Jou do not %ose reso%ution *$en +ou en%ar&e a true vector dra*in&

ecause it $as no intrinsic reso%ution.

3asic compression techniquesQ11 ata compression squeees data into a sma%%er numer of +tes t$an t$e data *ou%d occup+ if

uncompressed.

Q12 un(%en&t$ encodin& E! is a simp%e compression tec$nique t$at ta/es account of t$e fact t$at

some ima&es $ave %on& runs of pixe%s of t$e same co%our. Essentia%%+- consecutive memor+ ce%%s of t$e

itmap are compared. f t$ree or more consecutive ce%%s contain t$e same it pattern- t$en a run of ce%%s

$as een found t$at can e encoded in t*o +tes. #$e first +te stores t$e numer of identica%

consecutive conti&uous! memor+ ce%% +tes and t$e second +te stores t$e co%our code.

Q13 oss+ compression met$ods discard information *$ic$ is not considered important- e.&.

ac/&round scener+ is saved *it$ reduced reso%ution. ecompressin& an ima&e compressed *it$ a

%oss+ compression met$od resu%ts in an uncompressed ima&e t$at is different from t$e ori&ina% ut is

c%ose enou&$ to e usefu%. ecompressin& a un(en&t$(Encoded(compressed ima&e produces t$eori&ina% uncompressed ima&e exact%+- i.e. *it$out %oss.

Q14 #$e $uman e+e is &ood at seein& sma%% differences in ri&$tness over a re%ative%+ %ar&e area

&radua% c$an&es in pixe% ri&$tness va%ues t$at occur over man+ pixe%s!- ut not so &ood at

distin&uis$in& t$e exact stren&t$ of a $i&$(frequenc+ ri&$tness variation drastic c$an&es in pixe%

ri&$tness va%ues t$at occur over a narro* ran&e of pixe%!. #$is ma/es it possi%e to &et a*a+ *it$

&reat%+ reducin& t$e amount of information in t$e $i&$(frequenc+ components. t is a%so possi%e to

exp%oit t$e sensitivit+ of t$e e+e + reducin& t$e numer of its per pixe% for pixe%s t$at t$e e+e is %east

sensitive to.


Q1

a)icture ro/en do*n into pixe%s eac$ pixe% represented + 1 it

0 for %ac/- 1 for *$ite (or vice versa)

b)eed one +te to represent 1 pixe%

Q2

a)

i! ine t$ic/ness ) st+%e- %ine co%our- %ae% text!- oQect name- co(ordinates'

ii! ae% text! ) co(ordinates ) etc ( if not used for a!i! ( fi%% co%our ) st+%e- *idt$- $ei&$t

iii! ?ector &rap$ics stores properties of oQects )) vector &rap$ics use mat$ematica%

equations)formu%ae


39/76

iv! 4

v! Eac$ +te can represent 256 different numers)it patterns)cominations- eac$ numer

represents a different co%our- 2^8M256 and 8 its M 1 +te

vi! 1024 x 768 div 1024 ]< )) 768 ]

pa%ette data

5.4


(ound and DataQ1

)a :icrop$one.)b ne minute M 60 seconds

40 000 samp%es ta/en per second

#ota% numer of samp%es ta/en M 60 x 40 000 M 2400 000

Eac$ samp%e coded in 16 its or t*o +tes

#ota% numer of +tes M 2 x 2400 000 M 4800 000.

Q2 Ana%o&ue data is data t$at varies in a continuous manner- e.&. speec$.

i&ita% data is data t$at ta/es t$e form of discrete va%ues- e.&. temperature readin&s ta/en ever+ $our.

Q3 An ana%o&ue si&na% is an e%ectrica% or e%ectroma&netic si&na% t$at varies in a continuous manner

*$ereas ana%o&ue data is a non(e%ectrica% continuous%+ var+in& si&na%.

Q4 i&ita% to Ana%o&ue onverter or A.

&anaging and &anipu!ating (oundQ5 ,tates t$at samp%in& must ta/e p%ace at a frequenc+ *$ic$ is at %east t*ice t$e rate of t$e $i&$est

frequenc+ in t$e samp%ed si&na%.

Q6 "ua%it+ of recorded sound and fi%e sie of recordin& are affected + t$e samp%in& rate and t$e

numer of its a%%ocated per samp%e.

Q7 ,amp%in& more often means it is possi%e to trac/ t$e c$an&es in a rapid%+ var+in& si&na% more

accurate%+.

A%%ocatin& more its per samp%e means a more accurate representation of t$e si&na% *ave.

:ore samp%es and more its per samp%e means a i&&er fi%e sie ecause t$ere *i%% e more its to

store in ot$ cases.

Q8 ,+nt$esisin& sound means creatin& sounds ased on an interna% definition of t$e sounds to ep%a+ed and not a di&ita% recordin& of t$e actua% sound *aves. #$e pitc$- timre *$ic$ instrument

sound! and duration of eac$ required note ma/in& up t$e sound is read from a fi%e and t$e note- its

pitc$- timre and duration &enerated from e%ectronic circuits capa%e of &eneratin& individua% notes.

Q9 i&itised audio is received from a source and immediate%+ put into a uffer. nce t$ere is

sufficient audio data in t$e uffer- p%a+ac/ of t$e audio e&ins. As %on& as t$e p%a+er device is not

tr+in& to access data t$at $asn@t een received +et- streamin& *i%% e successfu%. f t$e uffer runs out

of audio data- t$e p%a+er *i%% pause unti% it receives more.


Q1

a) #$e samp%in& rate' t$e numer of its avai%a%e to represent eac$ samp%e (samp%in& reso%ution



40/76

b) Editin& out noise)*ron& notes or c$an&in& sounds to &et a specia% affects' sound can e

stored)transmitted di&ita%%+'

c) ,+nt$esisin& sound means creatin& sounds ased on an interna% definition of t$e sounds to ep%a+ed and not a di&ita% recordin& of t$e actua% sound *aves. #$e pitc$- timre *$ic$

instrument sound! and duration of eac$ required note ma/in& up t$e sound is read from a

fi%e and t$e note- its pitc$- timre and duration &enerated from e%ectronic circuits capa%e

of &eneratin& individua% notes.

Q2 a)

i)Ana%o&ue sound! is converted into di&ita% )) discrete va%ues'

ei&$t of ana%o&ue *ave! samp%ed at re&u%ar interva%s' ei&$t)va%ue represented + a numer)inar+ code)inar+ pattern'

ii)i&ita%(to(Ana%o&ue converter'

Q3 a)Ana%o&ue to i&ita% onverterb),ound samp%ed re&u%ar%+- samp%e $ei&$ts measured- $ei&$ts coded in inar+- inar+ va%ues

stored

6.1


(%stem !ife c%c!eQ1 Ana%+sis sta&e.

Q2 As/ customers to fi%% in questionnaires.

Q3 serve $o* t$e orders are co%%ected to find potentia% ott%enec/s of t$e s+stem.

Q4 urin& t$e imp%ementation p$ase.

Q5 #o c$ec/ t$at t$e different parts *or/ to&et$er correct%+.

Q6 #$ere ma+ $ave een misunderstandin&s + t$e ana%+st- t$e desi&ner or t$e pro&rammers.

Exam Practice Questions

Q1

S+stems anal+sis A detai%ed %oo/ at t$e current s+stem and esta%is$in& t$e oQectivesof t$e ne* s+stem.

S+stem desi*n #$e process invo%ved in t$e desi&n of user interface- processes and

data stora&e requirements.

&mplementation ro&rammin& t$e soft*are- insta%%ation of $ard*are and soft*are and

preparation of data fi%es. #rainin& of users and *ritin& t$e s+stem

documentation is a%so part of t$is p$ase.

estin* ,+stem testin& to ensure t$e *$o%e s+stems functions effective%+.

.-aluation evie* to confirm t$e ne* s+stem meets t$e ori&ina% requirements

and identif+ an+ necessar+ modifications.

Q2 omparison *it$ ori&ina% oQectivesumer of comp%aints ) rea/do*ns ) maintenance requests

Ease of use ) user feedac/ ) user satisfaction



41/76

Q3 ,imp%e c$an&e of a sin&%e coin; W1- W50p- 20p- 10p- 5p

$an&e made up of one of severa% coins; W38.5- 75p- 80p- 35p- 25p

$an&e made up of more t$an one of t$e same coins; 40p:inimum c$an&e t$at can e &iven; 5p


42/76

Q5

A

&nput

&nput

utput

0 0 1

0 1 1

1 0 1

1 1 0

&nput

&nput

utput

0 0 1

0 1 0

1 0 0

1 1 0

H

&nput

&nput

utput

0 0 0

0 1 1

1 0 1

1 1 0

Q6 o&ic &ate circuit s+mo%s;


H Jamp "!,upp%+

H L


43/76

&ate s+mo%

H &ate s+mo%


&ate s+mo%

A &ate s+mo%

# &ate s+mo%

A &ate s+mo%


44/76

Q7 Expression of ";

!. CBBA ++

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009


45/76

Q8 o&ic circuit A on%+!;

Q9 o&ic circuit on%+!;

Q10

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 !

A

.

A

.

A:.

.:A

%A:.&: %.:A& %A:.&: %.:A&

A

.

A

.

%A 7 .&A

%A 7 .&

%A 7 .& %A 7 .&7 %A 7 .& %A 7 .&7

./ -e organ@s la> C:- I C 7 -

IA:. 7 A:. %A 7 .& %A 7 .&7

%A 7 .& %A 7 .&:I

./ -e organ@s la> C:- I C 7 -

%A 7 .& %A 7 .&7


46/76

Q11

Q12

Q13

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 "

I%A 7 .& %A 7 .&: ultipl/ing out the to #raceted termsA:A 7 A:. 7 .:A 7 .:.

.:. I 0and.ut A:A I A:A I 0A:A 7 A:. 7 .:A 7 .:. A:. 7 .:AI

I %A 7 .& %A 7 .&7A:. 7 .:A./ -e organ@s la> C:- I C 7 -

I%A 7 .& %A 7 .&7 %A 7 .& %A 7 .&: ./ -e organ@s la> C:- I C 7 -

1:. I . 1 AN- . ill #e 1 hen . is 1 and 0 hen . is 0

Conse6uentl/5 1 And . simpl/ *ollos .

There*ore5 1:. is C:- I C 7 -

A:A:. 7 .:A:. I 7A:%A7.& .:%A7.& ./ -e organ@s la> C:- I C 7 -

7A:%A7.& .:%A7.& I A:A 7 A:. 7 .:A 7 .:.ultipl/ing out the

to #raceted termsIA:A 7 A:. 7 .:A 7 .:. A:. 7 .:A .:. I 0and.ut A:A I 0


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Q14


Q1 " M A.< T A..Q2

a!

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 '

A1 A2


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!

c! Equiva%ence tester- i.e. output is 1 if A1 A2 matc$


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iii!

A

A *rite and read man+ times optica% disc ompact isc! capa%e of

recordin& aout 600(700 :


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avin& pi&mented in/s for etter qua%it+'

Q2 a! arcode reader ) *and ) scanner

! i! %ess c$ance of error )) &reater accurac+)) scannin& + device faster

ii! t$e ars can e read up(side(do*n) $as vertica% s+mmetr+

7.2

End of topic questions(%stem soft)are

Q1 is/ formatter is part of s+stem soft*are.

Q2 #+pes of %an&ua&e trans%ators; assem%er- interpreter- compi%er.

Q3 An assem%er is used to trans%ate assem%+ code into mac$ine code.

Q4 _ is trans%ated usin& a compi%er.

Q5 #$e compi%er reads source code and produces oQect code.

App!ication soft)are

Q6


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Q1 a! ,oft*are is a pro&ram ) a sequence of pro&ram instructions.

! A pro&rammin& %an&ua&e trans%ator is a compi%er)interpreter)assem%er.

A dis/ defra&menter is a uti%it+ pro&ram.

A fi%e t$at is used + severa% app%ications pro&rams is a %irar+ pro&ram s+stem

soft*are!.

An examp%e of a &enera% purpose app%ications pro&ram is a *ord processor ) dataase

)spreads$eet.

Q2

Q3

a! ,econd &eneration %an&ua&e.

! irst &eneration %an&ua&e.

c! :emor+ address.

d! Assem%er.

e! 1(to(1- eac$ assem%+ %an&ua&e instruction trans%ates into one mac$ine code instruction.

Q4

a! i! ,+stem soft*are is t$e %a+er of soft*are *$ic$ ena%es users to operate t$e computer.

ii! app%ication soft*are is pro&rams *ritten to perform end user tas/s.

iii! an examp%e of s+stem soft*are is an operatin& s+stem or uti%it+ pro&rams.

! i! a t+pe of &enera% purpose app%ication soft*are is a *ord processor ) spreads$eet.

ii! ,pecia% purpose app%ication soft*are is a pro&ram *ritten to do a specific tas/.

c!i!


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ii! an advanta&e of espo/e soft*are over readi%+ avai%a%e soft*are is t$at it matc$es end

user requirements.

isadvanta&es are t$at it *i%% not e extensive%+ tried and tested and more expensive to u+.#$e customer $as to *ait for t$e soft*are to e *ritten and needs to specif+ requirements ver+

carefu%%+.

Q5

a! i! ard*are is t$e e%ectronic components of t$e computer.

ii! ,oft*are is t$e pro&rams t$at run on t$e $ard*are.

! An operatin& s+stem is soft*are.

c! A data us is $ard*are.

Q6

a! i! a compi%er trans%ates t$e *$o%e source code and produces oQect code.

ii! an interpreter ana%+ses eac$ %ine of code and executes it in turn *it$out producin& oQect

code.

! i! A compi%er is est used *$en execution s$ou%d run as fast as possi%e- *$en deve%opment

is finis$ed and for s$ippin& to t$e user.

ii! An interpreter is est used durin& deve%opment or to support p%atform independence.

c! an assem%er trans%ates an assem%+ %an&ua&e pro&ram *$ereas a compi%er trans%ates a $i&$ %eve%

%an&ua&e pro&ram.

Q7

a! Assem%+ %an&ua&e is t$e second &eneration of pro&rammin& %an&ua&es.

! A second(&eneration %an&ua&e pro&ram $as to e trans%ated into mac$ine code usin& an assem%er

efore it can e executed.

c! mperative $i&$ %eve% %an&ua&e pro&rams execute instructions in pro&rammer defined sequence.

d! Examp%es of imperative %an&ua&es are; asca%-


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.1


/e &nternet

Q1 #$e nternet is a net*or/ of computer net*or/s and computers usin& a &%oa%%+ unique address

space ased on t$e nternet rotoco% ! and #) to support pu%ic access to e(mai% and *e pa&es

amon&st ot$er t$in&s.

Q2 #$e =or%d =ide =e ===! or =e is a s+stem of inter%in/ed- $+pertext documents accessed

via t$e nternet.

Q3 ata or messa&e pac/ets f%o* una%tered t$rou&$ t$e nternet et*een t*o end points t$at contro%

t$eir communication. A messa&e is ro/en into varia%e %en&t$ pac/ets consistin& of a part of t$e

messa&e- a source and a destination address. #$e pac/ets trave% independent%+ of eac$ ot$er t$rou&$

t$e nternet ac/one ein& routed on t$e asis of t$e destination address.

Q4 A router is a specia% s*itc$ t$at receives pac/ets or data&rams from one $ost computer! or router

and uses t$e destination address t$at t$e+ contain to pass on t$e pac/ets- correct%+ formatted- to

anot$er $ost computer! or router. outers are used ecause it is not practica% to connect ever+ $ost

direct%+ to ever+ ot$er $ost. nstead- a fe* $osts connect to a router- *$ic$ connects to ot$er routers

and so on- to form a net*or/. osts are computers t$at run app%ications.

Q5

a! #$e end(to(end princip%e states t$at t$e t*o end computers s$ou%d e in contro% of t$e

communication across t$e nternet. #$e ro%e of t$e nternet is t$us de%e&ated to movin& pac/ets

et*een t$ese t*o end points.

! n t$e open arc$itecture net*or/in& approac$- desi&ners are free to desi&n t$e individua% net*or/s

in *$atever *a+ t$e+ *ant- a%%o*in& a diversit+ of net*or/s to interconnect and communicate. Eac$

net*or/ is connected to t$e nternet t$rou&$ a router>&ate*a+. t is t$e Qo of t$e &ate*a+ to overcome

t$e mismatc$ et*een different net*or/s.

c! #$e end(to(end princip%e requires t$at eac$ computer usin& t$e nternet s$ou%d e unique%+

identified. Eac$ computer on t$e nternet is %ae%%ed *it$ a &%oa%%+ unique address /no*n as an

nternet rotoco% ! address. #$e numerin& s+stem- v4- t$at is used toda+ a%%o*s for 232 different

addresses. A%% t$ese unique addresses ma/e up a sin&%e %o&ica% address space. At t$e inar+ %eve%- an

v4 address consists of 32 its 4 +tes!.

:omain names and &, addresses

Q6 1983

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 "!


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Q7 An+ t$ree from arp- com- edu- mi%- net- or&- int- &ov

Q8 A domain name identifies a net*or/ of computers *$i%st a fu%%+ qua%ified domain name unique%+

identifies a particu%ar $ost on t$is net*or/.

Q9 A , server trans%ates a fu%%+ qua%ified domain name into an address. osts use , servers

to reso%ve domain names into addresses efore connectin& to ot$er $osts on t$e nternet.

Q10 $ttp;))***.microsoft.com)index)index.$tm%

Q11 A is a t+pe of . A is an identifier for a resource. #$is resource ma+ e identified

+ its %ocation or its name. A identifies a resource via its net*or/ O%ocationO *$i%e a identifies it + name.

'lientser-er model

Q12 a! A ser-eris a soft*are process t$at provides a service requested + a c%ient soft*are process-

e.&. supp%ies a *e pa&e.

! A c%ient is a soft*are process t$at requests and uses t$e services provided + a server.

Q13 n t$e c%ient>server mode%- a c%ient soft*are process initiates a request for some service from a

server soft*are process *$ic$ responds to t$at request.

pplicationle-el protocols

Q14 A protoco% is a set of pre(a&reed si&na%s- codes and ru%es to e used for data and information

exc$an&e et*een s+stems.

Q15 #$e #) protoco% stac/ is a protoco% stac/ consistin& of four %a+ers; app%ication- transport-net*or/ and %in/.

#$e app%ication %a+er $and%es t$e detai%s of a particu%ar net*or/in& app%ication- e.&. a =e ro*ser

usin& t$e ## protoco%.

#$e transport %a+er esta%is$es- supervises and maintains a connection et*een t*o

communicatin& app%ications processes!- one on eac$ $ost. #$e transport %a+er ensures a re%ia%e

f%o* of data and re%ieves app%ications from $avin& to dea% *it$ t$e pro%ems of connectin& t$e

$osts- detectin& *$en errors occur- retransmittin& pac/ets and detectin& *$en a connection is

ro/en. #$e transport %a+er a%so sp%its data t$at t$e app%ications *is$ to send into ite(sied c$un/s

to fit pac/ets and reassem%es received pac/et data into data for app%ications.

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 ""


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#$e et*or/ or %a+er is responsi%e for addressin& pac/ets *it$ source and destination

addresses so t$at t$e+ ma+ e routed t$rou&$ t$e nternet.

#$e %in/ %a+er $and%es a%% t$e p$+sica% detai%s of interfacin& *it$ t$e ca%e- inc%udin& t$e net*or/

interface card and a device driver.

Q16 a! A port is an address for a soft*are process- e.&. an instance of a *e ro*ser.

! A soc/et is a comination of a $ost address and a port numer.

Q17 An+ t$ree from t$e fo%%o*in& t$ere are man+ more ut t$ese are ones t$at peop%e are most

fami%iar *it$!

ort 80 > =e server

ort 23 > #e%net server

ort 21 > # server

ort 25 > ,:# server

ort 110 > 3 server

Q18 A c%ient mac$ine sends a request messa&e to t$e server and t$e server responds *it$ a responsemessa&e. #$e response messa&e ma+ contain data of man+ different forms. #$e most popu%ar form is

textua% data formatted usin& +pertext :ar/ up an&ua&e #:!. t$er items- suc$ as &rap$ica%

ima&es or audio fi%es- ma+ a%so e transmitted. #$e simp%est request messa&e is;

FE# ) Keturn /e+ pressedI

Keturn /e+ pressedI

Q19

a! i%e #ransfer rotoco% #! is an app%ication(%a+er protoco% t$at ena%es fi%es on one $ost-

omputer


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ii read t$e #: text of a =e pa&e

iii retrieve e(mai%

iv send e(mai%.

A te%net c%ient connects to port 23 of a te%net server on t$e remote mac$ine a%%o*in& t$e c%ient to

mana&e t$e remote mac$ine- i.e. to create fi%es or fo%ders- to de%ete fi%es or fo%ders- to open fi%es for

vie*in&- etc.- as if t$e remote mac$ine *as t$e user@s o*n %oca% mac$ine.

e! +pertext #ransfer rotoco% over ,ecure ,oc/et a+er ## over ,, or ##,! is a =e

protoco% deve%oped + etscape t$at encr+pts and decr+pts user pa&e requests as *e%% as t$e pa&es t$at

are returned + t$e =e server. ##, uses a ,ecure ,oc/et a+er ,,! eneat$ t$e ##

app%ication %a+er. ##, uses port 443 instead of ## port 80 in its interactions *it$ #).

##, is *ide%+ used on t$e =e for securit+(sensitive communication- suc$ as pa+ment transactions

and corporate %o&ons.

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 "$


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Q1 nternet is a net*or/ of computer net*or/s and computers usin& unique addresses and#) protoco%.

#$e =or%d =ide =e is a s+stem of inter%in/ed $+pertext documents accessed via t$e nternet.

An intranet is a private computer net*or/ t$at uses nternet protoco%s > #)- ##- #-

3 and ,:# > and c%ient(server operations to secure%+ s$are part of an or&anisation@s

information or operations *it$ its emp%o+ees or memers. ,ometimes intranet refers to an

interna% *e site.

Q2

a!#o ensure t$e domain name is unique )) to a%%ocate a unique address to t$e domain.

! omain ame ,ervers store dataases of domain names and t$eir a%%ocated addresses.

addresses can e %oo/ed up from , dataases %ocated on t$e nternet'

Q3

a! %ient *or/station computers are provided *it$ a service from some centra% server- a%%

processin& required is done + t$e server- t$e processin& resu%ts are t$en returned to t$e

c%ient.

!

i! ,et of ru%es aout t$e *a+ t*o devices communicate.

ii!A%ice uses ,:# protoco% to send $er messa&e to t$e e(mai% server of $er ,. #$e

, %oo/s at t$e domain name to find t$e servers acceptin& messa&es for t$at

domain. #$e domain name is t$e second part of t$e destination address. #$e

messa&e is de%ivered to t$e mai% ox of t$e user.


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retrievin& e(mai% from remote mac$ine'

readin& a fi%e) %istin& contents of a fi%e on remote mac$ine'

searc$in& for a fi%e)director on remote mac$ine'

%istin& director+ contents of remote mac$ine'

.2


>eb Site :esi*n

Q1 Ka $refMC$ttp;))***.educationa%(computin&.co.u/CI %ic/ me to %in/ to E, tdK)aI

Q2 %ace anc$ors t$rou&$out document at positions *$ic$ users need to e a%e to Qump to usin& t$e

fo%%o*in& $tm%; Ka nameMCtopCIK)aI

%ace $+per%in/s in strate&ic p%aces to a%%o* users to Qump to t$e aove referenced parts of

document- e.&. t$e top of t$e document as fo%%o*s; Ka $refMC_topCI%ic/ $ere for t$e top of t$e

pa&eK)aI

Q3 Ko%I

K%iIasca% ro&rammin&K)%iI

K%iIataasesK)%iI

K%iI


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'ascadin* St+le S/eets

Q7 A st+%e s$eet descries in a st+%e s$eet %an&ua&e t$e presentation- e.&. font st+%e- font sie- co%our-of t$e contents of a document *ritten in a mar/up %an&ua&e suc$ as $tm%.

Q8 #: *as desi&ned to e used for mar/in& t$e structure of a *e pa&e- e.&. its $eadin&s and

para&rap$s- not for mar/in& $o* suc$ para&rap$s and $eadin&s s$ou%d e st+%ed. ,t+%e s$eets ena%e

t$e presentationa% aspects of a *e pa&e to e separated from its structura% aspects. #*o t+pes of st+%e

s$eet are an externa% st+%e s$eet and an emedded st+%e s$eet.

Q9 A st+%e ru%e consists of t$ree parts; a t+pe se%ector- a propert+ and a va%ue- i.e. se%ector `propert+ ;

va%ue

Q10 a! p text(a%i&n ; center' co%or ; red

Q11 ! $1 co%or ; %ue' font(sie ; 32pt' font(fami%+ ; OserifO

Q12 a! KdivIK)divI KpIK)pI K$_IK)$_I Ko%IK)o%I

Q13 ! KspanIK)spanI Kstron&IK)stron&I KemIK)emI

Q14 redo%d is a c%ass se%ector. An+ #: e%ement t$at $as t$e c%ass attriute redo%d *i%% app%+ t$e

co%our red to its enc%osed text.

Q15 s identif+ a specific e%ement and t$erefore must e unique on t$e pa&e. %asses mar/ e%ements

of a &roup and can e used mu%tip%e times- a defined st+%e ma+ e app%ied to mu%tip%e e%ements.

%ass se%ectors can e comined to&et$er in e%ements. s cannot e comined in t$is *a+.


Q1 a!

! p co%or; red

AQA Computing AS Level Teacher Notes Nelson Thornes Ltd 2009 '1

eading in larger *ont

Golloed #/ a #lan lineusuall/

.lan line #e*ore and a*terparagraph

Line #rea a*ter ?The end@

/perlin

Title


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c! Emedded- interna%

Q2 a!

! #$e /e+ difference et*een s and c%asses is t$at s identif+ a specific e%ement and

t$erefore must e unique on t$e pa&e > a specific can e used on%+ once per document.

%asses mar/ e%ements as memers of a &roup and can e used mu%tip%e times- as is t$e case if

a defined st+%e is app%ied to mu%tip%e e%ements.

c! se%ector identifier is prefixed *it$ _ not N.N.

.&reen,t+%e `co%or ; &reen' font(st+%e ; ita%ic

and

p.&reen,t+%e a`text(decoration ; under%ine

need to c$an&e to

_&reen,t+%e `co%or ; &reen' font(st+%e ; ita%ic

p_&reen,t+%e a`text(decoration ; under%ine

Q3 Externa%- interna%- emedded

Q4 :onoc$romatic > uses a sin&%e ase co%our and an+ numer of tints or s$ades of t$at co%our.

Ana%o&ous > Ana%o&ous co%ours are an+ t$ree co%ours *$ic$ are side + side on a 12(partco%our *$ee%- suc$ as +e%%o*(&reen- +e%%o* and +e%%o*(oran&e. sua%%+ one of t$e t$ree

co%ours predominates.


Title

/perlin underlined

/perlin underlined+aragraph teEt in green

Line #rea causes ello orldto appear on neEt line

.lan line #e*oreand a*terparagraph


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omp%ementar+ > consists of co%ours *$ic$ are %ocated opposite eac$ ot$er on t$e co%our

*$ee%- suc$ as &reen and red- +e%%o* and vio%et or oran&e and %ue.

1!.1


'urrent lawsQ1 =$en desi&nin& a user interface- +ou s$ou%d consider t$e ea%t$ and ,afet+ e&u%ations and

accessii%it+ &uide%ines to ensure users can vie* t$e information on screen comforta%+.

Q2 nder t$e $ea%t$ and safet+ re&u%ations s$ou%d e a%%o*ed rea/s or c$an&es in activit+ and $ave a

suita%e *or/ station *it$ adQusta%e c$air and monitor- detac$a%e /e+oard and *rist rests. A *or/station assessment ma+ e required and)or trainin& on correct posture.

Q3 #$e compan+ $as to aide + t$e ata rotection Act.

Jou need to ensure customers to t$e *esite are as/ed to a&ree t$at persona% information is

co%%ected. Jou a%so need to ensure t$is data is secure%+ stored.

Q4 nder t$e e&u%ation of nvesti&ator+ o*ers Act it is an offence to intercept a messa&e sent +

te%ecommunications s+stems. nce in t$e or&anisation@s mai% server t$e ata rotection Act app%ies.

.t/icsQ5 f +ou rea/ t$e code of conduct of +our or&anisation +ou ma+ e suQect to discip%inar+

procedures- t$is cou%d e a *ritten *arnin&- ein& arred from t$e computer s+stem or dismissa%.

Q6 Jou *ou%d e contravenin& t$e op+ri&$t- esi&ns and atents Act.Q7 ,oft*are %icences permit use of t$e soft*are- it does not mean +ou o*n t$e soft*are outri&$t. Jou

t$erefore do not $ave t$e ri&$t to se%% t$e soft*are. icences are not usua%%+ transfera%e' t$is means

+ou can not %e&a%%+ se%% a soft*are %icence to a t$ird part+.

Q8 #o restrict t$e use of di&ita% media- di&ita% ri&$ts mana&ement tec$no%o&ies ma+ e used suc$ as

encr+ption- di&ita% *atermar/s or t$e inc%usion of meta data in t$e di&ita% fi%e t$at records t$e

purc$aser@s detai%s.

.mer*in* tec/nolo*iesQ9 #$e di&ita% divide descries t$e &ap et*een t$ose peop%e *$o $ave access to information

tec$no%o&+ and t$ose *$o [email protected] omputer pro&rammers can *or/ from remote %ocations as %on& as t$e+ $ave access to a

computer and communication %in/s *it$ t$eir customers and)or co%%ea&ues. #$is means a &%oa% Qo

mar/et.

Q11 :ac$ines are ver+ &ood at repetitive tas/s *it$ c%ear%+ defined steps.

umans are etter at oQect and pattern reco&nition.

Q12 #$e rain *or/s in a ver+ comp%icated *a+ and *e sti%% do not fu%%+ understand $o* it *or/s.

Q13 and Q14 #$ese question are open ended and are desi&ned to stretc$ and c$a%%en&e more a%e

students.



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Q1 a!

i! #o minimise unaut$orised access pass*ord protect and)or encr+pt sensitive fi%es

and c$an&e pass*ords on a re&u%ar asis. $oose pass*ords t$at are difficu%t to &uess.

,et attriutes and access ri&$ts to restrict access to specific users. Automatic %o&(out

after a set time of user inactivit+.

ii! naut$orised access cou%d e detected t$rou&$ soft*are t$at monitors user activit+

and /eeps a %o& of fi%e access and c$an&es.

!

i! nsta%% a fire*a%% to protect from $ac/ers.

ii! se up(to(date virus c$ec/in& soft*are to protect a&ainst viruses.

iii! #o protect a&ainst s+stem fai%ure- re&u%ar automated ac/ups s$ou%d e done and

an uninterrupti%e po*er supp%+ s$ou%d e insta%%ed so t$at t$e s+stem can e s$ut

do*n safe%+.

c! #$e compan+ needs a &ood recover+ procedure- suc$ as p%ans *$ere to source a%ternative

$ard*are and $o* to insta%% ac/up fi%es.

Q3 ersona% data refers to information aout a %ivin& identifia%e individua%.

Q4 a! ea%t$ and ,afet+ isp%a+ ,creen Equipment! e&u%ations 1992

! ata rotection Act 1998

c! op+ri&$t- esi&ns and atents Act 1988d! #$e e&u%ation of nvesti&ator+ o*ers Act 2000

Q5 a! naut$orised access to computer pro&rams or data and unaut$orised

modification of computer materia%.

! Enforce stron& pass*ords- i.e. pass*ords t$at are not easi%+ &uessed.

]eep a %o& of a%% movements on c

as student book answers

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