COMPUTER MIDTERMS REVIWER.docx

7/25/2019 COMPUTER MIDTERMS REVIWER.docx

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1

WHAT IS A COMPUTER?

An electronic device operating under the

control of instructions stored in its own

memory that accepts data, processes data

into information and produces and produces

and stores results.

Computer is a programmable machine

designed to follow instructions.

COMPONENTS OF COMPUTER SYSTEMS

Hardware

Software

Peopleware

Dataware

Hardware

The Nuts and Bolts of the Machine

It refers to the physial o!po"e"ts of

the o!p#ter syste!$

Main Hardware Component Categories

1$ I"p#t De%ies

&$ Ce"tral Proessi"' U"it (CPU)

*$ Mai" Me!ory

+$ Seo"dary Stora'e

,$ O#tp#t De%ies

INPUT DE-ICES

Used to se"d i"for!atio" to the

o!p#ter fro! o#tside

Ma"y de%ies a" pro%ide i"p#t

.ey/oard0 !o#se0 sa""er0 di'ital

a!era0 !iropho"e

CENTR2 PROCESSIN3 UNIT (CPU)

The CPU is where !ost al#latio"s ta.e

plae$

It is the 4/rai" a"d heart5 of theo!p#ter syste!$

CPU is ho#sed i" a si"'le hip alled a

microprocessor.

COMPONENTS OF CPU

Control Unit 6 it ats as a s#per%isor

that o"trols a"d s#per%ises the

operatio" i" the CPU$

Arithmetic Logic Unit (ALU) 6 it

perfor!s the !athe!atial a"d lo'ial

operatio"s of the o!p#ter syste!$

MIN MEMORY

Itis a te!porary holdi"' plae for data

a"d i"str#tio"s$ Holds /oth pro'ra!

i"str#tio"s a"d data$

lso alled Ra"do! ess Me!ory

(RM)

Bit

S!allest piee of !e!ory

Sta"ds for bi"ary di'it

Has %al#es 7 (o80 false) or 1 (o"0

tr#e)

Byte

Is 9 o"se#ti%e /its

:ytes ha%e addresses

/yte a" hold o"e harater

SECONDRY STOR3E

Refers to the !edia o" whih data0

i"str#tio"s0 a"d i"for!atio" are .ept$

Seo"dary de%ies a" store i"str#tio"s

a"d data whe" they are "ot /ei"' #sed/y the syste! #"it$

Secondary Storage di8ers fro!

!e!ory0 that it a" hold i"str#tio"s or

ite!s per!a"e"tly$

Main Memory0 /y o"trast0 holds ite!s

o"ly te!porarily while the proessor

i"terprets a"d e;e#tes i"str#tio"s$

OUPUT DE-ICES

Used to se"d i"for!atio" fro! the

o!p#ter to the o#tside

Ma"y de%ies a" /e #sed for o#tp#t


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InputDevice

OutputDevice

SecondaryStorageDevices

Centra

ProcessingUnitMain

Me!ory

&

!o"itor0 pri"ter0 spea.er

Main Hardware Component Categories

Software

Bringing the Machine to Life

It refers to the i"str#tio"s or pro'ra!s

that tell the o!p#ter to do a spei


3/12

*

Pro'ra!!i"' 2a"'#a'e > e"a/le the

pro'ra!!ers to o!!#"iate with

the o!p#ter$

Pop#lar la"'#a'es@ CAA0 -is#al

:asi0 C0 Ba%a0 PHP

!ypes of rogrammingLang#ages

Mahi"e 2a"'#a'es

sse!/ly 2a"'#a'es

Hi'h>le%el 2a"'#a'es

MACH34$ LA45UA5$S

Mahi"e la"'#a'e 6 or low le%el la"'#a'e is

the !ost /asi la"'#a'e of a o!p#ter$

se#e"e of 7s a"d 1s$

Mahi"e la"'#a'es are the o"ly way to

o!!#"iate diretly with the o!p#ter$

Pro'ra!!i"' i" !ahi"e la"'#a'e are

tedio#s a"d error>pro"e a"d re#ireshi'hly trai"ed pro'ra!!ers$

E;a!ple@ 77171 17771 17777

ASS$MBL LA45UA5$S

sse!/ly la"'#a'es were de%eloped to

!a.e the pro'ra!!ers =o/ easier$

It is a low>le%el pro'ra!!i"' la"'#a'e

for o!p#ters0 !iroproessors0

!iroo"trollers0 a"d other

pro'ra!!a/le de%ies$

I" asse!/ly la"'#a'e0 a" i"str#tio" is

a" easy>to>re!e!/er for! alled

!"e!o"is$

Assembler> a pro'ra! whih tra"slates

the !"e!o"i la"'#a'e #"derstood

/y the pro'ra!!er i"to a /i"ary for!

#"derstood /y the o!p#ter$

E;a!ple@ :;0 ; (re'isters)

H35H6L$0$L LA45UA5$S

Hi'h>le%el la"'#a'es allows the

pro'ra!!er to #se E"'lish>li.e

i"str#tio"s$

Closer to spo.e" la"'#a'es a"d it !a.e

pro'ra!!i"' easier$

Compilers> tra"slate hi'h>le%el

i"str#tio"s i"to 7s a"d 1s or !ahi"e

la"'#a'e$

E;a!ple@ CAA0 C0 Ba%a0 PHP0 -is#al :asi

rocessing a High6Le1el

Lang#age rogram

Editi"' the pro'ra!

Co!pili"'

2i".i"'

E;e#ti"'

$-3!345

Yo# write a pro'ra! with words or

sy!/ols that are #"dersta"da/le to

h#!a" /ei"'s$

Yo# type the pro'ra! diretly i"to a

wi"dow or sree" a"d sa%e the res#lti"'

te;t as a separate


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+

This proess prod#es a" i"ter!ediate

o/=et spei/y>step

i"str#tio"s that direts the o!p#ter

what yo# wa"t it to do$

Pro'ra!s are writte" i" a pro'ra!!i"'

la"'#a'e > whih is a set of r#les that

pro%ides a way of telli"' the o!p#terwhat operatio"s to perfor!$

The perso" who reates o!p#ter

pro'ra! is alled o!p#ter pro'ra!!er$

S!$S 34 "5"AMM345

U"dersta"d the pro/le!

Pla" the lo'i

Code the pro'ra!

Co!pile the pro'ra! i"to !ahi"e

la"'#a'e

Test the pro'ra!

P#t the pro'ra! i"to prod#tio"

9. Understand the roblem

:efore writi"' the pro'ra! the

pro'ra!!er !#st


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,

the o"ly la"'#a'e

a o!p#ter ."ows$

Its o"sists of 7?s a"d 1?s$

Co!piler is a speial pro'ra! that

tra"slates hi'h>le%el la"'#a'e

i"str#tio"s i"to !ahi"e la"'#a'e$

Co!piler athes all sy"ta; errors$

=. !est the rogram

To e;e#te a"d the" r#" the pro'ra!$

The pro'ra! #po" e;e#tio" is /ei"'

s#/=eted to di8ere"t .i"ds of test data

to a"tiipate a"d orret errors that

!i'ht o#r /efore releasi"' the

pro'ra! to the #sers$

>. #t the rogram into rod#ction

The or'a"iatio" a" "ow #se the

pro'ra!$

Trai"i"' perso""el to #se the pro'ra!$

R#""i"' the pro'ra! #si"' the at#al

data$

Test for #ser?s appro%al$

AL5"3!HM

se#e"e of well>#"derstood steps for

a perso" to follow i" order to ao!plish

a ertai" tas. or to sol%e a parti#lar

pro/le!$

It is a


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TerminalblockInput/utput

block

!rocesssymbol

"ecision

symbol

n#pageConnector

ff#pageConnector

Initiali$ation

symbol

%lowlines

S$U-C-$

*L+CHA"!S

'raphial represe"tatio" of the lo'ial

steps that sol%es a pro/le!$

dia'ra! represe"ti"' the lo'ial

se#e"e i" whih a o!/i"atio" of

steps or operatio" is to /e perfor!ed$ It

is a /l#epri"t of the pro'ra!$

Pro'ra!!ers #se Jowharts to

#"dersta"d the lo'i proessi"' of data$

ltho#'h ti!e o"s#!i"'0 it?s the /est

tool for /e'i""ers$

BAS3C *L+CHA"!345 SMBLS

!erminal (0AL)

6 #sed to si'"ify the /e'i""i"' a"d e"d of

Jowhart

3nitiali?ation (H$8A54)

> si'"i perfor!s a"y al#latio"s that are to /e

do"e$

-ecision (-3AM4-)

> si'"i show the e"try or e;it poi"t of theJowhart$ "o">proessi"' sy!/ol #sed to

o""et o"e part of a Jowhart to a"other

witho#t drawi"' a Jowli"es$

@6page Connector ($4!A54)

> So!eti!es a Jowhart will "ot


7/12

K

4ames cannot contain spaces.

4ames cannot contain special

characters

"elational perators a" operators that

o!pares two %al#es a"d deter!i"es therelatio"ship /etwee" the!$

*o#r *lowchart Str#ct#res

Se#ence '-ecision '"epetition'

Case

S$U$4C$ S!"UC!U"$

Direts the o!p#ter to proess the

pro'ra! i"str#tio"s0 o"e after a"other0

i" the order listed i" the pro'ra!$

Series of atio"s are perfor!ed i"

se#e"e

-$C3S34 S!"UC!U"$

Ma.es a deisio" a"d the" ta.es a"

appropriate atio" /ased o" that

deisio"

E;a!ple@ waiti"' or rossi"' at railroad

tra.s depe"di"' o" si'"al li'hts

"$$!3!34 S!"UC!U"$

repetitio" str#t#re represe"ts part of

the pro'ra! that repeats$ This type of

str#t#re is o!!o"ly ."ow" as a loop$

CAS$ S!"UC!U"$

O"e of se%eral possi/le atio"s is ta.e"0

depe"di"' o" the o"te"ts of a %aria/le$

se#docode

detailed desriptio" of what a

o!p#ter pro'ra! or al'orith! !#st do$

te;t#al prese"tatio" of a Jowhart

Close to a "at#ral la"'#a'e

The o"trol str#t#res i!pose the

lo'i

May /eo!e a part of the pro'ra!

do#!e"tatio"

+here did C// come fromD

Deri%ed fro! the C la"'#a'e

C was deri%ed fro! the :

la"'#a'e

: was deri%ed fro! the :CP2

la"'#a'e

:CP2 > :asi Co!/i"ed

Pro'ra!!i"' 2a"'#a'e

+hy the E//FD

AA is a" operator i" CAA

C de%eloped /y De""is Rithie at TLT

:ell 2a/s i" the 1K7s$

Used to !ai"tai" UNI syste!s

Ma"y o!!erial appliatio"swritte" i" C

CAA de%eloped /y :=ar"e Stro#str#p at

TLT :ell 2a/s i" the 197s$

O%era!e se%eral shorto!i"'s

of C

I"orporated o/=et orie"ted

pro'ra!!i"'

C re!ai"s a s#/set of CAA

-e1eloping a program in C// re#ires at

least fo#r steps&


8/12

9

$diting the program6Yo# write a

pro'ra! with words or sy!/ols that are

#"dersta"da/le to h#!a" /ei"'s$

- Yo# type the pro'ra! diretly i"to a

wi"dow or sree" a"d sa%e the res#lti"'

te;t as a separate

speifeat#red I"te'rated

De%elop!e"t E"%iro"!e"t (IDE) > whih is a/le

to reate i"dows or DOS>/ased CAA

pro'ra!s #si"' the Cy'wi" o!piler$

3-$ 6 a syste! that i"l#des /oth editor a"d a

o!piler$

Mirosoft -is#al CAA0 :orla"d CAA are other

e;a!ple of IDE

Steps in Con,g#ring a -e16C// rogram

M$M" LCA!34

-ata !ype > i"diates what type of i"for!atio"

the address will store (e$'$0 "#!eri or te;t#al)$

3denti,er> allows the pro'ra!!er to refer to

the !e!ory loatio" elsewhere i" the pro'ra!$

> Na!es !ade #p /y the pro'ra!!er$

!ypes of 3denti,er

0ariables 6 are !e!ory loatio"s

whose %al#es a" ha"'e d#ri"' r#"ti!e

(whe" the pro'ra! is r#""i"')$ Most

!e!ory loatio"s are %aria/les$

Constants > are !e!ory loatio"s

whose o"te"t a""ot /e ha"'ed

d#ri"' pro'ra! e;e#tio"$ Ofte" "a!edi" #pperase letters$ E;a!ple@ PI

(o"sta"t)0 radi#s (%aria/le)

"#les 3n 4aming 3denti,ers (1ariables)

1alid or in1alid 1ariables


9/12

C// 7eywords

7eywordsare prede stores :oolea" %al#es (tr#e or

1 a"d false or 7)

short a"d int >store i"te'ers

("#!/ers witho#t a dei!al plae)

- Di8ere"es are ra"'e of %al#es a"d

!e!ory #sed (inthas the 'reater of/oth) oat a"d do#ble 6 store real

"#!/ers ("#!/ers with a dei!al

plae)

- Di8ere"es are ra"'e of

%al#es0 preisio"0 a"d !e!ory

#sed (do#blehas the 'reater

of eah)

char> stores haraters (letter0

sy!/ol0 or "#!/er that will "ot

/e #sed i" a al#latio")

- O"ly o"e harater stored at a

ti!e

string 6 is a #ser>de


10/12

17

co#t (see6o#t) console o#tp#t> se"d

i"for!atio" 4o#t5 to the #ser or o#tp#t to

the !o"itor

- Pair with the i"sertio" operator (JJ)

> to display i"for!atio" o" the

o!p#ter sree"

Starting a 4ew Line

endl (e"d li"e)6 is a strea!

!a"ip#lator that ad%a"es the #rsor

to the "e;t li"e o" the sree"

co#tJJ KHello' thereK JJ endlI

n 6 (sa!e as endl) a#ses a "ew

li"e to /e started o" the !o"itor

co#tJJ KHello' there nKI

:oth are e#i%ale"t to pressi"' the

E"ter .ey

rogram Statement

o#t QI"p#t the #sed to

o/tai" i"for!atio" fro! the .ey/oard

(pro'ra! pa#ses while #ser e"ters data)

- Pair with e;tratio" operator (NN) >

ta.es i"for!atio" fro! the .ey/oard

to a %aria/le a"d stores it i" i"ter"al

!e!ory

rogram Layo#t

Co!piler aepts al!ost a"y patter"

of li"e

/rea.s a"d i"de"tatio"

Pro'ra!!ers for!at pro'ra!s so

theyare easy to read


11/12

11

Plae ope"i"' /rae a"d

losi"' /rae ?

o" a li"e /y the!sel%es

I"de"t state!e"ts

Use o"ly o"e state!e"t per

li"e

-aria/les are delared /efore they

are #sed

Typially %aria/les are delared

at the /e'i""i"' of the

pro'ra!

State!e"ts ("ot always li"es)

e"d with a se!i>olo"

system (Kpa#seK)I

- pa#ses pro'ra! e;e#tio" a"d

display Press a"y .ey to o"ti"#e

!essa'e i" the o!!a"d pro!pt

wi"dow o" the o!p#ter sree" ret#rn OI

- ret#r"s the "#!/er 7 to the

operati"' syste! to i"diate

that the pro'ra! e"ded

"or!ally

Comment

is si!ply a !essa'e to the

perso" readi"' that pro'ra!

a"d is referred to as i"ter"al

do#!e"tatio"

:e'i" with (two forward

slashes) /efore the te;t yo#

wa"t treated as a o!!e"t

thro#'h the e"d of the li"e$

E;@ !his is a sample C//program.

Comment

Co!!e"ts a" spa" !#ltiple

li"es

:e'i" with Pa"d e"d with P

E;@

P6666666666666666666666666666

M#lti6line C// style comment

6666666666666666666666666666P

Pro'ra! o!!e"ts !ay /e

#sed a"ywhere i" the pro'ra!0

a"d are i'"ored /y the

o!piler$

Layo#t of a C// rogram


12/12

1&

Special Characters in C//

:#'> !ista.e i" a pro'ra!

De/#''i"'> Eli!i"ati"' !ista.es i"

pro'ra!s

!wo !ypes of rogram $rrors

Sy"ta; Errors

-

-iolatio" of the 'ra!!ar r#les of thela"'#a'e- Diso%ered /y the o!piler- Error !essa'es !ay "ot always show

orret loatio" of

errors

2o'i Errors

>Errors i" the pro'ra!?s al'orith!

>Most di#lt to dia'"ose

> Co!piler does "ot reo'"ie a" error

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