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CHAPTER 1 OVERVIEW OF A COMPUTER SYSTEM
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CHAPTER 1OVERVIEW OF A COMPUTER SYSTEMIntroduction to computer and its componentsComputer ard!areComputer so"t!are S#stem unit and memor#I$TRO%UCTIO$ TO COMPUTER A$% ITS COMPO$E$TSComputer& A set o" too's tat e'ps #ou per"orm in"ormation processin( tas)s*An e'ectronic de+ice tat inputs, stores, processes data and (enerates te use"u' in"ormation*-*I$TRO%UCTIO$ TO COMPUTER A$% ITS COMPO$E$TS T!o ma.or components o" computer&Hardware& / Consists o" te p#sica' de+ices tat ma)e up #our computer s#stem*/ An e0uipment tat processes data to create in"ormationinc'udes input, output, stora(e and processin( de+ice*Software 1a'so ca''ed as a program2 & / Set o" instructions tat #our computer ard!are e3ecutes to process in"ormation "or #ou*/ Step 4# step instruction tat te'' te computer o! to do te !or) *4Computer ard!are Hard!are inc'udes a'' o" tose de+ices tat #ou can touc 5 monitor, )e#4oard, a 6opp# dis) and etc* 7 cate(ories o" computer ard!are&1. Input devices "or capturin( in"ormation*2. Output devices "or presentin( in"ormation*3. CPU and RAM "or creatin( ne! in"ormation*4. Storae devices "or storin( in"ormation*!. "e#eco$$unication devices "or communicatin( in"ormation*%. Connectin devices "or mo+in( in"ormation to and "rom #our +arious ard!are*5- Computer ard!are 1. Input devicesCaptures in"ormation and trans'ates it into a "orm tat can 4e processed and used 4# oter parts o" #our computer* E(& use scanner to capture ima(es, +ideo camera to capture #our 'i)eness in te "orm o" a +ideo, )e#4oard to )e# in data, mouse to c'ic) te operation 4utton, and etc*2. Output devicesTa)es in"ormation !itin #our computer and present it in a "orm tat #ou can understand* Comp'ement to input de+ices 5 !i'e input de+ices e'p #ou enter in"ormation into a computer s#stem, output de+ices e'p #ou see, ear or oter!ise recei+e in"ormation stored !itin #our computer s#stem*E(& use a set o" spea)ers to ear music*6- Computer ard!are 8* CPU and RAMTe most important components o" ard!are to(eter ma)e up te rea' 4rains o" computer*Te central processing unit 1CPU or processor2 is te cip tat carries out instructions it recei+es "rom so"t!are*RAM 1Random Access Memory2 is temporar# memor# tat o'ds so"t!are instructions and in"ormation "or te CPU* It is rater 'i)e #our sort/term memor# !en #ou turn o9 #our computer, a'' in"ormation in RAM is (one* :* Storae devicesTemporar# in"ormation stora(e in RAM is not enou( need a means to more permanent'# store in"ormation so #ou can reca'' and use it at a 'ater time*A storage device stores in"ormation so #ou can reca'' and use tat in"ormation at a 'ater time* E(& dis) dri+e, ard dri+e, %V%/RW dri+e, C%/ROM dri+e*7- Computer ard!are ;* Te'ecommunication de+icesTe'ecommunication de+ices e'p communicate in"ormation to peop'e in oter 'ocation* E(& ce'' pones, emai', di(ita' pa(ers, modem, net!or) card and etc*7* Connectin( de+icesComputer contains a +ariet# o" connectin( de+ices so tat in"ormation can mo+e around a'' #our ard!are*For e3amp'e& #ou need some sort o" connection 4et!een #our computer and a printer*8- Computer ard!are ines, Sate''ite Computer So"t!areS&ste$ SoftwareApp#ication Software1* Uses to run computer*?* To contro' and maintain te operation o" computer and its de+ices*8* Ser+e as te inter"ace 4et!een computer ard!are, userand app'ication so"t!are*:* E3amp'e& Operatin( S#stem 1Windo!s, >inu3,Uni32 and Uti'it# Pro(ram1Anti+irus2*1* Pro(ram desi(ned to ma)e user more producti+e*?* Assist user to !it persona' tas) and per"orm speci@c in"ormation processin( tas) suc as !ritin( term paper, and creatin( presentation s'ide, and !ritin( and pro(ram*8* E3amp'e& Microso"t OAce ?BBC, Microso"t Po!erPoint ?BBC,spreadseets,(ames, in+entor# pro(ram*S#stem unit A'' computer s#stem a+e a s#stem unit* S#stem unit contains most o" te computerDs e'ectronic components* Te 4asic components in te s#stem unit, inc'udin( te s&ste$ 'oard, $icroprocessor, $e$or&, s&ste$ c#oc(, e)pansion s#ots and cards, 'us #ines, ports, ca'#es and power supp#& units*S#stem 4oard 5 connects a'' s#stem components to one anoter*Microprocessor 5 contro's operations and per"orms aritmetic and 'o(ica' operations*Memor# 5 o'ds data, instructions, and in"ormation*S#stem c'oc) 5 emits a 4eats or pu'se tat sets te operatin( pace "or a'' o" te components in te s#stem unit*E3pansion s'ots 5 pro+ide connections "or e3pansion cards to te s#stem 4oard*11- S#stem unit E3pansion card 5 a''o! e3terna' de+ices to connect to and e3pand a computerDs capa4i'it#*=us 'ines 5 pro+ide data pat!a#s tat connect +arious s#stem components*Ports 5 soc)et "or e3terna' de+ices to connect to te s#stem unit*Ca4'es 5 connect e3terior de+ices to te s#stem unit +ia te ports*Po!er supp'# unit 5 con+erts AC 1a'ternatin( current2 to %C 1direct current2, pro+idin( po!er to te s#stem unit*12: =ASIC TYPES OF MICROCOMPUTER SYSTEM U$ITS 1* %es)top s#stem unitsT#pica''# contain te s#stemDs e'ectronic components and se'ected secondar# stora(e de+ices* Input and output de+ices, suc as mouse, )e#4oard and monitor are 'ocated outside te s#stem unit*?* $ote4oo) s#stem unitsPorta4'e and muc sma''er*Tese s#stem units contain te e'ectronic components, se'ected secondar# stora(e de+ices, and input de+ices 1)e#4oard and pointin( de+ice2* >ocated outside te s#stem unit, te monitor is attaced 4# in(es*O"ten ca''ed 'aptops*13- : =ASIC TYPES OF MICROCOMPUTER SYSTEM U$ITS 8* Ta4'e PC s#stem unitsSimi'ar to note4oo) s#stem units*Hi('# porta4'e de+ice tat supports te use o" a st#'us or pen to input commands and data*:* Hande'd computer s#stem unitsTe sma''est and are desi(ned to @t into te pa'm o" one and*A'so )no!n as pa'm computer, tis s#stem contains an entire computer s#stem, inc'udin( te e'ectronic components, secondar# stora(e, and inputEoutput de+ices*Persona' %i(ita' Assistants 1P%As2 are te most !ide'# used ande'd computers*14Wi'e te actua' siFe ma# +ar#, eac t#pe o" SU as te same 4asic s#stem components inc'udin( s#stem 4oard, microprocessor, and memor#* Ho!e+er-HOW %O WE AS HUMA$ =EI$GS COMMU$ICATE WITH A$% CO$TRO> A>> THIS E>ECTRO$IC CIRCUITRY- HHHE'ectronic data and instructionsComputers cannot reco(niFe in"ormation te same !a# #ou and I can*Peop'e "o''o! instructions and process data usin( 'etters, num4ers and specia' caracters* For e3amp'e& i" !e !anted someone to add te num4ers 8 to ; to(eter and record te ans!er, !e mi(t sa# Ip'ease add 8 and ;*JHo!e+er- te s#stem unit, is e'ectronic circuitr# and CA$$OT direct'# process suc a re0uest 4ecause it CA$$OT U$%ERSTA$%* Tere"ore-=e"ore an# process can occur !itin te s#stem unit, a con+ersion must occur "rom !at !e understand to !at te s#stem unit can *+*C"RO,ICA++- process*15Wat is te most "undamenta' statement #ou can ma)e a4out *+*C"RICI"- HHH- E'ectronic data and instructions It is simp'# tis&It can 4e eiter on or o.* Indeed, tere are man# "orms o" tecno'o(# tat can ma)e use o" tis two/state onEo9, #esEno, presentEa4sent arran(ement*For instance, a 'i(t s!itc ma# 4e on or o., or an e'ectric circuit open or c#osed* Tis is te reason, ten, tat a t!o/state or 'inar& s&ste$ is used to represent data and instructions*16Wat is te 0I,AR- S-S"*M HHH=inar# codin( scemesTe decima' s#stem tat !eDre a'' "ami'iar !it as 1B di(its 1B, 1, ?, 8, :, ;, 7, C, K, L2* Te 4inar# s#stem, o!e+er consists o" on'# t!o di(its 1B and 12* Eac B or 1 is ca''ed a 'it 1sort "or 4inar# di(it2*In te s#stem unit, te 1 can 4e represented 4# e'ectricit# 4ein( o., and te 1 4# e'ectricit# 4ein( on*In order to represent num4ers, 'etters, and specia' caracters, 4its are com4ined into (roups o" ei(t ca''ed '&tes* Eac 4#te t#pica''# represents one caracter*$o!, 'et us consider an important 0uestion-17HOW ARE CHARACTERS REPRESE$TE% AS Bs A$% 1s 1Io9J and IonJ e'ectrica' states2 I$ THE COMPUTER HHH- =inar# codin( scemes Te ans!er is-4# usin( o" 0inar& Codin Sc2e$e- Wen #ou press )e# on te )e#4oard, a caracter is automatica''# con+erted into a series o" e'ectronic pu'ses tat te s#stem can reco(niFe*18CodeUses ASCII 1pronounced Ias/)e#J2 stands "or American Standard Code "or In"ormation Intercan(e* most !ide'# used "or MicrocomputersE=C%IC1pronounced Ie4/see/dic)J2 stands "or *3tended 0inar# Coded 3ecima' Intercan(e Code* de+e'oped 4# I=M and is used primari'#"or 'ar(e computersUnicode a 17/4it code ori(ina''# desi(ned to support Internationa' 'an(ua(es 'i)e Cinese and Mapanase*Te most popu'ar, use K 4its 11 4#te2S#stem 4oardTe s#stem 4oard is a'so )no!n as te $ain 'oard or $ot2er'oard*It is te communications medium "or te entire computer s#stem* E+er# components o" te s#stem unit connects to te s#stem 4oard*It acts as a data pat a''o!in( te +arious components to communicate !it one anoter*For e3amp'e, e3terna' de+ices suc as te )e#4oard, mouse and monitor cou'd not communicate !it te s#stem unit !itout te s#stem 4oard*It is a 'ar(e 6at circuit 4oard co+ered !it a +ariet# o" di9erent e'ectronic components inc'udin( soc)ets, s'ots and 4us 'ines*19Microprocessor In a microcomputer s#stem, te centra# processin unit 1CPU2 or processor is contained on a sin('e cip ca''ed $icroprocessor*Te microprocessor is I4rainsJ o" te computer s#stem*It as t!o 4asic components&1. Contro# unit &Te''s te rest o" computer s#stem o! to carr# out a pro(ramDs instructions* It directs te mo+ement o" e'ectronic si(na's 4et!een memor#, !ic temporari'# o'ds data, instructions, and processed in"ormation, and te aritmetic 'o(ic unit* It a'so directs tese contro' si(na's 4et!een te CPU and inputEoutput de+ices*2. Arit2$etic #oic unit & Usua''# ca''ed A>U, per"orms t!o t#pes o" operations& aritmetic and 'o(ica'* Aritmeticoperations as #ou mi(t e3pect, are te "undamenta' mat operation 1addition, su4traction, mu'tip'ication and di+ision2* >o(ica' operations consist o" comparison o" t!o pieces o" data 1N, O, P220Microprocessor cip Cip capacities are o"ten e3pressed in !ord siFes* A !ord is te num4er o" 4its 1suc as 17, 8?, or 7:2 tat can 4e accessed at one time 4# te CPU*Te more 4its in a !ord, te more po!er"u' and "aster te computer is*Ei(t 4its (roup to(eter to "orm a 4#te* So, a 8?/4it/!ord computer can access : 4#tes at a time* Ten, a 7:/4it/!ord computer can access K 4#tes at a time* 1Tere"ore, te computer desi(ned to process 7:/4it/!ord is "aster2*Te t!o most si(ni@cant recent de+e'opments in microprocessors are&1* 7:/4it processor po!er"u' and "aster microcomputer*?* %ua'/core cip pro+ides t!o separate and independent CPUsa''o!s a sin('e computer to run t!o pro(rams at te same time 5 para''e' processin(21Memor# Memor# is a o'din( area "or data, instructions, and in"ormation* >i)e microprocessors, memor# is contained on cips connected to te s#stem 4oard* Tere are tree !e''/)no!n t#pes o" memor# cips&1* Random/access memor# 1RAM2Ho'd te pro(ram 1se0uence o" instructions2 and data tat te CPU is present'# processin(*Ca''ed as temporar# or +o'ati'e stora(e 5 e+er#tin( in most t#pes o" RAM is 'ost as soon as te microcomputer is turned o9 1a'so 'ost i" tere is a po!er "ai'ure or oter disruption o" te e'ectric2*Cace memor# or RAM cace impro+es processin( 4# actin( as a temporar# i(/speed o'din( area 4et!een te memor# and te CPU computer detects !ic in"ormation in RAM is most "re0uent'# used* It copies tat in"ormation into te cace* Wen needed, te CPU can 0uic)'# access te in"ormation "rom te cace*22- Memor# ?* Read/on'# memor# 1ROM2ROM cips a+e pro(rams 4ui't into tem at te "actor#*Un'i)e RAM cip, ROM cips are not +o'ati'e and cannot 4e can(ed 4# te user*IRead on'#J means tat te CPU can read, or retrie+e data and pro(rams !ritten on te ROM cip* Ho!e+er, te computer cannot !rite 1encode or can(e2 te in"ormation or instructions*T#pica''# contain specia' instructions "or detai'ed computer operations* For e3amp'e& instructions to start a computer*8* Comp'ementar# meta'/o3ide semiconductor 1CMOS2CMOS cip pro+ides 6e3i4i'it# and e3panda4i'it# "or a computer s#stem* It contains essentia' in"ormation tat is re0uired e+er# time te computer s#stem is turned on / current date and time, amount o" RAM, t#pe o" )e#4oard, mouse, monitor and dis) dri+e* Un'i)e RAM, it is po!ered 4# a 4atter# and does not 'ose its contents !en te po!er is turned o9* Un'i)e ROM, its contents can 4e can(ed to re6ect can(es in te computer s#stem 5 suc as increased RAM and ne! ard!are de+ices*23S#stem c'oc) Te s#stem c'oc) is 'ocated on a sma'' specia'iFed cip tat produces precise'# timed e'ectrica' 4eats or impu'ses* Te s#stem c'oc) emits a 4eat or pu'se tat sets te operatin( pace "or a'' o" te components in te s#stem unit* A computerDs s#stem c'oc) as a @3ed speed tat cannot 4e +aried* For tat reason, a computer s#stemDs c'oc) speed is an important measurement indicatin( te speed o" processin( or po!er o" a computer s#stem* Te c'oc) speed or c'oc) rate "or po!er"u' microcomputers is measured in (i(aertF 1GHF2 or 4i''ions o" 4eats per second 5 te "aster te c'oc) speed, te "aster te computer can process instructions*24E3pansion s'ots and cardsMost microcomputers a+e open arc2itecture 5 a''o! users to e3pand teir s#stems 4# pro+idin( e)pansion s#otson te s#stem 4oard*Users can insert optiona' de+ices )no!n as e)pansion cards into tese s'ots*Tere are a !ide ran(e o" di9erent t#pes o" e3pansion cards* Some o" te most common'# used e3pansion cards are&1. 4ideo cards& a'so )no!n as rap2ics cards* Tese cards connect te s#stem 4oard to te computerDs monitor* Te cards con+ert te interna' e'ectronic si(na's to +ideo si(na's so te# can 4e disp'a#ed on te monitor*2. Sound cards& accept audio input "rom a micropone and con+ert it into a "orm tat can 4e processed 4# te computer* Tese cards con+ert interna' e'ectronic si(na's to audio si(na's so te# can 4e eard "rom e3terna' spea)ers*3. Mode$ cards& a'so )no!n as interna# $ode$* Tese cardsa''o! distant computer to communicate !it one anoter 4# con+ertin( e'ectronic si(na's "rom !itin te s#stem unit into e'ectronic si(na's tat can tra+e' o+er te'epone 'ines and oter t#pes o" connection*25- E3pansion s'ots and cards3. ,etwor( interface cards 5,IC6& a'so )no!n as networ( adapter cards, are used to connect a computer to one or more oter computers 5 users can sare data, pro(rams and ard!are* $IC t#pica''# connects te s#stem unit to a ca4'e tat connects to te net!or)*4. "4 tuner cards& can !atc te'e+ision, capture +ideo, and sur" te internet at te same time* 26 E3pansion cards @t into s'ots on te s#stem 4oard=us 'inesA 4us 'ine a'so )no!n simp'# as a 'us 5 connects te parts o" te CPU to eac oter*=uses a'so 'in) te CPU to +arious oter components on te s#stem 4oard*A 4us is a pat!a# "or 4its representin( data and instructions* Te num4er o" 4its tat can 4e tra+e' simu'taneous'# do!n a 4us is )no!n as te 4us !idt*A 4us is simi'ar toa mu'ti'ane i(!a# tat mo+es 4it rater tan cars "rom one 'ocation to anoter* Te num4er o" traAc 'anes determines te 4us !idt*A i(!a# 14us 'ine2 !it more traAc 'anes 14us !idt2 can mo+e traAc 1data and instructions2 "aster 5 is an important "actor re'atin( to te speed and po!er "or a particu'ar computer* For e3amp'e, a 7:/4it 4us is t!ice as "ast as a 8?/4it 4us*E+er# computer s#stem as t!o 4asic cate(ories o" 4uses&1. S&ste$ 'uses& connect te CPU to te memor# on te s#stem 4oard*2. *)pansion 'uses& connect te CPU to oter components on te s#stem 4oard*27Fi(ure K& =usPorts A port is soc)et "or e3terna' de+ices to connect to te s#stem unit*Some ports connect direct'# to te s#stem 4oard !i'e oter connect to cards tat are inserted into s'ots on te s#stem 4oard*Man# ports, 'i)e te mouse, )e#4oard,and +ideo ports, are "or speci@c de+ices* Oters, 'i)e tose 'isted 4e'o!, can 4e used "or a +ariet# o" di9erent de+ices*1. Seria# ports&are used "or a !ide o" purposes* Te# are o"ten used to connect a mouse, )e#4oard, modem, and man# oter de+ices to te s#stem unit* Send data one 4it at a time and +er# (ood "or sendin( in"ormation o+er a 'on( distance*2. Para##e# ports7are used to connect e3terna' de+ices tat need to send or recei+e a 'ot o" data o+er a sort distance*T#pica''# send ei(t 4its o" data simu'taneous'# across ei(t para''e' !ires*Most'# used to connect printers to te s#stem unit*28- Ports 3. Universa# seria# 'us 5US06 ports& (radua''# rep'acin( seria' and para''e' ports*Faster, and one US= port can 4e used to connect se+era' de+ices to te s#stem unit*4. 8ire9ire ports& a'so )no!n as i(/per"ormance seria' 4us 1HPS=2 ports*As "ast as US= ?*B ports and pro+ide connections to specia'iFed FireWire de+ices suc as camcorders*29PortsSummar# A computer 1or computer s#stem2 is a set o" too's tat e'ps #ou per"orm in"ormation/processin( tas)s*Your computer too's are eiter ard!are or so"t!are*So"t!areS&ste$ software& "or tecno'o(#/speci@c and essentia' tas)s*App#ication software& "or speci@c tas)s suc as !ritin( a paper or mana(in( in+entor#*Hard!are Input devices& suc as a mouse "or capturin( in"ormation*Output devices& suc as a printer "or presentin( in"ormation*CPU and RAM& #our computerDs 4rain, "or creatin( ne! in"ormation*Storae devices& suc as a dis) "or storin( in"ormation*"e#eco$$unication devices& suc as a modem "or communicatin( in"ormation to oter peop'e*Connectin devices& suc as a port "or mo+in( in"ormation around a'' #our ard!are*30- Summar# S#stem unit contains e'ectronic components* Four 4asic t#pes are& des)top, note4oo), ta4'et PC, and ande'd* %ata and instructions can 4e represented e'ectronica''# !it a t!o/state or 4inar# s#stem o" num4ers 1B and 12* Eac B or 1 is ca''ed a 4it* A 4#te consists o" ei(t 4its and represents one caracter* =inar# codin( scemes con+ert 4inar# data into caracters* Tree suc scemes are&ASCII 5 te most !ide'# used "or microcomputers*E=C%IC 5 de+e'oped 4# I=MQ used primari'# 4# 'ar(er computers*Unicode 5 17/4it codeQ ori(ina''# desi(ned to support internationa' 'an(ua(es 'i)e Cinese and Mapanese* To 4e a competent end user, #ou need to understand o! data and pro(rams are represented e'ectronica''#* Additiona''#, #ou need to understand te "unctiona'it# o" te 4asic components in te s#stem unit& s#stem 4oard, microprocessor, memor#, s#stem c'oc), e3pansion s'ot and cards, 4us 'ines and ports*31