Computer Components

Com
mputerr Components
The Motherbo
M
oard
The moth
herboard con
nnects all off the other paarts of the coomputer togeether and alloows the trannsfer
of data between all th
hese compon
nents.
herboard hou
uses the Cen
ntral Processing Unit (CP
PU), Basic Innput/Outputt System (BIIOS),
The moth
Random Access Mem
mory (RAM)), Read Only
y Memory (R
ROM), clockk/calendar bbattery and
connecto
ors for add-on
n cards and devices.
otherboards offer integraated video caards, expansiion USB porrts, and optioons for Solidd
Some mo
State Driives (SSD).
Motherbo
oards are con
nsidered inp
put / output devices.
d
The
T Cen
ntral Prrocessingg Unit (C
CPU)
Intel Lo
ogo
Considerred the “brain
n” of the com
mputer, the CPU
C
receivees and execuutes instructiions. The chhip
mounts directly
d
onto the motherb
board. CPUs are input / output devicces.
Shown ab
bove are thee Core i5 and
d i7 processo
or chips. Eacch generatioon of chip opperates fasterr,
and contaains more traansistors thaan the previo
ous generatioon of chips.
“Core” seeries of chip
ps contain 4 independent
i
t processors, which dram
matically incrreases proceessing
speed, ass each processsor can takee on a task seeparately froom another pprocessor.
The proccessor speakss a languagee called binarry (or machiine languagee). The operrating system
m (ie:
Windowss, Linux, Maac OS) acts as
a an interprreter, betweeen the user annd the proceessor.
These ch
hips are filled
d with millio
ons of “transistors”, whicch act like tiiny switches.
Before th
he use of tran
nsistors, com
mputers weree filled with thousands oof vacuum tuubes. Vacuuum
tubes were fragile, would
w
frequen
ntly blow ou
ut, used largee quantities oof electricityy, and generaated
excessivee heat.
The Hard
H
Drrive
d drive is a seealed unit, an
nd resides in
nside the com
mputer’s casse. It allows programs annd
The hard
documen
nts to be saveed for later retrieval.
r
Insside the hardd drive are a number of ppolished mettal
disks (plaatters) which
h have a mag
gnetic oxide coating. Allso inside arre magnetic rread/write heeads,
mounted on metal sp
pring loaded arms.
o read/write heads – onee above and one below. At rest, the
For each platter, therre will be two
heads sit on the platteer, but when
n the drive iss running at ffull speed (33,600 RPM) air pressure
o the platteer’s surface. The gap beetween the heeads
develops underneath the head and lifts it up off
and the platter
p
on a drive
d
that is spinning
s
fullly is betweenn 10 and 20 millionths oof an inch
(smaller than the wid
dth of a human hair!).
The reaso
on the hard drives
d
are bu
uilt in a clean
n room and ssealed to thee outside envvironment iss to
prevent dust
d from setttling on the platters. If a dust particcle was to coome into conntact with thee
read/writte head at thee speed the platters
p
weree turning, it w
would damaage the head or cause thee
head to im
mpact on thee surface of the platter. This is calleed a head craash, and usuually destroys the
drive.
When thee heads writee informatio
on, they causse small maggnetic particlles to either stand up or lay
flat again
nst the platteer’s surface. When the drive
d
reads innformation, tthey check tthe state of thhese
particles.. A standing
g particle rep
presents the binary
b
digit “1”. A partticle which iss lying downn is
read as th
he binary dig
git “0”. Com
mputers use ones
o
and zerros as a langguage.
Softwaree and documents remain on the hard drive even w
when the com
mputer is off
ff, because thhey
are stored
d magnetically. This is called
c
magnetic semi-peermanent stoorage, as data can still bee
erased. The
T hard driv
ve is an inpu
ut / output deevice.
CD-ROM, DVD and Blu-Ray Discs
CD-ROMs, DVDs and Blu-Ray Discs all work similarly to each other. All are input devices,
and are optical permanent storage.
A factory made CD (Compact Disc) is stamped from a master disc. Each CD has a thin layer of
aluminum foil, which is covered by a plastic coating.
The surface of a disc is made of “peaks” and “valleys”.
A laser beam shines down toward the surface of the CD. The CD-ROM player times how long it
takes for the beam to be reflected from the surface. The light takes less time to be reflected from
a “peak” than it does from a “valley”. The computer assigns the binary value of “1” to the
“peak” and “0” to a “valley”.
A CD-ROM Burner is an input / output device. Instead of “stamping” a CD at a factory, the CDROM burner uses a high powered laser beam, which can melt small “valleys” into the metal
inside the plastic coating of the disc.
DV
VD (Dig
gital Verrsatile D
Disc)
This form
mat was inveented in 1996
6. A single layer DVD ccan hold up to 1.46GB
of data.
The DVD
D burner usees a smaller wavelength
w
of
o light to crreate a smalller
valley in the disc, wh
hich allows more
m
storagee. Some DV
VDs are dual
layer, wh
hich uses diffferent frequeency laser lig
ght to read tthe lower layyer of
the disc, practically doubling
d
its capacity to 2.66GB.
2
Blu--Ray Dissc
Blu-Ray players were officially released
r
in 2006.
2
This w
was the samee
c
HD-D
DVD was inttroduced. Thhe battle to ssee
time anotther format called
which format would come out on
n top was callled “The Foormat War”, and
om 2006-200
08, when Blu
u-Ray won by the sheerr numbers off
lasted fro
players sold, and the number of titles
t
that weere available . This is sim
milar
to the waar between VHS
was the cleaar winner.
V
and Betta players in the 1980s, w
where VHS w
A Blu-Raay disc can hold
h
up to 50
0GB.
RAM (Random
(
m Accesss Memory)
This is an
n input/outpu
ut device. RAM
R
is a sett of chips thaat holds dataa and program
ms while theey
are poweered. The mo
oment the po
ower is remo
oved from thhe chips, theey lose their contents.
This is why
w you will lose all of your
y
project work
w
if you haven’t saveed to disk annd someone turns
your com
mputer off, orr the power goes out.
Similar Technology:
T
Digital Cam
mera memorry cards, PlayyStation “gaame save” m
memory cardss,
Pay-Phon
ne cards.
ROM
M (Read
d Only M
Memoryy)
These ch
hips contain instructions
i
(programs / graphics) foor the compuuter which caan not be
changed by the end-u
user. The RO
OM chip is an
a output deevice.
Where ca
an you find ROM?
R
- When you
y turn on a school com
mputer and you
y see the ““DELL” logo on the screeen.
- When you
y turn on your PlayStaation or Xbo
ox and see thhe Sony or M
Microsoft Xbbox logos.
- When you
y turn on your cellpho
one and you see the “Belll” or “Teluss” logo or thhe Apple logoo.
- The paarental contro
ols on the TV
V at home.
EPROM stands for Erasable
E
Prog
grammable Read
R
Only
Memory.. This is con
nsidered an input
i
device.
wn a device called
c
a “chiip burner”, you
y can
If you ow
change th
he instructions on this ch
hip by reprog
gramming itt.
The differen
d
nce betw
ween mem
mory an
nd storaage
The term
ms memory and storage are
a often seen
n as meaningg the same thhing. Memoory refers to the
amount of
o RAM insttalled in a co
omputer, whiile storage reefers to the H
Hard Drive oor some otheer
form of semi-perman
s
nent storage.
The file cabineet represents th
he computer's hhard disk, whicch provides stoorage for all thee files
and informatio
on you need in your office. W
When you comee in to work, yoou take out thee files
you need from
m storage and put them on youur desk for easyy access whilee you work on tthem.
The desk is lik
ke memory in the
t computer: iit holds the info
formation and ddata you need tto
have handy wh
hile you're worrking.
Consider the desk-and-file-c
d
abinet metaphoor for a momennt. Imagine whhat it would be like
if every time you
y wanted to look
l
at a docum
ment or folder you had to retrrieve it from thhe file
drawer. It wou
uld slow you do
own tremendouusly, not to meention drive yoou crazy. With
adequate desk space – our metaphor
m
for meemory – you caan lay out the ddocuments in uuse
nformation from
m them immeddiately, often w
with just a glancce.
and retrieve in
Here’s ano
other importantt difference bettween memory
y and storage: tthe informationn stored on a haard disk remainns
intact even
n when the com
mputer is turned
d off. Howeverr, any data heldd in memory iss lost when the computer is tuurned
off. In ourr desk space meetaphor, it’s ass though any filles left on the ddesk at closingg time will be tthrown away.
LCD
D Monitoor
We no lo
onger use larrge glass-tub
bed monitorss, called CRT
Ts (Cathode Ray Tubes)). CRTs havve
been phaased out since 2008. Now
w, it’s unusu
ual to see a ttube monitorr. Instead, we have moveed to
using flatt screens, wh
hich use a LC
CD (Liquid Crystal Dispplay). The saame technoloogy is used iin
laptops and
a your larg
ge screen TV
V.
LCD tech
hnology worrks by block
king light. An
n LCD is maade of two
pieces off polarized glass that con
ntain a liquid
d crystal matterial
between them. A baccklight createes light that passes throuugh the
first piece of glass. At
A the same time,
t
electriccal currents ccause the
ystal molecu
ules to align to allow varrying levels oof light to
liquid cry
pass thro
ough the seco
ond piece off glass and crreate the imaages you
see.
LCD monitors have many
m
advanttages over CRTs.
C
They take up
less desk
k space, and use
u less enerrgy. They have
h
a much higher
resolution
n, and sharp
per picture th
han CRTs do
o.
In order to
t calculate resolution,
r
we
w look at th
he number off individual dots of colouur, called
PIXELs (Picture
(
Elem
ments). We calculate th
he number off horizontal ppixels by thee number off
vertical pixels.
p
LCD monitors cause less eyestraain than CRT
T monitors ddo, because eeach elementt is being turrned
y, there is no
o flicker in th
he picture.
on or offf individually
Flat screeen monitors weigh very little. They can be adju sted easily ffor height. T
They can tilt and
swivel. They
T
can eveen be mountted on the wall or on a m
monitor arm. This helps to prevent
workplacce fatigue. The
T LCD mo
onitor is an output
o
devicee.
M
Mouse
A mouse iss a small dev
vice that a coomputer userr pushes acrooss a desk
surface in order
o
to poin
nt to a place on a displayy screen and select one oor
more action
ns to take fro
om that posiition. The m
mouse first beecame a widdelyused compu
uter tool when Apple Coomputer madde it a standaard part of thhe
Apple Maccintosh. Tod
day the mousse is an integgral part of thhe Graphicaal
User Interfface (GUI) of any personnal computerr. The mousse apparentlyy got
its name by
y being abou
ut the same ssize and coloour as a toy m
mouse.
A mousee consists of a metal or plastic housin
ng (casing), tthree micro--switches, a roller, a cam
mera
and a sm
mall LED ligh
ht or a laser. As the mou
use moves accross the surrface of the w
workspace, tthe
camera taakes a picturre of what is directly und
der the mousse. This is ccompared forr “landmarkss”
with the next
n picture. In this way
y, the mousee can determ
mine which ddirection it iss being moveed in.
Although
h the mouse has become a familiar part
p of the peersonal compputer, its dessign continuees to
evolve, and
a there con
ntinue to be other
o
approaaches to poinnting or posiitioning on a display. Thhe
mouse is an input dev
vice.
Keeyboard
d
puter keyboard uses the same key arrrangement aas the mechaanical and ellectronic
The comp
typewriteer keyboardss that preced
ded the comp
puter. The kkeyboard is aan input deviice. The
standard arrangemen
nt of alphabetic keys is kn
nown as QW
WERTY (proonounced KW
WEHR-tee)
keyboard
d, its name deriving
d
from
m the arrangeement of thee five keys att the upper leeft of the thrree
rows of alphabetic
a
keeys. This arrrangement, invented
i
forr one of the eearliest mechhanical
typewriteers, dates bacck to the 187
70’s.
IB
BM 101 Key “AT Style” Keyboard
Another well-known key arrangeement is the Dvorak (proonounced duuh-VOR-ak) system, whiich
was desig
gned to be easier to learn
n and use. The
T Dvorak kkeyboard waas designed with the most
common consonants on one side of the midd
dle or home rrow and the vowels on thhe other sidee so
ng tends to alternate
a
key
y strokes back
k and forth bbetween hannds. Althouggh the Dvoraak
that typin
keyboard
d has never been
b
widely used, it has people who support it.
Dvorrak Keyboarrd
Repetittive Stra
ain Inju
uries (RS
SI) and Ergonomics
Keyboard
K
with wrist-resst and track-rroller mousee control
oard users deevelop a cum
mulative trauuma disorderr, such as carrpal tunnel
Because many keybo
syndromee, a number of ergonomiic keyboardss have been developed. Approachess include
keyboard
ds contoured
d to alleviate stress, gel filled
fi
wrist-w
wrests and buuilt-in track--roller bar too
control mouse
m
functions.
Microsoft Ergonomic
E
K
Keyboard
Printers
Printers are
a output deevices.
Priinters older thaan 1995::
Daisy Wheel:
W
This is
i one of thee oldest typess of printers.. The wheell contains eaach characterr on a
step. Thee wheel spin
ns, and then a hammer sh
hoots the steem containinng the characcter towards an
inked rib
bbon. This im
mpacts on th
he paper, creeating an imaage. The advvantage of a daisy wheel
printer, iss that it wou
uld create shaarp characterrs. The disaadvantage is that you couuld not creatte
graphics,, as the charaacters were limited
l
stricttly to numbeer and letterss.
Dot Mattrix: A 9X9 matrix of stteel pins wou
uld strike a rribbon, transsferring an im
mage onto thhe
paper. The
T advantag
ge was that you
y could usee the pins to reproduce ggraphics. Thhe disadvanttage
was the 9X9
9 matrix would
w
cause some charaacters to lookk deformed, and the imagge quality w
was
not very sharp. Thesse printers ussed “tractor feed” paper,, which had hholes along the side of tthe
T
holes fitted
f
into pin
ns on each siide of the prrinter, whichh would advaance the paper
paper. These
through the
t printer.
Priinters newer th
han 19955
Ink Jet: This printerr shoots a mist
m of ink dro
oplets towarrd the paper. Ink Jet prinnters are
comparab
bly expensiv
ve to operatee. Each printter cartridgee costs $30-$$30. The carrtridges usuaally
last abou
ut a month (w
with average family conssumption). IInk Jet printeers use a waater-based inkk,
which wiill smear wh
hen it comes in contact with
w water. IInk cartridgees can dry ouut over time,
causing missing
m
liness where the jets
j can’t pu
ush the ink thhrough the plugged holess.
Laser Prrinter: Thiss printer usess toner, a fin
ne powder, w
which is depoosited onto tthe paper. T
The
toner is th
hen “fused” (melted) on
nto the paperr. Once the ttoner is fused onto the paper, it can nnot
easily be smudged. Laser
L
printerrs print very quickly, andd although thhe cost of buuying one is
more exp
pensive than an Ink Jet printer,
p
a toner cartridge costs $100 aand can last for several yyears.
Originallly, Laser prin
nters could only
o
print in black, but nnew Laser prrinters can prrint in full
colour.
Dye Sub
blimation Prrinter: Thiss type of prin
nter uses dyees instead off inks. This aallows the prrinter
to print onto
o
fabrics, ceramic and
d plastic, wh
hich is ideal ffor printing oonto coffee m
mugs and
identificaation cards.
Modem
M
This is an
n input / outp
put device. The acronym
m stands forr MODulatorr / DEModullator.
Old modems in the 1980`s and 1990`s createed a high pitcched warblinng sound callled a carrierr
signal. Here,
H
digital information
n was changeed into soundds that couldd be carried oover the anaalog
phone lin
ne (modulatiion). When the
t signal arrrived at the destination computer, thhe sounds were
converted
d back from an analog siignal into digital inform
mation (demoodulation).
Acco
oustic Modem
m
USRob
botics 9600 V.Everything
V
g Modem
USRobootics 56K Mo
Modem
Presently
y, we still call communiccation devicees “modemss”, although tthey no longger use the
regular phone
p
line to connect. We
W use eitherr DSL (Digittal Subscribeer Line) moddems or Cabble
modems now.
DSL Modem
M
Cabble Modem