B.A. (Mahayana Studies)
000-209 Introduction to Computer Science
November 2005 - March 2006
6. Choosing a Computer
Considering the hardware
choices involved in choosing a
computer.

Overview







1. How to Choose a Computer
2. The Processor
3. The Hard Disk
4. External Data Storage
5. Keyboard / Mouse
6. The Monitor
7. The Sound Card
continued
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




8. Room for Expansion
9. Laptop Battery Life
10. The Printer
11. A Computer's Life
12. The Software
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1. How to Choose a Computer


Decide how much to spend, and stick to it.
How will you use the computer?
 what

software will you need?
Hardware issues
 desktop
or laptop?
 processor, hard disk external storage, keyboard,
mouse, monitor, sound card, printers, etc.
 when to buy?
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Windows XP

Minimum hardware for Windows XP:
 Pentium
500 MHz processor, or higher
 256 MB of RAM or more

more memory is the best way to improve XP's speed
4
GB hard drive (1.5 GB for XP)
 a Super VGA monitor with (800x600) resolution

try 1024x768 or higher with 24-bit colour
 CD-ROM
or DVD-drive
 keyboard and mouse
 sound card and speakers
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1.1. Lotus, July 2005
and 3 others
cover, mouse pad, adapter,
microphone, speakers
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Free Items:
printer, ink, table,
chair, fax modem,
50 hours on Internet,
speakers, cover,
mouse pad, adapter,
microphone,
10 CD disks,
monitor frame
6
Some Buzzwords
Others Later

DDR: Double Data Rate SDRAM; faster RAM
HDD: Hard Disk Drive
FDD: Floppy Disk Drive

CD-RW 52-32-52:




the CD drive can write data at 52x speed, it can rewrite data at
32x speed, and it can read data at 52x speed
USB: Universal Serial Bus

a plug-and-play interface between a PC and devices such as hard
drives, audio players, scanners, and printers
continued
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
AGP: Accelerated Graphics Port; speeds up 3D


many companies sell AGP-compatible graphics cards
10/100 LAN: Local Area Network

dual speed 10/100 Mbps (bits/sec) with auto-sensing

HT: hyper threading; multiple threads of execution

VIA: VIA Technologies, Taiwan; makes motherboards
FSB: Front Side Bus; links motherboard to the CPU

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2. The Processor

Chip makers assign model numbers or names
to processors.
 the
chip model indicates the processor’s
architecture

Each new model is faster, with other
enhancements.
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Intel Chips

Pentium 4 with hyper-threading
 3.00
to 3.80 GHz
 model numbers include 670, 660, 650, 640, 630
571, 570J, 561, 560J, 560, 551, 550J, 550, 541, 540J,
540, 531, 530J, 530, 521, 520J, 520

Celeron
 can
do the same operations as the Pentium
 less expensive, but slower
 950 MHz to 2.80 GHz
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Intel Chip History

1982: Intel 286
 134,000

1985: Intel 386
 275,000

transistors, 33 MHz
1989: Intel 486
 1.2

transistors, 12.5 MHz clock speed
million transistors, 50 MHz
1995: Pentium Pro
 5.5
million transistors, 200 MHz
continued
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
1999: Pentium 3
 28

million transistors, 733 MHz
2000: Pentium 4
 42
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million transistors, 1.5 GHz (1500 MHz)
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Part of Intel's Range in 2005

Desktop


PentiumExtreme Edition, Pentium D,
Pentium 4 supporting Hyper-Threading,
Pentium 4, Celeron D, Celeron
Notebook

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Pentium M, Mobile Pentium 4 supporting Hyper-Threading,
Mobile Pentium 4, Mobile Pentium 4 Processor-M,
Celeron M, Mobile Celeron Processor
13
Factors Affecting Price

Clock speed
 indicates
how many instructions can be processed
per second


Level 1 cache - cache built into the processor
Level 2 cache - the cache is on a separate chip
 faster

than level 1 cache
Benchmark tests
a
set of standard processing tasks that measure the
performance of hardware or software
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Processor Overall Performance
July 2005 from
http://www.cpuscorecard.com/
:
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2.1. How much RAM?

The 'best' amount of RAM depends on the OS
and applications you plan to use.
 at
least 64 - 256 MB to run Windows XP
 256 MB or more is better
 a very good way of improving performance
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3. The Hard Disk

Storage capacity is measured in gigabytes (GB).
 get

at least 40 GB
Hard disk speed is usually measured in
revolutions per minute (RPM)
 the
higher the RPM , the less time you'll spend waiting
for your computer to access files
 best for desktops: 5400, 7200 RPM
 best for laptops: 4200, 5400 RPM
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Hard Drive Controllers

Disk drives are classified by their type of
controller
 the
hardware that rotates the hard disk, and moves the
read-write head

Popular drive controllers are:
 Ultra
ATA, EIDE, SCSI
 Ultra ATA is twice as fast as EIDE
 SCSI is slightly faster than EIDE
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4. External Data Storage

Floppy disk drives are on their way out.

Rewritable CDs (CD-RW) are popular.
 increasingly

with DVD support
Many computers include USB ports for flash
drives
 get
a USB port supporting version 2.0 (potentially 40x
faster than 1.1)
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Flash Drive

Uses flash memory
a
rewritable memory chip that
remembers its content without needing
a power supply (non-volatile)

A flash drive can be added/removed from the PC
while the macine is switched on (hot-swappable).

Storage capacities: 64 - 256 MB
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5. Keyboard/ Mouse
Microsoft’s Natural
Keyboard may help
prevent computer
related injuries.
Wireless
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Mouse Types





Mechanical, optical, laser mice
Cord or cordless?
How many buttons?
Mouse wheel?
Connector type
 serial
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port, USB port
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Laptop Input Choices
Track point
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Trackball
Touchpad
23
6. The Monitor

CRT (cathode ray tube) monitors use similar
technology to television sets
 inexpensive

and dependable
LCD (liquid crystal display) monitors produce
images by manipulating light within a layer of
liquid crystal cells.
 compact,
lightweight, easy to read
 standard on laptops
 flat-panel displays are available for desktops
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Flat Panel Displays

Advantages of LCD
 display
clarity
 low radiation emission
 portable
 compact

3x the price of a CRT
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Monitor Sizes

Screen size is the
measurement in inches
from one corner of the
screen diagonally across to
the opposite corner.

The viewable image size
(vis) excludes the screen's
black border from the
calculation.
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A monitor’s viewable image
size is less than the screen size.
26
Monitor Resolution

Dot pitch - a measure of image clarity
 smaller

dot pitch means a crisper image
Maximum resolution: the maximum number of
pixels a monitor can display
a
typical max. resolution is 1280 x 1024 pixels
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Graphics Cards

Often the graphics card may be a part of the
motherboard
 especially
in laptops
 the card should have 8 - 64 MB of video memory

The most powerful graphics cards are used for
3D graphics
 sometimes
called GPUs (graphics processing units)
continued
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
The main 3D graphics card manufacturers are:
 ATI

Technologies
cards: Radeon 7/8/9000 Series, Radeon X Series
 NVIDIA Corporation

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cards: GeForce including GeForce FX Series, GeForce 6
Series, GeForce 7 Series
29
SVGA Graphics Cards

Super Video Graphics Array (Super VGA or
SVGA) is the most popular display type.

SVGA graphics cards have a standard resolution
of 800x600 (480,000 pixels).

They should be able to offer resolutions up to
1280x1024, with 24-bit colour (16 million
colours).
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Laptop Display Screens

Passive matrix screen - relies on timing to make
sure the liquid crystal cells are illuminated.

Active matrix screen - updates rapidly
 essential
for crisp display of animation, video
 found on newer laptops
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7. Sound Cards

A sound cards improves a computer's sound
quality, and adds other sound capabilities:
 makes
it possible to use speakers, a stereo, and a
microphone to record and play sound
 some sound cards also include MIDI

Some sound card manufacturers
 Turtle
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Beach, Diamond, Creative Labs
32
MIDI


Musical Instrument Digital Interface
MIDI enables electronic instruments, such as
synthesizers, samplers, sequencers, and drum
machines, to communicate with one another and
with computers.
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8. Room for Expansion



When you buy a computer, make sure it has
expansion options.
Motherboard expansion slots to add peripheral
drivers.
Internal bays : mounting
brackets in the computer
case for devices.
continued
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
External bays: openings in the case so that
devices can be (temporarily) connected to the
computer.
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Laptop Expansion

PCMCIA expansion slots are found in many
laptops. Classified according to size:
 Type
1 - thinnest, for memory expansion
 Type 2 - for modems, sound cards, network cards
(most common)
 Type 3 - thickest, for hard disk drives

Make sure the laptop has plenty of USB ports (26).
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9. Laptop Battery Life

The length of time a laptop's battery will last
depends on:
 the
processor speed
 the screen type (e.g. active matrix LCD)
 how many peripherals are attached

Hot swap: the ability to swap batteries while the
computer is on.
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10. The Printer

Details to consider when choosing a printer:

Resolution
 printer
resolution is measured in dpi (dots per inch), the
number of dots it can print per linear inch
 more dpi means the final image will be clearer

Colour capability
 can
the printer support colour?
continued
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
Print speed
 print
speed is measured by pages per minute (ppm) or
characters per second (cps)
 colour printing takes longer than black and white
 text prints faster than graphics
 ten pages per minute is a typical speed
 duty cycle: the number of pages that can be printed per
month

Printer cost
 from
$100 to $5000
continued
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
Per-copy cost
 these
are the ongoing costs for the printer, including
ribbons, ink cartridges, and toner
 the cost estimate assumes that a page uses an average
amount of text, graphics, and colour

Warranty
 how
long does the warranty last for?
 does it cover all printer parts?
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Inkjet Printers

The most popular type of
printer
 it
produces low-cost colour
and black-and-white
printouts
Colour ink cartridge
Black ink cartridge
continued
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
The print head uses a series of nozzles that spray
coloured inks onto the paper
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Laser Printers

The laser in the printer charges an
electrostatically sensitive drum to accept toner
which is then fused to the paper.
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Features




Higher quality output than inkjets
More expensive to buy than inkjets
Less expensive to operate than inkjet
The toner cartridge and drum cost approx. $70
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Dot-matrix Printers?

Dot matrix printers prints by striking groups of
wires or thin rods onto an ink-coated ribbon
against paper.
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Features





Old/reliable technology: introduced in the 1970s
Low quality output
Can print onto multipart carbon forms
Used for “back-office” applications that need low
operating cost and dependability.
A $4 ribbon can print 3 million characters
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11. A Computer's Life

The lifecycle of a computer has five phases:
 product
development
 product announcement
 introduction
 maintenance
 retirement

Vaporware: computers (and software) that are
announced but never produced.
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Price Drops over Time

Toshiba Satellite





Pentium M, 1.50GHz,
256MB RAM
60 GB Hard Disk
CD RW / DVD
modem
average price
15.4 inch active matrix
display
high price
Weeks up to
July 2005
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low price
48
Computer Companies

Top-tier companies




computer business for many
years
Apple, Compaq, IBM
more expensive computers
responsible for many
innovations

Second-tier companies




newer companies
Gateway, Packard Bell, Dell
less expensive computers,
same quality
limited research and
development
continued
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
Third-tier companies






smaller startup companies
sell locally
less expensive
may use poorer quality
components
more likely to go out of
business
technical support depends on
the owner
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
Build your own



readily available parts
relatively easy assembly
customize to your own
needs
50
12. The Software

Software publishers produce software

Alpha test: first phase of testing done in-house
Beta test: conducted by off-site tester

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Software Versioning

The original version (release) of software is
typically version 1.0
a
new version is indicated by a new number (e.g. 2.0)
 a new version is usually a major improvement

Revision: a release that fix bugs or makes small
changes
 the
revision number is separated from the version
number with a period (e.g. 1.1)
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Software Pricing Issues


Street price: average discounted price
Version upgrade price: discounted price for owners of an
earlier version of the software

must show proof to the vendor

Competitive upgrade: special price for switching to a
competitor’s product

Upgrading software is important


less technical support for older versions
may lose eligibility for special pricing
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Other Software Issues



Compatibility with hardware/OS
Warranty
Technical Support
 help-lines,
local user groups, personal service
 Web-based technical sites, newsgroups, mailing lists
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