Computer Science 1000
Terminology III
Permission to redistribute these slides is strictly prohibited without permission

Motherboard
a printed circuit board
 the “connection” for your
other components

CPU
 RAM
 persistent storage
 input and output
 etc (power .. )


Motherboard

in addition to connecting components,
motherboards offer some built-in
functionality
stores first instructions executed by CPU (BIOS)
 video/audio output
 network connectivity


some of these are optional, depending on
the board

Motherboard

motherboards have many distinguishing
features
CPU socket (vendor-specific)
 RAM slots (more slots = more RAM
availability)
 data transfer speeds
 available ports (e.g. # of USB connections)


Motherboard - Ports


one of the most important features provided by motherboards
is the port
a port is an interface to your computer, for connecting a
device






keyboard
mouse
display
speakers
etc
without ports, we would effectively have no way to
communicate with the computer

Motherboard – Ports

you see ports all the time on your desktop/laptops
You have probably seen these on the
back of your machine.
http://ixbtlabs.com/articles3/mainboard/gigabyte-ma770t-ud3p-770-p1.html
http://images.yourdictionary.com/pc-input-output

Motherboard – Ports

you see ports all the time on your desktop/laptops
Inside the box, we see that the ports are
simply part of the motherboard
http://ixbtlabs.com/articles3/mainboard/gigabyte-ma770t-ud3p-770-p1.html
http://images.yourdictionary.com/pc-input-output

Motherboard – Ports

there are many types of ports available
video: VGA, DVI, HDMI
 network: LAN
 general connectivity: USB, PS/2
 plus many others


we can’t cover them all, but we’ll consider a few
common terms that you might hear

Display Ports – Analog vs. Digital


a variety of ports exist for connecting your display
one of the primary differences: analog vs. digital


engineering details beyond scope of class – we’ll keep it
simple
analog connector:



a constant (non-pulse) electric signal
signal can take on any “value” between
its lowest and highest intensity
example: VGA connector

Display Ports – Analog vs. Digital

digital connector




signal is a series of pulses
each pulse is the same length
create a series of 0s and 1s
example:


DVI-D
HDMI
http://www.justanswer.com/tv-repair/4d8nr-does-tv-connection-hdmi-cable-can-t-find.html

Display Ports – Analog vs. Digital

analog – advantages


comparatively inexpensive (usually)
in theory, no limit to colour variations



humans can’t distinguish infinitely many colours
your computer doesn’t store infinitely many colours
analog - disadvantages



subject to signal noise outside of cord
images stored in computer are digital, so they must be
converted
less clear at larger resolutions

Display Ports – Analog vs. Digital

digital – advantages




digital - disadvantages


no conversion from internal representation necessary
signals less susceptible to noise
sharper, especially at large resolutions
typically more expensive (less difference in recent times)
digital ports are typically favoured over analog ports

USB


stands for universal serial bus
a protocol for transmitting data



was designed specifically to make improve connections
between devices and computer



not the hardware itself
hardware is built to support USB
faster
universal (hence the name)
billions of devices today have USB support*
*http://www.pcworld.com/article/156494/superspeed_usb.html

USB

what does universal mean?


in the old days (before USB):




used (almost) universally amongst devices
your mouse/joystick would connect via a serial port or PS/2
your keyboard would connect via an AT (ISA) port or PS/2
your printer/zip drive would connect via a parallel port
now:


most devices connect via USB
furthermore, more than one device can be connected to a single port
(using a hub)
*http://hlasrinkosgorobogor.wordpress.com/2008/06/05/keyboard0/
http://2.bp.blogspot.com/-RSVGM9fJSBQ/Tk-yHnrC7BI/AAAAAAAAAfU/9by6cOS5U1o/s1600/Parallel-Port.jpg

USB - Speed

on its third iteration






USB 1.0 (Full Speed): 1996
USB 2.0 (High Speed): 2000
USB 3.0 (Super Speed): 2008
each iteration has improvements in speed
speed is measured using bandwidth
bandwidth is the amount of data that can be transmitted in a
fixed time



typically measured in bps (bits per second)
for example, if a connection can transfer data at 100 Kbps, then it can
transfer 100,000 bits every second
term is often used in mobile contracts and web hosting, to denote
maximum data transfer in a month (though this is a bit of a misuse*)
*http://www.mainhosting.com/web_hosting/bandwidth/

USB – Speed*
*http://www.totalphase.com/support/kb/10048/

Cards

small circuit boards that plug into motherboard



these cards are designed to augment the existing
functionality of motherboard


resemble the motherboard (but smaller)
also called daughterboards (not a popular term)
offer additional ports
common cards:


NIC (network interface cards)
video cards

Cards
This is an
example of a card
(NIC)…
… that plugs into
your motherboard …
… and gives you an
extra network port.
http://reviews.cnet.com/i/ff/wp/0128/step4_300.gif
http://i01.i.aliimg.com/img/pb/012/494/233/1262617804208_hz_myalibaba_web6_825.jpg
http://www.plus.net/images/support/broadband/gaming/computer_ethernet.png

Video Cards

a very popular type of card


primary purpose is to send video to your display


most mid- to high end machines have a video card
video means any visual display, not just imagery
what’s the big deal?


of all that your computer does, rendering video is one of its
bigger jobs
to see why, let’s revisit how imagery is stored/displayed

Computer Display


the primary method of computer output
imagery is rendered onto a computer monitor






text
images
video
animation
exact details of how imagery is rendered (e.g.
refresh rate) is beyond our current scope
for now, we will take a very simplistic view

Computer Display





your screen is essentially a 2 dimensional grid of squares
each grid cell is called a pixel (for picture element)
each pixel has a single colour
however, because the pixels are so small, we don’t see their
edges, and detect a smooth image
example:
http://en.wikipedia.org/wiki/Pixelation

Computer Display


the number of pixels defines your resolution
resolution is typically defined as two numbers



higher resolution is typically
preferred


e.g. 1280 x 1024
this means that my display is made up of 1280 pixels across,
and 1024 pixels down
sharper image
low resolution used in some
circumstances

e.g. identity protection
http://info.universalprinting.com/Portals/65507/images/Kittens.jpg
http://theglobalnews-terrorists.blogspot.com/2009/03/pixelated-faced-babies-on-increase.html

Pixel Colour


recall that I mentioned that a pixel colour is defined
by a series of bits
more bits = more pixel values




1-bit (monochrome): 2 values
16-bit: (High color): 65,536 values
24-bit: (True color): over 16 million
32-bit: (True color + transparency): over 4 billion

Colour Model


the colours defined by each series of bits depends on the
colour model
example: RGB (red-green-blue)



each colour is made up of a combination of red, green, and blue
the intensity of each colour determines the colour that we see
examples:






no red, no green, no blue = black
full red, no green, no blue = red
full red, full green, no blue = yellow
full red, no green, full blue = magenta
full red, full green, full blue = white
half red, no green, no blue = darker red

Computer Display – Subpixels


for LCD displays, each pixel is actually made up of
subpixels
for RGB display



each pixel has a distinct red, green, and blue component
too small for naked eye to detect
shown through microphotography

Example:

note: this is using a BGR display
from: http://electronics.howstuffworks.com/lcd5.htm

Colour Model - Representation

consider 24-bit RGB





8 bits = 255 possible levels for each colour



each colour has 24 bits to represent it
the first 8 bits represent its red channel
the next 8 bits represent its green channel
the last 8 bits represent its blue channel
00000000 = no colour
11111111 = full colour
hence, to represent magenta:



full red: 11111111
no green: 00000000
full blue: 11111111
=111111110000000011111111

Computer Display

revisiting my previous question: What’s the big deal?


each pixel must be stored before it is sent to output
each pixel represented as a series of bits



there are a lot of pixels on our screens



example used 24-bit
most of your desktops/laptops likely use 32-bit (an extra channel for
transparency)
my display: 1280x1024 = 1,310,720 pixels!
HD 1080: 1920x1080 = 2,073,600 pixels!
as a consequence, display requires considerable memory



2,073,600 pixels x 32 bits per pixel = 66.4 Mb (8 MB)
remember, that’s just for one screenshot
some applications (e.g. games) require buffering, or storing more than one
screenshot at a time

Computer Display

furthermore:

your screen is constantly being updated:




movies must be rendered




movies are just multiple images that are drawn quickly
these images must be sent to output
common rates: 30 frames per second
computer game imagery must be rendered



new images are displayed
your cursor moves
one window moves in front of another
textures on player characters
shadows
as a consequence, display requires a lot of processing

Computer Display

on many machines (particularly less-expensive
varieties):



however, because video is demanding, this takes
resources from your other applications


processing for display done by CPU
data stored in RAM
and performance suffers
solution: a video card

Back to Video Cards


what is so interesting about a video
card is that they share many features of
your computer in general
processing




like your computer, a video card has a
processor
instead of a CPU, it is called a GPU
(Graphics Processing Unit)
similar to CPU, but optimized for graphics
rendering (math and geometry calculations)
this GPU works so hard, it typically has its
own fan
http://computer.howstuffworks.com/graphics-card3.htm

Back to Video Cards


what is so interesting about a video
card is that they share many features of
your computer in general
memory



like your computer, a video card has RAM
volatile, like your computer RAM
typically less than your computer RAM

512MB-2GB is common, although bigger
cards are being produced
http://computer.howstuffworks.com/graphics-card3.htm

Video Cards

Video Cards

improve performance in two ways:
hardware is optimized for graphics
 relieves your CPU and RAM of a lot of work
for high-performance applications (e.g. newer
games), video cards make an incredible difference

