# My lecture notes - IT 318 by jianghongl

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Terms - memorize these
Term        Units          Unit Abbrev   Symbol                         Meaning
Voltage      Volts            V           E                 ElectroMotive Force (EMF)
Current      Amperes          A           I                 Flow of electrons
Resistance   Ohms                        R                 Opposition to electron flow
Power        Watts            W           P                 Energy/unit time – Joules/sec
Frequency    Hertz            Hz          f                 Cycles/sec
1 F = 1 Coulomb (6.24 x 1018
Capacitance     Farads        F               C             electrons) at 1 Volt

Scientific Prefixes - memorize these (p. 5 of packet)
Prefix Name         Symbol       Multiplier      Prefix Name             Symbol    Multiplier
-3
milli            m              10               kilo                k            103
-6
micro            µ              10               Mega                M            106
-9
nano             n              10               Giga                G            109
-12
pico             p              10               Tera                T            1012
-15
femto            f              10               Peta                P            1015
-18
atto             a              10               Exa                 E            1018
-21
zepto            z              10               Zetta               Z            1021
-24
yocto            y              10               Yotta               Y            1024

These are used in engineering notation, and must be used throughout this class.

Resistor Color Code:
0 = Black    5 = Green      1% = Black     five stripes
1 = Brown    6 = Blue      2% = Red
2 = Red      7 = Violet     5% = Gold
3 = Orange 8 = Gray         10% = Silver            four stripes
4 = Yellow 9 = White         20% = No stripe
Mnemonic: Better Boys Realize Our Young Girls Become Very Great Women
Examples:
47kΩ ±5% = yellow, violet, orange, gold       100Ω ±10% = brown, black, brown, silver
10Ω ±20% = brown, black, black, (blank)       82MΩ ±5% = gray, red, blue, gold
Orange, white, yellow, silver = 390kΩ ±10% Green, blue, green, gold = 5.6MΩ ±5%

M1: DC Electric Circuits (Supplemental, Chapter 1)
Ohm's Law: I = E/R and its derivatives
* Analogy to water, pump and faucet (*Fig 3-9, p. 47)
Power formula: P = IE and its derivatives, as well as I2R and E2/R
Go over some examples:
Power drawn by an 80% efficient, 2 HP electric motor
100 W incandescent light bulb

The Kilowatt-Hour
kW hours, measurement, calculation of total
Lab 1: Ohm's Law and Series Circuits
IT 318                 LECTURE NOTES                   (Winter/2013)                     Page 2

Series Circuits
Series
Voltage divider
RT, IT
Connected in series, each uses only a portion of the voltage (miniature Christmas lights)
Connect them in series for extra voltage

Parallel Circuits
Connect them in parallel, so they see the same voltage
Schematic diagrams of simple circuits (lights in room, flashlight w/ multiple bulbs. Discuss
analogy of load resistors to    actual loads. Connect them in parallel for longer-lasting under
higher current
Example: car battery for 12 V, 1200 A
Car battery for 24 V, 600 A
How can you make a flashlight brighter?
Does a voltage source also supply current? Why do we call them voltage sources?
Formula for RT of parallel resistors; RT < smallest of resistors
RT = 1/R1 + 1/R2 + ... + 1/RN
Discuss why this is intuitively so (that the total amount of resistance is less than the smallest)
Other useful relationships:
RT = (R1R2)/(R1 + R2) (Equation 6.5, p. 156)
If R2 >> R1, then RT has not changed appreciably
R1 = 1/10 R2, then RT = .909 R1 (10% decrease)
R1 = 1/100 R2, then RT = .990 R1 (1% decrease)
If R1 = R2, then RT = 1/2 R1
Example: amplifier driving two 8Sspeakers.
If R1 = 1/2 R2, then RT = .667 R1 (33% decrease)
If R1 = R2 = R3, then RT = 1/3 R1
If R1 = R2 = R3 = R4, then RT = 1/4 R1, Etc.!!

Lab 2: Parallel Circuits & the Power Formula

Power in Electricity
P=IE
P=I²R
P=E²/R
IT 318                LECTURE NOTES                   (Winter/2013)                Page 3
M2: Electronic Measuring Equipment (Supplemental, Chap 2)
Electronic Measuring Equipment (pp. 116 - 129)
You cannot measure anything without disturbing that which you are measuring. This in turn
means that any time you measure something, you are measuring only to some degree of
accuracy.
Accuracy: Degree of conformance to a known or given reference or standard.
Precision: Degree of repeatability; gives same reading each time for identical stimulus.
Resolution: The smallest increment that can be resolved. High resolution equals small
increments.
Example: True voltage = 3.00000000000 V
Reading 1 = 2.99 V---,       Accuracy = (Avg Measured-Actual)/Actual=(2.997-3.0)/3.0=.1%
Reading 3 = 3.01 V—-                            (3.01 - 2.99)/2.997 = .667%
Resolution = 1 part of 1000 (0 to 999) = .1%
Voltage measurement, parallel effects
1 M input impedance, circuit = 10 k, 10 k , 10 V.
1M input impedance, circuit = 10 M, 10 M, 10 V.
Current measurement, series effects
1 input impedance, circuit = 10 k, 10 k (parallel), 10 V.
1 input impedance, circuit = 1, 1, (parallel), 10 V.
Input impedance of various meters:
DMM: 10 M (voltage, other parallel measurements)
.01 (current)
Analog: 20 k /V (voltage, other parallel measurements)
.1 (current)
Oscilloscope: 1 M (x1 probe), 10 M (x10 probe) - (voltage, other parallel measurements)
Special probe required to measure current.
Note: Article on instrumentation loading: Electronic Design, Mar 17, 1997, pp. 155-162; by
Howard Johnson. "Probing High-Speed Digital Designs"

Operation of oscilloscopes
& Demo: Oscilloscope, function generator, power supply
@ Four main sections of scope (@Handout: Setting the Controls)
Screen control: intensity, focus, astigmatism, scale illumination, beam finder
Vertical amplifier
Cover various amounts of amplification
Horizontal timebase
Cover variable time/div sweeps
Triggering
Demonstrate need for and operation of triggering
Scope ground lead is connected to earth ground; do not try to make it otherwise.

Lab #3: Electronic Measuring Equipment

M3: Resistance, Resistors & Potentiometers (Lunt Chap 3)
Resistance opposes the flow of current and converts electrical flow (current) to heat.
Everything has resistance, except for superconductors.
Range of resistivities, division in to conductors, insulators, semi-conductors
IT 318                   LECTURE NOTES                   (Winter/2013)              Page 4
Lunt, CHAPTER 3: FIXED AND VARIABLE RESISTORS
@3.1: Fixed Resistors (@take envelope)
If the transistor is the star of the show, the resistor is the warm-up group (lead show)
Desirable characteristics:
Low age drift                           Low cost
Can handle current surges               Low parasitics
High reliability                        Small size
Low temperature drift                   Low (tight) tolerance
Wide range of values
IC resistors
*Carbon comp resistors (*Fig 3.1)
***Carbon and metal film resistors (***Figs 3.2, 3.3, 3.4)
**Network resistors (**Figs 3.5, 3.6)
**Wirewound resistors (**Figs 3.8 , 3.9)
*Chip resistors (*Fig 3.10)
*MELF resistors (*Fig 3.11)
*Summary (*Table 3.1)

@3.2: Variable Resistors (@take envelope)
Difference between pot and rheostat
Use of limiting resistor for rheostat applications
*Types: ceramic substrate (*Fig 3.15)
*      Wirewound (*Fig 3.16)
IT 318                 LECTURE NOTES                  (Winter/2013)                    Page 5

M4: AC Electric Circuits (Supplemental, Chap 3)
Alternating Voltage and Current
AC waveforms:
Triangle
Sawtooth
Square
Sinusoidal (the big one for analysis, & for power generation & distribution)
Why the sine wave is sinusoidal
*       Basic generator output voltage (*Figure 2-2, p. 38)
Analogy to pedaling a bicycle
Basic equation: v = Vp sin Θ
Units of Measure for AC Voltages and Currents
Vpeak, Vp-p, Vrms – go over examples of each
Go over relation between each, and why Vrms is used
Calculating power consumption in AC circuits
Frequency, Phasors, and Angular Velocity
f = 1/t; t = 1/f --- Go over examples, especially in estimating
* Phasors (*Fig 2-5, p. 40)
Review of complex algebra
Relating back to the Pythagorean Theorem, we know that z/Θ represents the hypotenuse of a
right triangle, and that from this information we can find the remaining two sides.
Likewise, x + jy represents the two sides of a right triangle, and that from this information,
we can find the length and angle of the hypotenuse.
z = √(x2 + y2)         x = z cos Θ        Vectors in electronics:
Θ = arctan (y/x)       y = z sin Θ        1+1≠2; if: (1/90°) + (1/-90°) it = 0!
Practice a few on your calculators, then learn how to use the shortcut your calculator has.
A few sanity checks:
3 + j4 = 5; 6 + j8 = 10; 30 + j40 = 50; 60 + j80 = 100; etc.; all / 's = 53.13°
1 + j1 = 1.414; 2+j2 = 2√2 = 2.828; 3+j3 = 2√3; all / 's = 45°
Hypotenuse must be longer than either side; both sides must be shorter than hypotenuse.
If j component > x component, / > 45°
If j component < x component, / < 45°
Inductance
"Since every current flow produces a magnetic field, and the field strength depends on the
current strength, this means that an alternating current produces a magnetic field that is
constantly varying in strength, and therefore induces a voltage in the circuit. The polarity of the
voltage thus induced always opposes the change in the current." (Packet, p. 42, first paragraph of
section 2-4). This property is known as self-inductance, or just inductance.
Thus, inductance opposes changes in the current. Therefore, in inductive circuits, the current
changes lag the voltage changes, or vice versa (ELI). This type of opposition to current
flow is known as reactance, and its symbol is X; units are Ohms (Ω).
XL is frequency dependent
XL = 2πfL (equation 2-7, p. 44)
Example: find the reactance of a 45µH inductor at 10.7 MHz. (XL = 2π (10.7MHz)(45µH)
3.025 kΩ
Analogy: hanging a mass on a spring (I=mass); also inertia in a moving mass on a frictionless
surface.
Inductors in series and in parallel
Inductors
IT 318                  LECTURE NOTES                    (Winter/2013)                      Page 6

Capacitance
Go over buildup of charge between two insulated, conductive plates; one electron at a time.
Analogy to 2-ported reservoir with diaphragm separating ports.
The current changes instantaneously, while the charge takes time to accumulate; thus the voltage
cannot change quickly, and therefore lags (ICE).
Thus, capacitance opposes changes in the voltage. This type of opposition to current flow is also
known as reactance, but is capacitive (XC). Units are Ohms (Ω).
XC is also frequency dependent, but is inversely proportional:
XC = 1/2πfC (equation 2-13, p. 46)
Example
Capacitors in series and in parallel

Lunt, CHAPTER 4: FIXED AND VARIABLE CAPACITORS
@4.1: Fixed Capacitors (@take envelope and supercapacitors)
Review of factors contributing to capacitance:
( 0 )(r )(a )
C
d        , which for a vacuum (εr = 1.00), a = 1m2, and d = 1m:
( 8.85x 1012 )(1.00)(1.0 m 2 )
C                                   8.85x 1012 , or8.85pF
1m
Analogy of reservoir with diaphragm
Desirable characteristics:
Low leakage -------------------------------------------------------------------┐
High dielectric strength; discuss relationship to thickness and size           │
*      Small size (*Table 4.1: dielectric strengths and constants)                    │
Low dissipation factor                                                         │
Wide value range                                                              │
Tight tolerance                                                               │
Wide useful frequency range                                                   ├Table 4.2
Wide value range                                                              │
Low cost                                                                      │
Low parasitic inductance and resistance (ESR)                                 │
Excellent temperature stability                                               │
Low dielectric absorption ----------------------------------------------------┘
*Comparison of various capacitor types (*Table 4.2)
Note 5 basic families of capacitor types and their similar characteristics
Discuss the manufacturing of electrolytics and super ’lytics.

@4.2: Variable Capacitors (@take one)
Both trimmer and user-variable
IT 318                 LECTURE NOTES                 (Winter/2013)                   Page 7

Transformers
Close proximity of two coils, one driven (primary), the other loaded (secondary).
ONLY works with AC; discuss why
* Symbol and construction (*Fig 2-15, p. 48)
Significance of turns ratio:
Vs/Vp = Ns/Np
Thus, I can step voltage up or down.
But: I can't get more power out than I put in (2nd law of thermodynamics, or law of entropy), so:
Ip/Is = Ns/Np
So, when I step voltage UP, the current gets stepped DOWN by the same amount;
AND vice versa.
Series Circuits Containing Resistance and Reactance
These are the real types of circuits; only imaginary circuits contain only one of these, although
many times we can ignore one as insignificant.
Resistive loads: heaters, power-corrected power supplies
Combination of R & X = Z, which is the vector sum of R + X.
Impedance Calculations for Series RX Circuits
Add all the resistive elements, then all the reactive elements, then find the result.
Example (from packet): R1=1k Ω; XC1=3k Ω; R2=2k Ω; XC2=1.5k Ω
RT=3k Ω; XT=4.5k Ω; Z = 5.41k Ω /56.3°
Example 2: f = 455 kHz; C = 116.6 pF; R = 1.0k Ω; L = 1.224 mH; V = 10 Vrms
ZT = 1.0 k +j500 Ω = 1.118 k Ω /26.56°
IT = (10 V/0°) / (1.118 k Ω /26.57° = 8.945 mA/-26.57°
vR = iR * R = 8.945 V/-26.57°
vL = iL * XL = 31.3V/63.43°
vC = iC * XC = 26.83V/-116.57°
Series LCR Circuits
Plot of XL and XC versus frequency
Note that Z = R + j(XL - XC).
Resonance
@ Note particularly what happens at XL = XC (@Handout of resonance plot)
Reactive elements store energy from the source, then give it back. But work is required to store
the energy first, so the source must supply this energy. Each cycle, this energy must be restored
to the reactive elements; thus the source is required to provide this energy, even though it is
given back. At resonance, with pure reactances, the energy is merely traded between C and L.
At resonance:
Z=R                 Q = 1/R √ (LC)
XL = XC
Φ = 0°
fr = 1/2π√ (LC)
Importance in tuned circuits
Circuit Q
Q = quality of tuned resonant circuit; depends generally on L, and on RL specifically. Q = XL/R.
Thus there are two ways to raise the Q: lower the resistance, or increase XL, most easily by
raising the frequency.
* BW = fr/Q; discuss the need for narrow bandwidths most of the time. (*Fig 2-31, p. 59)
IT 318                 LECTURE NOTES                  (Winter/2013)                    Page 8

M5: Motors (PowerPoint presentation; also Supplemental, Chap 4)
Main point: understand motor types, their characteristics and their applications.

M6: Connectors; Safety (Lunt, Chap 5; pp 7-9)
CHAPTER 5: DISCRETE TRANSISTORS AND DIODES; CONNECTORS
@5.2: Connectors (@take some)
*Fig 5.2 - Failures in electronic systems and their causes
Permanent, semi-permanent: chapter 11. This chapter: separable only
Specifications:
# of pins
Current
Voltage
Operating temperature range
# of mating cycles
Environmental conditions (dust, humidity, vibration)
Insertion force (per pin)
Physical size, weight
Problems in making a good connection: dirt, dust, oxide
Solutions:
*3-step operation of the actual connection part: contact, swage, swipe (*Fig 5.4)
Precious metals                                Hard contact metals for higher voltages
Note the many choices that exist for materials for the housing, pins, plating, wire, & insulation.

Safety (pp. 109 - 115) - read: http://web.bsu.edu/tti/3_3/3_3h.htm
@Video: Edit Electrocution (12 minutes)
Indirect Dangers:
Spark in combustible atmosphere
Surprise reaction
Direct Dangers:
Fibrillation
Burns
* *Figure 3-1, Effects of 60 Hz Electric Shock, from "Student Reference Manual for Electronic
Instrumentation Laboratories”.
Discuss Ohm's Law in relation to your body.
Skin: about 5 kOhms - 100 kOhms, depending on many factors. At 120 Vrms, 5 kOhms =
24 mA; 100 kOhms = 1.2 mA (not noticeable).
Very wet skin .1 kOhms; at 50 Vrms = 50 mA.
Try to keep the current from flowing through your heart (only use one hand)
Respect electricity; anything above 50 V can kill you directly; any electricity can kill you
Indirectly
Maximum safe voltage
How GFIs work
IT 318              LECTURE NOTES                  (Winter/2013)                   Page 9

M7: IC Manufacturing (Lunt, Chap 6)
CHAPTER 6: HISTORY, SUBSTRATES AND PATTERNING
6.1: Introduction
Level 0 only this chapter; levels 1-3 in later chapters.
6.2: IC Manufacturing (Level 0): Chips
Complexity of making ICs: 500 steps, alignment to 10 nm; 6 months. Facilities incredibly expensive
to build, equip, operate, maintain.
Average # of engineers/project = 50
Mask set = \$3M; EUV photolithography tool=\$60M (2010)
Average project length = 12 months (Design costs = 50*1*\$125,000 = \$6.25M = 80% total
cost)
Average re-spin cost = \$192,000                    Synthesis, place & route ≈4%
Configuration errors = 15%                        Hardware validation ≈8%
Expected revenue = \$32,744,625
Development margin = 20% –From “Distributed Design Teams: Survival of the Best
Connected”, by Ron Schneiderman, Electronic Design, 11/24/03, pp 66-72
*Out of IC mfg came the AFM and STM, new microscopes that allow atomic-level probing. *IBM
spelled with Xenon atoms on nickel substrate
ICs are at the foundation of modern society; essentially all modern products depend directly or
indirectly on them.
Moore’s “law” has held true for almost 40 years; presently we can put >100G transistors on a chip
# of off-the-shelf choices number >100,000.
Making the substrates: silicon mostly by the Czochralski method; results in monocrystalline growth
of the highest-purity material in the world. (*Fig 6.1)
*Sliced using an inside-diameter saw (a very thin band of diamond-coated metal stretched tight)
@ (*Fig 6.2) @take 8" wafer and 3" wafers
Main manufacturing processes: patterning; adding materials; removing materials
Photoresists:
Positive-acting (softened by exposure) = novolac resin w/ DNQ for Photo-Active Compound
(PAC) (DNQ = diazonaphthoquinones
Negative-acting (hardened by exposure) = cyclic synthetic rubber resin w/ bis-arylazide for PAC.
**Photolithography is main tool for patterning (*Fig 6.4; Fig 6.5)
Three main advantages of present photolithography:
1. Many chips can be done at the same time
2. Resolution limited mainly by λ, which can be quite small.
3. Can be highly automated.
**Main tool for photolithography: stepper (*Fig 6.6, 6.7)
Issues in photolithography: λ of process primarily limited by λ of light source, which is not small
enough. Problems:
Light must be monochromatic
Light must be collimated and in-phase helps even more.
Must be able to focus and move light (using optics or something!)
Presently we use deep UV (235 nm; moving to 150 nm), which requires calcium flourite optics
Much research going on in e-beam and x-ray for this, but nothing practical yet.
From “Preserving Moore’s Law Pushes Lithography to its Limits”, Marie Freebody, Photonics
Spectra, May 2011, p. 45:
“Keeping up with Moore’s Law over the past four decades has seen lithography wavelengths
drop from the 436 and 365 nm produced by mercury arc lamps to 248 nm by the krypton fluoride
excimer laser. In 1998, a group at MIT’s Lincoln Laboratory developed a 193-nm source with the
argon fluoride laser, which is used to produce today’s 45- and 32-nm IC technologies.”
“But the biggest question in the field today is this: What imaging method will be used to pattern
features that are 22 nm and below? Will shorter wavelengths such as the long-awaited extreme-
ultraviolet (EUV) be the answer, or can Moore’s Law be extended by other means?”
IT 318                  LECTURE NOTES                 (Winter/2013)                 Page 10
Other approaches used to push lithography even further include phase-shift masks, improved the
chemistry of photoresists, fabricated lenses with high NAs, and developed immersion lithography.

*IC dimensions (*Table 6.1)
Clues for remembering: hair 2-3 mils diameter, or 50-75 μm; radius of Si atom = 1.46 Å; spacing
between Si atoms = 4 Å. About 25 μm in a mil; about 40 mils in a mm.

SEEING DOUBLE: Some day chips might be made with X-rays. Until then, double-
patterning lithography will be the only game in town. By Chris A. Mack; IEEE
Spectrum, Nov 2008, pp 46-51.
1971: Intel introduces the 4004, the world’s first microprocessor, with 2300 transistors; capable
of 60,000 instructions/second. Today: 820 million transistors on Intel Core2 Extreme,
capable of 72GIPS.
1963: transistor cost ≈\$10, ≈ automobile tire. Today \$25/8 GB of flash memory (=64G
transistors, which = 390.6 p\$/transistor)
What’s stopping further progress? Hard limits on photolithography.
X-ray lithography, ion-beam lithography, even electron-beam lithography all work, but
only at extremely low volumes (not viable for production volumes). Issue: cycle
time (about 10-100 times too slow)
Process node ≈ .5 (λ/NA). For today’s limit of λ = 193 nm and NA = 1.35, this = 72 nm
(pitch; smallest dimension = 36 nm).
NA = 1.35 requires immersion lithography to get a refractive index >1, plus HUGE
lenses (HUGE = \$\$\$).
Photolithography tools have increased in cost: doubling every 4.4 years.
Options: EUV (down to 13.5 nm) and double-patterning lithography.
Problems with EUV: everything absorbs it (air, lenses); lenses terribly difficult (\$\$\$) to
make; sources far too weak for good cycle time; poor photoresists presently;
defects extremely hard to find and eliminate.
Problems with double-patterning: alignment (down to 2 nm); doubles lithography steps.
But EUV not available until 2011, 2012; until then, double-patterning lithography the only option.

From “Moore or Less?”, Kevin Lewis, ASEE Prism, March-April 2011, pp 38-39:
Looking farther out, carbon-based nanoelectronics – using nanotubes and nanoribbons made
out of grapheme, a single-atomic-layer sheet of carbon – is currently the leading candidate for a more
Semiconductors (ITRS) report, carbon-based nanoelectronic “exhibits high potential and is maturing
rapidly.” At the moment, though, the technology is still largely in the hands of academic researchers.
And Jeff Welser’s job is to make sure that research gets done. “The thing that’s interesting about
carbon right now is it can serve two different purposes: one, you can use it to make a FET [field-effect
transistor, the current standard], whether it’s a nanotube or graphene, that can potentially be a higher
performance FET than what you get with silicon; it also might be useful for interconnects between
silicon transistors; it’s an extremely good thermal conductor, so it might help you with getting rid of
some of the heat that you’re trying to dissipate on these chips right now. The other aspect that I think
makes carbon even more attractive as an area to put your money into far-out research is it’s got very
different physics, particularly in the grapheme, in terms of the way electrons move in it that you could
IT 318                LECTURE NOTES                   (Winter/2013)                  Page 11
use maybe to try to make totally different types of switches, maybe a switch based on spintronics,
where you’re manipulating the spin of the electron, or one based on something called pseudo-
spintronics, where you’re taking advantage of a quantum property of an electron in graphene that’s
unique to the graphene structure.”
IT 318                 LECTURE NOTES                  (Winter/2013)                   Page 12

M8: IC Manufacturing – Adding Materials (Lunt, Chap 7)
*    Dispensing and spinning: used primarily for photoresist; not a selective addition method. (*Fig
7.1)
*            Oxide growth (*Fig 7.2) for entire wafers or boats of wafers; again not done selectively. Oxide is
the main material used for patterning wafers.
Sputtering (*Fig 7.3) - mostly for metals
Evaporation (*Fig 7.4) - mostly for metals
*              CVD (*Fig 7.6) - for SiO2, Si3N4, polySi, Al2O3, other insulative materials, SiGe, metals, etc.
Very versatile, but uses many extremely dangerous feeder gases for the chemical reactions.
Note: CVD also heavily used in manufacturing optical fiber preforms.
Photochemical vapor deposition - similar to CVD, but uses light as catalyst.
Diffusion - occurs in ovens like for oxide growth; isotropic; inexpensive
*      Ion implanation - (*Fig 7.9); shoots ions of desired material into substrate (after patterning);
very expensive, but highly controllable and anisotropic. Also requires annealing afterward
*      MBE (*Fig 7.10)
IT 318                 LECTURE NOTES                  (Winter/2013)                    Page 13
M9: IC Manufacturing – Removing Materials (Lunt, Chap 8)
CHAPTER 8: REMOVING MATERIALS
Developing - used for photoresist; a chemical dissolving process for non-hardened photoresist,
very similar to developing film.
Stripping - used to remove hardened photoresist; attacks interface between hardened
photoresist and oxide beneath, causing liftoff but not dissolution. Must be filtered out of
stripping chemical.
Wet (chemical) etching - isotropic; requires chemical which dissolves exposed material to be
*       removed. (*Fig 8.1)
*   Dry (plasma) etching - anisotropic; uses chlorine or fluorine (highly reactive) (*Fig 8.2); can
*       be used to remove almost anything. Features created by this process: *Figs 8.3, 8.4
@Video: Creating an IC
Chip failure mechanisms:
Metal migration. Analogy for current flow: swarm of gnats
Localized line corrosion
Manufacturing defects
Bridging between adjacent conductive corrosion deposits
Each of the above failure mechanisms is accelerated by the presence of moisture, and other
corrosive agents in the atmosphere, so the final step in chip processing is passivation.
However, cracks may develop in this deposition
Metal migration is chiefly carried out by current densities.
All the above failure mechanisms are exacerbated by heat and moisture
Future of electronic devices
“Fundamental” limits seem to continue to move out, but eventually WILL stop us.
MOSFETs will probably not make it much beyond 2015 for cutting-edge ICs.
Other possibilities: Carbon nanotubes; molecular-level construction; quantum devices;
bioelectronics. Also see above article, SEEING DOUBLE.
IT 318                 LECTURE NOTES                 (Winter/2013)                  Page 14
M10: IC Packaging (Lunt, Chaps 9, 5)
CHAPTER 9: INTEGRATED CIRCUIT PACKAGES: PROCESSES AND MATERIALS
(LEVEL 1)
@Sometimes, the chip is the final packaging level for the IC manufacturer: @DCA, MCM, hybrids
Desirable characteristics for IC packages: (covered before in Chapter 2.2)
Provides large # of I/O pins
Allows for dissipation/removal of all the heat generated by the circuit
Structurally supports the circuit
Protects the circuit from the environment
Allows the circuit to be tested economically
Can be easily mass-produced
Very low cost
Occupies very little real estate
Very low weight
Very high reliability
*Four basic parts of IC package (*Fig 9.1)
*Categories of packages: (*Fig 9.2)
SMT vs through-hole
Peripheral leads vs array beneath package
Chip connected to frame via C4, TAB, or wire bonds
Package material = plastic (novolac: epoxy + phenolic), ceramic, or metal
Material of connection substrate = polyimide (TAB), A42/copper, organic (FR4), ceramic
(Al2O3)
** *Fig 9.3: thermocompression (a) and ultrasonic (b); also *Fig 9.4
**Tape Automated Bonding (TAB): **Figs 9.5, 9.6
*C4 (*Fig 9.7)
Package size           Pitch           Pin ruggedness           Attachment process
Speed of attachment I/O bonding speed
Packaging materials: issues
Cost      Weight             Hermeticity    Ruggedness            Thermal conductivity
*    Hermeticity (*Fig 9.8)
** Thermal conductivity (*Tables 9.1, 9.2)

CHAPTER 5: DISCRETE TRANSISTORS AND DIODES; CONNECTORS
@5.1: Discrete Transistors and Diodes (@take examples of common ones)
Discuss features of each of the main discrete package types
IT 318                LECTURE NOTES                  (Winter/2013)                  Page 15
M11: MCMs & Hybrids (Lunt, Chap 10)
CHAPTER 10: HYBIRDS, MCMs, AND PWBs
10.1: Hybrid ICs and MCMs (Level 1½)
**@ What they are: (**Figs 10.1, 10.2) (@take examples)
Advantages: greater density, less weight, lower cost @ high volumes, higher performance,
Disadv’s: high NRE costs, unfamiliar technology, not flexible for changes, KGD
Hybrids have a mixture: IC dies, chip Rs & Cs, film Rs

M12: PWB Manufacturing (Lunt, Chap 10)
10.2: Printed Wiring Boards: Fabrication
Old technology (about 1945); spawned some ideas for IC mfg.
@@*Process of making a core (*Fig 10.4) (@take sheet of FR4, @core)
*Multi-layer board (*Fig 10.5)
@video: Basic Multilayer Fabrication
Functions:
Mechanically fix components in place (solder depended upon, primarily)
Electrical connections formed (solder depended upon, primarily)
Electrically separate individual signals, voltages (dielectric)
Remove heat and spread it out
Provide testability
Desirable characteristics for conductive materials
Low-resistance         Low cost       Can be formed into thin sheets         Low CTE
High thermal conductivity
*       *Table 10.1
Desirable characteristics for substrate
Excellent insulator (high breakdown voltage, high electrical resistivity, low moisture absorption)
Chemically inert       Physically tough        Light weight Good thermal conductivity
Low CTE                Low dielectric constant          Low cost
*@      Properties of resin materials (*Table 10.2) @example of polyimide substrate in metal box
* Properties of fiber materials (*Table 10.3)
*PWB terms: via, blind via, buried via (*Fig 10.8)
PWB design: variables include shape, # of layers, thickness, width & thickness of lands, distance
between lands
*       Width & thickness of lands (*Fig 10.9)
* Distance between lands (*Table 10.4)
Future needs & challenges:
Cost, especially multilayer PWBs          Lower dielectric constant
Higher thermal conductivity               Higher frequencies
IT 318                LECTURE NOTES                   (Winter/2013)                     Page 16

M13: PWB Assembly (Lunt, Chap 11)
CHAPTER 11: PWB ASSEMBLIES (LEVEL 2)
@Take examples of each
Through-hole technology (old, very reliable, higher cost & size)
Insert components, clinch & trim leads
*      Wave solder (*Fig 11.1)
Surface-mount technology
**     Screen print solder paste (*Fig 11.3) for top side, or adhesive dot (*Fig 11.4) for top side
Place components
Reflow (for paste) or wave solder (for bottom side)
Mixed-mount technology:
Many combinations are possible and are being tried/used
Soldering
Very old, but terrific for our needs
Role of fluxes: clean oils, oxides (corrosive action); tradeoff between activity and need to
remove oxides, oils, dirt.
Role of thermal cycle in forming intermetallics
*      A good joint: (*Fig 11.5)
Common alloy for today: SAC 305 (3% Ag, 0.5%Cu, remainder - 96.5% - Sn)
*Hand Soldering Procedures: (*Fig 11.6)
Make sure the iron tip is clean. If it is a new tip, then tin it correctly:
Clean tip with fine sandpaper or steel wool until copper is bright
Heat and apply solder generously as it begins to melt
Leave tip hot and covered with solder for about 1-2 minutes, then cool
After completely cooled, reheat and wipe off excess solder
Make sure the joint to be soldered is clean and mechanically stable
Wipe tip on damp (not soaked) sponge.
Apply tip to joint; use enough area to get the heat transferred
A small amount of solder on the tip will help the heat transfer
Rosin in the solder is key to cleaning the surfaces to be soldered; the joint should be made only of
freshly melted solder.
Apply the solder to the other side of the joint and add until all surfaces are wetted. Do not use
too much or too little solder. A taper is desirable.
Remove iron and let cool naturally; do not blow on it.
Clean off flux with warm soapy water and toothbrush; alcohol is helpful sometimes

Future Challenges and Needs
Better no-clean past formulations
Better rheological agents
Finer solder spheres for lower cost
IT 318                 LECTURE NOTES                  (Winter/2013)                      Page 17

M14: Computers (Walters, Chap 1)
Text: The Essential Guide to Computing: The Story of Information Technology, by E. Garrison
Walters
Chapter 1: The Core of Computing: How the Key Elements of Hardware Work Together (pp 3-
37)
Basically, what is a computer? - An electronic instruction executer
@FDD, HDD
*Pictures of: CPUs; Motherboard; SIMMs; power supply; glue logic; cache; BIOS
Every morning when the CPU wakes up, it goes through a complete re-start:
I’m a microprocessor unit that can do whatever I’m told to do (this is hardware-designed into the
µPU). In this case, the µPU is to be the CPU of a desktop computer.
First thing I always do is go to address 0000, which points me to the system’s BIOS. BIOS does
a self-test (test memory, drives, devices); if all is well, I give control to the OS (Windows,
Apple, Linux, Unix)
OS: allows multiple programs to appear to run simultaneously on µPU; keeps track of occupied
memory, vacated memory and free memory; handles interaction with I/O devices. OS’s are
incredibly complex programs that have 4M ways they can go wrong; thus all the bugs.
*Organization of computer
*Organization of CPU
*Instruction cycle
*Storage hierarchy. Note that 1 kB = 1024 bytes; 1MB=1024 kBytes
*Memory allocation
Interrupts - analogy of working in my office; doing each task quickly creates the appearance of true
@A computer is always executing instructions; what does it do when there’s nothing to do?
@Demonstrate with Task Manager and Idle Process
What’s the future? Moore’s Law; normal and more exotic research
Carbon nanotubes; DNA research; quantum-level devices; other substrates
IT 318                LECTURE NOTES                 (Winter/2013)                    Page 18

M15: Computers (Walters, Chap 2)
Chapter 2: Memory, Storage and I/O
Loading files from disk to memory - one byte at a time, or more depending on data bus width
FAT tells where to find all the data
Discuss disk fragmentation
*Memory system of computer (*Fig 2.1, p. 43)
Access time a function of:
random/burst access mode
SRAM or DRAM
Degree of fragmentation of file/data
Data rate a function of:
Bus width, clock speed
*Role of each memory type (*Table 2.1, p. 44)
*Ways to make it go faster (*Fig 2.2, p. 47)
Need for proximity if you want speed
*20 years of change in DRAM (*Table 2.2, p. 53)
*Hard disk evolution (*Table 2.4, p. 56)
Access time a function of:
Seek time, which is a function of:
Latency, which is a function primarily of RPM
Track access time (moving head to proper track)
Degree of fragmentation of file/data
Density of data on drive
Data rate a function of:
Data density
Number of platters
The I/O Bus: a critical bottleneck
Industry Standard Architecture (ISA bus): 32 Mbps; 1982
Extended ISA (EISA): 64 Mbps; 1988
Peripheral Component Interconnect (PCI bus): 132 Mbps; 1992
PCI-X: 266 Mbps; 1998
External I/O
SCSI: 1984; 40 Mbps; SCSI2 = 80 Mbps (1995); SCSI3 (aka SCSI-160) = 160 Mbps (2000);
SCSI-320 = 320 Mbps (2006); SCSI-640 = 640 Mbps (2009)
Universal Serial Bus (USB): 1994: v. 1.0: 12 Mbps; 2000: v. 2.0: 480 Mbps; 2009: v. 3.0: 4.8
Gbps.
Firewire (IEEE 1394): 1996: 400 Mbps; 2005: 800 Mbps; declining in popularity.
Both USB and Firewire are hot-swappable
Ethernet: 10 Mbps, 1984; 100 Mbps, 1995; 1 Gbps, 2000; 10 Gbps, 2008–11–19
IT 318                LECTURE NOTES                   (Winter/2013)                    Page 19

M16: Digital Communications (Walters, Chap 10)
Chapter 10: Digital vs. Analog: Communications Basics
*The electromagnetic spectrum (*The Electromagnetic Spectrum, my file)
All of it travels at the speed of light (visible light is only one narrow portion of it); fast, but
sometimes not as fast as we’d want.
All of it can be used to transmit information, as demonstrated first by Heinrich Hertz, then by
Guglielmo Marconi (1901; first transmission across Atlantic Ocean)
The need for modulation:
Demonstrate with piece of string and teams; use message, “What hath God wrought!”
*         Things that can be modulated: amplitude, frequency, and phase (*Figs 10.3, 10.4, 10.5, pp
271, 272)
Bandwidth: the amount of spectrum used to carry information; also note that BW  capacity.
The BW required by a signal is a function of how fast it changes and how much information it
contains. Examples:
Telephone contains about 3.3kHz at the highest; BW 3kHz
Audio contains about 20 kHz at the highest; BW  20kHz
Video contains about 4.5 MHz at the highest, plus audio (to give TV), plus other 6MHz
Comparison of modulation characteristics:
Characteristics         AM         FM            Phase M                  Digital Mod
Simplicity of          Simple Complex        Very             Extremely
circuitry                                    complex          complex
Required bandwidth Low           Medium      Medium           High
Noise immunity         Low       High        High             Very high
Other advantages         None     None         None             EDC; compression; many others
Capacity of a carrier: (Shannon’s Law)
Capacity = BW * log2(1+SNR)
Example: phone lines (as exemplified by phone usage):
Capacity = 3.0 kHz * log2(1+4000) = 3.0 kHz * 11.966 = 35.898 kbps
Attenuation a complex function of frequency
LF and RF penetrates walls, travels long distances; reflected by ionosphere
Microwave, IR, visible light, etc, are line-of-sight only; also goes through ionosphere
Microwave attenuated by dust, clouds, rain; IR and up is stopped by it.
Water molecules absorb lots at certain frequencies
High frequencies contain more energy per unit bandwidth, so harder to generate at high powers.
Analog vs digital
Analog: continuously varying; infinite number of levels.
Technologies built on analog: AM, FM radio; TV; phone system; faxes; records; cassette
tapes
*         Noise and amplifier distortion which enter the wave are inseparable (*Figs 10.6, 10.7, p.
276). Extremely difficult to compress; already about as BW efficient as possible
Digital: varies in discrete increments; larger # of bits gives smaller steps (greater resolution)
Technologies built on digital: computers, floppies, CDs, DVDs, most cell phones, PDAs,
watches, cameras, toys, video games, etc.
*         Amplifiers (regenerator/amplifiers) can remove the distortion, noise, and even errors, up to
a point. (*Fig 10.9, p. 277). Can be readily compressed
IT 318                LECTURE NOTES                  (Winter/2013)                   Page 20

Sampling:
Nyquist criterion says: ≥2x highest frequency, or you lose something and get artifacts.
Example: audio has highest freq = 20 kHz; sampling rate used = 44.1 kHz
*   Recovered wave smoothness proportional to sampling rate (*Figs 10.11, 10.12, 10.13, 10.14, pp
279, 280, 281).
Resolution a direct function of #bits/sample:
4 bits = 16 steps; 8 bits = 256 steps; CDs use 16-bit samples. Most people can’t hear the
difference between 16 and 18 or 20 bits, but some claim it is audible.
So what does it take?
Audio: 44.1 ksamples/sec * 16 bits/sample = 705.6 kbps (per channel); stereo = twice that.
Video (TV): 486 x 720 pixels for NTSC * 10 bits per pixel * 30 frames/sec = 104.98 Mbps.
What capacity do we have in a 6MHz channel? - Comes out to about 19.3 Mbps
HDTV: 720 x 1280 pixels * 10 bits/pixel * 30 frames/sec = 276.48 Mbps
So how do you put an elephant through a straw?
Data Compression
Content-based:
Spatial compression: compresses the information in a single frame. Example with a picture.
Temporal compression: compresses the information between frames. Example with
changes between frames for a picture
JPEG standards (Joint Photographic Experts Group): .jpg files
MPEG standards: 1, 2, MP3, and 4 - adaptations of JPEG standards for moving pictures
Lossless vs. lossy compression
Lossy can compress more, but cannot be counted on to produce the exact original info. Fine
for video and audio if the stuff lost is imperceptible.
Lossless necessary with things like computer data, but cannot achieve great compression.
Noncontent-based: (based on data patterns)
Codes or dictionaries to represent repeating patterns of bits. Can give significant amounts
of compression on computer data, because it does not have random irregularities (noise)
as does video and audio data.
Statistical or Huffman codes: some patterns of data repeat more often than others; short
codes can be used to represent them, using longer codes for less-often repeating
patterns. Morse code is an example of this.
End result: digital video needs 3 Mbps; we have room for 19.3 Mbps!
Error Detection and Correction
When errors occur in digital, they must be at least detected, and if possible, corrected.
Error detection always relies on redundant information being added.
Simplest form of error detection: parity checking.
Example: adding even or odd parity bit to byte. Will detect 1-bit errors.
Next more complicated form: CRC, which adds a byte or more to the end of a packet or string.
Will detect most 1-bit errors, fewer 2-bit errors, fewer 3-bit errors, etc.
Most complicated form: forward error detection/correction
Redundant information added directly into data pattern in a complex, calculated method.
Example: FEC used at IBM for ½-inch tape, or at JPL for Voyager 1 & 2.
IT 318                LECTURE NOTES                  (Winter/2013)                     Page 21

M17: Industrial Networking (Walters, Chaps 11)
Chapter 11: Network Fundamentals
Overview
Mailroom analogy used in book; actually quite similar and useful. Files are broken up into packets, for
purposes of standardizing the material transmitted. A packet is like a letter, in that it contains all
necessary information to allow it to travel by whatever means, through whatever locations, to
reach the end destination.
Sending a File
TCP/IP: Transmission Control Protocol/Internet Protocol - the big rules for sending packets over the
Internet.
*   Internet: loosely connected group of computers, basically world wide, to which any computer
may be connected. (*Fig 11.4, p. 312)
Protocol: formal set of rules which must be followed for effective communication to occur.
*   Packet: contains letter info (sender addr, destination addr), plus wrapper to protect contents (error
detection/correction bits), plus sequence # (to know how to put it back together) (*Fig 11.1, p.
304)
Frame: higher-level envelope, using any of several protocols for its definition.
Router: opens envelope, finds destination address for each packet, determines best path there,
wraps it back up, and sends it on its way.
Allows use of any transmission medium
Allows use of any transmission format or standard
Allows transmission of all data types
Can grow to any size
Essentially infinitely flexible
The Importance of Packets
Dial-up phone lines used previously; dedicated connection for the duration of the link. Wasted
BW, but only way at the time. Used modems (modulator/demodulator).
Freeways are obviously much more efficient, because traffic may share each lane, instead of
needing a dedicated lane for each vehicle.
5 Issues with packets: (not issues with switched circuits)
Common addressing scheme for all packets
Routing necessary; algorithms of cost, distance, congestion, etc.
Sequencing must be recoverable
Accuracy essential (data integrity)
Latency and jitter must be within acceptable limits; primarily an issue with streaming audio,
video, phone service
Packet loss rate or ratio: % of packets lost
*   Anatomy of a packet (*Fig 11.1, p. 304)
Issues of packet size:
Fixed wastes packet bits, but only in last packet of each file
Packet sizes are therefore usually a function of data type (more on this later)
Protocol Stacks
ISO/OSI model uses 7 layers, 4 of which are most useful to us. Table 11.1 summarizes the function
of each layer. For our purposes, suffice it to say that each higher layer encapsulates
the layers below it into another envelope for transmission and 5 packet issues above. This
model allows for maximum flexibility in options for each layer, along with interoperability
among different vendor products.
IT 318                 LECTURE NOTES                     (Winter/2013)                     Page 22

Getting from A to B: Circuits, Virtual Circuits, and Circuitless Approaches

Network Type          How Switched?             Persistence of Link               Bandwidth
1        Circuit                      Permanent                    Highest; dedicated
2        Circuit                      Temporary                    Medium; dial-up
3        Packet                       None; no circuit             Low-Medium
4         Packet                      Virtual circuit                 High
Above table a summary of information presented on pp. 310 – 319

@Media (@take samples)
No such thing as perfect media; all have their respective advantages and disadvantages.
Wireless: RF           Penetrates walls, rain, clouds,         Limited distance, BW; much inter-
dust; proven technology                 ference; very crowded

Wireless:            Penetrates walls; proven technol-         Limited distance; some interfer-
Microwaves           ogy; BW greater than RF; greater          ence; some crowding; difficult and
capacity                                  expen\$ive circuit design
Wireless: Infrared   Massive capacity; nearly immune           Limited distance; can’t penetrate
to interference                           anything
Wired: Twisted-pair Cheap; Cat 5 up to 1 Gbps; Cat 6           Relatively difficult above 100 MHz
up to 10 Gbps, short lengths (25‘)
Wired: Coaxial cable Good to about 10 Ghz, 100 ft              Much more expen\$ive than twisted
pair
Wired: Fiber Optic     Massive capacity; immune to             More expensive; very expensive
EMI; lighter; much greater              emitters, detectors; very difficult to
distance between repeaters              splice

Topologies, Multiplexing, and Synchronization
*   Types: Star, Point-to-Point, Bus, Ring, Tree *Figs 11.9, 11.10, 11.11, 11.12, 11.14, pp. 328-333
Multiplexing:
TDM (packets, sharing)
CDM (cell phones; military)
The Plexes:
Duplex: two-way, but only one direction at a time (2-way radios)
Full duplex: two-way, both at same time (requires 2 channels)
The synchros:
Synchronous: uses a time signal to control flow of information
Asynchronous: uses control information between packets to control flow of information
Synchronous is usually faster than asynchronous (no overhead; no wasted bit periods)
IT 318                 LECTURE NOTES                 (Winter/2013)                     Page 23

Network Connecting Points
Hub: simply repeats and rebroadcasts packets or frames. Contains no intelligence.
Repeater: simply amplifies and repeats the signal. Contains no intelligence.
Bridges: connects 2 similar LANs and provides a filter so that only packets with appropriate
Routers: Special-purpose computers that decide where to send each packet, then re-encapsulate
them and send them on their way. Can connect different types of networks. Most of its work
is done in software.
Switches: Lower-layer router; does most of its work in hardware, so it is faster.

M18: Computers (Walters, Chaps 12, 14)
Chapter 12: Types of Networks
LANs
Ethernet
The most common type; defined about 20 years ago; improved from original of about
10 Mbps to 100 Mbps about 5 years ago (Fast Ethernet). Currently working on a spec
for a 1 Gbps Ethernet. *-see below
Uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD). Sounds weird,
but it works!
Each Ethernet card has a hard-coded address, 48 bits (281 T possibilities).
Maximum length: 185 m for 100 Mbps; 200 m for 1 Gbps; about 50 m for 10 Gbps
No guaranteed data rate or latency; great for bursty data, but not sustained data rates.
Token Ring - the only other significant option; about 10% of the market
Originally 4 Mbps; upgraded to 16 Mbps. Now available in 10 Gbps.
Guaranteed data rate and latency; great for short packets and high sustained data rates.
CANs
Multiple LANs; greater distances, and a need for very high data rates to interconnect them
FDDI: Fiber Distributed Data Interface
100 Mbps, then 1 Gbps, then 10 Gbps; token-passing
Much more expensive than cable, twisted pair approaches
ATM: Asynchronous Transfer Mode
Small cell (packet) sizes: 48 bytes data, 5 bytes header
Great for streaming data applications - developed by phone companies. Not so good for
bursty data
Standard is 155 Mbps over fiber                    Lengths to 80 km
Can handle all types of data                       NOTE: ATM not used much any more
*   Gigabit Ethernet
IEEE 802.3z requires optical fiber                 CSMA/CD
Length in the range of 4 km                        Cheaper than ATM
Also over CAT 5; 10 Gbps also available now
Lots of work going on to see if 100 Gbps over twisted pair can also be done.
Acess Networks
T-1 : 24 digital phone lines, each @ 64 kbps; plus 8 kbps for signaling gives 1.544 Mbps. Can
also be allocated to other uses besides phone calls. Usually over twisted pair (two pairs for
full duplex).
T-3 : 28 T-1s, or 45 Mbps. Usually over coax or microwave.
Both T-1 and T-3 are leased lines, meaning they are dedicated 100% to the entity that leases
IT 318                 LECTURE NOTES                  (Winter/2013)                     Page 24

them.
*    xDSL: Digital Subscriber Loop. Uses unoccupied bandwidth of ordinary phone lines which are
within a specified distance from the local office. (*Fig 12.5, p. 368)
Many flavors (which is what the x stands for). Several speeds, depending on distance and
flavor:

Chapter 12

DSL Flavor              Maximum Distance                   Downstream Speed
VDSL (V=Very high data                                           12.96 Mbps
rate)
VDSL                                                             25.82 Mbps
VDSL                                                             51.84 Mbps

Cable modems: take out 1 TV channel from cable service and devote it to computer data; has a
capacity of about 30 Mbps. Uses coaxial cable of the TV cable companies.
Network services:
Dial-up analog phone lines, using modems
ISDN (Integrated Services Digital Network)
Switched 56
X.25 (used by ATMs and credit-card verification devices at POS terminals)
Frame Relay
Switched MultiMegabit Data Service (SMMDS)
WANs
SONET (Synchronous Optical Network)
Self-healing, dual counter-rotating ring topology
*   Note data rates in *OC- table, p. 382
WDM (Wave Division Multiplexing)
FDM in optical domain; huge potential, being heavily researched and implemented.
Wireless WANs and Access Networks
Satellite links – serious possibilities, coupled with very serious challenges. Note failure of Iridium
project.
IT 318                LECTURE NOTES                   (Winter/2013)                    Page 25

Chapter 14: The Internet and Network Security

Origins of the Internet
DARPA in 1969 (later ARPA). Expanded by many people working at many universities, most notably
Berkely, Stanford, MIT, Carnegie-Mellon.
Grew because TCP/IP was cheap, effective, and flexible (for different types of hardware, and for
scalability). Today’s backbone of the Internet is provided predominantly by the long-distance
providers WorldCom, GTE, and Cable & Wireless; paid for initially by DARPA, later NSF.
The interface to the Internet, for 24 years, was a command-line interface to a text-based program. NO
GRAPHICS. Fascinating only to the nerds of the enterprises, and even then not many of them.
Apps: bulletin boards; email (text only); ftp
1993: Software by Tim Berners-Lee of CERN, creating a way to exchange documents and have them
look the same on any computer. This is HTTP, or Hyper-Text Transfer Protocol, and uses HTML
(Hyper-Text Markup Language). Demo: View Source option after right-clicking on a Web page.
This opened it up for everyone; WWW is the Internet, to most people. EXPLOSIVE growth.
Metcalfe’s Law: the value of a network (# nodes)²; note the rapid growth in the value of the Internet.
(Robert Metcalfe = originator of Ethernet, founder of 3COM).

Note that in the discussion of the 4 levels, POP refers to Point of Presence, not Post Office Protocol.
Levels:
4) ISP – now mostly local carriers (old phone companies, new communication companies)
3) Regional backbone - networks of ISPs, interconnected typically by T-1s and T-3s.
2) The backbone - lots of regions, interconnected typically by ATM over SONET; examples
include MCI (now part of WorldCom), Sprint, GTE.
1) The network access point - interconnection points between backbones, since there are
now multiple backbones.
Addresses: 32 bits, presently, which is 4.295 Gaddresses, which is a lot, but not enough. Looking
ahead, IPv6 (currently we are at IPv4) plans 128-bit addresses, which is 340.3x1036, or enough
for an address for every atom on the whole planet, including all life forms.
XML: next generation of HTML.
Making the Web Go Faster
Faster links are the main step. Other steps: better compression; more intelligent software; caching
Intranet: very common within companies; utilizes full TCP/IP protocols and web browsers, but is
isolated from all other networks.
Firewall: a server that sits between a LAN and a WAN to provide security and hide LAN computers
from the WAN.
VPN (Virtual Private Network): only appropriately encrypted packets leave or can enter; set up at the
interfaces between corporate/company and the Internet. Provides significantly greater security.
Network Security
Plaintext and cipher: Mathematically operate (multiply or other more complex operation) on a plaintext
and you get the cipher; extremely hard to reverse without knowing the exact way it was
encrypted. Very easy to do in hardware or software.
Secret key: requires secure exchange of the key, but is very secure. DES (Data Encryption Standard) is
the main one here.
Public key/private key: public key that all can use to encrypt, but cannot be used to decrypt. Private key
needed for decrypting. Thus all who wish to send to you may encrypt for your eyes only, and
the data thus encrypted can only be decrypted using your private key, which you do not release.
Pioneers Rivest, Shamir and Adleman (RSA) started company now strongest in this market.
PGP (Pretty Good Privacy) combines these to allow faster en/de cryption than public key allows.
128-bit encryption: @100 T possibilities/sec = 108 P years (x 1015).
IT 318                LECTURE NOTES                  (Winter/2013)                     Page 26

Digital Signatures
Combining a digital signature (using public key encryption to verify the identity of the sender) with a
digital envelope and a digital certificate or ID allows terrific security.
Biometrics are very helpful, but can also be captured and replicated.

Conclusion: The Next Stages of Computing (pages 451-463)

The State of the Foundation
Hardware – the great enabler
Software – major challenges, but also major progress. Windows 2000: ≈25M lines of code!
Networks – a connection for every home, store, kiosk, appliance, etc.

Four Emerging Technologies
4G Cellular – who needs 10 M bps for a phone call (actually only needs about 30k bps)?
VOIP and video, TV over IP – Wow!
Piconets

Seven Challenges to the Pervasive Future
1. Lithography
2. Portable power (battery limitations)
3. Software reliability
4. Network security
5. The last mile
6. Standards – they’re both good and bad!
7. Human factors – you know it’s been successful when the technology is no longer noticed, and its
use becomes widespread. Electricity is a great example here.

-END-

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