digital signal - Name

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1

ELEC1700

Computer Engineering 1




Week 1


Introduction



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2

•
Lecturers and tutors:

•
Lecturer and tutor:

»
Mr. Fernando Martinez (first 4 weeks only)

»
fernando.martinez.martos@gmail.com


•
Lecturer and tutor:

»
Mr. Brenton Schulz (rest of the course)

»
vk2mev@gmail.com



Teaching staff

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Lectures, tutorials and hands on
laboratories


Lectures:


Fridays 8:30am
–
11:30am


GP3
-
24


Tutorials/Labs:



Fridays 12:00pm
–
2:00pm


In EE107/8 for weeks 1
-
4, 6
-
9 and 11


end unless specified
otherwise(1
st

floor in Building EE over the Faculty of
Engineering)


In weeks 5 and 10: We will be doing hands on labs in room
EE103a (also 1
st

floor in Building EE over the Faculty of
Engineering)

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•
Because of Occupational Health and Safety rules, nobody is permitted to enter
the Electrical Engineering laboratories without having first passed the Safety
Induction test.

•
The tutorial work in this course is in EE107/108. Access to this room will be
provided by your tutor during normal tutorial hours, however, you will need a
pass to get in outside the tutorial hours.

•
In weeks 5 & 10, however, there will be laboratory work in one of the building
EE laboratories (EE103a), and you will not be permitted to do that laboratory
session until you have done a safety induction test. If you done this induction test
already this year, you don’t have to do it again.

•
It is therefore essential that you pass the Safety Induction test some time in the
first 4 weeks of the semester.


•
Arrangements for taking this test will be announced either in lectures or via
Blackboard. For more details, see

http://www.eng.newcastle.edu.au/eecs/ect/oh&s/generalsafety.html

Safety induction test and guidelines

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5

•
This year we will have two projects. One combinational project
(for which minimum documentation is needed and will be done
during your normal tutorial time) and a sequential project in which
a proper typed report must be submitted.

•
The demonstration of the second project will be done during your
normal tutorial time. More information about the projects and
project guidelines, can be found in the project guidelines document
and in the course overview.

•
Each student must do ALL projects. Working in groups is NOT
allowed.

Assignment projects

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Questions and help

•
If you have a question on the lecture material, then

1.
Look up a book! Be resourceful


A University degree is a certification of resourcefulness

2.
Ask your tutor during the tutorial session.

3.
Ask the question in Blackboard.

4.
See us during the break or after the tut/lecture.

•
If you come and ask us a question, but obviously haven’t tried to
work it out yourself, then we won’t help you other than to suggest a
book for you to read.

•
If you are still stuck after having tried your best, then we will be
happy to help you.

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Learning resources

•
Blackboard


on
-
line learning system:




blackboard.newcastle.edu.au


course documents (lecture slides, tutorial sheets etc.,
announcements, discussion forums + more)


Students are expected to login regularly
–

recommend daily



Logisim


A logic simulation software which can be down loaded from




http://ozark.hendrix.edu/~burch/logisim



for free an will be used in ELEC1700_NIC extensively.

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http://bit.ly/u3M7An


Textbook

•
Prescribed textbook:


Digital Fundamentals (International Edition,
10e), Thomas L. Floyd


Pearson Education, ISBN: 978
-
0
-
13
-
814646
-
7,
ISBN
-
10: 0
-
13
-
814646
-
2


•
Available in the Co
-
Op bookshop at the
Callaghan campus. Copies are also available in
the Auchmuty Library


•
Students are strongly encouraged to purchase a
copy


•
ELEC1700_NIC will follow this text very
closely

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Assessment



3 quizzes @10% each






30%

2 projects, demonstrated to tutor (5% & 15%)



20%

2 labs @ 5% each







10%

Final Examination








40%










100%



To pass the course you need to have an overall mark


of at least 50%

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Expected workload in ELEC1700_NIC



•
12 weeks of contact, plus final exam period

•
Sample time budget
—

your mileage may vary!


Lectures

–
Attendance/EchoSystem: 3 hours per week
×

12 weeks →

36

Textbook readings:

1 hour per week →




12

Tutorials (incl. in
-
class project demos)

–
Tutorial preparation: 1 hour per week
×

10 weeks →


10

–
Tutorial attendance: 2 hours per week
×

10 weeks →


20

–
Project #1 preparation →






4

–
Project #2 preparation →




12

Labs 1 and 2:

–
Preparation: 1 hour each
×

2 labs →






2

–
Attendance: 2 hours per week for weeks 5 & 10 →




4

Quizzes 1−3

–
Preparation: 3 quizzes @ 5 hours each →



15

–
Completion and attendance (done instead of lecture see above)→


0


Exam

•
Preparation →





10

•
Attendance →







3


•
36 + 12 + 10 + 20 + 4 + 12 + 2 + 4 + 15 + 3 + 10 + 3 =
128 hours

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What’s the temperature?

Ref:
http://bit.ly/wrgSSF


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Graph of an analog quantity

analog

quantity: has continuous values

most natural quantities that we experience are analog:


temperature, speed, force, sound intensity, light intensity, …

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Sampling and quantisation

Sampling

takes snapshots of signal (generally at regularly spaced time intervals)


Quantisation

rounds the amplitude to the nearest predefined value

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Sampling and quantisation

Analog

Sampling

Quantisation

Digital

A
digital signal

takes one of a finite number of values at each
sampling interval

Analog
-
to
-
digital converter (ADC)

converts analog signal to
binary

(a digital form which has only two values instead of many) as a series
of 1s and 0s

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15

Analog versus Digital

•
As already explained, the real world is basically composed of
Analog signals (voltage, pressure, velocity, temperature etc.).

•
In other words, signals that are continuously changing
with time.

•
Digital signals are Discrete signals in that they can only have
specific values.








a
n
a
l
o
g

s
i
g
n
a
l








v
a
l
u
e
t
i
m
e
t
i
m
e
d
i
g
i
t
a
l

s
i
g
n
a
l






v
a
l
u
e
V
a
l
u
e

1
(
m
a
n
y
v
a
l
u
e
s
)
V
a
l
u
e

2
V
a
l
u
e

3
Analog signal

Digital signal

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Analog and digital signals

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A Binary Signal

•
A binary signal is a digital signal which has only two finite number of values
(normally two different voltage values represented by High/Low, or ON/OFF,
etc. see next slide).








•
A digital signal need not be constrained to two levels only. Can, in theory, have
generic m
-
ary signals (see previous slide).

•
However, binary format almost universal.

•
Binary system has just two digits: 1 and 0

•
Each digit is called a
bit

=
bi
nary digi
t and
8
-
bits = one
byte

•
We will focus on binary systems in this course.

t
i
m
e
d
i
g
i
t
a
l

s
i
g
n
a
l

v
a
l
u
e
H
i
g
h
L
o
w
(
o
n
l
y

2
v
a
l
u
e
s
)
B
i
n
a
r
y

S
i
g
n
a
l
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Describing binary signals

•
Have two possible states; terminology varies. For positive logic (used in this
course):



True


&


False


High


&


Low






On


&


Off




“1”


&


“0”

(most popular and used in this course)


+5 V (V
CC
)

&


0 V

(based on the TTL logic family) etc.

•
Use these terms interchangeably:

t
i
m
e
V
o
l
t
a
g
e
H
i
g
h
/
O
N
/
"
1
"
/
+
5
V
L
o
w
/
O
F
F
/
"
0
"
/
0
V
B
i
n
a
r
y

S
i
g
n
a
l
Used, as H & L, in most manufacture
data notes
(See 74138 TT)

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Describing binary signals ...

•
Occasionally use
inverted

or
negative

logic:




True



&


False



High



&


Low



On



&


Off



“0”



&


“1”



0 V



&


+5 V (V
CC
)


•
We will be using positive logic in this course.


•
Therefore we can now define the following terms:

–
Logic level:

A voltage level that represents a defined digital state.

–
Logic HIGH (or logic 1): The higher of the two voltages in a binary signal.

–
Logic LOW (or logic 0): The lower of the two voltages in a binary signal.

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20

Logic levels

•
Digital electronics uses circuits that have
two states

•
These states are represented by two different voltage
levels called
HIGH

and
LOW

•
The voltages represent numbers in the binary number
system




HIGH = 1

and
LOW = 0


•
If the voltage at any given point in our digital circuit is
within the unacceptable logic range, then the digital
circuit will misbehave.

•
There are many reasons why this could happen, but the
main ones are:


(i) Power supply connections not clean (i.e. free of
noise), not connected or of the wrong value
(see
lect1demo1.ewb)


(ii) Overloading of one of the outputs (i.e. the output is
connected to too many inputs


(iii) A short circuit between the track/conductor in
question and any other point.


(iv) Floating inputs (not connected inputs)


(v) Transition between logic states (i.e. 1

0 or 0

1).


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Logic levels…

Range of LOW and HIGH voltages
depends on the digital circuit
technology being used

One type of circuit technology is
“
CMOS
”

CMOS =
C
omplementary
M
etal
-



O
xide
S
emiconductor

For CMOS:

LOW range: 0V to 0.8V

HIGH range: 2V to 3.3V

+3.3V

+0.8V

+2V

0V

Logic HIGH (1)

Undefined logic

Logic LOW (0)

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Logic levels…

Another type of circuit technology is
“
TTL
” (which we will be using in
this course, i.e. in labs and
examples).

TTL =
T
ransistor

T
ransistor

L
ogic

For TTL:

LOW range: 0V to 0.8V

HIGH range: 2V to 5V

+5V

+0.8V

+2V

0V

Logic HIGH (1)

Undefined logic

Logic LOW (0)

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Logic levels…

•
In real life a logic probe or indicator will show the three levels as shown below:








•
However in Logisim here are not such problems, unless we leave a wire
disconnected:





+5V

+0.8V

+2V

0V

Logic HIGH (1)

Undefined logic

Logic LOW (0)

(MultiMediaLogic(MML) Switches & indicators, an alternative free software)

Logic gates (see later)

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Logic levels…

•
Real life switches are as shown below:





SWA

Normally open (A)

Normally closed (NOT A)

(See later)

So to obtain a logic 1 (HIGH), or logic 0 (LOW) we need to wire up
the switch like this:


Key = A
VCC
Key = A
VCC
LOW (0)

HIGH (1)

To rest of the cct

To rest of the cct

26/10/2012

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25

Why use digital (binary)?

•
Easy to implement:
ON = +5 Volts (logic 1) or OFF = 0 Volts (logic 0)

•
Immunity to “noise”:
More immune to noise than analog.
We can reconstruct digital signal even if it is contaminated by (small amounts
of) noise by rounding to the nearest level.









•
Flexibility:


Can treat data, audio, video, images etc in the same way as each other


Can process, store, and transmit data more efficiently than analog

•
Cost:
Digital equipment is cheap, and getting cheaper

v
o
l
t
s
l
o
g
i
c

1
l
o
g
i
c

0
E
f
f
e
c
t

o
f

n
o
i
s
e

o
n

a

d
i
g
i
t
a
l

s
i
g
n
a
l
t
t
v
o
l
t
s
E
f
f
e
c
t

o
f

n
o
i
s
e

o
n

a
n

a
n
a
l
o
g

s
i
g
n
a
l
Logic level

threshold voltages

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26

How do we communicate in the real world?




Real

World

Analogue to

Digital

Converter

Digital

System

Digital to

Analogue

Converter

Real

World


i.e.

Transducer


Analogue


Signal

i.e. a voltage

ADC

i.e. computer


Binary


Signal

i.e. 01011001

1 = V
CC

0 = Reference


Binary


Signal

i.e. 01111111

1 = V
CC

0 = Reference

DAC


Analogue


Signal

i.e. a voltage

i.e. Relay,

Indicator, etc.


+ve logic used in this course

+12V

Relay ON

Ex.: D.E.:

Dig. systems 9/16

Dig. systems 8/16

Dig. systems 10/16

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26/10/2012

26/10/2012

…and from digital back to analog

Digital
-
to
-
analog converter (DAC)


Digital information stored on compact
disc. Scale at bottom of figure shows
1µm intervals

Ref: M. G. Carasso et al., Compact disc: Digital
audio
, Philips Tech. Rev.
, 40(6):151
–
180, 1982

http://bit.ly/y8Ug2t


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Positive
-
going pulse:

LOW logic level to a HIGH level and then back
again

Negative
-
going pulse
: HIGH to LOW to HIGH


Digital waveforms

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
Rise time

t
r
and

fall time

t
f


Measured between 10% to 90% of pulse amplitude


Pulse width

t
w


Measured between 50% points on rising and falling edges

Non
-
ideal pulses

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Digital waveforms

Digital waveforms: series of pulses, changing between LOW and
HIGH levels

These are
ideal pulses
: rising and falling edges change in zero time

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Waveform characteristics

Periodic

pulse waveforms

Composed of pulses that repeat in a
fixed interval called the
period (T)

•

measured in seconds (s)

The
frequency (f)

is the rate it repeats

•

measured in hertz (Hz)

T
f
1

f
T
1

Class exercise:

What is the period of a

repetitive wave if
f

= 1 GHz?


Period =

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Duty cycle

of a periodic waveform is the ratio of
t
W

to
T

•

often expressed as a percentage

•

measures fraction of period for which signal is HIGH

V
olts
T
ime
Pulse
width
(
t
W
)

Period,
T

Duty cycle

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Duty cycle:
Example


Duty cycle

=
t
w

/
T



= 1 / 10



= 10%

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A digital waveform carries binary information

In digital systems, all waveforms are synchronised with a basic
periodic timing waveform called the
clock

Example:

the speed of a computer is measured by the clock
frequency of it’s microprocessor, e.g. 3.5 GHz

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Time to transfer 8 bits in waveform A =

Clock frequency

= 1MHz

Clock exercise:

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A
timing diagram

is used to show the relationship between two or
more digital waveforms

A diagram like this can be observed
directly on a
logic analyzer

Timing diagrams

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Computer
Modem
1
0
1
1
0
0
1
0
t
0
t
1
t
2
t
3
t
4
t
5
t
6
t
7
Computer
Printer
0
t
0
t
1
1
0
0
1
1
0
1
Serial and parallel transfer of data

•
Data can be transmitted by either serial transfer or parallel transfer.


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Oscilloscopes: analog and digital

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1 V per vertical division

2 ms per horizontal division


= 2
×
10
-
3
s



Our Lab Oscilloscope: 2 channel
Tektronix Digital Oscilloscope

Coupling set to D.C.

No inversion

(Unless required)



Set to
×
1 (in our labs, as we are
using BNC
-
4mm cables



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Amplitude

=

Frequency

=

Duty cycle

=

Class exercise:

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Logic

•
Propositions:

statements which are true if certain




conditions are true


•
Example:

“The light is on” is true if:



the bulb is not burned out
AND
the switch is on


•
Boolean algebra
: formulate logic statements with symbols


named after Irish mathematician George Boole c1850s


•
Three basic logic operations: AND, OR, NOT

•
Just the basics today
–

lots
more in Weeks 3 and beyond

•
Logisim:

demo free software package for logic simulation

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True only if
all

input conditions
are true

True only if
one or more

input
conditions are true

Indicates the
opposite

condition

Basic logic operations and symbols

True/false conditions are represented by voltages:


HIGH = true

LOW=false

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NOT

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AND

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OR

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Why do we need to study logic gates?

•
Gates are made out of transistors.

•
Commercially available Integrated Circuits (I.Cs or chips,
see later) are made out of gates.

•
Custom I.Cs are made out of gates and I.Cs.

•
Semiconductor memories (e.g. RAM) are made of gates
as well.

•
Microprocessors are made out of a mix of the above.

•
Therefore if we understand the concepts and basics of
gates we will be able to analyse other more complex
circuits.

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Why do we need to study the basic gates?…

From these:

Q1
Transistor
U1A
AND
Gates

Integrated Circuits (I.C’s)

Memory

Surface mounted

devices

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Dual In line Packages (D.I.P.) and Integrated Circuits
(I.C.’s)

This in an I.C. The physical

package is called a D.I.P.

Notes:

1.
The distance between pins is 0.1” (adjacent) and


0.3” (across the I.C.)

2.
The pins are numbered anticlockwise. Pin 1 is the
first pin on the LHS of the top of the package.

3.
There is always some type of mark on the package
to show which is the top of the I.C.

4.
Most standard digital I.C’s have 0V on pin 7 and
+V
CC

on pin 14.

5.
The name of commercial I.C’s use a number to
specify their function (i.e. 7408)

6.
Gates within the I.C. must be differentiated in
circuits:


U2A
7408N
1
2
3
U2B
7408N
4
5
6
U2C
7408N
9
10
8
U2D
7408N
12
13
11
7408, Quad, two input

AND gate

Real life

DM7408

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Plastic
case
Pins
Chip
Cutaway view of DIP (
d
ual
i
n
-
line
p
ackage)

called DIP because of the two
rows of pins


Integrated circuits (ICs) = “chips”

Small outline IC (SOIC)

s
urface
m
ount
t
echnology
(SMT)
—

saves space

0.6”

0.1”

Pin 1

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SMT packages

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Quad 2
-
input AND gate chip

“Quad”

since there are 4 AND gates in one package

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Complexity classification

Small
-
scale integration (SSI)


up to 10


basic gates


Medium
-
scale integration (MSI)


10
–
100


encoders,









decoders









counters


Large
-
scale integration (LSI)


100
–
10,000


memories


Very large
-
scale integration (VLSI)

10,000
–
100,000

small









microprocessors


Ultra large
-
scale integration (ULSI)

more than 100,000

large









microprocessors

#gates

examples

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Pin numbering

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Laboratory prototyping

We’ll use prototyping
“breadboards” like this with
DIP chips in Labs 1 and 2


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Some applications

•
And
,
or
, and
not

elements can be combined to form various logic
functions. A few examples are:

•
Comparators

•
Mathematical functions like addition

•
Encoding

•
Decoding

•
Multiplexing/demultiplexing

•
Counting

•
Etc.


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Comparison

We’ll learn about binary
codes in Week 2

A
code

is a set of bits arranged in a
unique pattern

•

represents “information”

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Addition

We’ll learn how to design
logic circuits to perform
arithmetic in Week 6

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Encoding

We’ll learn about encoders
in Week 7

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Decoding

We’ll learn about decoders
in Week 7

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Multiplexing/demultiplexing

We’ll learn about
multiplexers and
demultiplexers in Week 7

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We learn about binary codes in Week 2

Counting

We’ll learn about counters
and other devices with
memory in weeks 8, 9 and 10

26/10/2012

Week 1
-
S
62

Fix
ed OR
array and
output logic
Programmable
AND array


Programmable Logic

•
Programmable logic devices

(PLDs) are an alternative to fixed
function devices. The logic can be programmed for a specific
purpose. In general, they cost less and use less board space that
fixed function devices.


•
A PAL device is a form of PLD that uses a combination of a
programmable AND array and a fixed OR array:


26/10/2012

Week 1
-
S
63

Basic setup for programming a PLD or FPGA

We’ll take a look at programmable logic in Week 11

PLD =
P
rogrammable
L
ogic
D
evice

FPGA =
F
ield
-
P
rogrammable



G
ate
A
rray

•

alternative to fixed
-
function ICs

•

PLD/FPGA: highly flexible; less
board space