: embedded computer, RAM, ROM, sensor,
the “Internet of things”
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This presentation introduces computers that
are embedded in special purpose devices.
We see that they have
the same functional
components as general purpose computers,
but you cannot change their function by
loading a new program.
We will see several examples of devices with
embedded computers and the sensors they
Where does this topic fit?
This is a technology presentation.
(programs and data)
This diagram stresses the direction of
information flows within a comp
With a laptop or desktop computer, the user
interacts with the input and output devices, for
example typing information on a keyboard,
pointing at the screen with a mouse, or reading
printed or displayed information.
Computers that are embedded in
purpose devices have the same functional
components, but the inputs, outputs or both
are often to and from things, not people.
Things with computers inside
Computers are embedded in all of these
Cars, cameras, cell phones, watches, TV sets,
microwave ovens, and ATM machines all
contain embedded computers.
Take a microwave oven for example.
When the user pushes the “start” button on a
microwave oven, the embedded computer
detects that it has been pushed and reads the
settings on the control panel.
It then adjusts the power level, sends a signal
to turn the oven on, tracks the elapsed time,
sends a signal to turn the oven off at the pro
time, and outputs a beeping sound to let the
user know the food is cooked.
The computer is able to output signals to adjust
the power level and turn the oven on and off.
There is a computer embedded in this
It can read input from the various dials and
buttons used to select options.
Light coming through the lens strikes an image
sensor that reads the intensity and color of the
light at each pixel point.
That information is output to the display on
back of the camera along with focusing
When the user pushes the shutter button, the
image is stored in flash storage.
The user can connect the camera to a laptop or
desktop and transfer images stored inside the
camera to the computer.
If the camera has a cellular or WiFi radio, it can
also upload stored images to the Internet.
a modern car.
Communication (e. g.,
This slide lists some of the computer controlled
systems in a modern car.
computers running millions of lines of
software are embedded in modern cars.
They are a major cost component and a possible
source of bugs and vulnerable to hacking.
In spite of that complexity, they make new
features possible and increase safety and
Programs in volatile,
random access memory
Programs in fixed,
read only memory
When we use our laptop or desktop computers,
we load different programs into memory to do
a word processing program for
writing, an image editor for draw
ing, and so forth.
Memory that can be changed is called RAM
(random access) memory.
When you turn the computer off, the contents of
RAM memory are erased
it is volatile.
The programs in an embedded computer don’t
your camera is always a
camera, never a
Since the function does not change, the camera
program is permanently stored in read only
ROM contents are permanent.
Flash memory chips are both changeable and non
That makes flash useful
for both memory and for
A final point
do not be confused by the term CD
ROM drives are storage devices, and have
nothing to do with ROM memory.
With conventional computers, people operate the
we type, speak into microphones,
scan images, and so forth.
Embedded computers also get input from sensors.
For example, the acceleration sensor in a tablet
computer or cell phone allows
the program to
detect and respond to motion
it knows when the
device is moved or rotated.
The devices shown on the left are temperature
They might be used by a computer that controls
heating and air conditioning.
are many other typ
es of sensor
Embedded computers typically get input from
sensors as well as people and they can control
This thermostat reads the desired temperature
dial rotated by a user.
It reads the current room temperature using a
And it turns the heater or air conditioner by
outputting a command to an effector.
Sensors are input devices from the environment
and effectors are output devices
The Internet of things
You may hear people speak of “the Internet of
We interact with computers using our
eyes and voices
Things interact using light, temperature and other
types of sensors.
from building light and heat
controls to soil moisture detectors to location
trackers on migrating birds
are connected to the
Internet every day.
(programs and data)
We saw that many special purpose devices have
computers embedded inside them.
They have the same functional components
input and output devices, memory, storage and
as general purpos
Embedded computers often get input from
sensors and send output to
Programs are stored in non
memory on embedded computers.
Devices with embedded computers are
increasingly being connected
to the Internet,
creating an Internet of things.
The Internet of things brings us new applications
and efficiency, but it also exposes us to risks from
program or machine errors or malware.
Is an embedded computer more likely to
keep its program in RAM or ROM? Explain.
What are the input, output and storage devices on a tablet computer?
What are the input, output and storage devices on a smart phone?
Are smart phones special purpose or general purpose computers?
What are the i
nput, output devices of an ATM machine?
Where do ATM machines store information?
Where is the program of an ATM machine?
When you cook
something in a microwave oven for one minute, what is the embedded computer
programmed to do when the time runs out?
alked of sensors for measuring temperature and acceleration. What other type of sensors are available
for today’s computer systems?
Give an example of an effector that is controlled by an embedded computer.
What is some of the information your car can communicate using onStar or Ford Synch?
What are some privacy issues raised by automotive information systems?
New York Times article on ARM, the leading designer of chips for embedded systems:
ARM Web site, with many examples of embedded applications and an overview of their product line:
Risks of embedded smart phones:
The risk of software error in cars:
The use of embedded computers in cars: