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Objective: Explain the use of binary numbers to represent a wide variety of phenomena in computation and communication. Also explain why binary numbers are preferred in creating computation and communication equipment. We will also consider physical and chemical measurements that can be reduced to binary numbers using microelectrical and micromechanical devises. The index for this section is:
What number system--base 2, binary; base 10, decimal, or the base of any other integer-- is best for machines? The answer depends on how many ways the number system can be represented. There are several ways in nature that one can create binary numbers. For example, a switch is open or closed, and a magnet has a north and a south pole. The principal device currently being used is the transistor, which is either on or off. Some uncommon devices are Josephson junctions and light switches. Moreover, circuits made with such 0-1 devices can be analyzed by Boolean algebra. Machines are designed based on binary numbers. Now the question becomes what can be do with binary numbers?
A partial equivalence table between decimal and binary numbers is
shown below.
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To process letters in a computer each letter or character is
assigned a number. Currently the possible numbers in an 8-bit byte
are usually used to define characters. There are several competing
conventions. To illustrate the process let us use the widely used
ASCII convention for 8 bit characters.
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The ASCII convention is an example of an industrial standard.
Standards are essential for advances in computing, communication and
automation because without standards interaction among machines or
even among software packages for a single machine is impossible. For
example, communication of information objects, such as a spreadsheet
or CAD design, between software programs and devices requires a
standard representation. In comparison with the standards for human
interaction, the standards for machine interaction are rigid and
exacting.
Firms have mixed motives in setting standards. Firms frequently try
to set proprietary standards to get customers locked into using their
products. However, if each firm were to adopt its own standard,
communication between equipment from different vendors would be
difficult. In a growing market, one way that standards are set is
that participants tend to follow the dominant firm or coalition of
firms. Another way standards are set is by consortia and other
organizations.
Today, the move is towards open standards to ease the problems of
creating systems of multivendor equipment. Standards expand the
market and allow the small firms to seek niches knowing their
specialty can be meshed with other equipment.
One example of a search for a standard is the representation of all
languages in the world. Obviously, oriental languages which use
pictures require larger words than languages which build words out of
characters. There is a debate. It appears that 16 bits should
suffice. Once a standard is set and accepted worldwide,
wordprocessors will be able to process any language easily.
As future managers you should be aware that in markets where there
are no standards, equipment can become obsolete overnight if new
standards are adopted.
Surf the Net: Check out the following sites promoting various
standards.
To return to the notes remember to click `back' at the top of your screen. You may have to click several times depending how deeply you delve into these files.
Sound is a single waveform which can be decomposed into pure
frequencies. For example, the music of a rock band is a single
waveform. Physiologically, however, the listener hears the different
instruments and the voice. In its natural state sound is an analog
phenomenon-that is a wave phenomenon. By measuring the single
waveform at frequent intervals and representing each measurement as a
binary number, sound can be digitized.
The quality of digital sound depends on the frequency at which the
sound is measured as well as the size of the word used to represent
the wave form. To convert the voice into a telephone quality binary
signal the voice is sampled 8000 times a second. The measured
waveform is converted into a seven-bit binary number with an eighth
bit added for error checking. This means a telephone conversation is
converted into a stream of 64,000 bits per second. The telephone
system is presently analog between telephones and the switchboard,
but an increasing portion of long distance phone traffic is being
sent digitally. The phone conversation is converted at the telephone
exchange (switch) prior to long distance transmission. In the future
all telephone conversations will be converted to digital at the
phone( 10 to 30 years). Corporate internal communications are rapidly
becoming digital so that the corporation can use the installed
telephone lines for simultaneously voice and data transmission. In
order to obtain stereo quality sound you need a larger word size (16
bits) and much more frequent sampling to capture the high frequency
sounds. One scheme for digital recordings measures the sound 44,000
times a second using a 16-bit( 2 byte) word for 1.4 million bits a
second. The new stereo sound TV samples about 36,000 times a second
and used a 14 to 16-bit word for the measurements.
Computer graphics: The fundamental characteristic which
determines the clarity of a computer screen is the number of picture
elements which are called pixels. On a computer screen these pixels
are arranged in a rectangular grid and the size of the grid varies
considerably among computers. For example, if each character is
represented by a rectangle of 9 lines and 9 columns, then an 80
character by 24 line text display would have a total of 216 lines and
720 columns. For graphic pictures from satellites, 256, 512 and 1024
lines and columns are grid sizes frequently used. On computer screens
and television sets there are 4 columns for every 3 lines. In
contrast, the aspect ration of movie screens is 16 to 9 (broader
field of vision). Currently 640 columns and 480 lines is a fairly
common size grid for 14 inch computer screens. For computer assisted
design more detail is desirable; hence, workstation screens are 16
inch or larger with 1280 columns by 846 lines or greater. For this
purpose the new IBM PC2 offer cards with grids up to 1024 by 1024.
The number of bits associated with each pixel determines the number
of colors that can be represented. For example, black and white, 4,
16, 256, thousands, and millions of colors would be represented by a
pixel of 1,2,4, 8, 16, and 24 bits respectively. There is no point
going beyond 24 bits because the human eye can not distinguish more
colors. Computer graphics are digital; however, as humans prefer an
analog signal, it is sometimes converted to analog just before
display.
To avoid flicker on a computer screen the image must be redrawn about
60 times a second. The number of bits of information which must be
processed each second to output to a computer screen is the refresh
rate times the number of columns times the numbers of rows times the
number of bits used to represent each pixel. For current PC's this
number can be as large as 60 x 640 x 480 x 4 = 73,728,000 bits per
second.
The trend in computer screens is a higher and higher resolution and a
greater number of colors. Since for most purposes no more than ten
thousand colors are required for quality pictures, this limit may
become common. Currently television-type monitors are cheaper and
better than flat screen displays, such as those in notebook
computers. In the future quality flat screen displays may displace
television-type monitors. Currently, there are many types of
competing flat screen technologies.
Surf the Internet: Remember that the resolution of a computer screen
is much less than the resolution in a media magazine. A picture in a
media magazine generally has 2600 pixels/inch: whereas a picture on a
computer screen only has 70 pixels/inch. It is a real challenge to
make computer pictures look real. The following list shows examples
of different aspects of art, graphics and pictures on the Net. Surf
to each example.
There are thousands of sites devoted to art, graphics and pictures. The following provide Yahoo lists of each category:
Commercial TV graphics: TV has a single light waveform
(analog). The single waveform corresponds to the position of the
electron beam as it moves across the TV screen in a 525 (US standard)
line zigzag pattern. On one pass the electron beam draws the odd
lines and on the next the even lines(interlacing). The entire picture
is refreshed, that is redrawn, 30 times a second. Color is
represented by adding red, blue, and green light. Current TV is a low
resolution device with about 300 columns and 200 lines. Note that
when text is presented on a TV screen you almost never see more than
20 characters in a line. If they tried to present 80 characters, all
you would see is a blur. TV looks realistic because it is an analog
device which displays millions of colors.
To digitize a TV picture the signal is sampled at twice the frequency
humans can discriminate, which is about 5 million cycles per second,
and the colors represented by a 24 bit word. The resulting raw
digital signal varies from 90 million bits to 220 million depending
on the standard. The digital signal is converted back to analog for
viewing, a process which functions to smooth out the discrete digital
points.
There was a commercial battle between Japan, France and the US for the
next generation of high definition television, Japan and France both
adopted analog standards with approximately double the resolution of
current TV. The US to leapfrog the competition has organized a
competition between major firms. The final standard is digital and will
probalby come online by 2010. To switch to digital TV there must be an
inexpensive box which will convert the digital signal to analog for the
existing TVs. Also the broadcasting industry will have to see new
profit potential to justify the replacement of all their current analog
technology. Also, the consumer must be offered new interesting services
to want to purchase the new TVs.
HDTV Resources
The power of computers processing binary numbers in medical, manufacturing, environmental, and many other processes is dependent on being able to make biological, chemical, and physical measurements and convert the measurements to binary numbers. Increasingly with microminaturization these measuring devices are being placed in individual ICs.
Biological measurements include DNA testing. Chemical measurements include devices to measure the presence and amount of multitude of chemical molecules. Physical measurements include touch, pressure, temperature, acceleration and various electrical quantities.
Three human senses that are now being constructed on ICs are touch, taste and smell.
Touch screens are primarily for computers, but as computer and TV screens tend to merge it is certainly possible that you could have TV touch screens. From the perspective of binary numbers, a touch screen reacts to the specific location on the screen that was touched (1). Thus you have a 0-1 property.
To add touch to a computer screen you need four basic components.
One technology to create a touch screen is by adding a capacitive conductive coating to a clear glass sensor. Voltage is applied to the corners. When the screen is not in use the voltage is spread out into a uniform field. When the field is touched by a finger, the X-Y position is recognized by the disturbance in the field. A second technology is a resistive touchscreen which conducts electricity when touched and the position where touched can be calculated.
The use of touchscreens in point of sale, POS, devices can speed up the transaction process and reduce employee training time. People who are computer illiterate find touchscreens easier to use than keyboards. Touch screens are also better in locations where keyboards are inconvenient or will be damaged.
In our tongue we have four types of taste buds (sensors): sweet, sour, salt and bitter. We can distinguish numerous flavors because, for example, the sweet taste buds respond differently to different types of sweet molecules. Thus the pattern on the four types of sensors determines the taste (along with the aroma of the food?). The sensors in the tongue look like:
Thus to digitize taste, we need to create a device to measure the pattern of sweet, sour, salt, and bitter and digitize the measurements.
Electronic Taste
Smell is more complicated than taste in that we have millions of odor receptors of perhaps 10,000 different types. Dogs have more receptors and many more types. A diagram of the process of smell is:
These many receptors send signals to the brain where the pattern is recognized by the human neural network. Smells are learned through experience. We do not know the exact chemical composition of what we are smelling but recognize the pattern from previous experience.
Smell
What does this mean? The point is that transmission and
manipulation of data, words, voice, of pictures occurs through the
use of binary numbers. A general purpose communications network with
multimedia computers as nodes can manipulate and communicate numbers,
words, voice, and images. You don't need special purpose hardware for
each phenomenon. Also with the move to digital communication, the
communication engineer needs to know the number of bits he has to
transmit per second, but not what is being transmitted.
Fundamental Economic Point: It is much cheaper to have a single
computing and communication technology which will compute and
communicate numbers, text, symbols, voice and all types of images than
require separate technologies for each. In the marketplace, the
boundary line between communications and computer companies is becoming
fuzzy. Future competition in the combined computer-communications
industry will be fierce. One of the reasons for the breakup of the
phone system is AT&T's desire to penetrate the computer market. To
counter AT&T's move, IBM has entered the communications market.
Neither has had much success in the other's territory. The most
successful in this new world were the growth of firms to produce
routers for the internet such as Cisco.
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