hello world I'm Carrie Anne and welcome
to crash course computer science over
the course of this series we're going to
go from bits bytes transistors and logic
gates all the way to operating systems
virtual reality and robots we're going
to cover a lot but just to clear things
up we are not going to teach you how to
program instead we're going to explore a
range of computing topics as a
discipline and the technology computers
are the lifeblood of today's world if
they were to suddenly turn off all at
once the power grid would shut down cars
would crash planes would fall water
treatment plants would stop spot markets
would freeze trucks with food wouldn't
know where to deliver and employees
wouldn't get paid even many non computer
objects like dftba shirts and the chair
I'm sitting on amazing factories run by
computers computing really has
transformed nearly every aspect of our
lives and this isn't the first time
we've seen this sort of Technology
driven global change advances in
manufacturing during the industrial
revolution brought a new scale to human
civilization in agriculture industry and
domestic life mechanization meant
superior harvests and more food
mass-produced Goods cheaper and faster
travel and communication and usually a
better quality of life and computing
technology is doing the same right now
from automated farming and medical
equipment to global telecommunications
and educational opportunities and new
frontiers like virtual reality and
self-driving cars we are living in a
time likely to be remembered as the
electronic age and with billions of
transistors in just your smartphones
computers can seem pretty complicated
but really they're just simple machines
that perform complex actions through
many layers of abstraction so in this
series we're going to break down those
layers and build up from simple ones and
zeroes to logic units CPUs operating
systems the entire internet and beyond
and don't worry in the same way someone
buying t-shirts on a webpage doesn't
need to know how that webpage was
programmed or the web designer doesn't
need to know how all the packets are
routed or route engineers don't need to
know about transistor logic this series
will build on previous episodes but not
be dependent on them by the end of this
series I hope that you can better
contextualize computing role both in
your own life and society and how
humanity's arguably greatest invention
is just in its infancy with its biggest
impact yet to come but before we get
into all that we should start at
computing
origins because although electronic
computers are relatively new the need
for computation is not
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the earliest recognized device for
computing was the abacus invented in
Mesopotamia around 2500 BCE it's
essentially a hand operated calculator
there helps add and subtract many
numbers it also stores the current state
of the computation much like your hard
drive does today the abacus was created
because the scale of society had become
greater than what a single person could
keep and manipulate in their mind there
might be thousands of people in a
village or tens of thousands of cattle
there are many variants of the abacus
but let's look at a really basic version
with each row representing a different
power of 10 so each bead on the bottom
row represents a single unit in the next
row they represent 10 the row above a
hundred and so on let's say we have 3
heads of cattle represented by 3 beads
on the bottom row on the right side if
we were to buy 4 more cattle we would
just slide 4 more beads for the right
for a total of 7 but if we were to add 5
more after the first 3 we would run out
of beads so we would slide everything
back to the left slide one bead on the
second row to the right representing 10
and then add the final two beads on the
bottom row for a total of 12 this is
particularly useful with large numbers
so if we were to add 1251 we would just
add one to the bottom row 5 for the
second row 2 to the third row and one
for the fourth row we don't have to add
in our head and the abacus stores the
total for us over the next 4,000 years
humans developed all sorts of clever
computing devices like the astrolabe
which enabled ships to calculate their
latitude at sea or the slide rule for
assisting with multiplication and
division and there are literally
hundreds of types of clocks created it
could be used to calculate sunrise tides
positions of celestial bodies and even
just the time each one of these devices
made something that was previously
laborious to calculate much faster
easier and often more accurate it
lowered the barrier to entry and at the
same time amplified our mental abilities
take note this is a theme we're going to
touch on a lot in this series as early
computer pioneer Charles Babbage said at
each increase of knowledge as well as on
the contrivance of every new tool human
labor becomes a bridge however none of
these devices were called computers the
earliest documented use of the word
computer is from 1613 in the book by
Richard Braithwaite and it wasn't a
machine at all it was a job title
Braithwaite said I have read the truth
computer of times and the best
arithmetician that ever breathed and he
reduces lay days into a short number in
those days computer was a person who did
calculations sometimes with the help of
machines but often not this job title
persisted until the late 1800s when the
meaning of computers started shifting to
refer to devices and notable among these
devices was the step reckoner built by
German polymath Gottfried Levin it's in
1694 Leoben it's said it is beneath the
dignity of excellent men to waste their
time in calculation when any peasant
could do the work just as accurately
with the aid of a machine it worked kind
of like the odometer in your car which
is really just a machine for adding up
the number of miles your car is driven
the device had a series of gears that
turned each gear had ten teeth to
represent the digits from 0 to 9
whenever a gear bypassed 9 it rotated
back to zero and advanced the adjacent
gear by 1/2 kind of like when hitting 10
on that basic abacus this worked in
Reverse when doing subtraction - with
some clever mechanical tricks the step
reckon I was also able to multiply and
divide numbers multiplications and
divisions are really just many additions
and subtractions for example if we want
to divide 17 by 5 we just subtract 5
then 5 then 5 again and then we can't
subtract any more fives so we know 5
goes into 17 3 times with 2 left over
the step reckon I was able to do this in
an automated way and was the first
machine that could do all 4 of these
operations and this design was so
successful it was used to the next three
centuries of calculated design
unfortunately even with mechanical
calculators most real-world problems
required many steps of computation
before an answer was determined it could
take hours or days to generate a single
result also these handcrafted machines
were expensive and not accessible to
most of the population before the 20th
century most people experienced
computing through pre complicated tables
assembled by those amazing human
computers we talked about so if you
needed to know the square root of
8675309 instead of spending all day hand
cranking your step reckoner you can look
it up at a huge book for the square root
tables in a minute or so speed and
accuracy is particularly important on
the battlefield and so militaries are
among the first to apply computing to
complex problems a particularly
difficult problem is accurately firing
artillery shells which by the 1800s
could travel well over a kilometre or a
bit more than half a mile
add to this varying wind conditions
temperature and atmospheric pressure and
even hitting something as large as a
ship was difficult range tables were
created that allowed Gunners to look up
environmental conditions and the
distance they wanted to fire and the
table would tell them the angle to set
the Canon these range tables worked so
well they were used well into World War
two the problem was if you change the
design of the Canon or of the shell a
whole new table had to be computed which
was massively time-consuming and never
to being led to errors Charles Babbage
acknowledged this problem in 1822 in a
paper to the Royal Astronomical Society
entitled note on the application of
machinery to the computation of
astronomical and mathematical tables
let's go to the thought-bubble
Charles Babbage proposed a new
mechanical device called the difference
engine a much more complex machine that
could approximate polynomials
polynomials describe the relationship
between several variables like range and
air pressure or her mount of pizza
carrier nets and Happiness polynomials
could also be used to approximate
logarithmic and trigonometric function
which are a real hassle to calculate my
hand
Babbage started construction in 1823 and
over the next two decades tried to
fabricate and assemble the 25,000
components collectively weighing around
15 tons
unfortunately the project was ultimately
abandoned but in 1991 historians
finished constructing a difference
engine based on Babbage's drawings and
writings and it will work but more
importantly during construction of the
difference engine Babbage imagined an
even more complex machine the analytical
engine
unlike the difference engine step reckon
on all other computational devices
before it the analytical engine was a
general-purpose computer it could be
used for many things not just one
particular computation it could be given
data and run operations in sequence it
had memory and even a primitive printer
like the differents engines it was ahead
of its time
I was never fully constructed however
the idea of an automatic computer one
that could guide itself through a series
of operations automatically was a huge
deal and would foreshadow computer
programs English mathematician Ada
Lovelace wrote hypothetical programs for
the analytical engine saying a new a
vast and a powerful language is
developed for the future use of analysis
for her work ada is often considered the
world's first programmer the analytical
engine would go on to inspire arguably
the first generation of computer
scientist who incorporated many
of Babbage's ideas in their machines
this is why Babbage's often considered
the father of computing thanks port
bubble so by the end of the 19th century
computing devices were used for special
purpose tasks in the sciences and
engineering but rarely seen in business
government or domestic life however the
US government faced a serious problem
for its 1819 census but demanding the
kind of efficiency that only computers
could provide the US Constitution
requires that a census be conducted
every 10 years for the purposes of
distributing federal funds
representation in Congress and good
stuff like that and by 1880 the u.s.
population was booming mostly due to
immigration that census took seven years
to manually compile by the time it was
completed it was already out of date and
it was predicted that the 1819 census
would take thirteen years to compute
that's a little problematic when it's
required every decade the Census Bureau
turned to Herman Hollerith who built a
tabulating machine his machine was an
electromechanical used traditional
mechanical systems for keeping count
likely minutes his step reckoner but
coupled them with electrically powered
components polar ice machine used punch
cards which were paper cards with a grid
of locations that could be punched out
to represent data for example there was
a series of holes for marital status if
you were married you would punch out the
married spot then when the card was
inserted in tolerance machine this whole
metal pins would come down over the card
if a spot was punched out the pin would
pass through the hole in the paper and
into a little vial of mercury which
completed the circuit this now completed
circuit powered an electric motor which
turned a gear to add one in this case
for the married total Haller ice machine
was roughly ten times faster than manual
tabulations
and the census was completed in just two
and a half years saving the census
office millions of dollars businesses
began recognizing the value of computing
and saw its potential to boost profits
by improving labor and data intensive
tasks like accounting insurance
appraisals and inventory management to
meet this demand Haller I founded the
tabulating machine company which later
merged with other machine makers in 1924
to become the International Business
Machines Corporation or IBM which you've
probably heard of these
electromechanical business machines were
a huge success transforming commerce and
government and by the mid 1900s the
explosion in world population and the
rise of globalized trade demanded even
faster and more flexible tools for
processing data setting the stage for
digital compete
which we'll talk about next week crash
course computer science is produced in
association with PBS Digital Studios at
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this episode was filmed at the chad and
stacey emigholz studio in indianapolis
indiana and it was made with the help of
all these nice people and our wonderful
graphics team thought cafe thanks for
watching I'll see you later
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