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DAVID MALAN: All right,
welcome to computer science 50,

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introduction to computer science 1.

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My name is David Malan, and I will
be your instructor this semester.

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So even if you have no idea
how the computer you own,

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or the laptop you own, works--

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and perhaps some of you are just a
little bit scared of it-- you probably

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know at the end of the day, everything
that goes on inside that computer

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boils down to zeros and ones, a.k.a.

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bits.

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So where are all these
zeros and ones stored?

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Well, you probably also know that
inside your computer somewhere is

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this thing called a hard drive,
whether you have a desktop,

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you'll have something
like this, a laptop,

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you'll have something like this.

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But mechanically, they
pretty much work the same.

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In fact, in some of your iPods,
or devices much like these--

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quick question, how
do these things work?

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This is literally like
a 200 gigabyte hard

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drive that I pulled from a
non-functioning desktop computer.

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What goes on inside these things?

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Well, as you can kind of tell-- and
I'll start passing this around--

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there are these things called platters.

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Essentially, these metal
disks inside of hard drives

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that have millions, billions of tiny
magnetic particles on top of them.

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And essentially, if you align
these magnetic particles,

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say north-south, we might say that that
particle is simply representing a 1.

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By contrast, if you flip
that magnetic particle

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over putting it south to north, well we
might say that particle is essentially

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representing a 0.

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And it's certainly a bit
more complicated than that,

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but at the end of the day, the
storage of zeros and ones--

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the so-called language of computers--
all boils down to-- on hard drives,

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at least--

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the storage of these magnetic particles.

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Well, it turns out that these larger
devices are much like these floppies,

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that probably most of you in
this room don't even use anymore,

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and most of your computers
probably don't even come with them.

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But go ahead and very carefully slide
this little silver metal piece--

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if you took a floppy on your
way in-- and you can sort of see

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just part of one of these circles.

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This one is in fact floppy, as
the name of the disks implies.

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But it functionally works almost
exactly the same as the hard drive.

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So let's go ahead and turn our attention
for a moment to little video-- granted,

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a cheesy video-- but
nonetheless, a bit illustrative.

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[VIDEO PLAYBACK]

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- [INAUDIBLE] works with 3
and 1/2 inch floppy disks.

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DAVID MALAN: Let's not, actually.

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[VIDEO PLAYBACK]

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- The floppy drive you see here--

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DAVID MALAN: All right.

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What a perfect way to begin today.

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[LAUGHTER]

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- They're the type most often
used to carry new programs.

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DAVID MALAN: I'm the
only one that doesn't see

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where this program is actually running.

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[LAUGHTER]

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[VIDEO PLAYBACK]

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- See it's actually
just a hard plastic--

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DAVID MALAN: There we go.

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All right, it opened the wrong part.

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Wow, it makes you want to start
this lecture all over again, huh?

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All right, let's go ahead and play
it with the right software this way.

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And here we go.

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[VIDEO PLAYBACK]

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- The floppy drive you see here works
with 3 and 1/2 inch floppy disks.

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They're the type most often used
to carry new programs, same data,

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or a new file from one PC to another.

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So part of the disk we see is
actually just a hard plastic shell.

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The working disk, which is inside, is
protected by a sliding metal shutter.

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This thin, inner disk,
called the cookie,

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is coated not with chocolate chips,

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[LAUGHTER]

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--layer of magnetic material.

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When you slip the disk into your
floppy drive, a system of levers

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pushes back the metal shutter.

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The levers also pinch to read/write as
closer so they almost touch the cookie.

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A motor at the base of
the drive spins the cookie

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based on commands from your PC.

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The PC also signals another motor
to move the read/write heads

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back and forth over the surface of the
disk so they can read or write data.

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Before your PC writes
data, your drive first

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checks the write protect tab of
the corner of the floppy disk.

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If it is open, light from
a tiny diode shines through

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and strikes a diode on the other side.

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This diode then says to your
PC, go write on this disk.

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[LAUGHTER]

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But if the tab is closed,
no light gets through,

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and the PC knows it's OK to write data.

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[END PLAYBACK]

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DAVID MALAN: All right, so
admittedly, it's a little embarrassing

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even showing you that video.

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I have never once, other
than this man's voice,

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heard the thing inside of this
thing referred to as a cookie.

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[LAUGHTER]

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But nonetheless, let's go
ahead and do the following.

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Ultimately, this course is about tearing
apart conceptually, a lot of which

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is currently unfamiliar to you.

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Go ahead-- watching out
for your neighbors eyes,

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though, since there's a little
spring in these things--

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and just go ahead and
pull off the metal tab

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that you slid over just a moment ago.

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So now you can actually push your
finger against that little floppy disk,

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so to speak.

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And let's take this one step further,
if only for the sake of drama here.

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Go ahead and insert your fingers
wherever it seems possible,

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and just take the plastic
cover off this thing,

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and literally take out
the so-called floppy disk.

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I know, right?

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So pretty underwhelming once
you actually get inside there.

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But that's exactly the takeaway.

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Underneath all of this
technology, at the end of the day,

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are fairly simple things.

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You can't see these magnetic particles.

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But if you do go ahead and wipe
your fingers across this disk,

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you've certainly hurt or corrupted any
of the data that might, in fact, have

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been on these floppies.

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[LAUGHTER]

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But again, the takeaway is
just the simplicity of it all.

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And those of you who are
sitting in this room thinking

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that, computer science is perhaps
not for you, technology in general

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has never been for you, just
realize that all of this stuff

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has been man made over the years.

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And at its core, some of these
things are fairly simple.

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It's just that we have
30, 40 years of technology

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built on top of some of these simplest
technologies to get us to the point

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where we are today.

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Just to make this a bit
more technical now--

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and this is not an electrical
engineering course by any means,

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especially as this topic is about
to be introduced by this same voice

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again-- let's just take a
look at exactly how these here

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magnetic particles are, in fact,
aligned in the spirit of ones and zeros.

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[VIDEO PLAYBACK]

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- To write data on your
floppy disk, your PC

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tells the drive to send tiny pulses
of electricity through the head.

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The pulses make the head act
like little electromagnets.

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Each head creates a magnetic field
that reaches the surface of the disk.

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Remember the magnetic
coating on the cookie?

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The magnetic field alters the
tiny particles in this coating.

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Its current runs through
the heads one way.

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The particles are arranged at the
north and south poles in one direction.

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But if current flows through
the head the opposite way,

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the polarity reverses.

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To read data from the
disk, the read/write

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heads move into the same
position over the cookie.

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But this time, the process is reversed.

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The cookie particles create a
magnetic field in the coils of wire,

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and this creates a current
in the read/write head.

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The disk drive detects this flow of
electricity and passes it onto the PC.

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The PC translates the back
and forth current changes

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into a series of ones and zeros, the
binary language of computer data.

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[END PLAYBACK]

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DAVID MALAN: OK, so
at the end of the day,

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it just boils down to the
magnetization of these particles.

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You get zeros and ones.

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But let's ask the more
interesting question now.

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Who cares?

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So suppose you do have this ability
to store nothing other than zeros

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and ones inside of a computer.

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Well why is that, in fact, even useful?

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Well, it turns out-- as
this woman's voice now

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suggested-- that using the so-called
binary alphabet of zeros and ones,

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you can represent any possible number.

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We all speak the
so-called decimal system--

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0 through 9, and then
combinations thereof.

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Computers only speak binary
combinations of zeros and two.

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So let's take a moment here--
and for those unfamiliar--

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teach you how to count, not in decimal--

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1,2,3, 4,5,6, 7,8, 9, 10--
but instead, in binary.

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And I'll toss a softball out there.

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If all you have in the world are zeros
and ones, just take a stab at it.

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How would you go about representing
the decimal number we know as zero?

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AUDIENCE: Zero.

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DAVID MALAN: OK, so not
a hard class thus far.

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So in fact, it's true.

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So it's just all zeros.

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So you often hear of zeros
and ones talked about in terms

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of turning something on--

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a one, turning something off.

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A zero, like a light bulb is
on, might represent a one.

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A light bulb is off, it
might represent a zero.

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Often intertwined in
that kind of conversation

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is mentioned of fairly technical
things like transistors,

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which are nothing more than
switches that turn something

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on or turn something off.

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So we might represent 8 bits--

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that is 8 zeros and ones-- by
say, these light bulbs here.

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And if all eight of those bulbs--

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a byte, B-Y-T-E of bits, if you
will-- if are all set to off,

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well that number there is
simply representing zero.

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Now take another stab.

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If you have only zeros
and ones in the world,

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how do you go about
representing the number one?

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AUDIENCE: One.

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DAVID MALAN: All right, so
again, not all that non-obvious.

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All the things to the left are
just like the leading zeros.

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You could put as many zeros to the
left of a decimal number as you want,

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but 00123 is still the
number we know as 123.

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Same in this case.

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We've got 8 bits, but we only
needed one of them, so that's fine.

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The rest are assumed to be zeros.

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Well, how do you count up from there?

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Well, then you start toggling
these bits, so to speak.

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You turn one off.

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You turn the next one
over to the left on.

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How would you go now
to the number three?

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Well, take a guess.

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If we've now got represented on the
board zero, one, two, intuitively,

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what's probably the pattern here?

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AUDIENCE: One, one.

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DAVID MALAN: So one, one.

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Just flip on the bit that's still off.

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And so now we have one, one.

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So now, we're sort of
in this situation where,

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if we want to represent the
number four, we can't just

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use those two right
most bits, because it

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looks like the biggest
number we can represent

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with just two light bulbs, two
bits, looks like the number three.

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Well, how do we go about making
room for the number four?

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Well, take a guess.

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What do we do with these bits to
get to the decimal number four?

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AUDIENCE: [INAUDIBLE]

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DAVID MALAN: So turn off those
two, but flip the next one on.

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So now we have light bulb on,
light bulb off, light bulb off.

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Now how do you actually-- and just to
make this more real, here's the before.

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Turn those light bulbs
into zeros and ones after.

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So before, after.

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What you have here is
what we simply know

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as bytes of bits in the binary system.

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So what's really the pattern here?

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Well, as you might have noticed that
the top row of this little chart,

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there's these column
headers, which I've labeled

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the ones column, the twos column,
the fours column, the eights column.

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There's clearly a pattern
there-- multiples of two

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going on up from right to left.

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But why are those
placeholders actually useful?

239
00:10:33,820 --> 00:10:37,420
Well, take note of say, this last
row of bits that we have here.

240
00:10:37,420 --> 00:10:39,340
One, zero, zero.

241
00:10:39,340 --> 00:10:43,000
Well, why does that represent what
we know as the decimal number four?

242
00:10:43,000 --> 00:10:43,780
Well, take a look.

243
00:10:43,780 --> 00:10:45,760
In the fours column, we have a one.

244
00:10:45,760 --> 00:10:48,130
So that's like 4 times 1 is 4.

245
00:10:48,130 --> 00:10:52,120
So plus a 0 in the twos
column, a 0 in the ones column,

246
00:10:52,120 --> 00:10:54,970
and so the additive sum is just 4.

247
00:10:54,970 --> 00:10:56,890
You use that same logic
for the number three.

248
00:10:56,890 --> 00:10:59,600
So for the number three,
in the second to last row,

249
00:10:59,600 --> 00:11:04,480
we had nothing in those 128s
through the fours columns.

250
00:11:04,480 --> 00:11:07,790
But in the twos column and
the ones column, we had ones.

251
00:11:07,790 --> 00:11:12,400
So we have one 2, plus one 1 gives us
the decimal number we know as three.

252
00:11:12,400 --> 00:11:16,600
And just to make this more clear,
this is not wholly unfamiliar to us.

253
00:11:16,600 --> 00:11:22,180
If you consider what we know as the
decimal number 123 from grade school,

254
00:11:22,180 --> 00:11:25,720
why is that the decimal number 123?

255
00:11:25,720 --> 00:11:28,030
Well, recall the same
system, the same trick.

256
00:11:28,030 --> 00:11:32,260
We had the ones place, we had the
tens place, we had the hundreds place.

257
00:11:32,260 --> 00:11:34,390
So why is this 123?

258
00:11:34,390 --> 00:11:41,770
It's one 100, plus 2 times 10, plus 3
times 1, gives us what we know as 123.

259
00:11:41,770 --> 00:11:45,280
So this idea of binary, or
base 2, as it might be known,

260
00:11:45,280 --> 00:11:46,630
is not so foreign to you.

261
00:11:46,630 --> 00:11:49,120
It's simply all you have at
your disposal, ultimately,

262
00:11:49,120 --> 00:11:51,190
is just two values, zeros and ones.

263
00:11:51,190 --> 00:11:52,900
Where as, from grade
school onward, we've

264
00:11:52,900 --> 00:11:57,580
been used to having 10 digits
at our disposal, 0 through 9.

265
00:11:57,580 --> 00:12:02,950
So with that said, a little application
of knowledge, just learned perhaps--

266
00:12:02,950 --> 00:12:06,040
Cambridge's zip code is 0 2 1 3 8.

267
00:12:06,040 --> 00:12:08,920
If you're a freshman and don't
know that yet, you will soon.

268
00:12:08,920 --> 00:12:10,990
0 2 1 3 8--

269
00:12:10,990 --> 00:12:14,255
what is that in binary?

270
00:12:14,255 --> 00:12:16,630
Granted, the easiest way to
answer this is skipping ahead

271
00:12:16,630 --> 00:12:20,050
in your lecture notes, but
there are dashed lines here

272
00:12:20,050 --> 00:12:25,020
for your intellectual stimulation.

273
00:12:25,020 --> 00:12:31,020
0 2 1 3 8 is what in binary,
from top to bottom row?

274
00:12:31,020 --> 00:13:07,555


275
00:13:07,555 --> 00:13:08,055
All right.

276
00:13:08,055 --> 00:13:10,770


277
00:13:10,770 --> 00:13:13,020
The solution is now on the board.

278
00:13:13,020 --> 00:13:16,710
Hopefully, the first row,
everyone got zero, all zeros.

279
00:13:16,710 --> 00:13:19,498
One, similarly pretty easy, because
we just did that a moment ago.

280
00:13:19,498 --> 00:13:21,540
But hopefully your answers
check up against this.

281
00:13:21,540 --> 00:13:24,360
Turns out, the only value we
haven't already seen on the board

282
00:13:24,360 --> 00:13:25,290
is that eight.

283
00:13:25,290 --> 00:13:26,410
Well, why does that work?

284
00:13:26,410 --> 00:13:31,710
Well, one, zero, zero, zero on that last
row is obviously one 8, plus zero 4s,

285
00:13:31,710 --> 00:13:34,285
plus zero 2s, plus zero 1s.

286
00:13:34,285 --> 00:13:35,160
All right, that's it.

287
00:13:35,160 --> 00:13:39,000
That is all there is to binary,
to the so-called zeros and ones

288
00:13:39,000 --> 00:13:40,410
that only computers speak.

289
00:13:40,410 --> 00:13:45,720
And sad to say is perhaps,
aspiring computer scientist, you

290
00:13:45,720 --> 00:13:49,890
can now appreciate the, dare say,
humor of such comics as these.

291
00:13:49,890 --> 00:13:57,610


292
00:13:57,610 --> 00:14:00,520
Yeah, if you're laughing you
belong in computer science perhaps.

293
00:14:00,520 --> 00:14:01,660
[LAUGHTER]

294
00:14:01,660 --> 00:14:04,030
So, all right, so that's
all fine and good.

295
00:14:04,030 --> 00:14:07,540
You can represent number 0
through 8 certainly, and beyond,

296
00:14:07,540 --> 00:14:09,880
if we just keep using more
and more of these bits, more

297
00:14:09,880 --> 00:14:11,300
and more of these zeros and ones.

298
00:14:11,300 --> 00:14:14,500
But that's not all that useful when
computers today don't obviously

299
00:14:14,500 --> 00:14:16,150
just calculate numbers.

300
00:14:16,150 --> 00:14:19,023
They have graphics and they
display characters of text.

301
00:14:19,023 --> 00:14:20,440
They allow you to write documents.

302
00:14:20,440 --> 00:14:23,148
Well, it turns out-- and we'll
revisit this later in the course--

303
00:14:23,148 --> 00:14:25,660
that computers are as
sophisticated as they are today

304
00:14:25,660 --> 00:14:29,770
because they use those zeros and
ones, this trivial alphabet of zeros

305
00:14:29,770 --> 00:14:35,290
and ones, to represent any possible
types of data, including, for instance,

306
00:14:35,290 --> 00:14:36,340
alphabetical letters.

307
00:14:36,340 --> 00:14:39,940
So this chart-- scary or
overwhelming as it might seem now--

308
00:14:39,940 --> 00:14:44,710
is simply a mapping, using what's
called the ASCII coding system, where

309
00:14:44,710 --> 00:14:47,740
in the right hand columns
that are each in red,

310
00:14:47,740 --> 00:14:50,150
you have some familiar
characters in red.

311
00:14:50,150 --> 00:14:52,150
These are like characters
on the keyboard.

312
00:14:52,150 --> 00:14:53,800
So you have A through A in lowercase--

313
00:14:53,800 --> 00:14:57,190
A through Z in lowercase,
A through Z in uppercase,

314
00:14:57,190 --> 00:14:58,930
a whole bunch of punctuation.

315
00:14:58,930 --> 00:15:00,940
And then next to each
of those red characters,

316
00:15:00,940 --> 00:15:04,510
you essentially have the numeric
codes that computers traditionally

317
00:15:04,510 --> 00:15:06,890
used to represent those values.

318
00:15:06,890 --> 00:15:10,480
So with that said-- and the left most
column under dec just means decimal--

319
00:15:10,480 --> 00:15:15,940
what is the decimal value that a
computer uses to represent internally

320
00:15:15,940 --> 00:15:18,880
the letter capital A?

321
00:15:18,880 --> 00:15:20,230
AUDIENCE: 65.

322
00:15:20,230 --> 00:15:22,150
DAVID MALAN: All right, so 65.

323
00:15:22,150 --> 00:15:23,710
And how about lowercase A?

324
00:15:23,710 --> 00:15:24,710
AUDIENCE: 97.

325
00:15:24,710 --> 00:15:25,990
DAVID MALAN: 97.

326
00:15:25,990 --> 00:15:30,280
OK, if you take away no two other
numbers from this so-called ASCII

327
00:15:30,280 --> 00:15:33,610
coding system two weeks from
now in a forthcoming problem,

328
00:15:33,610 --> 00:15:37,210
know that by just remembering
65 and 97 turns out

329
00:15:37,210 --> 00:15:41,380
you can remember 50 other additional
characters, as well, because they're

330
00:15:41,380 --> 00:15:44,020
all obviously linearly increasing.

331
00:15:44,020 --> 00:15:45,430
So that's it for today.

332
00:15:45,430 --> 00:15:48,580
That's the hardcore Introduction
to zeros and ones, binaries,

333
00:15:48,580 --> 00:15:49,990
how computers speak.

334
00:15:49,990 --> 00:15:53,270
What then is this course all about?

335
00:15:53,270 --> 00:15:54,220
So here's the deal.

336
00:15:54,220 --> 00:15:57,640
CS50 certainly has a
reputation, and it has for 10,

337
00:15:57,640 --> 00:16:01,420
20 or so years since it's been around,
even if some of its prior forms.

338
00:16:01,420 --> 00:16:04,660
I, myself, was an
undergrad in '95 to '99,

339
00:16:04,660 --> 00:16:07,990
and I was a gov major for the first
year and a half that I was here.

340
00:16:07,990 --> 00:16:10,450
And I certainly came
into this school as sort

341
00:16:10,450 --> 00:16:13,178
of a geek, the kind of kid
who, I heard it up here,

342
00:16:13,178 --> 00:16:15,970
might have laughed at like the fox
trot cartoon once I knew binary.

343
00:16:15,970 --> 00:16:16,630
[LAUGHTER]

344
00:16:16,630 --> 00:16:19,810
But even so-- and I was
a UA at the time, too--

345
00:16:19,810 --> 00:16:23,290
even so, CS50 had this
reputation that I think

346
00:16:23,290 --> 00:16:25,450
it's still, to a large
extent, has today, which

347
00:16:25,450 --> 00:16:27,260
is that it takes a lot of work.

348
00:16:27,260 --> 00:16:28,090
It's really hard.

349
00:16:28,090 --> 00:16:30,940
It's really only for those
computer genius friends of yours.

350
00:16:30,940 --> 00:16:36,070
Or in any case, it has a reputation that
I think is much larger, much scarier,

351
00:16:36,070 --> 00:16:37,900
than say, the course actually is itself.

352
00:16:37,900 --> 00:16:40,810
And just on a whim really, or
finally come sophomore year,

353
00:16:40,810 --> 00:16:43,400
I had some additional confidence
perhaps, and I decided,

354
00:16:43,400 --> 00:16:43,990
all right, what the heck.

355
00:16:43,990 --> 00:16:44,695
I'll take CS50.

356
00:16:44,695 --> 00:16:46,660
I know I like this kind of stuff.

357
00:16:46,660 --> 00:16:49,120
I'll just ignore all
of the sort of advice

358
00:16:49,120 --> 00:16:51,220
that my friends have
given me to the contrary.

359
00:16:51,220 --> 00:16:54,400
I took the course pass/fail
up until the last possible day

360
00:16:54,400 --> 00:16:56,110
when you could switch to a letter grade.

361
00:16:56,110 --> 00:17:00,040
And for me, the change was simply
because, for the first time,

362
00:17:00,040 --> 00:17:03,580
in really of any of the courses I had
taken thus far as an undergrad-- like,

363
00:17:03,580 --> 00:17:04,790
I love this stuff.

364
00:17:04,790 --> 00:17:07,869
And it was the first time for me--
and you can make fun of me for this

365
00:17:07,869 --> 00:17:09,220
in subsequent classes--

366
00:17:09,220 --> 00:17:12,339
it was the first time for me
that homework honestly was fun.

367
00:17:12,339 --> 00:17:15,490
And there was this coincidence
of sort of my interest

368
00:17:15,490 --> 00:17:17,680
sort of on an extracurricular level--

369
00:17:17,680 --> 00:17:20,770
and though, I did other things
besides computers extracurricularly--

370
00:17:20,770 --> 00:17:22,990
and what actually was assigned work.

371
00:17:22,990 --> 00:17:27,700
And this is absolutely more of a
commentary on perhaps my social life

372
00:17:27,700 --> 00:17:29,690
at the time than on
computer science 50--

373
00:17:29,690 --> 00:17:30,190
[LAUGHTER]

374
00:17:30,190 --> 00:17:34,090
--but I used to look forward,
frankly, to sitting down on Friday

375
00:17:34,090 --> 00:17:37,450
night, and tackling the
newest problem sets.

376
00:17:37,450 --> 00:17:41,090
And that, too, is worthy of making
fun of me for in the future.

377
00:17:41,090 --> 00:17:43,480
But this is only to say
that this course certainly

378
00:17:43,480 --> 00:17:44,817
has personal significance to me.

379
00:17:44,817 --> 00:17:47,650
And all of these folks you see
sitting here in these blue t-shirts--

380
00:17:47,650 --> 00:17:49,780
the teaching fellows, who I'll
introduce again in a bit--

381
00:17:49,780 --> 00:17:51,790
really feel passionately
about this course.

382
00:17:51,790 --> 00:17:56,020
For me, it really turned me on to
an academic field, and ultimately

383
00:17:56,020 --> 00:17:59,470
a degree program, that I just had no
idea I would take such an interest in.

384
00:17:59,470 --> 00:18:02,140
And the funny thing is,
these days, last year,

385
00:18:02,140 --> 00:18:04,540
the past five years,
most of you in this room

386
00:18:04,540 --> 00:18:06,460
are certainly not going to become--

387
00:18:06,460 --> 00:18:09,200
certainly, as a result of this
class-- computer science majors.

388
00:18:09,200 --> 00:18:12,820
In fact, CS majors constitute
the significant minority

389
00:18:12,820 --> 00:18:15,790
of the students in CS50 these
days, because rather, we

390
00:18:15,790 --> 00:18:18,160
have students taking this
class as an elective,

391
00:18:18,160 --> 00:18:21,490
as a related field requirement
for their own concentration.

392
00:18:21,490 --> 00:18:24,880
And the fact of the matter
is, because this course really

393
00:18:24,880 --> 00:18:29,560
is sort of a side effect, or as a
framework for introducing computer

394
00:18:29,560 --> 00:18:32,350
science, teaches you programming.

395
00:18:32,350 --> 00:18:36,010
Honestly, the rewards of a course
like this, an introductory course

396
00:18:36,010 --> 00:18:38,980
in computer science, really
are huge in that they really

397
00:18:38,980 --> 00:18:41,750
can be applicable to your own
field, whether you're a science

398
00:18:41,750 --> 00:18:44,500
major, whether you're a math major,
whether you're simply involved

399
00:18:44,500 --> 00:18:46,330
in a student group and
need to actually use

400
00:18:46,330 --> 00:18:49,660
computers to use websites to
actually make your lives easier,

401
00:18:49,660 --> 00:18:51,260
and automate some processes.

402
00:18:51,260 --> 00:18:53,650
So just realize that the
takeaways from this course

403
00:18:53,650 --> 00:18:57,880
are far more than I think than can be
conveyed in this fairly arcane language

404
00:18:57,880 --> 00:18:59,470
that you see in the course catalog.

405
00:18:59,470 --> 00:19:01,660
Frankly, you read this
description, and it doesn't

406
00:19:01,660 --> 00:19:03,380
sound like the course for most people.

407
00:19:03,380 --> 00:19:06,220
But if you dive deeper into the
syllabus, the course's website,

408
00:19:06,220 --> 00:19:09,440
conversations with these folks
here who have all taken the course,

409
00:19:09,440 --> 00:19:12,820
hopefully you'll realize
that this course is not

410
00:19:12,820 --> 00:19:16,940
what its reputation perhaps
makes itself out to be.

411
00:19:16,940 --> 00:19:19,090
So with that said, what
are the expectations

412
00:19:19,090 --> 00:19:21,520
of students who do, in
fact, take this course?

413
00:19:21,520 --> 00:19:24,970
Quite simply, attend all lectures and
sections, complete eight problem sets,

414
00:19:24,970 --> 00:19:27,550
take three quizzes,
produce a final project.

415
00:19:27,550 --> 00:19:30,010
A popular question to address
at the start of the term

416
00:19:30,010 --> 00:19:31,430
is is there a final exam?

417
00:19:31,430 --> 00:19:33,220
And the answer is no.

418
00:19:33,220 --> 00:19:36,230
Grades are computed and
will be weighted as follows.

419
00:19:36,230 --> 00:19:39,220
Essentially, the breakdown will
be as such-- this is elaborated on

420
00:19:39,220 --> 00:19:40,070
in the syllabus.

421
00:19:40,070 --> 00:19:43,120
But realize, because this course
is certainly a lot of work,

422
00:19:43,120 --> 00:19:44,350
it does have this reputation.

423
00:19:44,350 --> 00:19:45,880
And I should make this point clear.

424
00:19:45,880 --> 00:19:50,860
Undoubtedly, computer science 50
comes with a non-trivial workload.

425
00:19:50,860 --> 00:19:54,790
And by that, we mean 10 plus
hours a week, 10, 15 hours a week.

426
00:19:54,790 --> 00:19:59,260
For many of you freshmen in the room,
that sounds like a scary lot of hours.

427
00:19:59,260 --> 00:20:02,530
Hopefully, if you're sophomore,
junior, senior, or beyond,

428
00:20:02,530 --> 00:20:06,130
you realize that, ha ha, 10 hours,
that wasn't so bad back in the day.

429
00:20:06,130 --> 00:20:07,908
So just realize that your--

430
00:20:07,908 --> 00:20:10,660
[LAUGHTER]

431
00:20:10,660 --> 00:20:14,983
--perception of courses and course
loads, I do think, changes over time.

432
00:20:14,983 --> 00:20:16,900
And just to give you the
extreme counterpoint,

433
00:20:16,900 --> 00:20:18,733
perhaps to scare you
out of computer science

434
00:20:18,733 --> 00:20:22,330
altogether-- when I took computer
science 161, operating systems,

435
00:20:22,330 --> 00:20:26,230
when I was in undergrad, that course,
by contrast-- and it's an elective.

436
00:20:26,230 --> 00:20:30,137
You don't have to take this course-- was
about 40 hours a week every other week.

437
00:20:30,137 --> 00:20:33,220
So that's sort of the other extreme,
and that explains my Saturday nights,

438
00:20:33,220 --> 00:20:34,210
as well, that semester.

439
00:20:34,210 --> 00:20:35,570
[LAUGHTER]

440
00:20:35,570 --> 00:20:39,550
So with that said, the course
definitely comes with its own workload,

441
00:20:39,550 --> 00:20:40,510
a non-trivial amount.

442
00:20:40,510 --> 00:20:43,360
But the thing is, you're not
going to learn computer science.

443
00:20:43,360 --> 00:20:47,020
You're not going to learn how to program
listening to a guy like me up here,

444
00:20:47,020 --> 00:20:49,420
or even listening to your
teaching fellow once a week.

445
00:20:49,420 --> 00:20:52,330
It's only in sitting down
in front of your own machine

446
00:20:52,330 --> 00:20:55,240
and actually solving problems,
fighting with the computer,

447
00:20:55,240 --> 00:20:59,140
making it do what you want it to do,
and getting your programs to work,

448
00:20:59,140 --> 00:21:02,000
that you really exit
with a new skill set.

449
00:21:02,000 --> 00:21:05,020
So it is simply par for the course,
frankly, putting a lot of time

450
00:21:05,020 --> 00:21:06,590
into a course like this.

451
00:21:06,590 --> 00:21:09,970
But again, what you get out of it,
hopefully, is the ability to one,

452
00:21:09,970 --> 00:21:13,690
solve problems in ways that your
peers simply cannot, without say,

453
00:21:13,690 --> 00:21:18,200
even that skill of programming alone,
and honestly, at speeds that others,

454
00:21:18,200 --> 00:21:21,910
including yourself as of now perhaps,
could not solve those same problems

455
00:21:21,910 --> 00:21:25,127
that computers facilitate
precisely those kinds of solutions.

456
00:21:25,127 --> 00:21:27,460
However, because there is a
lot of work and we certainly

457
00:21:27,460 --> 00:21:30,700
appreciate that we all have
occasional bad days or weeks,

458
00:21:30,700 --> 00:21:33,110
you will be able to drop
your lowest problem set.

459
00:21:33,110 --> 00:21:35,260
You'll be able to drop
your lowest quiz score.

460
00:21:35,260 --> 00:21:37,330
And there's a great
deal more infrastructure

461
00:21:37,330 --> 00:21:40,450
in place of support structure
for you throughout the semester.

462
00:21:40,450 --> 00:21:43,810
You may, as I started two years
ago, take the course pass/fail,

463
00:21:43,810 --> 00:21:47,200
simply come up to me or one of the
teaching fellows to discuss as much.

464
00:21:47,200 --> 00:21:49,480
But we are fine, certainly, with that.

465
00:21:49,480 --> 00:21:52,630
The course's website will
contain much of what you need

466
00:21:52,630 --> 00:21:55,390
to succeed or to review in this course.

467
00:21:55,390 --> 00:21:59,500
We'll defer a walkthrough of
salient features in the future.

468
00:21:59,500 --> 00:22:03,130
For your keystroke saving
convenience, you can also just

469
00:22:03,130 --> 00:22:06,250
type CS50.org these days,
and it will redirect you

470
00:22:06,250 --> 00:22:09,100
to the FAS address, which is
a little harder to remember.

471
00:22:09,100 --> 00:22:12,310
The email address for the staff on which
I and all the teaching fellows are,

472
00:22:12,310 --> 00:22:15,190
is simply cs50@fas.

473
00:22:15,190 --> 00:22:17,830
But one of the features of this
course that, over the years,

474
00:22:17,830 --> 00:22:23,740
has proved rather popular, if only
because of its anonymization of posts

475
00:22:23,740 --> 00:22:27,940
and its 24 hour accessibility,
is the so-called bulletin board

476
00:22:27,940 --> 00:22:28,960
on the course's website.

477
00:22:28,960 --> 00:22:30,880
You're presumably familiar
with this concept.

478
00:22:30,880 --> 00:22:33,520
The bulletin board will be
accessible in about a week's time.

479
00:22:33,520 --> 00:22:35,350
But we do urge you
throughout the semester

480
00:22:35,350 --> 00:22:38,427
to post your questions
anonymously to this bulletin board

481
00:22:38,427 --> 00:22:40,510
so that you certainly might
benefit from an answer

482
00:22:40,510 --> 00:22:43,960
from fellow students or ourselves,
or certainly, other students

483
00:22:43,960 --> 00:22:47,290
can benefit from the same.

484
00:22:47,290 --> 00:22:50,950
All right, books-- there are
four at the Coop, all of them

485
00:22:50,950 --> 00:22:52,790
unreasonably expensive.

486
00:22:52,790 --> 00:22:54,800
Here's the deal with the books.

487
00:22:54,800 --> 00:22:57,110
So there are no required
books for this course.

488
00:22:57,110 --> 00:23:00,190
These days, I'm not really a fan
of coercing students to buy books,

489
00:23:00,190 --> 00:23:02,080
particularly because of their cost.

490
00:23:02,080 --> 00:23:05,980
The course is not designed
around using a specific textbook.

491
00:23:05,980 --> 00:23:10,760
However, we did go ahead and recommend
any of four books as follows.

492
00:23:10,760 --> 00:23:13,690
Essentially, with the trend that
this course fights over years

493
00:23:13,690 --> 00:23:16,960
is to balance as effectively as
possible those students coming

494
00:23:16,960 --> 00:23:19,480
into this course who are very
comfortable with computers,

495
00:23:19,480 --> 00:23:21,880
maybe took AP Computer
Science, and are here

496
00:23:21,880 --> 00:23:23,630
really to fill in holes
in their knowledge

497
00:23:23,630 --> 00:23:25,210
so they can move to
higher level courses.

498
00:23:25,210 --> 00:23:27,002
And then there's the
other type of student,

499
00:23:27,002 --> 00:23:28,960
who is genuinely scared
of their computer,

500
00:23:28,960 --> 00:23:32,590
or feels that they should know something
about programming or computer science,

501
00:23:32,590 --> 00:23:36,520
but just generally feels that they
are not quite at the same skill level

502
00:23:36,520 --> 00:23:38,810
as say, some of the
students in their sections.

503
00:23:38,810 --> 00:23:42,340
So to accommodate these two
different sort of unofficial tracks

504
00:23:42,340 --> 00:23:44,980
within the course, one approach
that we've taken this year

505
00:23:44,980 --> 00:23:47,290
is to recommend either of two books.

506
00:23:47,290 --> 00:23:49,550
Essentially, the way we've
spun these is as follows.

507
00:23:49,550 --> 00:23:51,490
This is a recommended
book in the syllabus

508
00:23:51,490 --> 00:23:54,580
for quote unquote those less
comfortable with either computer

509
00:23:54,580 --> 00:23:57,570
science, computers, with
the idea of programming.

510
00:23:57,570 --> 00:24:01,400
By contrast, this book is what we
recommend for those more comfortable,

511
00:24:01,400 --> 00:24:03,900
those of you who have maybe had
some programming experience,

512
00:24:03,900 --> 00:24:07,200
or even if you haven't, just feel like
you're going to be fine in this course.

513
00:24:07,200 --> 00:24:10,590
This is more at your level.

514
00:24:10,590 --> 00:24:12,930
Effectively, these two
books in particular

515
00:24:12,930 --> 00:24:16,950
are designed to be at home
supplements to lectures and sections.

516
00:24:16,950 --> 00:24:20,640
If you are simply the type of student
who learns well from reading books,

517
00:24:20,640 --> 00:24:26,010
if you enjoy sort of the crutch that
having a book by your side sort of

518
00:24:26,010 --> 00:24:28,950
brings after lectures or
adjourn, then by all means,

519
00:24:28,950 --> 00:24:31,290
flip through either of these two texts.

520
00:24:31,290 --> 00:24:35,010
Bye one of them, or perhaps, just
take a look at it in the library.

521
00:24:35,010 --> 00:24:36,770
Though I would urge
any of you, if you go

522
00:24:36,770 --> 00:24:40,020
this route of buying any of the books,
follow the link on the course's website

523
00:24:40,020 --> 00:24:43,560
to say, Amazon, and you can get
these books significantly discounted.

524
00:24:43,560 --> 00:24:46,440
You will not need them for
at least a week or two,

525
00:24:46,440 --> 00:24:49,860
so you certainly won't be at a
disadvantage placing a super saver

526
00:24:49,860 --> 00:24:51,720
order sometime this week.

527
00:24:51,720 --> 00:24:56,280
This book here is bundled at a
discount, quote unquote, at the Coop.

528
00:24:56,280 --> 00:24:57,587
[LAUGHTER]

529
00:24:57,587 --> 00:25:00,420
I probably shouldn't really say all
these things on film these days,

530
00:25:00,420 --> 00:25:01,190
but so be it.

531
00:25:01,190 --> 00:25:03,150
[LAUGHTER]

532
00:25:03,150 --> 00:25:04,950
This is just a lot of fun, this book.

533
00:25:04,950 --> 00:25:08,820
This book is in the spirit of those,
granted, cheesy videos that we showed

534
00:25:08,820 --> 00:25:11,010
just a bit ago in that
it's essentially--

535
00:25:11,010 --> 00:25:14,310
a picture book is the wrong word,
because it's more technical than that--

536
00:25:14,310 --> 00:25:17,160
but it's very easily digestible.

537
00:25:17,160 --> 00:25:18,960
And it addresses things
like how does RAM

538
00:25:18,960 --> 00:25:21,870
work, how does a hard drive
work, how does a joystick work,

539
00:25:21,870 --> 00:25:24,480
how does Mac OS boot up at startup.

540
00:25:24,480 --> 00:25:27,690
It's very bite-sized kinds
of topics that, if you just

541
00:25:27,690 --> 00:25:30,877
like to sort of know a bit more
about computer and the internet,

542
00:25:30,877 --> 00:25:32,460
it's an interesting book to reference.

543
00:25:32,460 --> 00:25:36,090
And laced throughout the problem sets
this semester will be sort of one

544
00:25:36,090 --> 00:25:39,210
liner questions like, how
does a hard drive work.

545
00:25:39,210 --> 00:25:41,460
And two, this book,
you can turn-- will let

546
00:25:41,460 --> 00:25:43,680
you turn to like, Wikipedia
and Google in general,

547
00:25:43,680 --> 00:25:44,970
for those kinds of questions.

548
00:25:44,970 --> 00:25:47,190
But really, the purpose
of this book in the course

549
00:25:47,190 --> 00:25:51,690
is really just to encourage you to
dabble in some useful knowledge,

550
00:25:51,690 --> 00:25:56,470
but that certainly isn't aligned with
the academic spirit of the course.

551
00:25:56,470 --> 00:25:59,370
Finally, for those handful of
you who might consider yourself

552
00:25:59,370 --> 00:26:02,070
to be, or want to be, hackers--

553
00:26:02,070 --> 00:26:05,730
a wonderfully esoteric book
is this Hacker's Delight.

554
00:26:05,730 --> 00:26:09,240
You find it perhaps advantageous
for a couple of the courses problem

555
00:26:09,240 --> 00:26:10,110
sets this year.

556
00:26:10,110 --> 00:26:12,780
But really, this is a good
reference book for those of you

557
00:26:12,780 --> 00:26:15,660
who know you're going to be
computer scientists, or really

558
00:26:15,660 --> 00:26:17,070
intense programmers.

559
00:26:17,070 --> 00:26:20,160
It's a wonderful book as to how
to optimize, that is, improve

560
00:26:20,160 --> 00:26:20,940
your own code.

561
00:26:20,940 --> 00:26:23,437
And I found this a wonderful
reference in graduate school

562
00:26:23,437 --> 00:26:26,520
when a lot of the challenges at hand
were not just getting things to work,

563
00:26:26,520 --> 00:26:29,770
but getting them to work
better than existing solutions,

564
00:26:29,770 --> 00:26:31,570
getting them to work faster.

565
00:26:31,570 --> 00:26:35,040
So as with a lot of the courses
here at Harvard, ours, too,

566
00:26:35,040 --> 00:26:36,250
comes with sections.

567
00:26:36,250 --> 00:26:37,590
And if I could draw
attention to you guys,

568
00:26:37,590 --> 00:26:39,590
if you wouldn't mind
standing for just a moment.

569
00:26:39,590 --> 00:26:41,760
Among our course's teaching
fellows are those here

570
00:26:41,760 --> 00:26:44,430
in the stylish, blue t-shirts today.

571
00:26:44,430 --> 00:26:46,770
You will see these in the
basement of the Science Center

572
00:26:46,770 --> 00:26:50,340
whenever one of these guys is
on duty during office hours,

573
00:26:50,340 --> 00:26:52,350
though I suspect as
semester progresses, they'd

574
00:26:52,350 --> 00:26:54,810
much rather you recognize their
faces than these t-shirts.

575
00:26:54,810 --> 00:26:57,150
So look at them now.

576
00:26:57,150 --> 00:27:01,360
These folks will be holding sections,
which are 60 to 90 minute sections once

577
00:27:01,360 --> 00:27:01,860
a week.

578
00:27:01,860 --> 00:27:03,600
They won't start until next week.

579
00:27:03,600 --> 00:27:06,400
We won't officially do
sectioning until next week.

580
00:27:06,400 --> 00:27:10,560
So the first week of sections next
week will just be "come as you are."

581
00:27:10,560 --> 00:27:13,650
Attend any of the available
sections, so no rush on that.

582
00:27:13,650 --> 00:27:15,070
Thank you guys very much.

583
00:27:15,070 --> 00:27:19,050
Let me also draw your attention in back
to Katie and Thomas, the course's head

584
00:27:19,050 --> 00:27:20,040
teaching fellows.

585
00:27:20,040 --> 00:27:24,960
These guys are together, as a pair,
responsible for managing the course

586
00:27:24,960 --> 00:27:26,130
administratively.

587
00:27:26,130 --> 00:27:29,380
They are a wonderful
liaison to the course,

588
00:27:29,380 --> 00:27:32,522
if you feel more comfortable
speaking with either of them.

589
00:27:32,522 --> 00:27:34,980
If, perhaps, you'd like to
discuss your own teaching fellow

590
00:27:34,980 --> 00:27:37,320
and how section's going
with someone else or myself,

591
00:27:37,320 --> 00:27:40,710
just know that these two here are
a wonderful resources, as well,

592
00:27:40,710 --> 00:27:44,820
and will be responsible for taking
care of sectioning in a week's time.

593
00:27:44,820 --> 00:27:50,590
So this is, again, a course with a
good amount of challenges with it.

594
00:27:50,590 --> 00:27:53,940
So what we will be offering in
addition to these traditional sections

595
00:27:53,940 --> 00:27:57,000
is what we've dubbed "super
sections," once per week.

596
00:27:57,000 --> 00:28:01,740
Essentially, these are sections that
students from any individual section

597
00:28:01,740 --> 00:28:03,930
are welcome to attend optionally.

598
00:28:03,930 --> 00:28:06,000
They'll be led by one or
more teaching fellows,

599
00:28:06,000 --> 00:28:09,870
and they'll cover the same material from
the week from lectures and sections,

600
00:28:09,870 --> 00:28:13,900
but usually with different examples,
from a different person's perspective.

601
00:28:13,900 --> 00:28:18,570
So these super sections, which
will also be filmed and put online,

602
00:28:18,570 --> 00:28:21,390
are designed really, for those of
you who are feeling uncomfortable

603
00:28:21,390 --> 00:28:23,220
in the course throughout
the semester, who

604
00:28:23,220 --> 00:28:26,460
feel like you benefit from
hearing things multiple times,

605
00:28:26,460 --> 00:28:29,160
and just generally want more
of a support structure in place

606
00:28:29,160 --> 00:28:29,850
for yourselves.

607
00:28:29,850 --> 00:28:33,750
These are purely optional, but they
do exist to facilitate your success,

608
00:28:33,750 --> 00:28:37,290
and really lowering your level
of stress in a course like this.

609
00:28:37,290 --> 00:28:41,220
In addition, office hours are a
traditionally very popular aspect

610
00:28:41,220 --> 00:28:42,190
of this course.

611
00:28:42,190 --> 00:28:45,150
Now, I know this photo makes you
almost want to go to office hours

612
00:28:45,150 --> 00:28:48,930
in this very Utopian kind of
place known as the Science Center.

613
00:28:48,930 --> 00:28:51,930
Once you get to the basement, it
doesn't look so green and fun anymore.

614
00:28:51,930 --> 00:28:52,890
[LAUGHTER]

615
00:28:52,890 --> 00:28:57,340
But a very popular, and a very
common memory of this course,

616
00:28:57,340 --> 00:29:00,640
is, in fact, the time students
spend alongside the teaching

617
00:29:00,640 --> 00:29:04,353
fellows in the so-called terminal
room, room B14 of the Science Center.

618
00:29:04,353 --> 00:29:05,770
It's down the stairs, take a left.

619
00:29:05,770 --> 00:29:09,760
It's got a bunch of Linux computers
these days, Macintosh computers, PCs.

620
00:29:09,760 --> 00:29:12,910
And essentially, we hold weekly
office hours for many hours a week

621
00:29:12,910 --> 00:29:16,060
down there, so that you can
really have some one on one,

622
00:29:16,060 --> 00:29:21,040
hands on assistance with the current
problem set, or most anything else.

623
00:29:21,040 --> 00:29:25,240
Also this year, what we will be
offering on an experimental basis--

624
00:29:25,240 --> 00:29:28,150
is what The Crimson apparently
broke the story this morning

625
00:29:28,150 --> 00:29:30,520
before we even had a
chance to announce it--

626
00:29:30,520 --> 00:29:32,090
the virtual office hours.

627
00:29:32,090 --> 00:29:34,510
So thanks to technology,
not only will we

628
00:29:34,510 --> 00:29:37,720
be able to help you in the basement
of the Science Center one on one,

629
00:29:37,720 --> 00:29:41,920
we'll also be offering what we dubbed
"virtual office hours" in the course's

630
00:29:41,920 --> 00:29:43,750
virtual terminal room this year.

631
00:29:43,750 --> 00:29:47,500
Essentially, what this will mean is
that you from your laptop or desktop

632
00:29:47,500 --> 00:29:49,450
computer, whether you're
in your dorm room,

633
00:29:49,450 --> 00:29:52,780
whether you're away on vacation perhaps,
or whether you're at brain break

634
00:29:52,780 --> 00:29:57,250
in the dining hall, you can log in to
what's effectively, a fancy chat room,

635
00:29:57,250 --> 00:30:00,730
that has not only the ability for
teaching fellows, a.k.a. moderators,

636
00:30:00,730 --> 00:30:05,050
to chat with you, either via text based
instant messaging interface, or even--

637
00:30:05,050 --> 00:30:07,780
though I think this is of
questionable efficacy--

638
00:30:07,780 --> 00:30:10,360
VoIP, voice over IP, using microphones.

639
00:30:10,360 --> 00:30:13,870
You can communicate in two ways
with your teaching fellow privately,

640
00:30:13,870 --> 00:30:17,770
but we can also share control
of, and observe your own screen.

641
00:30:17,770 --> 00:30:22,020
So you can think of this sort of like
CS50's tech support with problem sets.

642
00:30:22,020 --> 00:30:23,770
You'll be able to stay
in your dorm rooms.

643
00:30:23,770 --> 00:30:25,930
We'll be able to stay in
our dorm rooms or homes,

644
00:30:25,930 --> 00:30:30,220
and nonetheless, meet online to
assist you with these problem sets.

645
00:30:30,220 --> 00:30:33,250
It will be up to you
guys to really dictate

646
00:30:33,250 --> 00:30:36,580
where we allocate our resources--
more to the traditional Science Center

647
00:30:36,580 --> 00:30:39,290
office hours, or more to
these virtual office hours.

648
00:30:39,290 --> 00:30:41,620
You are as much a part
of this experiment

649
00:30:41,620 --> 00:30:44,030
as we are over the
course of the semester.

650
00:30:44,030 --> 00:30:46,660
So we'll demonstrate
that in a future lecture,

651
00:30:46,660 --> 00:30:51,820
and let you loose on it for
the course's first problem set.

652
00:30:51,820 --> 00:30:54,760
So administratively,
are there any questions

653
00:30:54,760 --> 00:30:58,210
before we survey the
material and such that you'll

654
00:30:58,210 --> 00:31:01,620
be exposed to in this course?

655
00:31:01,620 --> 00:31:02,300
Anything at all?

656
00:31:02,300 --> 00:31:02,800
Yes?

657
00:31:02,800 --> 00:31:06,120
AUDIENCE: How long are
these problem sets?

658
00:31:06,120 --> 00:31:07,870
DAVID MALAN: How long
is each problem set?

659
00:31:07,870 --> 00:31:12,400
I would say a typical student spends
about 10 hours, maybe 15 hours, maybe

660
00:31:12,400 --> 00:31:15,160
five hours, on a given problem set.

661
00:31:15,160 --> 00:31:19,850
And there are eight of them spread over
roughly 13 or 14 weeks of the semester.

662
00:31:19,850 --> 00:31:21,920
Other questions?

663
00:31:21,920 --> 00:31:22,420
No?

664
00:31:22,420 --> 00:31:25,660
OK, as with several courses
here these days, this course

665
00:31:25,660 --> 00:31:28,360
is and will be filmed
throughout the semester.

666
00:31:28,360 --> 00:31:32,890
Usually within 72 or 96 hours,
videos and quick time formats,

667
00:31:32,890 --> 00:31:37,240
flash formats, NP3 formats, will be
posted online via the course's website

668
00:31:37,240 --> 00:31:40,850
in the form of a podcast, and also
in the form of the web page itself.

669
00:31:40,850 --> 00:31:42,023
So you can tune in that way.

670
00:31:42,023 --> 00:31:45,190
Tonight's lecture, for instance, if you
have to duck out early for shopping,

671
00:31:45,190 --> 00:31:47,770
periods should be online
around midnight or so tonight,

672
00:31:47,770 --> 00:31:52,330
and the same will be true with a
96 hour window in future lectures.

673
00:31:52,330 --> 00:31:56,470
It's also my philosophy with
lectures and such that it is more

674
00:31:56,470 --> 00:31:59,860
of a distraction than anything--
certainly, for students like myself--

675
00:31:59,860 --> 00:32:04,082
to be constantly scribbling notes for
a 60 minute or a 90 minute lecture.

676
00:32:04,082 --> 00:32:06,790
Really, to the detriment, I think,
of the intellectual experience

677
00:32:06,790 --> 00:32:10,840
of sitting in on class, and
engaging, dare say, with the person

678
00:32:10,840 --> 00:32:13,090
at the podium who's asking
and answering questions.

679
00:32:13,090 --> 00:32:16,420
So toward that end, one of the
additional pieces of support structure

680
00:32:16,420 --> 00:32:19,570
we'll provide you with this semester,
thanks to the teaching fellows,

681
00:32:19,570 --> 00:32:22,090
will be a canonical
set of scribe notes, so

682
00:32:22,090 --> 00:32:25,660
to speak, whereby one of the
teaching fellows each lecture will

683
00:32:25,660 --> 00:32:28,180
be responsible for producing
an official, if you will,

684
00:32:28,180 --> 00:32:31,693
set of lecture notes that are not meant
to take the place of your own notes

685
00:32:31,693 --> 00:32:32,860
that you might want to take.

686
00:32:32,860 --> 00:32:37,060
But are meant to alleviate you of the
mental obligation, or the inclination,

687
00:32:37,060 --> 00:32:40,870
or the stress, of trying to scribble
down absolutely everything that

688
00:32:40,870 --> 00:32:43,330
may be said, particularly
when I or when lectures

689
00:32:43,330 --> 00:32:45,250
themselves tend to go a bit quickly.

690
00:32:45,250 --> 00:32:49,970
So know that, in addition, that support
structure will be in place for you.

691
00:32:49,970 --> 00:32:53,680
So with that said, any questions?

692
00:32:53,680 --> 00:32:57,140
So what's on the agenda
for the next several weeks?

693
00:32:57,140 --> 00:33:02,260
Well, in the course's first week,
namely this Wednesday and Friday,

694
00:33:02,260 --> 00:33:06,250
will we introduce you right away
to this world of programming.

695
00:33:06,250 --> 00:33:10,120
Ultimately, the course focus is
on a language called C. It's C,

696
00:33:10,120 --> 00:33:14,170
and then C++, and nowadays, C#, that
a lot of the programs on your own

697
00:33:14,170 --> 00:33:17,200
computers, particularly
Windows computers, are written.

698
00:33:17,200 --> 00:33:19,870
And it's in C that the
course's focus ultimately is.

699
00:33:19,870 --> 00:33:22,120
In the beginning, though,
we're going to introduce you

700
00:33:22,120 --> 00:33:23,500
to the idea of programming.

701
00:33:23,500 --> 00:33:27,130
And the concepts underlying programming,
without the distraction of what you'll

702
00:33:27,130 --> 00:33:31,790
quickly come to appreciate or
abhor, as parentheses and semicolon,

703
00:33:31,790 --> 00:33:34,750
and what on first glance, is
otherwise fairly arcane syntax.

704
00:33:34,750 --> 00:33:38,200
And what we'll introduce instead, in
just the first week of the course,

705
00:33:38,200 --> 00:33:41,680
is a programming environment, a
graphical programming environment,

706
00:33:41,680 --> 00:33:42,820
known as Scratch.

707
00:33:42,820 --> 00:33:46,600
Scratch essentially will allow
you to program, quote unquote,

708
00:33:46,600 --> 00:33:49,690
merely by dragging
puzzle pieces of sorts,

709
00:33:49,690 --> 00:33:53,050
that are color coded and shaped
according to the type of logic

710
00:33:53,050 --> 00:33:54,100
that they implement.

711
00:33:54,100 --> 00:33:56,560
This is perhaps best
explained for today's purposes

712
00:33:56,560 --> 00:33:58,540
by way of a little demonstration.

713
00:33:58,540 --> 00:34:03,040
What I've brought along with us today
is, for instance, one Scratch project

714
00:34:03,040 --> 00:34:04,900
that a former student
of mine implemented.

715
00:34:04,900 --> 00:34:07,690
And this is your 5 second overview
of what the interface looks

716
00:34:07,690 --> 00:34:10,719
like on Wednesday and Friday
when we dive into programming

717
00:34:10,719 --> 00:34:12,250
in the context of this thing.

718
00:34:12,250 --> 00:34:14,860
But I'm going to go ahead and
play what, for this student,

719
00:34:14,860 --> 00:34:18,610
was the outgrowth of just one
week of class, the semester she

720
00:34:18,610 --> 00:34:21,610
took this class, a two day
introduction to Scratch.

721
00:34:21,610 --> 00:34:23,800
And this is what she
submitted for her homework.

722
00:34:23,800 --> 00:34:26,980
It's in the spirit of an
animation, or a fairy tale.

723
00:34:26,980 --> 00:34:29,020
And that there is her first bug.

724
00:34:29,020 --> 00:34:30,502
[LAUGHTER]

725
00:34:30,502 --> 00:35:10,476


726
00:35:10,476 --> 00:35:10,976
[SCREAMS]

727
00:35:10,976 --> 00:35:13,466
[LAUGHTER]

728
00:35:13,466 --> 00:35:24,460


729
00:35:24,460 --> 00:35:27,190
All right, so what was
most gratifying for us,

730
00:35:27,190 --> 00:35:29,290
the teachers, that
semester was this student

731
00:35:29,290 --> 00:35:30,940
really had not programmed before.

732
00:35:30,940 --> 00:35:33,220
And again, after just
a few hours of time

733
00:35:33,220 --> 00:35:36,760
with us introducing Scratch, and
introducing some basic programming

734
00:35:36,760 --> 00:35:40,090
constructs like loops, and
conditions, and statements,

735
00:35:40,090 --> 00:35:43,360
and Boolean expressions, was she able
to come back just a few days later

736
00:35:43,360 --> 00:35:45,550
and present this to her class.

737
00:35:45,550 --> 00:35:47,800
The nice thing about Scratch
then is that, certainly,

738
00:35:47,800 --> 00:35:50,020
for those among you who have
never programmed before,

739
00:35:50,020 --> 00:35:52,853
and are just a little bit daunted
by the idea of this course at all,

740
00:35:52,853 --> 00:35:55,570
is that in just a week's
time, you, too, will be

741
00:35:55,570 --> 00:35:57,760
submitting something along these lines.

742
00:35:57,760 --> 00:36:01,600
Subject entirely to your own creativity,
we make no requirements really

743
00:36:01,600 --> 00:36:04,392
as to what the thing must
do, look like, or sound like.

744
00:36:04,392 --> 00:36:06,100
But you'll have this
experience, we hope,

745
00:36:06,100 --> 00:36:09,610
very early on of actually
producing an interactive,

746
00:36:09,610 --> 00:36:11,560
or a dynamic, computer program.

747
00:36:11,560 --> 00:36:15,250
And the fact of the matter is with more
traditional languages like, Java, C,

748
00:36:15,250 --> 00:36:20,440
C++, you just can't get to GUEs,
graphical user environments,

749
00:36:20,440 --> 00:36:25,480
or really sexy software, in just one
semester because there's so many steps

750
00:36:25,480 --> 00:36:29,170
that you must take before getting to a
point of sophistication where you can

751
00:36:29,170 --> 00:36:33,100
implement that stuff in these
more traditional languages.

752
00:36:33,100 --> 00:36:35,530
For this next demonstration
of Scratch, and this teaser

753
00:36:35,530 --> 00:36:40,240
of where we're going next week, I
do need a volunteer from the crowd.

754
00:36:40,240 --> 00:36:43,042
The catch is-- it's a
non-speaking role, so you don't

755
00:36:43,042 --> 00:36:44,500
need to feel that kind of pressure.

756
00:36:44,500 --> 00:36:46,520
The catch is you will
appear here on film.

757
00:36:46,520 --> 00:36:50,087
And so to satisfy the lawyers and such,
we need you to sign your name away,

758
00:36:50,087 --> 00:36:52,420
just saying that you realize
that you were filmed today,

759
00:36:52,420 --> 00:36:53,920
and you're OK being on the internet.

760
00:36:53,920 --> 00:36:55,710
[LAUGHTER]

761
00:36:55,710 --> 00:36:57,460
I don't know-- Thomas
is not volunteering.

762
00:36:57,460 --> 00:36:59,350
So we do need one volunteer.

763
00:36:59,350 --> 00:37:02,620
If ever there were way to prove to
your parents that you go to class,

764
00:37:02,620 --> 00:37:03,250
come on down.

765
00:37:03,250 --> 00:37:04,300
[LAUGHTER]

766
00:37:04,300 --> 00:37:05,410
Come on.

767
00:37:05,410 --> 00:37:10,120
So this program here simply
requires that-- this was a student--

768
00:37:10,120 --> 00:37:12,520
Carlos was his name-- who
implemented essentially

769
00:37:12,520 --> 00:37:15,490
a soccer program, whose functionality
will largely speak for itself.

770
00:37:15,490 --> 00:37:19,120
The only instructions you need to
know are that as soon as I click go,

771
00:37:19,120 --> 00:37:22,250
you're going to simply want to click
with the mouse on the player himself.

772
00:37:22,250 --> 00:37:24,280
And he will run and kick the ball.

773
00:37:24,280 --> 00:37:24,950
So here we go.

774
00:37:24,950 --> 00:37:26,852
I'm starting the program.

775
00:37:26,852 --> 00:37:29,310
So go ahead and just click the
player with the mouse button

776
00:37:29,310 --> 00:37:30,910
when you want him to kick the ball.

777
00:37:30,910 --> 00:37:32,495
And the goal is, of
course, to hit the target.

778
00:37:32,495 --> 00:37:34,287
VOLUNTEER: Oh, so it's
like a timing thing?

779
00:37:34,287 --> 00:37:35,170
DAVID MALAN: Exactly.

780
00:37:35,170 --> 00:37:36,122
[WHISTLE BLOWS]

781
00:37:36,122 --> 00:37:38,502


782
00:37:38,502 --> 00:37:40,257
[LAUGHTER]

783
00:37:40,257 --> 00:37:40,882
[WHISTLE BLOWS]

784
00:37:40,882 --> 00:37:41,465
VOLUNTEER: Oh!

785
00:37:41,465 --> 00:37:42,688
[LAUGHTER]

786
00:37:42,688 --> 00:37:50,000


787
00:37:50,000 --> 00:37:51,000
DAVID MALAN: Keep going.

788
00:37:51,000 --> 00:37:52,035
This is harder than it looks.

789
00:37:52,035 --> 00:37:52,776
[WHISTLE BLOWS]

790
00:37:52,776 --> 00:37:53,748
AUDIENCE: Oh!

791
00:37:53,748 --> 00:37:56,525


792
00:37:56,525 --> 00:37:57,150
[WHISTLE BLOWS]

793
00:37:57,150 --> 00:37:57,650
Oh!

794
00:37:57,650 --> 00:38:02,923


795
00:38:02,923 --> 00:38:04,090
DAVID MALAN: Yeah, one more.

796
00:38:04,090 --> 00:38:07,370


797
00:38:07,370 --> 00:38:10,670
[WHISTLE BLOWS]

798
00:38:10,670 --> 00:38:12,710
OK, a round of applause, if we could.

799
00:38:12,710 --> 00:38:16,063
[CLAPPING]

800
00:38:16,063 --> 00:38:18,435


801
00:38:18,435 --> 00:38:21,310
You know, I heard those comments,
and yeah, it's a non-speaking role,

802
00:38:21,310 --> 00:38:24,280
but you try hitting a moving target
with 200 people watching you.

803
00:38:24,280 --> 00:38:25,958
It's probably not the easiest thing.

804
00:38:25,958 --> 00:38:28,000
This last demonstration
that I wanted to give you

805
00:38:28,000 --> 00:38:31,360
also is a teaser as to where we're
going in just one week's time,

806
00:38:31,360 --> 00:38:32,830
starting this coming Wednesday.

807
00:38:32,830 --> 00:38:36,160
Was actually submitted by
one of the teaching fellows.

808
00:38:36,160 --> 00:38:39,520
We sort of, as a "get to know each
other" exercise this past week,

809
00:38:39,520 --> 00:38:42,400
all produced our own Scratch
program, so that we, too,

810
00:38:42,400 --> 00:38:44,680
would experience the same
experience that you're

811
00:38:44,680 --> 00:38:46,430
about to have over the coming week.

812
00:38:46,430 --> 00:38:51,970
This was a favorite of mine,
but I love them all, of course.

813
00:38:51,970 --> 00:38:53,290
[LAUGHTER]

814
00:38:53,290 --> 00:38:55,660
And this one is not
interactive, but also

815
00:38:55,660 --> 00:38:58,870
speaks to the dynamism
and the capabilities

816
00:38:58,870 --> 00:39:01,330
of this particular environment
that you, yourselves, will

817
00:39:01,330 --> 00:39:02,980
be unleashed on coming this Wednesday.

818
00:39:02,980 --> 00:39:06,310
[MUSIC PLAYING]

819
00:39:06,310 --> 00:39:44,947


820
00:39:44,947 --> 00:39:48,384
[MUSIC - THE WEATHER GIRLS, "IT'S
 RAINING MEN"]

821
00:39:48,384 --> 00:40:33,645


822
00:40:33,645 --> 00:40:36,900
DAVID MALAN: So we'll make that
available for download on the website.

823
00:40:36,900 --> 00:40:38,210
[LAUGHTER]

824
00:40:38,210 --> 00:40:41,710
[CLAPPING]

825
00:40:41,710 --> 00:40:47,210


826
00:40:47,210 --> 00:40:49,610
All right, so that's just week 0.

827
00:40:49,610 --> 00:40:51,240
What are we doing the next week?

828
00:40:51,240 --> 00:40:54,860
So it's in week 1 of this course--
computer scientists, of course,

829
00:40:54,860 --> 00:40:57,650
count starting at zero--
is the good joke there--

830
00:40:57,650 --> 00:41:00,410
we'll introduce C. So
come next Monday, will you

831
00:41:00,410 --> 00:41:03,080
be introduced to this more
traditional language of C, which

832
00:41:03,080 --> 00:41:06,643
certainly, on first glance, is, in fact,
more arcane say, than the puzzle pieces

833
00:41:06,643 --> 00:41:08,060
you've just glimpsed a moment ago.

834
00:41:08,060 --> 00:41:10,685
But it's literally in the second
week of this course that we'll

835
00:41:10,685 --> 00:41:14,030
dive in to programming in
a more traditional sense,

836
00:41:14,030 --> 00:41:17,270
with a lot of those constructs, if
you will, out of the way in a fun

837
00:41:17,270 --> 00:41:18,710
and engaging environment.

838
00:41:18,710 --> 00:41:21,830
In week 2 of the course, we'll
continue our exploration of C,

839
00:41:21,830 --> 00:41:25,640
and the functionality thereof, how to
program at a more sophisticated level.

840
00:41:25,640 --> 00:41:28,400
But we'll do this, as will be
the case throughout the semester,

841
00:41:28,400 --> 00:41:29,810
in an interesting domain.

842
00:41:29,810 --> 00:41:33,140
We'll look at cryptography,
the art of concealing data,

843
00:41:33,140 --> 00:41:35,780
among other topics in that same context.

844
00:41:35,780 --> 00:41:40,160
In week 3, we'll look at some
of the more canonical program

845
00:41:40,160 --> 00:41:41,540
problems in computer science.

846
00:41:41,540 --> 00:41:45,800
Among them, searching, a la Google,
and sorting with which you can actually

847
00:41:45,800 --> 00:41:50,450
expedite things like searches, figuring
out-- not out of, say, 12 or 16 doors--

848
00:41:50,450 --> 00:41:53,540
but out of a billion doors,
behind which is a number

849
00:41:53,540 --> 00:41:55,550
that you actually want to find.

850
00:41:55,550 --> 00:41:58,910
In week 4, we'll talk about
what it means to debug software,

851
00:41:58,910 --> 00:42:00,973
and what it means to
design software well.

852
00:42:00,973 --> 00:42:03,140
We'll come back to that
particular picture, but that

853
00:42:03,140 --> 00:42:05,720
is quite literally a picture of a bug--

854
00:42:05,720 --> 00:42:07,190
dare say, the first bug.

855
00:42:07,190 --> 00:42:09,890
In week 5 of the course
will look similarly

856
00:42:09,890 --> 00:42:13,250
in more technical detail at
what it means to run a program.

857
00:42:13,250 --> 00:42:15,290
When you double click
that icon on your desktop,

858
00:42:15,290 --> 00:42:18,110
what exactly is going on
inside of the computer?

859
00:42:18,110 --> 00:42:21,470
What is going on with the
so-called memory and RAM?

860
00:42:21,470 --> 00:42:26,780
We'll also look at a rather sexy
context for this exploration

861
00:42:26,780 --> 00:42:31,910
of digital forensics, recovering data,
undeleting files, and introducing you

862
00:42:31,910 --> 00:42:34,310
to those kinds of ideas, as well.

863
00:42:34,310 --> 00:42:36,680
In week 6 of the course will
we begin to look at what

864
00:42:36,680 --> 00:42:38,850
are typically called data structures.

865
00:42:38,850 --> 00:42:41,510
There are entire courses on
data structures at Harvard.

866
00:42:41,510 --> 00:42:46,190
What we'll do is scratch the
surface at some of the most useful

867
00:42:46,190 --> 00:42:49,280
of them, with some of the most common
of them, most canonical of them.

868
00:42:49,280 --> 00:42:51,920
Among them tries, and
hash tables, and heaps,

869
00:42:51,920 --> 00:42:54,390
binary search trees, and linked list.

870
00:42:54,390 --> 00:42:56,490
It's OK if none of these
topics make sense to you

871
00:42:56,490 --> 00:42:59,030
now, if you've never heard of them,
that's precisely the point of being

872
00:42:59,030 --> 00:43:00,050
here in the first place.

873
00:43:00,050 --> 00:43:02,360
In week 7, we'll look
at data compression.

874
00:43:02,360 --> 00:43:06,710
How do you take a very big file,
a very big essay, for instance,

875
00:43:06,710 --> 00:43:09,350
and compress it down into
something much smaller?

876
00:43:09,350 --> 00:43:11,360
We'll look, therefore,
at Huffman coding.

877
00:43:11,360 --> 00:43:12,980
We'll back to this idea of bits.

878
00:43:12,980 --> 00:43:16,610
How can you actually start
writing individual zeros and ones

879
00:43:16,610 --> 00:43:21,920
to files on disks in the interests
of using as few bits as possible?

880
00:43:21,920 --> 00:43:24,090
In week 8, we'll take a
look underneath the hood,

881
00:43:24,090 --> 00:43:27,290
so to speak, at what's going on
when you actually run a program,

882
00:43:27,290 --> 00:43:30,470
not in terms of memory,
but in terms of its CPU.

883
00:43:30,470 --> 00:43:33,680
We'll look at an
assembly language that is

884
00:43:33,680 --> 00:43:38,000
known as Ants, which is about as low
level as you can get to a computer's

885
00:43:38,000 --> 00:43:42,590
actual CPU before the language
itself becomes just zeros and ones.

886
00:43:42,590 --> 00:43:45,350
In week 9, we'll look at a
topic known as secure coding.

887
00:43:45,350 --> 00:43:47,300
Ask me in about 10
weeks time-- or better

888
00:43:47,300 --> 00:43:49,730
yet, tell me in 10
weeks time-- why there's

889
00:43:49,730 --> 00:43:52,620
a picture of a canary on this slide.

890
00:43:52,620 --> 00:43:56,570
And in week 10, what we introduce one
of the topics that's new to the course

891
00:43:56,570 --> 00:44:00,440
this semester, which is an introduction
to web based programming and PHP.

892
00:44:00,440 --> 00:44:03,290
So in addition to
Scratch and Ants and C,

893
00:44:03,290 --> 00:44:07,430
we'll also introduce a popular
language called PHP this semester.

894
00:44:07,430 --> 00:44:11,330
Those of you who have log
into Facebook obsessively--

895
00:44:11,330 --> 00:44:13,640
and perhaps are logged
into Facebook right now--

896
00:44:13,640 --> 00:44:14,525
might recognize--

897
00:44:14,525 --> 00:44:16,190
[LAUGHTER]

898
00:44:16,190 --> 00:44:18,620
--might recognize that
early on-- and I believe,

899
00:44:18,620 --> 00:44:22,070
to this day-- was the language in
which Mark Zuckerberg wrote Facebook.

900
00:44:22,070 --> 00:44:24,350
SQL is the language
in which the database

901
00:44:24,350 --> 00:44:27,110
queries of Facebook and
innumerable other websites

902
00:44:27,110 --> 00:44:30,120
use to actually get at
databases worth of information.

903
00:44:30,120 --> 00:44:33,410
So by week 10 in this course, will you
know not just how to make a web page,

904
00:44:33,410 --> 00:44:37,160
since we'll spend perhaps 20 minutes on
that particular process, but actually

905
00:44:37,160 --> 00:44:41,330
how to create dynamic, interactive
database driven websites.

906
00:44:41,330 --> 00:44:43,647
In week 11 of the course,
we will figure out

907
00:44:43,647 --> 00:44:45,980
what to do based on the kinds
of questions and interests

908
00:44:45,980 --> 00:44:48,080
that arise over the
course of this semester.

909
00:44:48,080 --> 00:44:52,700
And in week 12, we have a fun and
exciting conclusion, if you will.

910
00:44:52,700 --> 00:44:54,830
But it's really in the
course's problem sets

911
00:44:54,830 --> 00:44:57,590
that you'll get your hands the
dirtiest with this material.

912
00:44:57,590 --> 00:45:01,250
And it's in the problem sets
completion that you'll gain, I think,

913
00:45:01,250 --> 00:45:02,480
the most from this course.

914
00:45:02,480 --> 00:45:05,450
To give you a sense of what
kinds of topics and domains

915
00:45:05,450 --> 00:45:08,360
will be looking at this
semester-- the first one,

916
00:45:08,360 --> 00:45:13,638
problem set 0, will quite simply be,
go make your own Scratch project.

917
00:45:13,638 --> 00:45:16,430
We'll lay out just a few basic
requirements, but for the most part,

918
00:45:16,430 --> 00:45:19,670
you are free to design
anything that comes to mind,

919
00:45:19,670 --> 00:45:23,180
and anything within the boundaries
of your own imagination.

920
00:45:23,180 --> 00:45:25,580
In problems set 1, in
a couple of weeks time,

921
00:45:25,580 --> 00:45:28,610
will we introduce C and
a bit of Linux to you.

922
00:45:28,610 --> 00:45:31,130
In problem set 2, we'll
look at cryptography.

923
00:45:31,130 --> 00:45:35,660
And you'll actually implement programs
that both incipher and decipher data

924
00:45:35,660 --> 00:45:37,250
that you might want to keep secure.

925
00:45:37,250 --> 00:45:42,740
Problem set 3 will implement the game
of 15, which is a name I didn't even

926
00:45:42,740 --> 00:45:44,360
know what it applied to.

927
00:45:44,360 --> 00:45:47,520
This is that silly, little
plastic game with all the numbers,

928
00:45:47,520 --> 00:45:50,280
and you can move the numbers
up and down and left and right.

929
00:45:50,280 --> 00:45:52,922
And there's 15 numbers, and
one of the squares is empty.

930
00:45:52,922 --> 00:45:54,630
And you try to move
those numbers around.

931
00:45:54,630 --> 00:45:56,280
Apparently, it's called the game of 15.

932
00:45:56,280 --> 00:45:58,470
And that's what we've
been doing the course has

933
00:45:58,470 --> 00:45:59,887
been doing for the past few years.

934
00:45:59,887 --> 00:46:02,820
You, yourselves, will implement
that in the language known as C.

935
00:46:02,820 --> 00:46:06,960
In problem set 4, we'll look at
this sexy art of digital forensics.

936
00:46:06,960 --> 00:46:09,480
Odds are, we will hand to
one of the teaching fellows

937
00:46:09,480 --> 00:46:13,485
a digital camera and a memory card, have
them go take some photos around campus.

938
00:46:13,485 --> 00:46:15,360
They'll then turn the
camera back over to me.

939
00:46:15,360 --> 00:46:19,530
I will accidentally erase the camera's
memory card, turn it over to you

940
00:46:19,530 --> 00:46:21,870
all, and you're going to
recover those photos for us.

941
00:46:21,870 --> 00:46:27,630
And you'll also search through some data
sets for hidden information of sorts.

942
00:46:27,630 --> 00:46:32,370
Problem set 5, you will be challenged
with implementing a faster spell

943
00:46:32,370 --> 00:46:34,120
checker than your classmates.

944
00:46:34,120 --> 00:46:37,470
And we'll turn this into a bit of a
contest, whereby to test your code,

945
00:46:37,470 --> 00:46:41,040
we'll give you some software
that essentially runs your spell

946
00:46:41,040 --> 00:46:44,490
checker against some fairly
large predetermined inputs,

947
00:46:44,490 --> 00:46:48,210
and then will post to the course's
website automatically, say, the top 10

948
00:46:48,210 --> 00:46:52,860
or top 20 students' results, so that
we can see exactly who is outputting

949
00:46:52,860 --> 00:46:54,840
the most efficient code at that point.

950
00:46:54,840 --> 00:46:57,030
In problem set 6, we'll
implement what's called

951
00:46:57,030 --> 00:47:00,360
"huff and puff," the Huffman coding
algorithm, with which you, yourselves,

952
00:47:00,360 --> 00:47:03,810
will implement software with
which to compress and decompress

953
00:47:03,810 --> 00:47:05,310
files on your own computers.

954
00:47:05,310 --> 00:47:08,640
And finally, in problem
set 7 will you actually

955
00:47:08,640 --> 00:47:13,470
implement your own dynamic
database driven website.

956
00:47:13,470 --> 00:47:16,050
It, though, is the final
project that we dare

957
00:47:16,050 --> 00:47:19,180
say is ultimately the most
gratifying aspect of this course.

958
00:47:19,180 --> 00:47:22,890
The problem sets come to a conclusion
a week or so before winter break,

959
00:47:22,890 --> 00:47:26,280
and the final project is not due
for a month or so thereafter.

960
00:47:26,280 --> 00:47:29,730
And it's out of the final project
that some of the most amazing and most

961
00:47:29,730 --> 00:47:32,490
interesting projects
come from this course,

962
00:47:32,490 --> 00:47:35,970
not only from students who came in with
a background in AP Computer Science,

963
00:47:35,970 --> 00:47:39,330
but those who have quite
literally never programmed before.

964
00:47:39,330 --> 00:47:43,440
Here, too, it will be completely
up to you what kind of program--

965
00:47:43,440 --> 00:47:47,340
software programs you produce
as part of your final project.

966
00:47:47,340 --> 00:47:50,775
But the gauntlet we throw down
before you today ultimately--

967
00:47:50,775 --> 00:47:53,400
and we'll remind you of throughout
the course of the semester--

968
00:47:53,400 --> 00:47:57,660
is ideally, to solve an actual
problem, to make something useful,

969
00:47:57,660 --> 00:48:00,480
or best yet, somehow impact campus.

970
00:48:00,480 --> 00:48:02,850
For the next four months,
as you walk around campus,

971
00:48:02,850 --> 00:48:06,840
and have conversations with folks
in your extracurricular activities,

972
00:48:06,840 --> 00:48:11,190
in your dorm rooms and such, identify
problems that might exist on campus,

973
00:48:11,190 --> 00:48:14,220
or opportunities for
software based solutions.

974
00:48:14,220 --> 00:48:17,550
Just a few years ago, there
was not a very good Facebook

975
00:48:17,550 --> 00:48:18,990
on Harvard College's campus.

976
00:48:18,990 --> 00:48:21,060
And a student, who
you've all heard of, went

977
00:48:21,060 --> 00:48:24,690
about solving that problem himself,
having just had a background

978
00:48:24,690 --> 00:48:27,930
in just a few courses in programming.

979
00:48:27,930 --> 00:48:30,810
The Just a few years
ago-- and I'm trying

980
00:48:30,810 --> 00:48:34,170
to spin this without it being attached
to my name-- just a few years ago,

981
00:48:34,170 --> 00:48:37,620
there was no way for students to
look up shuttle schedules dynamically

982
00:48:37,620 --> 00:48:41,700
on computers, or via text message,
or via AOL Instant messaging.

983
00:48:41,700 --> 00:48:44,470
So some student who awhile
back had taken CS50,

984
00:48:44,470 --> 00:48:47,830
went about implementing software
that solved that particular problem.

985
00:48:47,830 --> 00:48:50,640
So the spin that we'd like to give
to the final project this year--

986
00:48:50,640 --> 00:48:53,850
and you have four months to figure out
what problem you're going to solve,

987
00:48:53,850 --> 00:48:56,400
and what contribution you're
going to make to this campus--

988
00:48:56,400 --> 00:48:57,810
and not to set the bar too high.

989
00:48:57,810 --> 00:49:00,900
You can also just make a
simple game or a program that's

990
00:49:00,900 --> 00:49:02,460
perhaps less ambitious than that.

991
00:49:02,460 --> 00:49:06,030
But we want to [INAUDIBLE] you early on
in the semester is to keep an eye out

992
00:49:06,030 --> 00:49:09,352
for opportunities, processes
that you can automate,

993
00:49:09,352 --> 00:49:11,310
programs you can write
for your student groups,

994
00:49:11,310 --> 00:49:14,340
and ultimately, give a little
something back based only

995
00:49:14,340 --> 00:49:16,470
on your own experience in this course.

996
00:49:16,470 --> 00:49:20,252
Ultimately, it would be a wonderful
thing if your software-- not only say,

997
00:49:20,252 --> 00:49:21,960
garners the attention,
I dare say, of say

998
00:49:21,960 --> 00:49:26,650
The Crimson, a few of you-- but to make
something that outlives this course.

999
00:49:26,650 --> 00:49:28,363
So should you take computer science 50?

1000
00:49:28,363 --> 00:49:30,780
I will stick around, as will
some of the teaching fellows,

1001
00:49:30,780 --> 00:49:32,100
for the next short while.

1002
00:49:32,100 --> 00:49:35,790
But today, tomorrow, and Thursday,
in this same room from 4:00 to 5:00

1003
00:49:35,790 --> 00:49:38,610
PM, we'll be here to answer
questions, address concerns.

1004
00:49:38,610 --> 00:49:41,870
Otherwise, I will see you on Wednesday.

1005
00:49:41,870 --> 00:49:51,040