 All right, welcome back to computer science e1. This is lecture 12 exciting Conclusion so it's a big day for me I've been saying for six months that I am going to switch from PCs to Macs and here we have the Mac So I will ineptly stumble my way through any Demonstrations while Dan outperforms me on the same laptop over there But I figure much like you all might struggle sometimes with the hardware new software now You can see me do it perhaps as well So I had a little training before class began today So today's really just about wrapping up the course and giving you a taste hopefully of where you started this course And hopefully where you are now looking back on some topics briefly that you may once have found Fairly unfamiliar but perhaps now you're a little more comfortable talking about some of the stuff and along the way We've got a few demonstrations that we can have a bit of fun with so we began this course recall Way back in lecture one when we talked about Hardware in our discussion of hardware focused on the lowest level details bits and bytes and ascii CPUs motherboards and so forth and maybe just to get things warmed up here Let me ask let's start with a medium difficulty question. How do you represent the number seven in binary? Oh good thought we'd have some awkward silence there So one one one right and what the fours column the twos column and the ones column so there you have the number Seven all right. Let's come up with a slightly harder question. What is the decimal equivalent of the ASCII letter? capital a Wow 65 Look, yeah, 65 is indeed correct. How about lowercase a? Oh 97 wow, we should really have had prizes for this. All right, let's try and what I thought would be an easy question What is say a typical amount of love well actually? This is medium typical amount of level to cash that you might have in a computer these days Eight megabyte that feels a little high actually can I reject that? Yeah. Yeah, that's too high. Okay. Nice try though Something more reasonable Yeah, I don't hear very committal answers, but yes So like a megabyte two megabytes and L2 cash. All right, so let's flip things around ask Dan a question about hardware Why me? More awkward this way Okay, so I guess moving on to lecture two a little bit. We talked a bit more about Hardware and we went into some more detail about some of the specific components in the computer Whereas level one was very low level. We showed you a lot of the the bits and bytes and and how to convert between binary and decimal level two or Lecture two is really about talking about specific things such as how hard drives work and how what virtual memory is and How the relationship between a CPU the RAM and the hard drive all sort of Works together in order to produce the images and the text that you see on the screen And so just as a refresher. What is virtual memory? Virtual memory. Yes Right, very good. So it's when part of the hard drive space is used for RAM So this can happen frequently if you have run out of RAM where which is used for your currently running programs And the operating system will open up some space or will use some of the open space on your hard drive In order to place some of these running programs and of course, what's the downside to having virtual memory though? So that virtually extends your memory. What's the downside to it? Yes? That's right. It's a lot slower. So if you remember this diagram that we had where we were showing as the capacity of certain elements grew so for example the hard drive is the Largest capacity memory in your computer the RAM is lower capacity and and onto the L2 cache L1 caching finally the registers As these storage units become larger. They're actually also slower as well So that means that these things that are closer to the CPU the registers are very very fast They just don't have a lot of memory to Store a lot of data where? This these cheaper devices hard drives and RAM come into play in order to store a lot of these things And we also talked a bit about other peripherals such as CD players DVD drives We didn't talk a lot about some of the newer optical drives like blu-ray and the now defunct HD DVD drives that that were popular just a couple years ago, but we're beaten out by blu-ray, but these are all Examples of peripherals that are used for external storage. So whereas the hard drive is used for Storing your programs while your computer is off These same peripherals can do the same thing except obviously store data that you want to bring on to your computer Let's see. We also talked a lot about some of the internal devices that you can plug in a lot of the plugs or connectors that are available On the motherboard and what are some of those to remember? For example, what kind of plugs exist for us to connect a hard drive to the motherboard of a machine? There were a couple of ports or connectors inside the the motherboard Anyone remember some of these connections? Yes So MIDI is as a file format for audio and yeah, we did go through a lot of Acronyms, so I understand one of them. Yes DVI that's that is an external port for Monitor connections or digital. It's basically digital video interface. So for example, some projectors will have it more Digital monitors will have a DVI connector, but internally you will most likely see IDE or SATA or SATA connectors to connect your hard drive. Of course, if you have an external hard drive What are some of the common or what is the most common? Port you might use if you have an external hard drive. Yeah USB Which of course is the general port you can plug in just about everything minus your kitchen sink perhaps into it so you got all those components and You might know how they all interconnect, but these days you typically buy them all together So we've ended lecture two and transitioned to lecture three by talking about how to buy a computer So you go into a typical Store say Microcenter and what's the first thing you should do when you want to buy a computer in that case? Hopefully turn around and walk out right so don't go to stores like Micro Center because you'll probably pay way more than you have to Right. So in fairness you can get deals at stores these days even Best Buy sells I think Dell computers these days, but beware going into stores I mean in fact case in point I went into staples in Harvard Square just the other day because very Suddenly I needed to get a external USB actually hard drive and they make these wonderfully small USB hard drives these days that actually have inside of them those drives that are known as two and a half inches So this is a two and a half inch hard drive and take a guess how many gigs are on this hard drive And this is just a USB cable. What's that? Yeah, so this was 500 and unfortunately at staples I paid 189 dollars then I went home later that day hopped on Google guess how much I found it for at Amazon Not as good but 129 so like 60 dollars cheaper and this is just I mean the reality if you had to if your instinct is to Head to these local brick-and-mortar stores odds are you will end up paying more? But whether you're shopping in a store or shopping online What are some of the questions that or what are some of the specs that are perhaps relevant to you the consumer? So what kinds of numbers what kinds of hardware do you actually have some discretion over when choosing a computer? Yeah, so RAM so what's a typical amount of RAM that you might want these days in a new computer be it a laptop or desktop? Yeah Three gigabytes. Yeah, so I mean definitely one two and even three these days Vista I think sort of hopes that you have two three gigabytes And you can have even way more than that in higher-end desktop So somewhere in the gigabytes the low gigabytes range for RAM is sort of where you want to be at mentally What else do you have choice over when buying a computer? Yeah, so size of the hard drive so clearly a valid answer to that question is something in the 500 gig range But what else is perhaps a common value that you might want to have inside your own? Again, there's no right one right answer here Okay, so like 160 gigs especially if it's a laptop because they tend to be somewhat smaller 320 Maybe 750 you can buy terabyte drive. So a terabyte is a thousand gigabyte So that's like but you know that sounds like a lot But that's just two of those tiny little things these days so very quickly do things change What other values do you have discretion over or some consumer choice? Yeah, so our pms of the hard drive right in a desktop common values were 7200 and 10,000 and high-end PCs or 5400 you don't have as much discretion there but if you're really being a geek for instance and you're worried about the amount of heat in your computer or in my case years ago when I Was upgrading my Tivo manually by opening it up and it's just a computer running Linux I Realized having read online a bit that it wasn't really designed to have multiple hard drives inside And so a lot of the geeks online would suggest that you really get a slower hard drive So that it generates less heat if you're putting twice as many drives in there even though there's the same number of fans So sure, that's certainly a metric. What else what sort of the brains of the computer that you really have influence over? Yeah, so what's a typical CPU value these days? That's very specific. Okay, so 2.67. Oh Gigahertz right so for CPUs. It's also in the giga range these days So one gigahertz 1.2 to gigahertz and then for even higher in PCs You can get almost into the you know the threes or so range But you kind of see a glass ceiling of sorts at least if you're paying for Some of the top of the line PCs these days You don't have like a 10 gigahertz computer, but rather what do you have the more and more you pay in the higher end? You go these days Yeah, so you have multiple cores which is kind of like and we don't go into great detail here But it's kind of like having multiple CPUs each of which is maybe 1 gigahertz or 2 gigahertz So you might have a total of like 10 gigahertz of power But that it only means that say one program say Microsoft Word can use 2 gigahertz of power Whereas another program running quote-unquote simultaneously can use the other CPU So it's not necessarily an aggregate. So remember that while we were talking about gigahertz and cores in these lectures We also mentioned something to be wary of and that is in multiple computers You can compare the amount of RAM that each has so for example You have two computers side by side one has two gigabytes of RAM The other has three gigabytes of RAM and you know that the one with three gigabytes of RAM We'll be able to run more programs without needing to access its virtual memory as frequently However, when you are talking about the speed of a CPU It's difficult to compare the speed of of different models of CPUs So for example for example Intel CPUs to AMD CPUs Even though they would have different gigahertz ratings the one that is lower might indeed be faster. So nowadays What we see is marketing speak coming from these companies trying to say, you know, append more and more Adjectives to their their course for example, what is Intel up to Intel? Quad core extreme to something like that which becomes ridiculous But frequently if you want to find the fastest CPU out there You usually have to look around especially on the internet for people who actually test These CPUs to find out which one is faster because just because there is one that has a higher gigahertz rating doesn't necessarily mean That it is any better. However That being said generally within the same model range. So for example within these Intel CPUs If you do have one that's higher gigahertz then most likely it will be faster than the lower gigahertz one So not meant to confuse of course, it's just that there are some terms or there are some Values when you are buying a computer that that can affect the performance more than others So for example, like I said when you're comparing RAM, you really can compare between two machines But when you're comparing the CPU you have to be a little bit more careful And realize too when you exit this course that we've thrown a lot of technical jargon and specifications at you But when it comes to normal computing and a typical person in this room buying a computer Realize that you don't necessarily have to understand all the nuances between the various models of CPUs and such And if I can be so bold as to just offer subjective device advice I would say if you're going out to buy a new computer tomorrow or say within the next six months Minimally it should be a dual-core computer of some sort because just having two CPUs or the effective the effect of two CPUs in your Computer is generally a good thing because that means literally two things can be happening Simultaneously and given how many of us do multiple things at once run multiple programs at once That's typically in fact a good thing and in terms of speed these days at least one gigahertz and probably closer to 1.5 or 2 but it's really only the true geeks in this class or sort of in general that really might care about a lot of these Specifics so if you are really into graphic design and Photoshop So if you really liked our focus on multimedia several weeks ago And you really want to get into Photoshop and play with some high-end filters Certainly video or audio well It's people like that that actually do need to spend a bit more money and maybe do a bit more research as to which computer can really Be up to the task of what's high-end graphics processing Similarly, if you're a real gamer and you like to play really nice interactive 3d games Well, you're probably gonna give some more thought and some more money to getting a really good CPU or really good graphics card But for most of us frankly myself included who spends 90% of his time using the web and using email You know most any computer out there is a is a pretty good bet these days And so really price is perhaps the biggest factor I would say in fact if you're gonna go out and buy a new computer So I personally am sort of anti brick-and-mortar and certainly Microcenter given their their pricing. I mean where what sites have we proposed? What sites have you used to go out and find deals in other words? Where should you begin? Yeah Sorry so CNET has wonderful reviews especially about specific pieces of hardware when I was buying a printer fairly recently I did some googling. I think it was a Canon laser printer of some sort the model number I forget But CNET popped up with some really good reviews. What other sites? So del.com, you know love them or hate them They actually do have very aggressive pricing and pretty good support contracts So even for home computers if you're comfortable with buying a computer online or from the Sunday bro Sure as opposed to from a store Certainly get some pretty good deals from them and how about some of those sites? We've recommended even myself in particular and sort of pushed you toward deals oriented sites. What's a URL or two? Yeah, so new egg.com is a very good site in terms of pricing that a lot of people shop at Personally, I would only caution about new egg that they are annoying when it comes to returns They very they try to stick you with restocking fees whereas someone like Amazon is Wonderfully generous when it comes to doing things like return. So do beware with some of the fine print, but they're very popular What else? Okay, Tiger Direct is popular too. What about sites though that aggregate deals on the internet? I think we offered up at least one or two URLs Yeah, so personally I love deal news you go to deal news comm They've got categories on the right-hand side and whether you're looking for a hard drive or a computer even a TV They very nicely have everything categorized and they're not particularly biased They just say here are some current deals from the week You go ahead and buy it from any of these stores that you might be interested in deal ram.com is a related site Where if you're buying RAM for your computer, it's wonderful and that you tell them Assuming you have a popular computer the make and model and they'll tell you exactly what kind of RAM you can get as well It's even made some fairly good points just a few moments ago when he mentioned that What we've been talking about having high amounts of RAM having very fast CPU Though it is important when you start working on specific tasks or tasks that are very intensive for CPU intensive or graphics intensive Most modern computers really even the very cheap ones are very good at just checking email or browsing the web so What many people seem to be doing lately is having One machine or so that is very very powerful that can do the tasks that that it needs to do very well So for example if you become a gamer or a photoshop junkie Then what you might do is buy a higher-end machine with lots and lots of RAM or a high graphics card depending on the need Then you might have just some smaller machines that are just not as expensive and and maybe At the most bump up the RAM a little bit so that you can have a lot of web browsers open For example and have your email and various other programs and those are usually good enough to just get web browsing and these sort of common tasks out of the way even computers now are Obviously they they're shrinking and And we've seen now some of this trend lately towards these this class of computers called netbooks Which are very very small laptops. They're of course Underpowered compared to desktops or even they're much larger laptops But just doing what they are intended to do checking email and going on to the web They're very well designed for that because there is enough speed to get it done So why you could absolutely geek out and say oh man I really want that extra 0.2 gigahertz in a CPU Really doesn't seem to be that important these days to just be able to get work done or to just have a little bit Of fun which might involve email or or web surfing and if I can hop up on the soapbox here before we move on to software Like honestly if you take nothing else away from the earliest lectures in this course with all the acronyms and all with all the technical minutia like if you don't Understand some term that you see in some print doors on some advertisement just Google it right so one of the takeaways Hopefully of this course has been to give you a sense that it doesn't matter so much if you know every little detail about these Things but you know where to find the information you know where to find better prices You know it to turn to sites like Wikipedia or web apedia or any of the sites that we've sort of promoted during the semester And it's all freely available information It's people like Dan to be honest that I turn to when you know I don't have a clue as to how to get my Mac to start projecting on the screen Or I don't know some low-level detail about my digital camera And so hopefully you'll get from this course in exiting it Perhaps a little more confidence that if you don't really know something that's fine You at least know how to go figure it out we spent our third lecture in the course on a Video instead of an actual discussion of software But what we thought we would do here to sort of break the ice or loosen things up is give you some examples of some prototypical Software related errors the sorts of things that cause people to scratch their head or even swear at their computer It's unfortunately a little blurry But that's just as well since most of us probably don't even know what this thing for years has been trying to say to us But this is the so-called what? BSOD or blue screen of death and random e1 anecdote one year a lecture fell on Halloween and Halloween happened to be exam ones date and just to be fun We decided to say if you show up in costume to your exam We'll give you an extra point on your actual exam so a gentleman very creatively showed up as the blue screen of death and he walked into the lecture hall literally with a Box on his head. I think it had a couple of eye holes But it had this blue screen on the facade So, you know, you're in a see a computer science class when you show up wearing a blue screen of death We have next for you this particular example Come on this example here. Well, see here's that ineptitude. I promised. Oh True error message, right? What do you do when you actually get something like this? So not only is this indicating some kind of error. It's also revealing an error on whose part All right, the the programmer the person who actually wrote the code in C or C plus plus or whatever That was supposed to clearly have some kind of error message or informative message there But it was not to be how about this one you can read the text Right, so that's just you kind of scratch your head when you account or something like this another fun one is This is classic actually Right this is infuriating if you're trying to get past this point at your computer not uncommon, right? If you you'll see in computer's bios screens PC's bios is where you get just the black background and the white text there too If there's no keyboard found there's absolutely been instances where the bios is told the user, you know Press F keyboard not found press F1 to continue like this though was from what this was from Windows 95 How about this one? All right, so this is when your blue screen of death really becomes public so this is some kind of billboard in some some city and Clearly that billboard was being driven by Windows and you see this thing pretty often in fact another instance I think it's up next where Windows was clearly being used was in this case You can recognize some airports arrivals and departures so Windows is used in many different contexts Even if it doesn't look like Windows that doesn't mean it's not if the program simply happens to be full-screened as apparently as the case here Another example is this joke, right back in the day when you were constantly hitting control alt-delete Why not have a dedicated little keypad for such and let's see if we have a another little one here No, not yet. So who spoiled that part. Okay back to Dan Okay, so after a software which really was a fun look into Some of the history behind Apple and Microsoft we started talking about the interweb or the internet and We really started to pick it apart and and go into some of the nitty-gritty details about how it works and Packets how how a packet being sent from your computer can be routed to another person's computer and We introduced this idea of an IP address where it's basically just an address for your computer that allows other Computers on the internet to be able to communicate with it very much like your mailing address at home where you're able to receive and send mail via that mailing address and we talked about some some of the specific Protocols I think I don't know that was the next lecture so we did talk about email and some of these protocols associated With it who remembers some of these protocols that are associated with email There are three more acronyms here that yes SMTP okay, that's very good. That's for outgoing email yep I map that's another one. That's incoming mail and I'm sorry Yep pop so there there are two different kinds of protocols for incoming mail I map and pop and each one has its advantages and disadvantages though Nowadays if you have multiple computers or you're on the road a lot It's generally recommended that you use I map protocol if you're going to be checking your email Unless you're using some sort of web mail Email function like a Google or hotmail for example where it really doesn't matter You're not really using either of those protocols What protocol would you be using in that case if you were trying to access your gmail or your hotmail? How do you access? Though that email. Yes That's right. HTTP So you go to it via web page and you're using then by using a web browser using the HTTP protocol Which of course remember we talked about this notion beyond IP addresses and protocols But ports that are associated with specific things on Or specific protocols on the internet. So for example HTTP protocol always operates or almost always operates out of port 80 There's a couple of other famous ports out there, but pretty much every Software that you use communicates or that that communicates with the internet does so through a port and Beyond that we talked about the secure version of those so there's HTTP and then there's its secure version which is Right HTTPS, which is mostly used of course with Credit card transactions banking that sort of thing where your data must be Encrypted in some way, but the downside to HTTPS would be what? Yeah That's right. It's slower because it does have to be encrypted not only by your computer But it has to be decrypted on the server side So it takes not only your computer just a little bit of extra time to communicate over HTTPS But also it takes the server just a little bit more time to do it. So this is frequently why Many times when you log into a site such as Facebook and Amazon comm when you're actually typing in your user details I think Gmail might do this as well You type in your user details it sends it over HTTPS But then it forwards you over to an HTTP or a non-secure version of the site because once you're logged in They assume that that data isn't really doesn't really need to be encrypted So it saves them some money in terms of having more cycles in their computer in order to Access more users or for more users to access them and it also frees up your computer a bit as well So what are the implications of that once you have logged into Gmail or Facebook or MySpace or whatnot? And you're sitting there in Starbucks sipping your coffee. What do you have to appreciate? Even if you accept this reality Hmm It's not secure right the lack of encryption means that that random person next to you at Starbucks could be running a program like the Packet sniffer that I ran a few weeks ago Where they too are seeing all these packets fly by on their screen if they get a little curious or a little too curious They can start diving into those packets and look at the most recent instant message You sent to someone or most recent email that you've sent or if you are visiting a website that doesn't use SSL at all They'll see your username and password. So what should the takeaway there be? What's your takeaway perhaps Yeah, so it's kind of up to you as to where the line is between, you know What's acceptable and what's just not acceptable? But yeah, don't do anything particularly sensitive at least if it's not at all encrypted and as I've preached before I personally Never check like my Bank of America accounts on any computer other than my own even if it's on HTTPS Because if I sit down in some internet cafe or even some kiosk at Harvard, you know I don't know what the person before me put on that computer. There might be some trivial little program That's doing what very easily Yeah logging every keystroke type and just uploading those keystrokes or emailing those keystrokes out to whoever that adversary was So again appreciate the threats and don't necessarily let it cripple you or keep you off the internet entirely But at least know what some of those implications are we spend more time in our follow-up lecture on the internet Talking about some of the wiring now and how you actually build networks So in our first lecture on the internet we focused on the applications the services that the internet provides mail and web and so forth But then we dove down a little deeper and my apologies that this projector only seems to be getting more blurry here But we talked about interesting protocols like DHCP DHCP. Why is that useful even if it's an odd-sounding acronym? Yeah Yeah, so it assigns your computer upon booting up we're connecting to the internet or to the local network and IP address And that's what you need a unique IP address to actually be on the internet But even that's a bit of a white lie in what sense do you not necessarily need a unique IP address to be on the internet these days Or put another way in what contexts are you actually sharing an IP address? answer either question Why why do they have these private IP addresses and Exactly Exactly So most any of us here who have multiple computers at home or multiple people on this multiple computers or perhaps just a wireless computer at home Probably have some kind of router some kind of access point some kind of home router It can be called any number of things these days And that thing's purpose in life is to either one make your connection wireless or to share your connection among multiple People whether they're wired computers or wireless computers and to do that even though Comcast or Verizon are only giving you one IP address They have to create the illusion internally that every computer does in fact have a unique IP address And so you get these these fake or these private IP addresses that almost always by convention or the form one nine two dot one six Eight dot something dot something But as soon as your packets go out on the internet and through your home router out into the cloud that is the internet They are exposed by way of the one IP address that Comcast or Verizon or whoever has actually assigned to you And then when it comes back into the router the reason that that router is actually a router It's not just a dumb switch or hub is that it actually remembers who sent some packets out Was it one nine two one six eight dot one dot one or was it dot two or was it dot three? And it figures out to whom inside your home to send that that data back to So we discussed a variety of ways of connecting your computer to a network So David just mentioned for example wired and wireless and more specifically There would be Ethernet using an Ethernet cable and Wi-Fi respectively But there is another way or there are other ways of connecting to the internet as well and though we didn't really talk about this It seems useful to mention now and certainly what you'll what you see nowadays is that there are a variety of Telecom companies such as Verizon or AT&T T-Mobile that are offering devices such as these which have a USB port on one of them And they actually allow you to connect to the internet using these networks Using the network that's that's available to you from each of these carriers and this isn't Wi-Fi and this isn't obviously wired. It is a different technology altogether It works basically upon the same principle as your cell phone You can sit in a cafe that may not have Wi-Fi or it may have some annoyingly Some Wi-Fi that you annoyingly have to pay for and you can plug in This device and usually they they have a whole variety of acronyms that are associated with them as well But you can you can plug in a device such as this into your computer and be able to access the internet that way And it just seems worthwhile to note that though this technology does exist It is limited of course by the network So if you have let's say a dead zone in your house You will have a you will be in a dead zone with that device in that same location as well So it has the same sort of limitations as cell phones But it also has the same advantages you can then use this sort of technology in a car while you're driving down the highway Hopefully you're not the one driving but someone else could be and I mean There's just a whole variety of uses that that this sort of technology is is useful There is this push for this new technology called W when I think which is based upon the same idea of Wi-Fi and just generally speaking it seems to be a merge of of Wi-Fi and these This wireless network or these cellular telephone network capabilities But it would have to be deployed city-wide And so there just seems to be too much Infrastructure to overcome for that so most likely we'll just have to maintain these 3g devices as they're called and Wi-Fi for now But one thing that you may or may not know is that if your phone has data capabilities for example blackberries or Some of these newer Android phones for example, they by themselves can't connect to the internet over your Cellular networks data connection, which is basically the same sort of technology as as this device that I was just showing you and some of these Phones can even be used as an intermediary So you can connect your computer to your phone, and then your phone will connect to the internet In the same in the same similar way. It's called tethering and many phones that have data capability do have it And it's actually pretty interesting. So if that's something you are interested in you should Certainly take a look to see if your phone supports data and if it supports tethering But just be aware that may have to of course pay for such such a convenience So then we got on to some fun stuff some multimedia This is something we look at most every day you pull up a web page and you see a whole bunch of multimedia formats among them Jpeg Jiff Yeah, that's pretty much it but yeah Tiff is another one. We talked about EPS briefly PDF Certainly in the video formats There's a whole slew flash formats and quick time and windows media But at least in the context of graphics where we spend some time dabbling dabbling so much so that you yourselves Ended up exhibiting atop our website these new designs, which that's a cute one So we added all of these pseudo randomly to the course's website so that anytime you pull up the page It tends to change or if you click the image explicitly it will actually change and remarkably So we found a color scheme that doesn't look too bad with completely. That's a really nice one random. Oh, that's cute We love them all equally actually is is what the point is But they all came out very nice But you probably had to make a choice between using jiff or jpeg and what might motivate choosing one over the other Everything will literally be clearer soon Okay, so lossy versus lossless compression So lossless as the word implies means that you don't actually lose any quality But you nonetheless gain some compression lossy by contrast is a file format like what? Jpeg so the way jpeg actually save some bits is by throwing away useful information So you may have experienced in Photoshop if tinkering with photographs in particular That if you move that little slider from quality equals maximum at 12 or quality equals minimum at 1 You really do start to see what dan showed a few weeks ago as the blotchiness things really much like this things get a little less clear What else is distinguishes jiff from jpeg? Yeah, so jiff's have the ability to have Transparency and this was useful if you're trying to overlay an image on top of something else And you don't want to have that ugly rectangular background that underneath it all actually constitutes a graphic pings or PNG is also support Transparency unfortunately some browsers like older versions of Internet Explorer don't render transparency properly So unfortunately, it's an imperfect world anything else that distinguishes jiff from jpeg So the ability to animate if we our favorite little dancing hamsters, which have yet to make an appearance today We're a whole bunch of animated gyps or little cartoons that were one jiff after the other but all self-contained within a file So besides these types of files we talked about a different type So all of these are forms of raster files or raster images where In some form or another each and every pixel is defined by the file So what does this mean for example when we start zooming in very very far to one of these files? Right pixelation exactly and so there's another format that's used to battle this Yes vectors so though we have vector images They're mostly used for things such as clip art or more cartoonish sort of images if you remember We had the the four horses that would sing acapella and that was done in vector form so that we could Make the the browser window as large or as small as we wanted and it would still remain sharp And so though vectors are very cool in this in this in this way They're just not as useful for photographs for example because it's just a lot easier or it's it just makes a lot More sense when talking about digital cameras for example or when scanning in something that we can Represent a photo with individual dots or with individual pixels so besides this we talked about some other formats as well Such as audio and we came up with a variety of them of course the most popular Audio type nowadays is mp3 you hear that all over the place, but there's other ones as well a ac Media if you remember which is a different type all together and what what distinguishes a media file from an mp3? Or some other a ac format for example. Yes That's right. So basically all a media file is it's just a Collection the computer records a collection of notes and it says that okay This collection of notes must be played by this instrument This note must have duration of this long for example and so in this way It's essentially you can think of it essentially like putting Music or sheet music into a file that the computer then reads and plays back for you So obviously you lose certain things such as voice It's there's no way to record voice which a file with a file such as this And it can sound different on different computers because one computer may play it's a little bit differently than the other So if you want Exact reproduction you certainly would want something more popular such as mp3 But if you just want to get your music out there or just share your music You would certainly use something such as media and in fact if you are interested in or if you are if you are a musician yourself You will probably find a lot of information on media where you can play your instrument whether it be piano Sometimes guitar drums all sorts of different instruments You can play them while this instrument is connected to your computer and your computer will record the notes and the duration and be able to Basically create a media file for you or Essentially create a score just the musical score that can be used there So besides this we then sort of mashed all of this stuff together and talked about video So there's many different types of video out there. There's quick time. There's Windows media and Real player there's just all sorts of video out there. Some of it can be streamed and some of it cannot so streamed video You've probably seen on our website to flash now has video capabilities that can be streamed I'll like YouTube for example quick time can be streamed variety of other things. We even talked a bit about HD video So what makes a video HD? High definition the big the big term now that everybody throws around Yeah, so it's basically the size of the image so when we have a video that's a certain size and it's usually something along the order of Let's see. I think it's 1280 by 720 pixels for example, then suddenly that Video is considered HD. It's more specifically 720p So as you get video that's even larger than that you have higher rated HD or higher rated high definition Which compares to traditional TV which might be much smaller something along the order of 500 pixels by something like 400 pixels or or 600 by 400 something along those lines So what you're paying for whenever you buy some HD related object is you're basically just paying for more pixels That you see at a time. How many of you in fact are ready for this DTV switch over next month? Or know what it is How many of you are not ready for the digital TV turnover either because you haven't gotten around to it or because you're not Still not quite sure what's going on if you want to fess up to that. Okay, excellent So do you have cable or satellite or just bunny ear antennas or some kind of other? Oh? Wow Okay, well either way if you have cable TV It's not a problem because the cable company will deal with all of this and you can keep using your same TV your same hardware Not a problem at all same goes for satellite and yourself. Do you have? antennas or cable or satellite TV? Yep. No, no, you know we know you have cable Oh, so you do so you too are set so you can just ignore everything that's going on out there because everything will work Just fine as well Okay Okay So I am not and let me let me tweak list we be remiss so high definition not high density But sure, but we're quibbling So you're saying the the symphony it the orchestra Okay, I Think I've heard about this some movie theaters are you basically sit in a movie theater as if you're going to watch a movie But instead of watching a movie. It's like a live broadcast from TV. Yeah, it's essentially a very large screen TV That's an HD. Okay Very close to you Yeah, I only I've only heard about this I haven't actually attended any of these any of these showings But it certainly seems like an interesting alternative to actually going to one of these operas in the Mets or overseas You can go to a local theater that supports this sort of program and you can watch live this opera I believe it's live this opera and it's basically transmitted in HD or better than HD Resolution to this theater, which is pretty interesting. Yes, but are you going to do either? No, I'm not going But a good good good tie-in than the last we did have one question. Sorry. Yep Yes, so beyond HD there there so I believe the highest rated HD right now is is 1080p Which is an image size of 1920 by 1080 and there are Resolutions that are higher than that used usually for movies and I think I'm not too familiar with with this round But I believe it's called 2k and 4k Which brings image sizes up to double that so something like 2048 and then up to 4096 and some some various other things which are much much higher and you would not see this in in consumer televisions or Or even your own tape recorder for example your count your own camcorder for a while But movies I believe are recorded in these in these higher resolutions And I would suspect that the same sort of technology that's used to transmit the operas would most likely be in a higher Resolution just because Movie theaters have so much screen to fill so many pixels to fill that they would try to use the higher resolution And I max must be no I max is definitely higher resolution as well I don't I don't know specifics, but when when it before it was digital Movie theaters had 35 millimeter film, which is you know very traditional Film your still camera would have it for example and I max had something many many times larger So that there was much more film to cover so that means that you would get much more detail in the same sort of The same sort of thing applies to the digital area as well But I think I max might still be filmed just because there's so much I think so yeah If you've been to the museum of science they have those ways that the mean no That's the Omni theater there, but at the right, but it's same idea for the most part They those huge reels of film that I think they put behind the glass as you're waiting there online to get into the theater It's actually rather remarkable. So two little teasers before we move take our break and then move on to peanut butter jelly time Things are still a little unclear, but our our intention here is by the end of the lecture everything will be clear How's that? security so we talked at this point in the course about Who cares about all these little details? What are the actual implications actually using a computer to either your the privacy or the security of your actual data and We talked about say Things like spyware right and viruses and worms and what was one takeaway there? What can you do to protect yourself against what are apparently fairly omnipresent threats? Yeah, so antivirus software most of you probably have something like McAfee or Norton and we put forth the argument that you Don't necessarily need to pay for this stuff There are some free alternatives out there that are perhaps less annoying than the incessant prompting of a lot of these programs because one of Underlying problems of a lot of the software is that they're very high in what you'd call false positives They think something's wrong when really it's just some behavior that the program wasn't designed to actually recognize as being okay So here too, there's this trade-off and it will be this trade-off for years Probably whereby the more restrictive you are the more you annoy the user or confuse the user But in theory the safer the user actually is this is why Vista for instance can get so frustrating sometimes because the default case for most Behaviors is to say who do you really want to do this? Do you really want to do this and there comes a point where even myself it just starts hitting yes? Yes, okay, and you don't even read what the message is. So there's some interesting sociological implications there We move from security, which is hopefully all the more familiar to to website development And hopefully that's where you've been dabbling the past couple of weeks on final projects And we introduced XHTML and a little bit of cascading style sheets and to be sure this was not a course about Website design or was it a course about programming? But hopefully you got a taste of how people do these things and given that there are tools out there whether it's dream weaver Or other such programs there It's not actually that hard to make things that are nice that are that are clean and that are actually Live they're out on the internet and then did you want to supplement something here before? No, I wasn't paying attention So and streaking as my pitch was why don't we go ahead and take our five minute break and when we come back It will indeed be peanut butter jelly time It is not in fact peanut butter jelly time just yet Dan so I actually thought it would be helpful to take a minute because I know that there's there seems to be a lot of confusion surrounding the digital TV transition and so on on one of the one of the websites that I tend to frequent called Consumerists and it's consumerists.com It they had a couple of months ago Basically just a flow chart for to see what you are supposed to do for the digital TV Transition and so one thing that's really important to note is that DTV digital TV is not does not imply HD TV or high definition TV So if you have a regular TV Doesn't matter you still must follow this flow chart just to make sure and also the other thing is that The the DTV transition doesn't mean that you have to buy an HD TV So unless you've already done that don't worry about doing it So this is the flow chart Do you have a television if you don't then do nothing if you do you have to answer the question Do you use an antenna to watch television? And so this means not cable not satellites if you use bunny ears to watch television Then you go on to the next section So if you if you do use cable or satellite then you do nothing basically if you use an antenna You see if your TV has a digital tuner and if you you'll know or you should know because most TVs will advertise this On the box or even on the TV itself and my TV for example has a very unnecessarily large DTV Text right next to the logo So I know that that it has digital TV if it does not have a digital tuner And you're using an antenna to watch TV Then you have to buy this digital transition box that everybody's talking about and they have Coupons, I think the government has sponsored some coupons But unfortunately, I think they ran out of money and I think they're supposed to be delaying it There's a whole it's just a big big mess But basically if you have very old TV you're using bunny ears to watch TV Then you will need a tuner to be able to watch TV or what they call converter boxes Otherwise, you don't have to do a thing if you're just watching cable television if you're just watching satellite television Don't worry about it. You are covered But but but but but but no there really is nothing that you have to do Do nothing so remember just again DTV doesn't necessarily imply HDTV though HDTV does require digital television or DTV So digital television comes in two formats your regular standard television like as Like many of us have and of course the higher definition or HDTV That's why it's part of the reason why we are transitioning any questions about that Okay back to you all right now it is peanut butter jelly time So we thought that if you're looking a little skeptical this will soon be fun As we like to do with some of our demonstrations get at least a couple of folks involved And what we thought we would do is pluck off some of our favorite Problems sets for which you and students past submitted some how to Implement a peanut butter and jelly sandwich now the submissions varied this year as always from the shortest of answers to the Ridiculously most detailed answers and we typically try to pick on some of the shorter ones since they are typically fraught with problems Previous to class. We we took a couple volunteers one of whom was John C. League unbeknownst to him And another of whom was Dan Armandar as and then the third of course is to be one of you We need one brave volunteer to come on up here and stand beside. Yes come on up John and Dan So what we have here and I think this is John's first experience with this are some representative program So this is take one of peanut butter how to make a peanut butter and jelly sandwich all of which hopefully started with the phrase Locate jars of peanut butter and jelly as loaf of bread and a knife all of which we just so happen to have right here We don't have the best of tables. So we're gonna do this on top of these two beautiful flat-screen TVs over here So hopefully it won't be too much of a mess But what we thought we'd do is one involve these guys and an execution of these programs and see just how Correct they were and then to involve all of you and see if we can at the climax of this course much like we changed a baby a Few weeks ago make the simplest peanut butter and jelly sandwiches So with that said if each of our volunteers could begin by facing their table I'll go ahead and call out the instructions the first of which is locate jars of peanut butter and jelly a loaf of bread and A knife all of which is hopefully somewhere before them now mind you our volunteers should only do what I or what this Student has said you should make few or no assumptions because after all you are now simply computers Executing a computer program step two if customer orders a special sandwich If only jelly requested then so I think we're gonna have to answer a question here Has the customer requested a special sandwich? No, I heard no first So we're gonna go with no and branch on the other condition with which is if else if customer orders a regular sandwich Here we go dip knife in peanut butter dip knife into peanut butter and spread across bread Okay, don't look at these guys just execute the program and spread across bread then Dip knife into jelly braver Computers would be thrusting harder It's pretty tough. I could have regretted that Dip knife into peanut butter dip knife into jelly and spread across bread. I don't think we're getting a sandwich out of this one excellent Then add another piece of bread and give to server That's not how to all right So perhaps we should just bought this one all together much like we would have the the grading of this particular one And let's move on to take two so take two in this case Was one of those ridiculously long version so rather than work our way through this which is clearly an instance of Perfection shall we say why don't we move on to this one as our take two? Which is a little more confined to the screen so version two here locate jars of peanut butter and jelly alofa bread and a knife then open bag of bread Already an improvement Oh Open bag of bread and remove two slices Then remove lid front mind you this is their indentation not ours So then remove lid from peanut butter jar step forward Remove lid from peanut butter jar remove lid from peanut butter jar and jelly jar Then if peanut butter or jelly are empty then get a new jar Good handling of that air condition else Let's give up So else give up so moving on step seven We'll just assume that we haven't given up entirely step seven using knife spread peanut butter on one slice of bread All right progress Sort of Using knives spread peanut butter on one slice of bread then mind you we'll be having peanut butter and jelly sandwiches at the Class today then using knife spread jelly on top of peanut butter. I Don't want to do this on top of these TVs Okay And this is where things go bad Then place second slice of bread on top of first Dan will enjoy the climax here Then eat All right, let's abort that one. Let's take one last take this time will involve you the audience It's one thing to make fun of these submissions. Let's see if we can't improve upon them So step one for everyone one last time here locate jars of peanut butter and jelly a loaf of bread and a knife As best you can at this point and now step two from the audience first to call it out What do you want them to do? Give me something Remove two pieces of bread from the opening of the bag And place them on the table flat side down That's good though, that's good next step grasp the knife careful Yeah, what's next use other hand to open jar be more precise jelly jar got lucky on that one Next step remove lid from peanut butter next step control C Next step. Oh good. I'm gonna go here remove paper from top of jar Peel sorry peel peel delicately If there's less than a tablespoon of peanut butter Then replenish the jar we seem to be okay But good good air handling next step Next step carefully insert knife into jelly jar and carefully extracts. You're making an assumption each of you Spread Gently I think we're being a little iconic here. What's next spread what spread the knife Spread the knife that has the jelly on it. I don't think that's right Next I'm gonna lose the audience here. We don't finish this up next Okay, hold the knife and okay yet that I'm not good with long sentences. Hold the jelly jar and spread the okay do this Do this. I think he was right. That was a pretty good. Okay good progress next Someone from the middle middle is kind of copying out here. What do you got? Staring at the floor does not exempt you from the exercise certain knife into peanut butter jar and through top of peanut butter jar and Bring us home someone Getting awkward Scoop out approximately a tablespoon of peanut butter Did not define tablespoon with knife shall we add And Next Okay, spread peanut butter evenly over surface of bread Without sorry the other slice of bread John have a lot of extra footage tonight next step. I Feel like we have room for one or two more steps before we get cancelled Second the last step place two pieces together and the last step shall be eat That was another disaster, but thank you perhaps a round of applause for our volunteers here alright, so You we began this course we began this course with a promise that you would be hit with a whole lot of information This in fact is on page two of the syllabus this hack from MIT in which we promise that you would be hit Many of you most of you all of you with way more information Perhaps then you could swallow over the course of the semester and the metaphor here was that much like this hack promise that getting an Education from MIT is like drinking from a water fountain perhaps for many of you this course has felt much the same Especially when you get hit with new acronyms and with new topics and week after week new topics But hopefully as we said earlier tonight at least one takeaway will be even if you haven't retained all of this information You at least now have a better sense of where you can go dig up more information Where you can go and find out what something means and even barring that so that you're at least a little more comfortable With the fact that you might not know each and every one of these technical details So the grand finale here tonight Besides enjoying some peanut butter and jelly sandwiches shall be to reveal fall 2008 mouse pad a number of you voted over the past week We have gone to press with one of these designs which will be mailed out to those of you who opted in with your address So we thought in these final moments We would go ahead and reveal the winner of fall 2008 mouse pad, which will be forever immortalized on Desks and the winner is I hope you enjoy that that took a lot of while in Photoshop Actually, okay, and the winner is Congratulations, you have all survived computer science that you want Dan's got nothing so let's call it a night We'll stick around if you have any questions big Thanks to Chris and John as well for a wonderful semester and it's really been a pleasure having you all here week after week Thank you all. Bye