hi and welcome to ICT revision notes today we're looking at chapter three story devices and media in this chapter we intend to revise magnectic media and story devices Optical media and a story devices solid state media and their story devices and finally we look at the future of story devices all right now I want to encourage you to hit the subscription button make a like and then share the video let others also benefit all right so let's kick start now we want to talk about magnetic media so when we talk about magnetic media we are basically referring to a technology that make use of the principle of magnetism to store data all right now it works by using a special quoting made of ion oide that can be magnetized to represent binary values and by this we mean ones and zero now these methods allow large amount of data to be stored in a very small space and the most common devices that utilize this magnetic properties magnetic tape drive and hard drive here are some pictures of uh magnetic drive hardex drive and then magnetic tapes all right now let's look at magnetic tape drive now a magnetic tape drive is just a thin strip of plastic that is being quoted with ion oide so what we mean is this here so this brownish plastic here is what we refer to as a thin strip of plastic okay so this thin strip of plastic is being quoted with ion oide and data is being stored on those plastic in two forms one as magnetized area and then demagnetized area representing Z all right now to assess data read and right head is being utilized in magnetic tapes and this makes it possible to read and sore information on the tape now again to access data on this Magnetic Tape you do it in a Serial manner now what this means is that you cannot just jump from one one part and go to the other and and so let's take an example for example if you have a video you are watching a video and you want to assess some part of the video let's say you want to assess a specific thing on the video you can then jump from one point and move straight to the scene you want to watch you have to go through every other scene before you get to what you want to watch and so this makes it a very slow um process to use if you are dealing with real life application now magnetic tapes are used for batch processing they are used for backups and again they used for long-term iiving all right now let's look at some advantage of magnetic save right they are very cost effective per by and then they are robust and stable over time and then they have high data storage capacity compared to other um stor media um and that is why they are used for backup right now again they have a fast uh data transfer rate but very slow access time and and this is a disadvantage so the disadvantage with the Magnetic Tape Drive is that they have a slow data access due to their serial nature of accessing data all right and then again they require multiple tastes for update which can introduce some form of Errors now what this means is that if you have for example a tape that is quite large right magnetic tape that is quite large and you have some information on on it and you want to transfer it to another tape because it's getting older or something or or for a backup now what what happens is that if the size of the tape is not as big as the first one it means that you're going to need an additional tape to do the recording and when that happens you end up introducing some errors in the recording process and that is what that step means and then finally for a dis Advantage they are vulnerable to strong magnetic field um because they are made of magnets when you introduce them to very strong magnetic field they can easily corrupt the data on it these are good examples of magnetic tapes all right now we move to hardex drive magnetic dis Drive uh also uses magnetic surfaces referred to as plats to store data and they have multiple PL and read and write hand that make it very quick to access data now the process of accessing data on hard this drive is the direct access so what it means is that if you are watching a movie and you want to quickly make reference to something you've watched earlier you can just jump straight to that point and click on play to watch it unlike the magx tape where you have to go through everything in order to arrive at the part you want to watch all right so that is it for direct access now they are used to store operating system application and working files again they are using in real life system such as robot and online reservation system again they can be used in networking um for file servers to solve large amount of file and for data management there are some advantages to the use of hard dis drive that is one the rate at which data is transferred and access is much faster compared to the Magnetic Tape drive and then again they have large memory capacity to store any information you want the disadvantage of hard drive is that they are susceptible to physical damage because they have moving Parts when you drop it you can easily damage it okay and then they contain moving Parts which can also affect the way they reliable now because the moving Parts keep on spinning meing uh anything can happen and then they stop working uh all of a sudden then again they have noisy operation compared to solid state drive which not have any moving part now because of their moving Parts when it's getting older you kind of hear some sound in the way it works when it's the head is spinning all right so these are some disadvantages and advantage of hardc strive next we look at portable hardc strive now portable dis Drive are very much similar to hard dis Drive except that these ones are portable right so they are just external hard this drive that are connected with USB port and they are used basically for backups and transfer of files okay so backups and then transfer of files so again you can transfer file from one or movies or anything you want to use from one computer to the other making use of the portable hard dis Drive now some advantages of the portable hard dis Drive is that they have lightweight and Compact and that make it very easy to carry around again it is ideal for backing up any file to data loss and then again it provide a large amount of stor page and very affordable compared to the solid state drive now what this means is that if you take um a solid state drive that is about 1 gab right and compare it to the price of a solid state drive that is 1 gab you notice that the price of the hard disc drive in this case a portable hard dis Drive they have slower data transfer speed compared to solid state drive and then again they are sensitive to damage when you drop them now they can easily also be misplaced because they are very portable someone can just also steal them all right and then the last part is that because they have the mechanical parts that keep on spinning and spinning I mean it can easily wear out over time and that can also uh cause you to lose every information you have on the portable hardage try all right next we move to Optical media and their story devices so when we talk about Optical media we are referring to story devices that use Laser Technology to read and write data okay the most common types of tical media we have is the CDs the DVD and the Blu-ray all right now now when it comes to CDs and DVD there are three main description that you need to remember the first one is R which is recordable and then we have the RW which is rewritable and then the ROM which is the read only memory now the moment you you write or B data on this on a CDR or a dvdr it automatically becomes a Rong all right we'll explain that as we progress now there are other technology is behind the way CDs and um DVDs behave now one both CDs and DVDs make use of a thin layer of metal alloy or a light sensitive organic Dy coating to store data and again data is T in bits and LS on a spir track that runs from the center of the Tex to the Edge CDs and DVDs uh make use of red laser okay to read and write data and again the read and the right head do not touch the surface of the dis all right and then the disc is been divided into sectors that allow you to directly access the data that you interested in then finally DVD um mostly have what is referred to as double layer that means they have the capacity to store two individual recordings on a layer okay okay and and they have what is referred to as a semi transparent layer that allows the laser to focus on either the first or the second layer and read from it so we're looking at CDR and DVD RS so R means what recordable okay all right so some uses of CDR and dvdr um they amazing use for recording music films um or any data that you want to store for a later use you can just to record them on the CD or a DVD R all right now it has some advantages they are very cheaper than the rewritable disc and then once you BN any information on this uh CDR they become a what this means is that once data is written on it it's permanent right so you can't do anything to wrate again so it becomes a Rong you can only read from it right now some disadvantages to the CD and DVD are is that they can only be recorded once and so because you can rewrite on them it makes it a disadvantage so anytime you want to do any burning it means you have to go and buy some more CD r or dvdr now not all players or devices are able to recognize the DVD r or the DVD R okay the CDR and dvdr are not compatible with all players all right here's some pictures on some dvdr and cdrs okay next we look at CD rewritable and DVD rewritable now they are basically used for recording TV programs multiple times and then they can also be used in CCTV um systems as well as for backups all right so now because they can be Rewritten over it it comes as an advantage and um they have different file form that can be recorded on this um CDs or DVD and then the last one is that they are less wasteful than CDR or dvdr so you don't have to buy a lot of CDs to do the recording once you have a CDR dvdr that you don't want to use again um for whatever is on it that you don't want to use again you can overwrite on it and then uh make use of the new recording on it some disadvantages are that they relatively um expensive compared to the CDR and then the risk of accidentally overwriting on data is also really high now so because we can rewrite on it which is an advantage it can also become a disadvantage so for example if you have some information on that CD or DVD and you forget yourself you can rewrite on it so what it means is that whatever was on it initially cannot be retrieve once you write over it okay then the last one is that CD and DVD um RWS typically have slower um right speed compared to the rate at which information is rting on the CDR and the dvdr here again are some images of cdrw and DVD RW okay then we look at CD ROM and DVD ROM now they are basically used to um store files of data permanently so for music software computer games and any large files that you want to record some advantages of this is that they are less expensive than hardex drive and then the disadvantage is that they are they have a slower data transfer and access rate now in in time pass if you want to install for example an operating system say Windows 7 you need a DVD room okay so this year has a software on it already record on it already and the only thing you can use it for is to install the operating system and that is it then this is here um and again you have some um video um CDs here and then we have um PlayStation 2 recording so you have games on this year and this here has um an encyclopedia which has some recorded um informations on it more or less like a dictionary and you can do nothing to the CD B to read information that have been recorded on it so that is what we mean by CD ROM and DVD RS right now we come to Blu-ray dis now Blu-ray disc use blue laser for reading and writing data and this makes it to have a very high Precision to write data on pits compared to the CD and DVD CDs all right now the also have a much larger data capacity they are able to hold large data capacity compared to the DVDs so for single layer uh Blu-ray um discs you have a maximum of 27 GB and for double layer de you have um about 50 um gab as compared to 8.5 GB for DVDs DVD radex comes with some automatic encryption that helps it to prevent people from pirating um piles that are written on it right then again um the other a very fast data transfer rate of 36 megab per second compared to DVDs that are 10 megab per seconds finally Blu-ray technology allow for greater interactivity um enbl features such as recording high definition TV programs creating playlist and then editing um record recorded content and accessing online features now again the uses of Blu-ray discs are one for home video games console and then for storing and playing high definition video or movies all right and again they are used for data storage and backups the advantages of Blu-ray decks are one they're able to store large data and then they have inbuilt encryption that enhances security tacking parac and then again they have a fast data transfer and access rate the disadvantage to um Blu-ray decks are one they have high cost compared to DVD of course um the storage capacity of the Blu-ray is much larger than the DVD and then the next one is that they have potential encryption issue when storing video now because they have some heing encryption properties storing videos on it sometimes can be problematic then finally they um have the competition from some um high definition DVD players that has lessen some of the Blu-ray dick advantages all right now so here are some images of devices um that use Blu-ray dick and um and an image of a Blu-ray dick right there okay next we're moving to solid state drive the last but one now solid state media such as SSD and U SB drives um stop data in memory cells all right and just like the one here all right and um each cell contains what is referred to as a floating gate transistor and so this a a typical diagram of the floaty gate transistor where we have the control gate and the floaty gate so the control gate controls the flow of electrons and it is used to program um the floating gate and in Flash memories each intersection right contains what is referred to as a control gate and a floating gate like you can see and um they are being separated by De electric Coatings so this blue area here are de electric coins basically insulators that do not allow the floating Gates uh the electrons the floating gates to move to the control gate and in the process they retain their charge now the in the solid state device sometimes may leak if they are not being if they are not being used for um over a period of 12 months they can leak from the floating gate to the control gate all right now let's look at some uses of solid state drives now solid state drives are basically used for storing files application operating systems and they are basically replacing the traditional hardest drive that we already have some advantages to the solid state drive is that they do not have any moving part and as a result um they reduce the rate at which they fill okay and they are very tiny and very light in weight and then again when you have um an SSD in your device uh compared to an H uh HDD you'll notice that this SSD boot much faster compared to the HDD one dis advant perent AG of ssds are that they usually um rated for about 20 GB of writing per day over 3 years now what this means is that once the um SSD is being used over a period of time what happens is that the N flash memory begins to lose the ability and when it happens is that they become less reliable and so um with time I mean they begin to lose their reliability then they now we move to pen drives now pen drives are also known as memory sticks and uh there are small portable devices that make use of solid state technology right and this pen drives draw their power when they are being connected to the computer so they get their power from the USB ports that they are being connected to and so they do not require any external power now flash drive is a broader term that that is uh mostly used to refer to as this Solid State Technology such as pen drives so it's either a flash drive or a memory stick right and these are some pictures of pen drives memory sticks or flash drives okay so um uses of pen D is basically to move files from one computer to another and they are also used as dongles to prevent um software Pary okay some advantages of P drives are that they are very Compact and portable and robust and durable again you do not need an additional software to use these pen drives and then they are not affected by magnetic fields right the disadvantages of pen drives are that they cannot um protect data by making it read only um anyone who has your pen drive can easily copy what is there it is not made r o and then again um easy to lose due to their small size you can EAS throw it away or someone can easily pick it and use for you all right and then finally um if you do not carefully remove pen drive when they are being induced you can easily corrupt it or you can it can stop working if you don't uh inject it properly before you um pull it out of your computer all right so again here are some pictures of pen drives that we know of next we look at memory cards now memory cards again use solid state Technologies to store data and they are inserted into devices to read or write data onto them so mostly we make use of this in our phones or cameras and we can even ins set it onto our computers to retrieve files that are being stall on them um three main types of memory cards that we're supposed to know as far as the slus is but is SD card SD cards that are mostly small and they have very high capacity memory and they are using cameras and smartphones and tablets again we have XD cards that are also designed for cameras and then we have the cast cards that can also be used in cameras high definition cameras all right now memory cards basically are used to Sol pictures okay on digital cameras and um used to move information from um probably your smartphone to um a computer and they can also be used to um can also be using MP MP3 players to store music and they can also be used for back apps some advantages of memory cards is that they are easily removable for use in other devices and then they are durable because they do not have moving part um again you can hold substantial amount of data on this cards and then devices that can read and write uh to memory cards facilitate easy transfer of data okay all right now some disadvantages of memory cards are one they are more expensive per gigabyte compared to hard dis stri so in some cases uh some of the memory cards can be more expensive okay and then another disadvantage is that they have less storage than hardex drive then they have limited read and write cycle now finally not all computers are built with um memory card slot or readers um to facilitate the U reading of those memory cards again these are some um pictures of the types of um memory cards that we have available finally we want to look at the future of storage devices now you agree with me that CDs and DVDs are becoming obsolete um and not a lot of people are making use of CDs nowadays rather people prefer to use flash drives or um or pen drives to transfer data okay and when it come to listening to music a lot of people will prefer to have the music say on their hard dis drive or MP3 devices okay or they want to play straight from the cloud or using streaming sites okay so most Smart TVs enables um people to stream um videos without the need of DVD or Blu-ray um players all they need is an internet and once you connect to the internet they able to um play or watch any movie they want all right so that bring us to the end of chapter 3 I encourage you to hit the subscription button um share the video make some comment and hit the like button and let others also benefit from this video uh there are some few questions here on what we've done on chapter 3 and once you click on the chapter 3 it sent you to the quiz and um I encourage you to take time and take the quiz and see how much information you have rried watching this particular um medium so to me the