Magnetic storage devices

Magnetic storage devices INTRODUCTION: Magnetic storage and magnetic recording are the term that refer to the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to store data and is a form of the non volatile memory. Using one or more read/write heads the information is accessed . Magnetic storage stores data by magnetizing microscopic particles on the surface of the device, whether its a disk or it is a magnetic tape. There are several typesof magnetic storage devices such as: Hard Disks, Floppy Disks, and Tapes. They can use Random Access or Sequential Access memory. Some magnetic storage devices can be moved from computer to computer and some cant. Some of them can be easily broken, and some are not, but most are sealed with a protective case. Magnetic storage media and devices store data in the form of tiny magnetised dots. These dots are created, read and erased using magnetic fields created by very tiny electromagnets. In the case of magnetic tape the dots are arranged along the length of a long plastic strip which has been coated with a magnetisable layer (audio and video tapes use a similar technology). In the case of magnetic discs (e.g. floppy disc or hard-drive), the dots are arranged in circles on the surface of a plastic, metal or glass disc that has a magnetisable coating. HISTORY: Oberlin Smith was the first one to publicize magnetic storage in the form of audio recording on a wire in 1888. He filed a patent in September, 1878 but did not pursue the idea as his business was machine tools. The first publicly demonstrated magnetic recorder was invented by Valdemar Poulsen in 1898. Poulsens device recorded a signal on a wire wrapped around a drum. In 1928, Fritz Pfleumer developed the first magnetic tape recorder. Early magnetic storage devices were designed to record analog audio signals. Computer and now most audio and video magnetic storage devices record digital data. Magnetic storage was also used for primary storage in a form of magnetic drum, or core memory, core rope memory, thin film memory, twistor memory or bubble memory at old times. Unlike modern computers, magnetic tape was also often used for secondary storage. Magnetic recording classes Analog recording Analog recording is based on the fact that remnant magnetization of a given material depends on the magnitude of the applied field. The magnetic material is normally in the form of tape, with the tape in its blank form being initially demagnetized. When recording, the tape runs at a constant speed. The writing head magnetizes the tape with current proportional to the signal. A magnetization distribution is achieved along the magnetic tape. Finally, the distribution of the magnetization can be read out, reproducing the original signal. The magnetic tape is typically made by embedding magnetic particles in a plastic binder on polyester film tape. The commonly used magnetic particles are Iron oxide particles or Chromium oxide and metal particles with size of 0.5 micrometers. Analog recording was very popular in audio and video recording. In the past 20 years, however, tape recording has been gradually replaced by digital recording. Digital recording Instead of creating a magnetization distribution in analog recording, digital recording only need two stable magnetic states, which are the +Ms and -Ms on the hysteresis loop. Examples of digital recording are floppy disks and HDDs. Since digital recording is the main process nowadays and probably in the coming future, the details of magnetic recording will be discussed in the rest of the project using the HDD as an example. Magneto-optical recording Magneto-optical recording writes/reads optically. When writing, the magnetic medium is heated locally by a laser, which induces a rapid decrease of coercive field. Then, a small magnetic field can be used to switch the magnetization. The reading process is based on magneto-optical Kerr effect. The magnetic medium are typically amorphous R-Fe Co thin film (R being a rare earth element). Magneto-optical recording is not very popular. One famous example is Minidisc developed by Sony. Domain propagation memory Domain propagation memory is also called bubble memory. The basic idea is to control domain wall motion in a magnetic medium that free of microstructure. Bubble refers to stable cylindrical domain. The information is then recorded by the presence/absence of bubble domain. Domain propagation memory has high insensitivity to shock and vibration, so its application are usually in space and aeronautics. Magnetic Storage Devices: The read/write capability of computer disk drives requires the relative motion of a magnetic media and a read/write magnetic head. Physical contact between the media and the head occurs during loading and unloading cycles. Tailoring the mechanical properties of the media and the head has become critical in order to minimize damage and loss of data. This application note is focused on the mechanical properties of the head slider. The tested head sliders are composed of an Al2O3-TiC composite with a thin 10 -20nm diamond-like-carbon protective overcoat. As shown in Figure 3, the slider surface is composed of two phases, Al2O3 and TiC. The Hysitron Tribo Scope was the first instrument to report hardness differences for two material phases used in head sliders. The TriboScope is a quantitative depth sensing nanoindenter that can be interfaced with a scanning probe microscope to provide This imaging capability distinguishes between phases in a composite material, making it possible to select the phase in which the indentation is to be performed. Once theindentation is performed, the surface is imaged a second timeto characterize the indent. The applied force and the penetration depth of the indenter into the surface are measured simultaneously. The lighter regions in theimage correspond to the TiC phase while the darker regions can be attributed to the Al2O3 phase. The insets in Figure 1 show the indentations made in each phase. Both indentations were performed at the same peak applied force of 50Â µN. Types of magnetic storage devices There are basically two type of storage devices Removable storage devices Fixed storage devices Fixed storage devices Fixed hard drive A hard-drive built into the case of a computer is known as fixed. Almost every computer has a fixed hard-drive. Fixed hard-drives act as the main backing storage device for almost all computers since they provide almost instant access to files (random access and high access speeds). Removal magnetic storage devices Portable Hard Drive A portable hard-drive is one that is placed into a small case along with some electronics that allow the hard-drive to be accessed using a USB or similar connection. Portable hard-drives allow very large amounts of data to be transported from computer to computer. Many portable music players (such as the iPod classic) contain tiny hard-drives. These miniature devices are just not much bigger than a stamp, but can still store over 100MB of data! Magnetic Tape Magnetic tape is a large capacity, serial access medium. Because it is a serial access medium, accessing individual files on a tape is slow. Tapes are used where large amounts of data need to be stored, but where quick access to individual files is not required. A typical use is for data back-up (lots of data, but rarely only accessed in an emergency) Tapes are also used and in some batch-processing applications (e.g. to hold the list of data that will be processed). Floppy Disc A removable, portable, cheap, low-capacity (1.44MB) storage medium. Floppy discs are random access devices used for transfer small amounts of data between computers, or to back-up small files, etc. Access times are slow. Almost every PC used to have a floppy disc drive. These are obsolete now, having been replaced by higher capacity technology such as CD-ROMs, DVDs and USB memory sticks. Zip Disc A removable and portable storage medium, similar in appearance to a floppy disk, but with a much higher capacity (100MB, 250MB or 750MB). Zip discs are random access devices which were used for data back-up or moving large files between computers. Another obsolete storage device, zip discs were a popular replacement for floppy discs for a few years, but they never caught on fully before being superseded by cheaper media like CD-ROMs and CD-Rs Jaz Disc A removable and portable storage medium based on hard-drive technology, with a large capacity (1GB or 2GB). Jaz discs are random access devices which were used for data back-up or moving large files between computers. Discs were expensive to buy and not very reliable. Like the Zip disc, this system never really caught on and was superseded by far cheaper and more reliable and cheaper technology. Overview The Zip system is based loosely on Iomegas earlier Bernoulli Box system; in both systems, a set of read/write heads mounted on a linear actuator flies over a rapidly spinning floppy disk mounted in a sturdy cartridge. The linear actuator uses the voice coil actuation technology, related to modern hard drives. The Zip disk uses smaller media (about the size of a 9 cm (3Â ½) microfloppy, rather than the Compact Disc-sized Bernoulli media), and a simplified drive design that reduced its overall cost. This resulted in a disk that has all of the 9 cm (3Â ½) floppys convenience, but holds much more data, with performance that is much quicker than a standard floppy drive .The original Zip drive had a data transfer rate of about 1 megabyte/second and a seek time of 28 milliseconds on average, compared to a standard 1.44MB floppys 500kbit/s (62.5KB/s) transfer rate and several-hundred millisecond average seek time. Todays average 7200RPM desktop hard drives have average seek times of around 8.5-9ms. Early generation Zip drives were in direct competition with the Super Disk or LS-120 drives, which held 20% more data and could also read standard 3Â ½ 1.44MB diskettes, but they had a lower data transfer rate due to lower rotational speed. The rivalry was over before the dawn of the USB era. Compatibility Higher capacity Zip disks must be used in a drive with at least the same capacity ability. Generally, higher capacity drives also handle lower capacity media. However, the 250MB drive writes much more slowly to 100MB disks than does the 100MB drive, and its unable to perform a long (i.e., thorough) format on a 100MB disk. The 750MB drive cannot write to 100MB disks at all, though they are the cheapest and most common of the three formats. The retroreflective spot differs on the three media sizes such that if a larger disk is inserted in a smaller capacity drive, the disk is immediately ejected again without any attempt being made to access the disk. Current usage As of 2007, common uses of magnetic storage media are for computer data mass storage on hard disks and the recording of analog audio and video works on analog tape. Since much of audio and video production is moving to digital systems, the usage of hard disks is expected to increase at the expense of analog tape. Digital tape and tape libraries are popular for the high capacity data storage of archives and backups. Floppy disks see some marginal usage, particularly in dealing with older computer systems and software. Magnetic storage is also widely used in some specific applications, such as bank checks (MICR) and credit/debit cards (mag stripes). Future A new type of magnetic storage, called MRAM, is being produced that stores data in magnetic bits based on the GMR effect. Its advantage is non-volatility, low power usage, and good shock robustness. However, with storage density and capacity orders of magnitude smaller than e.g. an HDD, MRAM is a niche application for situations where small amounts of storage with a need for very frequent updates are required, which flash memory could not support REFERENCES http://hyperphysics.phy-astr.gsu.edu/hbase/audio/tape2.html http://www.everspin.com/technology.html http://www.crocus-technology.com/pdf/BH%20GSA%20Article.pdf http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=218000269 A.V. Kimel, A. Kirilyuk, P.A. Usachev, R.V. Pisarev, A.M. Balbashov, and Th. Rasing, Ultrafast non-thermal control of magnetization by instantaneous photomagnetic pulses, Nature, 435, 655 (2005). F. Hansteen, A.V. Kimel, A. Kiriluyk, and Th. Rasing, Femtosecond photomagnetic switching of spins in ferrimagnetic garnet films, Phys. Rev. Lett., 95, 047402 (2005). GUPTA J.B, Electronic devices and circuit, 3rd edition

Ramona and Beezus

Ramona has a very creative imagination but hilariously brings her to many mishaps in school and even at home. She is nine years old and very Jolly who takes things seriously that makes her brain works to create many ideas to solve a certain problem. She has this big sister named Beatrice who is shucked with a nickname Buzzes. According to Ramona, when she was very little and is starting to learn how to speak, she accidentally called Beatrice Buzzes because that's what little children do.They mispronounce words and sometimes get stuck in it. Buzzes and Ramona most of the mime has quarrels and arguments at home. Ramona said that her sister hates her very much because Buzzes calls her a pest. However, Ramona showed great respect for the elders even if they don't listen to what she wants to express and is misunderstood that performs many acts of silliness. Ramona continued her imaginative adventure until a problem in the family gone very far to the extent that their parent's quarrel over small things.What I like most about this movie is that it simply shows what happens at home in reality. Our relationship with our parent's and siblings brings us many memories and lessons in life such as understanding one's emotions, giving comfort, being patient, being kind, and being respectful. In the family, when one doesn't understand another, there'll be quarrelling and arguments which will lead to another problem. This is what I don't want to happen in my own family.Just like Ramona, I want to help my family solve some problems in my own little ways. I want to be productive and not be a problem to them. So, if there's a problem at home, I am really doing my very best to help. I really love Roman's adventures and this inspires me to be sensitive in other people's feelings. The movie also taught me to love my own family no matter what they are and who they are, because the family is the first group of people you can run to in times of trouble/ problem.They are truly God's gift that no other treasures I can compare. Finally, despite of the problems we encounter everyday, we must be like Ramona: Brave and full of Joy. We have to face our problems lightly in order for us to concentrate in seeking possible solutions to it. We have to bear in mind that no problems we can't endure if we only let God help us as what a famous quote says: A family that prays together, stays together.

Ability to Communicate with People at All Levels Free Essay Example, 1000 words

I possess computer literacy in Access Database, Microsoft Word 6.0 and 7.0, Email services and PowerPoint Presentation. Furthermore, I have developed organisational skills and time management skills from academic studies as well as practical work. Gap Analysis I have identified that I possess different skillsets in relation to communication, computer literacy, time management skills and organisational skills. The present competent accounting job scenario requires an individual to possess different advanced skills in the IT field and communication. Presently, accounting professionals are required to deal with financial information that includes liabilities, assets, expenditures and income. Additionally, accounting professionals are required to recognise, verify, record and interpret financial information suitably. Moreover, accounting professionals are also required to communicate financial information to management of business organisations in having a comprehensive understanding of financial performances. Correspondingly, in order to develop as a competent candidate in the accounting profession, I need to acquire skills in communicating financial information. Additionally, I need to develop my IT skills in order to identify and record fi nancial transactions appropriately and correspondingly, I require to acquire experience in accounting operations. I am also required to develop problem-solving abilities with the aim of conducting required tasks successfully. We will write a custom essay sample on Ability to Communicate with People at All Levels or any topic specifically for you Only $17.96 $11.86/page

Ray Bradbury s Worthy Of The Curriculum - 1796 Words

Collin Rineer CP American Lit and Comp Mrs. Mayo Nov 10, 2014 Ray Bradbury, Worthy of the Curriculum? Ray Bradbury is an American author who has written many books including Fahrenheit 451. Ray Bradbury should be included in Penn Manor’s American Literature Curriculum because of his works of science fiction, one being Fahrenheit 451, that use politics and a unique style to create these situations and settings that show the strange things that happen in the human mind rather than strange things that happen to them. Politics are an important part of his books and supports why Bradbury should be included. In Fahrenheit 451, Ray Bradbury tells about a fireman named Guy Montag where his job is simple, burn books. Montag loved his job and always followed orders. Then a seventeen year old girl named Clarisse moved next door and changed his whole outlook of the world that hes been living his life in. (1-24) The government in Fahrenheit 451 controls the entire society by keeping the expansion of knowledge low by banning books and burning them. In the world of Fahrenheit 451 he uses adv anced technology, such as the mechanicals hounds, to be the peacekeepers of the world. The style works well with his use of the setting and political influences but these are only some of the reasons why he should be included in the CP American Literature Curriculum. Bradbury uses politics in Fahrenheit 451 to control and convey the story. In Bradbury’s dystopian society the government basically