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Storage and Multimedia

Storage and Multimedia. Benefits of Secondary Storage Magnetic Disk Storage Optical Disk Storage Multimedia Magnetic Tape Storage Backup Systems Organising and Accessing Stored Data. Benefits of Secondary Storage.

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Storage and Multimedia

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  1. Storage and Multimedia • Benefits of Secondary Storage • Magnetic Disk Storage • Optical Disk Storage • Multimedia • Magnetic Tape Storage • Backup Systems • Organising and Accessing Stored Data

  2. Benefits of Secondary Storage • Secondary storage is the type of storage that is separate from the processing • By using secondary storage, software and data can be stored on a permanent or semipermanent basis. • Secondary storage is necessary because memory, or primary storage, can be used only temporarily and it has limited capacity. • Advantages of secondary memory • space, • reliability, • convenience, and • economy

  3. Magnetic Disk Storage • Diskettes and hard disks are magnetic media, • Magnetic data storage is based on a technology of representing data as magnetized spots on the disk.

  4. Magnetic Disk Storage • Diskettes are made of flexiblematerial. • The most important advantage of diskettes, compared to hard disks is their portability.

  5. Magnetic Disk Storage • A hard disk is a metal platter coated with magnetic oxide that can be magnetized to represent data.

  6. Magnetic Disk Storage • Most disk packs combine the disks, access (actuator) arms, and read/write heads in a sealed module. • Hard disks for personal computers are 3½-inch disks in sealed modules. Notebooks use 2½-inch disks. • Hard disk capacity for personal computers can be hundreds of millions of bytes, or gigabytes.

  7. Several disks can be assembled into a disk pack. A disk pack is a stack of multiple disks, rotating all together

  8. Magnetic Disk Storage • The disk access arm moves a read/write head into position over a particular track, where the read/write head hovers above the track. • A head crash occurs when a read/ write head touches the disk surface and causes all data to be destroyed.

  9. Access Arm Read Write Head Moves back and forth Disks Rotate

  10. Concentric rings are called tracks Slices on the disk are called sectors • The surface of each disk has concentric tracks on it.

  11. Magnetic Disk Storage • The sector method of recording data on a disk divides each track into sectors that hold a specific number of characters. • The cylinder method is a vertical organization of data on a disk pack.

  12. Magnetic Disk Storage • Personal computer users may supplement hard disk storage with a removable hard disk cartridge, which, once filled, can be replaced with an empty one.

  13. Magnetic Disk Storage • A redundant array of inexpensive disks, or simply RAID, uses several small hard disks that work together as a unit. • RAID method duplicates data on separate disk drives. This is calleddata mirroring.

  14. Optical Disk Storage • Optical disktechnology uses a laser beam to enter data as spots on the disk surface. • To read the data, the laser scans the disk, and a lens picks up different light reflections from the various spots. 0 bit 1 bit

  15. Optical Disk Storage • CD-ROM (compact disk read-only memory) has a disk format identical to that of audio compact disks. • Regular CD-ROMs can hold up to 700 megabytes per disk. • CD-RW technology permits writing on optical disks. • DVD-ROM, for digital video disk, has astonishing storage capacity, up to 17GB if both layers and both sides are used.

  16. Flash Memory • Flash Memory: An electronic circuitry that offersa nonvolatile and rewritable type of memory. • It functions like a combination of RAM and hard disk.

  17. Flash Memory • Flash memory is durable, operates at low voltages, and retains data when power is off. • Flash memory cards are used in digital cameras, cell phones, printers, handheld computers, pagers, and audio recorders.

  18. Multimedia • Multimedia software typically presents information with text, illustrations, photos, narration, music, animation, and film clips. • Multimedia has become possible because of the large capacity of secondary storage. • MPEG (Motion Picture Experts Group) is a set of widely accepted video standards.

  19. Multimedia • MP3 (Mpeg Layer 3) By using MPEG audio coding, you may shrink down the original sound data from a CD by a factor of 12, without losing sound quality. • iPodplays songs, shows photos, plays video, podcasts. It can store up to 30GB and 60GB of multimedia documents.

  20. Magnetic Tape Storage • Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. • The amount of data on a tape is expressed in terms of density, which is the number of characters per inch (cpi) that can be stored on the tape. • The highest-capacity tape is digital audio tape, or DAT, which uses a different method of recording data.

  21. Backup Systems • A backup system is a way of storing data in more than one place to protect it from damage and loss. Most backup systems use tape. • Systems storing data should be backed-up on a regular basis.

  22. Organising and Accessing Stored Data Student ID BA 1306 145082-3 145081-2 145080-6 145079-4 145078-1 3 1 2 Year 1 2 1 Thursday 10:15 Lale Akalın Can Kurtal Cenk Gür Name Yusuf Pehlivan Pelin Nalça BA 1306 IR 3304 BA 1308 BA 2301 BA 2301 BA 1306 Course IR 3304 BA 1308 Student ID Crd. 3 1 4 4 3 3 1 Year 3 Friday 8:40 Thursday 10:15 Monday14:30 Thursday 11:45 Monday14:30 Thursday 10:15 Day Time DayTime Friday 8:40 Thursday 11:45 Student ID Course Grd 145078-1 BA 1306 AA 145078-1 BA 1308 DC 145079-4 BA 1306 BA 145079-4 BA 1308 CB 145079-4 BA 2301 AA B • A character is a letter, digit, or special character (i.e. $, ?, or *). BA 1306 • A field contains a set of related characters. • A record is a collection of related fields. • A tableis a collection of related records. • A database is a collection of interrelated tables stored together with minimum redundancy; specific data items can be retrieved for various applications.

  23. Organising and Accessing Stored Data 145078-1 145078-1 BA 1306 BA 1306 AA AA 145078-1 145078-1 BA 1308 BA 1308 DC DC 145079-4 145079-4 BA 1306 BA 1306 BA BA 145079-4 145079-4 BA 1306 BA 1306 BA AA 145080-6 BA 2301 CC 145080-6 IR 3304 BA 145080-6 BA 1306 DC 145081-2 BA 1306 FF 145081-2 BA 1308 CB 145081-2 BA 2301 FD • In Sequential file processing, records are processed in a certain order • If a particular record in a sequential file is wanted, then all the prior records in the file must be read before the desired record is reached. Student ID Course Grd 145079-4 BA 1308 CB 145079-4 BA 2301 AA • When a record is updated, it is added to the end.

  24. Organising and Accessing Stored Data 145079-4 BA 1306 AA 3 145080-6 BA 2301 CC 145080-6 IR 3304 BA 145080-6 BA 1306 DC 145081-2 BA 1306 FF 145081-2 BA 1308 CB 145081-2 BA 2301 FD • Direct file processing, or direct access, allows the computer to go directly to the desired record by using a record key. • In addition to instant access to any record, an added benefit of direct access organization is the ability to read, change, and return a record to its same place on the disk; this is called updating in place. Key Student ID Course Grd 1 145078-1 BA 1306 AA 145078-1 BA 1308 DC 2 145079-4 BA 1306 BA 3 4 145079-4 BA 1308 CB 5 145079-4 BA 2301 AA 6 7 8 9 10 11

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