Understanding Different Types of Digital Storage Media - Prof. Barbara Guillott, Study notes of Computer Science

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Discovering Computers 2009 Chapter 7 Storage Chapter 7 Contents Magnetic Disksagnetic Disks Optical DisksOptical Disks TapeTape PC Cards and Expresscard modulesPC Cards and Expresscard odules Miniature mobile storage mediainiature mobile storage media Microfilm and Mocroficheicrofilm and ocrofiche Enterprise storageEnterprise storage Putting it all togetherPutting it all together StorageStorage Storage Medium (hard disks, CDs, DVDs, USB flash drives, etc.) Storage How does volatility compare? p. 355 - 356 N o n vo la ti le  Storage medium is ____________—contents retained when power is off Contents retained Contents available to user Memory (most RAM) (chips on motherboard) Screen Display ON OFF V o la ti le Display disappears Data and instructions available to user Display appears Data and instructions erased  Memory is ________—holds data and instructions temporarily Writing Process of transferring items from memory to storage media riting Process of transferring items from memory to storage media Storage What is a ________________? p. 356 Reading Process of transferring items from storage media to memory Reading Process of transferring items from storage media to memory Hardware that records and retrieves items to and from storage media Functions as source of input Creates output Storage What is _____________? p. 357 Fig. 7-4 1. Time it takes storage device to locate item on storage medium 2. Time required to deliver item from memory to processor  The speed of storage devices and memory measuring Perpendicular recording Magnetic Disks What is a ______________? p. 358 Fig. 7-6  High-capacity storage  Consists of several inflexible, circular platters that store items electronically  Components enclosed in airtight, sealed case for protection Longitudinal recording Magnetic Disks What are characteristics of a hard disk? p. 359 Fig. 7-7 Sample Hard Disk Characteristics Advertised capacity 500 GB Platters 4 Read/write heads 8 Cylinders 16,383 Bytes per second 512 Sectors per track 63 Sectors per drive 973,773,168 Revolutions per minute 7,200 Transfer rate 300 MBps Access time 8.5 ms actual disk capacity Magnetic Disks How does a hard disk work? p. 360 Fig. 7-8 Magnetic Disks What is a _____________? p. 361 Fig. 7-11  Portion of memory that processor uses to store frequently accessed items second request for data—to hard disk first request for data—to disk cache Magnetic Disks What is _________? p. 362  Redundant Array of Independent Disks  A group of two or more integrated hard disks  Connects multiple smaller disks into a single unit that acts as a single large hard disk Magnetic Disks What is a ______________________? p. 362 Fig. 7-13  Provide greater storage capacities than flash memory  Smaller than notebook computer hard disks  A __________________, as another type of miniature hard disk, is a self-contained unit Magnetic Disks What is ________________? p. 364 - 365 Fig. 7-15  Others can be authorized to access your data  Service on Web that provides storage for minimal monthly fee  Files can be accessed from any computer with Web access  Large files can be downloaded instantaneously Magnetic Disks What is a ____________? p. 365 Fig. 7-16  Portable, inexpensive storage medium (also called diskette) Thin, circular, flexible film enclosed in 3.5” wide plastic shell Optical Discs What are ____________? p. 366 Fig. 7-17  Most PCs include an optical disc drive  Flat, round, portable metal discs made of metal, plastic, and lacquer  Can be read only or read/write Optical Discs What is a ____________? p. 369 Fig. 7-22  Compact disc read-only memory  Cannot erase or modify contents  Typically holds 650 MB to 1 GB  Commonly used to distribute multimedia and complex software Optical Discs What is the data transfer rate of a CD-ROM drive? p. 369 75X Ranges from 48X to 75X or faster 75  150 KBps = 11,250 KBps or 12.25 MBps 75X is 150 KBps (KB per second) 48X: 48  150 KBps = 7,200 KBps or 7.2 MBps Optical Discs What are ________ and ___________? p. 370 Must have CD recorder or CD-R drive Cannot erase disc’s contents (compact disc-recordable) —cdisc you can write on once _________ (compact disc-rewritable) —ce rasable disc you can write on multiple times Must have CD-RW software and CD-RW drive Tape What is ________? p. 374 Fig. 7-27  Magnetically coated plastic ribbon capable of storing large amounts of data at low cost  Primarily used for backup Tape How is data stored on a tape? p. 374  Sequential access  Unlike direct access — used on hard disks, CDs, and DVDs — which can locate particular item immediately  Reads and writes data consecutively, like music tape PC Cards and ExpressCard Modules Removable devices. p. 374 Figs. 7-28  ____________________: a thin credit card sized removable flash memory deice.  _____________________________________: a removable device, smaller than ______________.  They can be used for adding memory, storage, communications, multimedia, and security capabilites. Miniature Mobile Storage Media What is a _______________? p. 377 Fig. 7-32  Plugs in a USB port on a computer or mobile device  Storage capacities up to 64 GB  May eventually make the floppy disk nearly obsolete Miniature Mobile Storage Media What is a ______________? p. 378 Fig. 7-33  Stores data on microprocessor embedded in small card  Input, process, output, and storage capabilities Microfilm and Microfiche What are ______________ and __________? p. 379 Fig. 7-34 Images recorded using computer output microfilm recorder Store microscopic images of documents on roll or sheet of film _____________ — 100- to 215-foot roll of film _________— small sheet of film, usually 4”  6” Putting It All Together What are recommended storage devices for small office/home office (SOHO) users? p. 380 Fig. 7-37  1 TB hard disk  Online storage  CD or DVD drive  External hard drive for backup  USB flash drive Putting It All Together What are recommended storage devices for mobile users? p. 380 Fig. 7-37  250 GB hard disk  Online storage  CD or DVD drive  Card reader/writer  Portable hard disk for backup  USB flash drive Putting It All Together What are recommended storage devices for power users? p. 380 Fig. 7-37  2.5 TB hard disk  Online storage  CD or DVD drive  Portable hard disk for backup  USB flash drive