2Chapter 5 Objectives Differentiate among CD-ROMs,Differentiate between storage devices recordable CDs, rewritable CDs, and storage media DVD-ROMs, BD-ROMs, HD DVD- ROMs, recordable DVDs, and Describe the characteristics of rewritable DVDs magnetic disks Describe the characteristics of Identify the uses of tape a hard disk Discuss various types of miniature, Discuss PC Cards, ExpressCard external, and removable hard disks modules, and the various types of miniature storage media Describe the characteristics of optical discs Identify uses of microfilm and microfiche
3Learning OutcomeSuccessful students will be able to: Describe the characteristics of computer hardware devices and explain their functionalities.
4StorageWhat is storage? Holds data, instructions, and information for future use Storage medium is physical material used for storage Also called secondary storage
5StorageWhat is capacity? Number of bytes (characters) a storage medium can hold Kilobyte (KB) 1 thousand Megabyte (MB) 1 million Gigabyte (GB) 1 billion Terabyte (TB) 1 trillion Petabyte (PB) 1 quadrillion Exabyte (EB) 1 quintillion Zettabyte (ZB) 1 sextillion Yottabyte (YB) 1 septillion
6 Storage How does volatility compare? Storage medium is nonvolatile—contents retained when power is off Memory is volatile—holds data and instructions temporarily ON OFF Screen Display Display DisplayVolatile appears disappears Memory Data and Data and (most RAM) instructions instructions erased (chips on motherboard) available to userNonvolatile Storage Medium Contents Contents (floppy disks, Zip disks, available to user retained hard disks, CDs)
7StorageWhat is a storage device? Hardware that Reading records and Writing Process of transferring retrieves items Process of transferring items from storage to and from items from memory media to memory storage media to storage media Functions as source Creates output of input
8StorageWhat is access time? Time it takes storage device to locate item on storage medium Time required to deliver item from memory to processor faster Transfer rates Stores … transfer rates Primary Storage Memory (most RAM) Items waiting to be interpreted and executed by the processor Secondary Storage Hard Disk Operating system, application software, user data and information Flash Memory Cards Digital pictures or files and USB Flash Drives to be transported CDs and DVDs Software, backups, movies, music Tape Backups slower transfer Floppy Disk Small files to be transported rates
9Access time & Transfer rateMemory accesses items in billionths of a second(nanoseconds)Storage devices access items in: thousandths of a second (milliseconds) or millionths of a second (microseconds)Transfer rate is the speed with which data, instruction &info transfer to & from a device, stated as: KBps & MBps
10Magnetic Disks Use magnetic particles to store items on a disk’s surface Alignment of magnetic particles represents the data – either a 0 bit or a 1 bit Must be formatted first: Dividing the disk into tracks & sectors, so the OS can store & locate items on disk A sector stores up to 512 bytes of data
11Magnetic Disks Track Sector is narrow recording band stores up to that forms full 512 bytes circle on disk of data Formatting prepares disk for use
12Magnetic Disks For reading & writing purpose, sectors (2-8, depending on OS) are grouped into clusters Cluster (allocation unit) is the smallest unit of disk space that stores an item Each cluster holds data from only one file Even if a file consists of only few bytes, it uses an entire cluster One file, anyhow, can span many clusters Sometimes, a sector has defect & cannot store data. When format, OS marks these bad sectors as unusable
13 Magnetic Disks hard disk mounted in system unitWhat is a hard disk/hard disk drive/hard drive? High-capacity storage: 80 – 750GB & more Consists of several inflexible, circular platters that store items electronically Components enclosed in airtight, sealed case for protection Longitudinal recording Perpendicular recording Fixed h/d & portable h/d
14Magnetic DisksWhat are characteristics of a hard disk? 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 actual disk Revolutions per minute 7,200 capacity Transfer rate 300 MB per second Access time 8.5 ms
15Magnetic Disksh/d capacity determined from num of platters andcomposition of magnetic coating on the plattersPlatter diameter: 3.5 inches in– desktop; 2.5 inches – notebook & mobile devices made of aluminum, glass or ceramic – coated with alloy – allow items to be recorded magnetically on its surface. The coating is 3 millionths of an inch thick Each has 2 read/write heads, one for each sideh/d arms move read/write heads to the proper location –read & write items in the drive as it barely touches thedisk/s recording surfaceLocation of read/write heads referred to by its cylinder – avertical section of a track that passes through all platters
16Magnetic DisksHow does a hard disk work? Step 3. When software requests a disk access, read/write heads determine current Step 2. or new location of data. Small motor spins platters while computer is running. Step 4. Head actuator positions read/write head arms over Step 1. correct location on platters Circuit board controls to read or write data. movement of head actuator and a small motor.platters rotate at high speed: 5400 – 15000 revolutions per minute (rpm) – until power is removed
17Magnetic Disks platterWhat is a cylinder? track Vertical section of sector track through all platters Single movement of read/write head arms accesses all platters read/write in cylinder head platter sides cylinder
18Magnetic DisksWhat is a head crash? Occurs when read/write head touches platter surface Spinning creates cushion of air that floats read/write head above platter Clearance between head and platter is approximately two-millionths of an inch A smoke particle, dust particle, or human hair could render drive unusable
19Magnetic DisksWhat is a disk cache/buffer? Portion of memory (memory chip on h/d) that processor uses to store frequently accessed items 2MB – 16MB (the greater, the faster the h/d) first request second request for data—to disk cache for data—to hard disk
20Magnetic DisksWhat is RAID? Redundant Array of Independent Disks Connects multiple smaller disks into a single unit that acts as a single large hard disk What is backup? A duplicate of a file, program or disk placed on a separate storage medium that user can use in case the original is lost, damaged or destroyedWhat is density? Number of bits in an area on a storage medium High density = high capacity
21 method- Backup method- Hard Disks How does RAID work? Disk system that duplicates data, instructions, and information to improve data reliability Mirroring has one backup disk for each disk Striping stores data across multiple disks mirroring(RAID Level 1) striping
22Magnetic DisksWhat is a miniature hard disk? Provide greater storage capacities than flash memory: 4GB – 160GB – mostly use perpendicular recording Smaller than notebook computer hard disks A pocket hard drive is a self-contained unit User can insert in & remove from a slot in a device or a computer or plug-in a USB port on a computer
23Magnetic DisksWhat are external hard disks and removable hard disks? Used to back up or transfer files External hard disk—freestanding Removable hard disk—hard disk hard disk that connects to system unit that you insert and remove from hard disk drive
24External & Removable Hard DiskExternal h/d: Connects with cable to USB or FireWire port on SU Some include multiple h/d act as one, having capacity up to 1TBRemovable h/d: Sometimes the drive is built in the SU Others are external devices – connect with cable to USB or FireWire port on SU. Has up to 500GB capacityADVANTAGES??
25Magnetic DisksWhat is a disk controller? Chip and circuits SATA (Serial Advanced Serial that control transfer Technology Attachment) controller Attachment) uses serial signals to transfer data, of items from disk instructions, and information EIDE (Enhanced Integrated Drive SCSI controller supports up to fifteen E Electronics) controller supports four devices including hard disks, CD hard disks, provides connections for and DVD drives, tape drives, printers, CD and DVD drives scanners, network cards
26Magnetic DisksWhat is online storage? 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 Others can be authorized to access your data REASONS??
27Magnetic DisksWhat is a floppy disk? Portable, inexpensive storage medium (also called diskette) Consists of thin, circular, flexible plastic Mylar film with magnetic coating Enclosed in 3.5” wide plastic shell Storage capacity: 1.44MB Access time: 84 ms Transfer rate: 250 – 500KBps Contains 80 track on each side ≈ 18 sectors per track
28Magnetic Disks liner shutter metal hub magnetic flexible shell coating thin film
29Magnetic Disks sector 18 per track track 80 per side 80 tracks per side X 18 sectors per track X 2 sides per disk X 512 bytes per sector = 1,474,560 bytes
30Optical Discs Push the button toWhat are optical discs? slide out the tray. Flat, round, portable metal discs made of metal, plastic, and lacquer Can be read only or Insert the disc, read/write label side up. Most PCs include an optical disc drive Push the same button to close the tray.
31Optical DiscsHow does a laser read data on an optical disc? disc label lens pit land lens Step 3. Step 2. Reflected light is 0 1 If light strikes deflected to a a pit, it scatters. light-sensing diode, If light strikes a which sends digital prism land, it is prism signals of 1 to light- reflected back light- computer. Absence Step 1. sensing toward diode. sensing of reflected light is Laser diode diode diode read as digital shines a light laser laser signal of 0. beam toward disc. diode diode
32Optical DiscsHow is data stored on an optical disc? Typically stored in single track Track divided into evenly sized sectors that store items single track spirals to edge of disc disc sectors
33Optical DiscsHow should you care for an optical disc?
34Optical DiscsWhat is a CD-ROM? Compact disc read-only memory Single-session disc Cannot erase or modify contents Typically holds 650 MB to 1 GB Commonly used to distribute multimedia and complex software
35Optical DiscsWhat is the data transfer rate of a CD-ROM drive? Ranges from 48X to 75X 75X or faster 75 × 150 KBps = 11,250 KBps X is 150 KBps or 11.25 MBps (KB per second) 48X: 48 × 150 KBps = 7,200 KBps or 7.2 MBps
36Optical DiscsWhat is a Picture CD? Film developers Can be Stores digital offer modified versions of Picture CD using photo roll of film service editing software Step 1. Drop off film to Step 3. be developed. At home, print images Mark the Picture from Picture CD on CD box on the Step 2. your ink-jet photo printer. film-processing When you pick up envelope. prints and negatives, a At a store, print images to Picture CD contains Picture CD at kiosk. digital images of each photograph.
37Optical DiscsWhat are CD-Rs and CD-RWs? Must have CD recorder or CD-R drive CD-R (compact disc-recordable) — multisession optical disc — can write on once, but not erase Cannot erase disc’s contents CD-RW (compact disc-rewritable) — erasable multisession disc ce — can write on multiple times Must have CD-RW software and CD-RW driveDisc reliability drop with each successiverewriteSpeed: 52/24/52 [write – 52X or more, rewrite –24X or more, read – 52X or more ]
40Video CD Store video on a CD-R Can be played in CD or DVD drives, DVD players & some game consoles Hold 74 – 80 minutes of video Digital media copy RIPPING PROCESS
41Optical DiscsWhat is a DVD-ROM (digital versatiledisc-ROM or digital video disc-ROM)? Must have DVD-ROM drive or DVD player to read DVD-ROM Stores databases, music, complex software, and movies Blu-ray discs have storage capacity of up to 100 GB HD-DVD discs have storage capacity of up to 60 GB UMD can store up to 1.8 GB
42Optical DiscsHow does a DVD-ROM store data?1. Dense disc – closer pits2. Two layers of pits are used, lower layer is semitransparent so laser can read through3. Some are double-sidedMany types of recordable and rewritable DVDs are available DVD-R and DVD+R DVD-RW and DVD+RW
43TapeWhat is tape? Magnetically coated plastic ribbon capable of storing large amounts of data at low cost Primarily used for backup Low cost Long term storage
44TapeHow is data stored on a tape? Sequential access Reads and writes data consecutively, like music tape Unlike Direct access/Random access— used on hard disks, CDs, and DVDs — which can locate particular item immediately
45PC Cards and ExpressCard ModulesWhat are PC Cards and ExpressCard Modules? Adds capabilities to computer Credit-card-sized device commonly used in notebook computers Add memory, storage, communications, multimedia, and security capabilities to a computer
46Miniature Mobile Storage MediaWhat is miniature mobile storage media? Storage for small mobile devices
47Miniature Mobile Storage MediaWhat are common types of flash memory cards? CompactFlash Secure Digital xD Picture Card Memory Stick Memory Stick PRO Duo
48Miniature Mobile Storage MediaHow does one type of flash memory card work?
49Miniature Mobile Storage MediaWhat is a USB Flash Drive? Plugs in a USB port on a computer or mobile device Storage capacities up to 64 GB May eventually make the floppy disk obsolete Also called U3 Smart device Transfer rate: 12 MBps
50Miniature Mobile Storage MediaWhat is a smart card? Stores data on microprocessor embedded in small card Input, process, output, and storage capabilities Used to store medical records, vaccination data, and other health-case and identification information; tracking information – employee attendance or customer purchase, authenticating users for building access Are credit cards smart cards?
51Microfilm and MicroficheWhat are microfilm and microfiche? Store microscopic images of documents on roll or sheet of film Images recorded using computer output microfilm recorder Microfilm — 100- to Microfiche — small sheet 215-foot roll of film of film, usually 4” × 6” Used to store back issues of newspapers, magazines, inactive files, transactions and cancelled checks,…
52Microfilm and MicroficheHow do life expectancies of various media compare? Microfilm and microfiche are inexpensive % have longest life of any storage media
53Putting It All TogetherWhat are recommended storage devices for homeusers? 250 GB hard disk Online storage CD or DVD drive Card reader/writer USB flash drive
54Putting It All TogetherWhat are recommended storage devices for smalloffice/home office (SOHO) users? 500 GB hard disk Online storage CD or DVD drive External hard drive for backup USB flash drive
55Putting It All TogetherWhat are recommended storage devices for mobileusers? 100 GB hard disk Online storage CD or DVD drive Card reader/writer Portable hard disk for backup USB flash drive
56Putting It All TogetherWhat are recommended storage devices for powerusers? 1.5 TB hard disk Online storage CD or DVD drive Portable hard disk for backup USB flash drive
57Putting It All TogetherWhat are recommended storage devices for largebusiness users? Desktop computer 500 GB hard disk CD or DVD drive Smart card reader Tape drive USB flash drive Server or Mainframe Network storage server 40 TB hard disk system CD-ROM or DVD-ROM server Microfilm or microfiche
58Summary of Storage Internal hard disks HD DVD discsExternal and removable hard disks Recordable and Rewritable DVDs Floppy disks Tape CD-ROMs PC Cards and ExpressCard Recordable and Rewritable CDs modules Flash memory cards and USB flash drives DVD-ROMs Smart cards, microfilm, and microfiche Blu-ray Discs (BDs)Chapter 5 Complete