Levi Krein Associate Professor CIS CIS 101: Introduction to Computers Chapter 7 Storage

Levi Krein Associate Professor CIS What is storage? p Fig. 7-1  Holds data, instructions, and information for future use  Storage medium is physical material used for storage  Also called secondary storage

Levi Krein Associate Professor CIS What is capacity?  Number of bytes (characters) a storage medium can hold Largest single database is 500 Terabytes at an east coast university (nuclear accelerator data) Kilobyte (KB)1 thousand Gigabyte (GB) 1 billion Megabyte (MB)1 million Petabyte (PB)1 quadrillion Terabyte (TB)1 trillion Exabyte (EB)1 quintillion Zettabyte (ZB)1 sextillion Yottabyte (YB)1 septillion

Levi Krein Associate Professor CIS How does volatility compare?  Storage medium is nonvolatile—contents retained when power is off  Memory is volatile—holds data and instructions temporarily

Levi Krein Associate Professor CIS Writing Process of transferring items from memory to storage media Writing What is a storage device? Reading Process of transferring items from storage media to memory Reading MemorySDRAM Functions as source of Input Records Output Hardware = I/O or Read/Write Devices

Levi Krein Associate Professor CIS Access time is the combination of two tasks:  Time it takes storage device to locate item on storage medium  Time required to deliver item from memory to processor faster transfer rates slower transfer rates Data Transfer Rate Secondary Storage Primary Storage Hard Disk Flash Memory Cards and USB Flash Drives CDs and DVDs Tape Items waiting to be interpreted and executed by the processor Operating system, application software, user data and information Digital pictures or files to be transported Software, backups, movies, music Backups Memory (most RAM) Stores … Remember, the access time of RAM is 200,000 times faster than a hard drive

Levi Krein Associate Professor CIS What is a hard disk? hard disk installed in system unit  High-capacity storage  Consists of several inflexible, circular platters that store items magnetically  Components enclosed in airtight, sealed case for protection  High-speed platters spin at rpm Link to “How Hard Disks Work” Hard Drive = 7200 rpm 120 rpSecond

Magnetic Disks Formatting prepares disk for use Track is narrow recording band that forms full circle on disk Sector stores up to 512 bytes of data

Levi Krein Associate Professor CIS How does disk storage work? Disks are Magnetic = data is stored by aligning positive & negative particles

Levi Krein Associate Professor CIS Magnetic Disks What are characteristics of a hard disk? p. 361 Fig Sample Hard Disk Characteristics Advertised capacity120 GB Platters3 Read/write heads6 Cylinders16,383 Bytes per second512 Sectors per track63 Sectors per drive234,441,648 Revolutions per minute7,200 Transfer rate133 MB per second Access time8.9 ms actual disk capacity 750 GB Fall 2006 Check the capacity of our lab computers

Levi Krein Associate Professor CIS How does a hard drive look? Platters are made of metal (aluminum), glass, or ceramic & has a metal surface that can be magnetized.

Levi Krein Associate Professor CIS Video: Install a New Hard Drive Speed up your computer with a new hard drive Obsolete $65 Sale $90 Sept Hard Drive Video $60 New 1 Terabyte $60

Levi Krein Associate Professor CIS What is a cylinder?  Vertical section of track through all platters  Same track number on multiple surfaces  Single movement of read/write head arms accesses all platters in cylinder; reduce access time platter read/write head platter sides cylinder track sector

Levi Krein Associate Professor CIS Maintaining Hard Disk Data A little Preventive maintenance! Defragment = reorganize files to make better used of space; programs will run faster Two ways: 1 – Start, Accessories, System Tools 2 – My Computer, Properties, Disk Cleanup & Tools

Levi Krein Associate Professor CIS What is a head crash? clearance read/write head platter hair dust smoke  Spinning creates cushion of air that floats read/write head above platter  Occurs when read/write head touches platter surface  A smoke particle, dust particle, or human hair could render drive unusable  Clearance between head and platter is approximately two-millionths of an inch

Levi Krein Associate Professor CIS hard disk What is a disk cache?  Portion of memory that processor uses to store frequently accessed items second request for data—to hard disk disk cache first request for data—to disk cache processor

Levi Krein Associate Professor CIS What are external hard disks and removable hard disks? External hard disk — freestanding hard disk that connects to system unit Removable hard disk — hard disk that you insert and remove from hard disk drive  Used to back up or transfer files Hard drive is designated as drive C

Levi Krein Associate Professor CIS What is a miniature hard disk?  Provide greater storage capacities than flash memory  Smaller than notebook computer hard disks  A pocket hard drive is a self-contained unit

SAS controller supports many connected devices at once, including hard disks, CD and DVD drives, printers, scanners, digital cameras, and more EIDEEnhancedIntegratedDrive Electronics) controller supports four hard disks, provides connections for CD and DVD drives EIDE (Enhanced Integrated Drive Electronics) controller supports four hard disks, provides connections for CD and DVD drives Magnetic Disks – What is a disk controller? SCSI controller supports up to fifteen devices including hard disks, CD and DVD drives, tape drives, printers, scanners, network cards Serial Advanced Technology Attachment) controller uses serial signals to transfer data, instructions, and information SATA (Serial Advanced Technology Attachment) controller uses serial signals to transfer data, instructions, and information  Chip and circuits that control transfer of data from disk

Levi Krein Associate Professor CIS What is online storage?  Others can be authorized to access your data  Offsite backup of 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 Video

Magnetic Disks – What is a floppy disk?  Portable, inexpensive storage medium (also called diskette) Thin, circular, flexible film enclosed in 3.5” wide plastic shell Obsolete?

Levi Krein Associate Professor CIS Push the same button to close the tray. Optical Discs = CDs and DVDs  Most PCs include an optical disc drive  Flat, round, portable metal discs with protective plastic coating  Can be read only or read/write Insert the disc, label side up. Push the button to slide out the tray. Disc: Alternative spelling of disk. Disc is often used for optical discs, while disk generally refers to magnetic discs, but there is no real rule.diskoptical

Levi Krein Associate Professor CIS How does a laser read data on a CD or DVD? laser diode prism light- sensing diode 01 lens pitland disc label Step 1. Laser diode shines a light beam toward disc. Step 2. If light strikes a pit, it scatters. If light strikes a land, it is reflected back toward diode. Step 3. Reflected light is deflected to a light-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0. Link to “How CDs Work”

Levi Krein Associate Professor CIS How is data stored on a CD or DVD?  Typically stored in single track  Track divided into evenly sized sectors that store items single track spirals to edge of disc disc sectors

Levi Krein Associate Professor CIS What is a CD-ROM?  Compact disc read-only memory  Cannot erase or modify contents  Single-session  Typically holds 650 MB to 1 GB  Commonly used to distribute multimedia (music) and complex software

Levi Krein Associate Professor CIS What is the data transfer rate of a CD-ROM drive? Original CDs Transferred at 150 KBps (kilo bytes per second) 1X 10X = 150 x 10 or 1,500 KBps 48X: 48  150 KBps = 7,200 KBps or 7.2 MBps 1X 10X 48X 75X ? 75  150 KBps = 11,250 KBps or MBps

Levi Krein Associate Professor CIS What is a Picture CD? p Fig Film developers offer Picture CD service Can be modified using photo editing software Stores digital versions of roll of film Step 3. At home, print images from Picture CD on your ink-jet photo printer. At a store, print images to Picture CD at kiosk. Step 1. Drop off film to be developed. Mark the Picture CD box on the film-processing envelope. Step 2. When you pick up prints and negatives, a Picture CD contains digital images of each photograph. A CD-ROM drive can read a Picture CD & other CDs (but CAN NOT read DVDs) Kodak

Levi Krein Associate Professor CIS What are CD-Rs and CD-RWs? Must have CD recorder or CD-R drive Cannot erase disc’s contents CD-R (compact disc-recordable) — c disc you can write on once CD-RW (compact disc-rewritable) — ce erasable disc you can write on multiple times Must have CD-RW software and CD-RW drive Multi-session?

Levi Krein Associate Professor CIS digital versatile disc -ROM or digital video disc -ROM? DVD DVD drive  High capacity disc capable of storing 4.7 GB to 17 GB  Must have DVD-ROM drive or DVD player to read DVD-ROM  Stores databases, music, complex software, and movies What is a DVD-ROM ?

Levi Krein Associate Professor CIS DVDs  Blu-ray discs storage capacity = 100 GB  Blu-ray has won the high definition storage medium for movies  HD-DVD discs lost out to Blue-ray  HD-VMDs have storage capacity of up to 40 GB or more  Competitor to Blu-ray  20 layers  UMD can store up to 1.8 GB  Mini-DVD; PlayStation Portable

Levi Krein Associate Professor CIS How does a DVD-ROM store data? DVD-ROM Storage Capacities SidesLayersStorage Capacity 1147 GB GB GB 2217 GB  Two layers of pits are used, lower layer is semitransparent so laser can read through  Some are double-sided  Data is packed (pits are closer together) more densely  DVD-RW is a rewritable DVD  It can write on CD-R, CD-RW, DVD-R & DVD-RW

Levi Krein Associate Professor CIS What is tape? p Fig  Magnetically coated plastic ribbon capable of storing large amounts of data at low cost  Sequential access, like music  Primarily used for backup Sequential access is the opposite of Direct access — used on hard disks, CDs, and DVDs — which can locate particular item immediately

Levi Krein Associate Professor CIS What is a PC Card?  Adds capabilities to computer  Credit-card-sized device commonly used in notebook computers

Levi Krein Associate Professor CIS What is miniature mobile storage media?  Storage for small mobile devices Miniature mobile storage media CompactFlashSecure Digital xD Picture Card Memory Stick

Levi Krein Associate Professor CIS What is a card reader?  Reads information stored on miniature mobile storage media  Type of card determines type of card reader needed

Levi Krein Associate Professor CIS What is a USB Flash Drive?  Plugs in a USB port on a computer or mobile device  Storage capacities up to 64 GB How flash drives are made. Check out the robotics. 8 minutes

Levi Krein Associate Professor CIS What is a smart card?  Stores data on microprocessor embedded in small card  Input, process, output, and storage capabilities  Sometimes called intelligent smart card Prepaid telephone cards

Levi Krein Associate Professor CIS What are microfilm and microfiche? Store microscopic images of documents on roll or sheet of film Microfilm — 100- to 215-foot roll of film Microfiche — small sheet of film, usually 4”  6”

Levi Krein Associate Professor CIS How do life expectancies of various media compare?  Microfilm and microfiche have longest life of any storage media

Drive Letter Designations Floppy Disks Drive Letter A & B Hard Disks Drive Letter C More Hard Disks = D, E, etc. Optical Drives Next available letter after hard disks Flash Drives Next available letter after optical drives Levi Krein Associate Professor CIS

Levi Krein Associate Professor CIS Other Storage Devices Dogtags View Video

Levi Krein Associate Professor CIS Other Storage Devices Storage Cube View Video Notice Floppy Disks and Magnetic Tape

Levi Krein Associate Professor CIS Summary of Storage Chapter 7 Completed