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Secondary Storage

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  1. Secondary Storage • What is a cylinder? A track? • What is secondary storage? • What is flash memory? See Unit B in your Concepts Book Course Guide p. 255 CS 105 Fall 2006

  2. What is (Auxiliary) Storage? • CD-ROM • Tape Backup • Hard disk • Zip Drive • Floppy Disks • DVD RAM primary storage main memory, Needs power ROM is built in, Can change only slightly CS 105 Fall 2006

  3. Booting a computer uses ROM • Bootstrapping: “to lift yourself up by your own bootstraps.” • ROM is built-in memory, doesn’t change, needed when the power comes on. • BIOS is a kind of Flash Memory, and can have some settings changed. Its name comes from basic input/output system (BIOS) • Finally, software loaded into RAM CS 105 Fall 2006

  4. Size of storage • A binary digit; 0 or 1 = a Bit • 8 bits, or one character = a Byte (used for one letter) 1000001 is the letter A (65 in ASCII) CS 105 Fall 2006

  5. Thinking of storage • The letter A is one byte • 1 GB is like 1 billion letter A's. • What if you could transfer one letter in each second? • If there are 31,557,600 seconds in a year, and it would take about 31 years and seven months to transfer 1 GB of information that way! CS 105 Fall 2006

  6. More…. • a Bit True or False • a Byte used for one ASCII letter • 1 Kilobyte capacity of a standard UIUC ID • 1 Megabyteroughly a minute of compressed music • 1 Gigabyte 18 hours of MP3 music • 1 Terabyte 6 minutes of UHDV data CS 105 Fall 2006

  7. Units of Measure of Storage • A binary digit; 0 or 1 = a Bit • 8 bits, or one character = a Byte • 1024 Bytes = 1 Kilobyte • 1024 Kilobytes = 1 Megabyte (1024*1024) • 1024 Megabytes = 1 Gigabyte • 1024 Gigabytes = 1 Terabyte CS 105 Fall 2006

  8. Secondary Storage Devices Provide permanent storage Slower to access than RAM Direct access Magnetic Storage Removable (Floppy disk/diskettes) Fixed (Hard disk) ____________Disk (CD) Sequential access Magnetic ___________ Used for cassettes, archives CS 105 Fall 2006

  9. Disk Organization Tracks : Concentric circles where data is stored Sectors : Pie-shaped wedges of tracks CS 105 Fall 2006

  10. Storing data on a hard drive CS 105 Fall 2006

  11. Disk Organization Tracks and __________ Track 00 Access Arm Track 39 CS 105 Fall 2006

  12. Hard Disk Organization • Cylinder:Combination of same-track locations • on multiple-surface disks CS 105 Fall 2006

  13. Formatting a disk, losing your data • When you format a disk, the operating system erases all bookkeeping information on the disk, tests the disk to make sure all sectors are reliable, marks bad (damaged) sectors, etc. You must format a disk before you can use it. • Reformatting a disk does not erase the data on the disk, only the “directory” to find files. CS 105 Fall 2006

  14. CDs Digital to Analog CS 105 Fall 2006

  15. Solid state storage and its advantages • Flash memory in cameras and phones and home video game players, as secondary storage rather than RAM • CompactFlash or SmartMedia cards are examples CS 105 Fall 2006

  16. Why not use Flash Memory everywhere? • Flash memory is noiseless. • It allows faster access. • It is smaller in size. • It is lighter. • It has no moving parts. BUT: • You can buy a 40-gigabyte (40,000-MB) hard drive for less than $200, while a 192-MB CompactFlash costs more! CS 105 Fall 2006

  17. Since we are talking about Flash memory, what is a Smart Card? • The term Smart Card is loosely used to describe any card with a capability to relate information • Magnetic stripe • Memory, optical • Microprocessor cards CS 105 Fall 2006

  18. Memory card with a magnetic stripe –Memory is rewritable • Your i-card has a cash stripe on the back of the card. • The dollar value placed on this stripe can be used to make copies and for some campus purchases. • You add funds to the stored value stripe through many of the Value Card Teller machines CS 105 Fall 2006

  19. Sim Cards • A smart card fitted in every modern mobile phone which stores the phone's identity and settings. • Phone numbers can be stored on the card • Its primary function is to allow the networks to identify your phone to make calls. • You can move the sim card from phone to phone, taking your info with you • YOU CAN BACK UP YOUR SIM CARD, IN CASE YOUR CELLPHONE IS LOST! CS 105 Fall 2006

  20. Intelligent Smart Cards • See definition: http://www.scsite.com/dc2000/ch6/display_terms.cfm?term=intelligent_smart_card • Smart cards must have a central processing unit (CPU), random access memory (RAM), read only memory (ROM), and storage. • The card not the terminal executes the series of commands and sends the results to the terminal CS 105 Fall 2006

  21. How are they used? • Electronic purses (EP): smart cards which have stored value of electronic cash. • No authentication is necessary • Cards can be charged at special dispensers or by telephone and can be locked by a four digit code • Can store value in up to five currencies • Secure transactions—storing biometric data, etc. CS 105 Fall 2006

  22. Where do they get the power from? • Smart cards rely on electricity from a smart card reader for the power they need to run. • Wireless smart cards do not require electricity; instead, they have a built-in antenna that absorbs energy from nearby short-range electromagnetic fields. • Thus, everyday objects can be made intelligent via "smart" devices. CS 105 Fall 2006

  23. PC cards (USB Flash cards) • PC Cards are credit card-size peripherals that add memory, mass storage, and other capabilities to computers—you plug them into the side of your laptop, usually. Examples: • Hard Drives • Joystick Interface Cards • Memory Cards - Flash, SRAM, and many others • Modem and Ethernet Combination Cards CS 105 Fall 2006

  24. Preset stations on your car’s radio • If you turn the ignition off, a car radio still pulls a tiny amount of current from the battery. It saves its data in its RAM. (called also Flash RAM) • That is why the car radio will lose its preset stations if your car battery dies or the wires are disconnected. • Car radios ought to use Flash Memory—maybe one day they will. CS 105 Fall 2006