cs 105 spring 2006 slide 1
TRANSCRIPT
CS 105 Spring 2006 Slide 1
Secondary Storage
• What is a cylinder? A track?
• What is secondary storage?
• What is flash memory?
See Unit B in your Concepts Book
CS 105 Spring 2006 Slide 2
What is Secondary (Auxiliary) Storage?
CD-ROMTape BackupHard disk Zip Drive
Floppy DisksDVD
RAMprimary storagemain memory,Needs power
ROM is built in,Can change only
slightly
CS 105 Spring 2006 Slide 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 Spring 2006 Slide 4
Units of Measure of Storage
• A binary digit; 0 or 1 = a Bit• 8 bits, or one character = a Byte (used for one letter)
• 1024 Bytes = 1 Kilobyte + or - 170 words
• 1024 Kilobytes = 1 Megabyte (1024*1024) + or - 175,000 words, about one floppy disk
• 1024 Megabytes = 1 Gigabyte • 1024 Gigabytes = 1 Terabyte + or - 179 million words
CS 105 Spring 2006 Slide 5
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 Spring 2006 Slide 6
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 Spring 2006 Slide 7
More….
• A binary decision = 1 bit • A single text character = 1 byte • A typical text word = 10 bytes
• The complete works of Shakespeare = 5 megabytes
• A pickup truck filled with books = 1 gigabyte
• The contents of a DVD = 17 gigabytes
• A collection of the works of Beethoven = 20 gigabytes
CS 105 Spring 2006 Slide 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 accessMagnetic ___________
Used for cassettes, archives
CS 105 Spring 2006 Slide 9
Disk Organization
Tracks : Concentric circles where data is stored
Sectors : Pie-shaped wedges of tracks
CS 105 Spring 2006 Slide 10
Storing data on a hard drive
CS 105 Spring 2006 Slide 11
Disk Organization
Track 00
Track 39
Tracks and __________
Access Arm
CS 105 Spring 2006 Slide 12
Hard Disk Organization
•Cylinder : Combination of same-track locations on multiple-surface disks
CS 105 Spring 2006 Slide 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 Spring 2006 Slide 14
CDs
Digital to Analog
CS 105 Spring 2006 Slide 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 Spring 2006 Slide 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 Spring 2006 Slide 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 Spring 2006 Slide 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 Spring 2006 Slide 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 Spring 2006 Slide 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 Spring 2006 Slide 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 Spring 2006 Slide 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.
• A toy, necklace, watch, shirt, etc. etc.
CS 105 Spring 2006 Slide 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 Spring 2006 Slide 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.