CS 105 Fall 2006 # 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

RAMprimary storagemain 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 Megabyte roughly 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 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 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 Fall 2006 # 9

Disk Organization

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

Disk Organization

Track 00

Track 39

Tracks and __________

Access Arm

CS 105 Fall 2006 # 12

Hard Disk Organization 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.