1. SECONDARY STORAGE
Secondary storage devices are used to save, to back up, and to transport files
Over the past several years, data storage capacity has expanded from saving numbers and text to include digital images and video
Competent end uses need to know the capabilities, the limitations, and the uses of floppy disks, hard disks, opticak disks, and other types of secondary storage

2. Competencies Distinguish between primary & secondary storage
Discuss the different types of storage media
Describe the traditional floppy disk and the high capacity floppy disks
Describe various types of hard disk devices

3. Competencies cont. Describe ways to improve hard-disk operations
Describe the different types of optical disks
Describe other kinds of secondary storage devices

4. Storage RAM Primary storage Secondary storage
Volatile
Temporary
Secondary storage
Nonvolatile
Permanent
Secondary storage characteristics
Media
Capacity
Storage devices
Access speed
Permanently save information for: future use; to share info with others; to modify at later date
Secondary storage is nonvolatile – stores programs and data as opposed to temporary storage (RAM)
RAM

5. Secondary Storage Devices
Floppy disk – inexpensive and removable
Optical disks – large storage capacity
Hard disk – large storage capacity and fast retrieval times

6. Traditional Floppy Disk
Floppy Disks
Diskettes
Floppies
Portable storage media
Floppy disk drives (FDD)
Traditional Floppy Disk
Floppy disks are removable storage media. Today’s standard is 1.44 MB. Data recorded in rings called called tracks; tracks divided into wedge-shaped sections called sectors
Most disks manufactured currently preformatted w/tracks and sectors
While called floppy, actually pieces of flat Mylar rotating within a hard plastic jacket
The bits of data are represented by the presence or absence of magnetic charges

7. Traditional Floppy Diskette
Storage capacities range from 360 KB to 1.44 MB
Write-protect notch or window to prevent inadvertent erasure or write-over
Density refers to how tightly the bits can be packed next to one another
A shutter on the disk slides to the side to expose the recording surface

8. Types of Floppies High capacity Known as a floppy-disk cartridge
Require special disk drives
Three well known types
Zip disks
HiFD disks
SuperDisks
Zip disks – usually manufactured by Iomega; 100 to 250 MB worth of storage; requires own drive
Super disks – usually manufactured by Imation; 120 MB capacity; popular with notebooks; use std floppy drive
HiDF disks – usually manufactured by Sony Corp; 200 MB capacity
Biggest advantages: can use HiDF disk in floppy drive
Zip disks – 100 MB, 250 MB or 750 MB
HiFD disks MB or 720MB
SuperDisks – 120 MB or 240 MB

9. Hard Disks Use thicker, metallic platters for storage
Faster than a floppy diskette
Large capacity
Sensitive instruments
Composed of metallic rather than plastic disks
Fast information storage and retrieval
Read-write head is inch above surface
An internal hard disk is also known as a fixed disk

10. Materials that Cause a Head Crash
Head crashes occur when the read-write head contacts the disk surface or with particles on the disk's surface
Head crashes are now rare
A smoke particle, human hair or fingerprint could cause a head crash

11. Internal Hard Disk Located inside system unit Known as a fixed disk
Designated as the C drive
Advantages over floppies
Access speed
Capacity
Located inside the system unit; also known as fixed disk
Used for storing the operating system, other programs and large data files

12. Hard-Disk Cartridges Removable hard disks
Used to complement internal hard disk
Capacities of 10 to 20 GB
PC Card Hard Disks
Capacity limited only by number of cartridges; used to complement internal hard disk.
PC Card hard disk available for notebooks with a capacity of up to 5 GB
Popular vendors: Iomega and Peerless

13. Hard-Disk Packs Removable Massive storage capacity
Common in mainframes
Resembles stack of vinyl records
Massive storage capacity
Common in mainframe systems
Composed of a larger number of platters, resembling a stack of record albums
Most platters offer read-write surfaces on top and bottom
Access time - time between the computer’s request for data from secondary storage and the completion of the data transfer; usually access time is faster with this type of secondary storage

14. Hard-Disk Pack Removable storage devices
Multiple recording platters aligned one above the other
Found on mainframes
Hard-disk packs are stored in a hard plastic cover that is removed when mounted onto a special drive

15. Performance Enhancements
Disk caching
Redundant arrays of inexpensive disks (RAID)
File compression and decompression
Disk caching
Uses hardware and software to anticipate data needs
Frequently used data is stored in memory; when needed, the access time is much faster
Redundant arrays of inexpensive disks (RAID)
Groups of low cost hard-disk drives grouped together using networks and special software
Performs as a single large-capacity disk; but faster than a single disk of comparable size
File compression and decompression
Increase storage capacity
Reduce space required for storage; reduce up to ¼ of original size
WinZip and PKZip are well-known programs

16. Optical Disks Compact Permanent storage Laser beams reflect off pits
Two common types CD
DVD
Use laser technology. CD and DVD are optical disk formats.
Compact, high capacity form of permanent storage (up to 17 gigabytes of data
Laser beam writes by creating a pattern of pits (holes) and lands (flat areas) to encode data bits
Laser beams reflect off the pits and lands to read the data
Optical disks come in many different sizes
Most common is 4 ¾ inches
Stored in a protective case called jewel boxes

17. Compact Disc Optical format From 650 MB to 1 GB capacity
Rotation speeds vary
Types
Read only: CD-ROM
Write once: CD-R
Rewriteable: CD-RW
Picture CDs and Photo CDs
CD stands for compact disc
Standard on most computers
Can store from 650 MB up to 1 GB
Speed determines how fast data can be transferred
Read only: CD-ROM
Commercial music CD
Read only means it can't be written on or erased
Used to distribute large databases and references
Write once: CD-R (CD –recordable)
Known as burners
Used to archive data or to record music downloaded from the Internet
Rewriteable: CD-RW
Known as erasable optical disks
Can be changed
Used to create and edit multimedia presentations
Picture CDs and Photo CDs
Special format developed by Eastman Kodak to store digital images
Two types
Single-session
Multi-session
Ideal for use as permanent data archives for essential company information

18. Digital Versatile Disc
Digital Versatile Disk or Digital Video Disk (DVD)
Similar to CDs, but can store more data
Types
Read only
Write once
Rewritable
DVD-ROM
Known as DVD players
Used for videos
DVD-R and DVD+R
Two competing write once formats
Write once format
Expensive and not widely used
DVD-RAM or DVD-RW - rewritable version
DVD-RW
DVD+RW
DVD-RAM

19. DataPlay Optical disk Write once format Quarter size
500 MB capacity
Holds 5 hours of CD-quality sound
Use for storing and playing music files
Optical write once format similar to CD-R
Size of a quarter
Used to store music
Harder to copy
Music industry is supporting this format

20. Other Types of Secondary Storage
Solid-state storage
Internet hard drives
Magnetic tape
Solid-state storage
No moving parts
Reliable, but expensive
Internet hard drives
Magnetic tape
Slower sequential access
Stores data and programs
Used for making backups of data

21. Solid-State Storage Flash memory cards Key chain hard drives
Widely used in notebook computers
Used to record MP3 music files
Key chain hard drives
Key chain flash memory devices
Connects to a USB port
Key chain hard drives have recently been introduced
Very compact
Worn as a necklace or on a key ring
Connect to a USB port
Predicted that they will replace the floppy disk for transporting data
Capacities up to 1 GB

22. Internet Hard Drives These are Web sites that provide storage space
Also called i-drive or online storage
Not used for storing highly personalized or sensitive information

23. Magnetic Tape External storage Provides sequential access
Information stored in sequence
Slower than disks which provide direct access
Magnetic tape streamers or tape cartridges used by both mainframes and microcomputers
Magnetic disk offer fast, direct access to data programs; sequential access because they have to be fast forwarded or rewound before a specific location can be reached. *A common sequential access method of permanent storage method -- common form of data backup in companies with larger computer systems
*Two forms of tape storage
Magnetic tape streamers
Backup tape cartridge units used with microcomputer systems
Capacities range from 120 MB to 5 GB
Digital audio tape (DAT)

24. A Look to the Future Blu-Ray Technology
New standard in storage
Blu-Ray
New disks use blue laser light instead of the red laser light used in traditional CD players
Disks may ultimately hold
Over 30GB on one-sided disks
Over 50GB on two-sided disks
A new type of storage
May hold over 30GB on one-sided disks and 50GB on two-sided
HDTV broadcasts and streaming audio and video can be recorded on these new disks

25. FAQs
What is the difference between primary storage and secondary storage?
What kinds of floppy disks are available?
What is the C drive of a computer?
When would I use a hard-disk cartridge?
What is the difference between a CD and a DVD?

26. Discussion Questions
Discuss three ways to improve the performance of hard disks.
Describe the different types of compact discs.
Describe the different types of DVDs.
What are the advantages and disadvantages of using an Internet hard drive?
Describe solid state technology. Discuss the many uses for key chain flash memory devices.