This document discusses various types of external storage devices, including hard disk drives, solid state drives, flash memory, optical discs, and future technologies. It provides details on how hard disk drives use spinning disks and magnetic heads to read and write data. Solid state drives have no moving parts and use integrated circuits for memory. USB flash drives are small, removable flash memory devices. Optical discs like CDs and DVDs store data in spiral tracks of tiny bumps burned by a laser onto the disc's surface. Future storage technologies may use helium instead of air in hard drives for higher capacity and kinetic drives that interface over ethernet.

1. External Storage Device

2. INTRODUCTION
A Data Storage Device is a device for recording (Storing)
information(Data).

3. TYPES OF STORAGE
Hard Disk Drive
Solid State Storage
Flash Memory
Magnetic Storage
Optical Storage Device like CD, DVD

4. HARD DISK
A Hard Disk drive is a data storage device used for storing
and retrieving digital information using rapidly rotating disks
(patters_ coated with magnetic material.
An HDD consists of one or more rigid rapidly rotating disks
(platters) with magnetic heads arranged on a moving
actuator arm to read and write data to the surfaces.

5. SOLID STATE DRIVE (SDD)
Data storage drive using integrated circuit assemblies as
memory to storage persistently.
SDD technology uses electronic interfaces compatible with
traditional block input/output hard disk drives, thus
permitting simple replacement in common applications.
SD’s are typically more resistant to physical shock, run
silently, have lower access time and less latency.

6. USB FLASH DRIVE
• A USB flash refers to a type of computer technology that stores
data , does not need constant electricity, and can be electrically
erased and reprogrammed.
• Flash memory is used in many different appliances including
memory card, PDAs.
• Information is stored in an array of memory cells made from
floating-gate(FD) transistors.
• UDB flash drive are typically removable and rewritable and
physically much smaller than an optical disk.

7. COMPACT DISK
Compact Disk(CD) is a circular disk of diameter of 120
millimeters(4.7inch)
A CD can hold up to 80 minutes of uncompressed audio or
703 MB.

8. UNDERSTANDING THE CD
• A CD has a single spiral track of data circling from the
inside of the disc to the outside.
• Spiral track starts at the centre means that the CD can be
smaller than 4.8 inches(12cm) if desired.
• Mini CD diameter only 2.4 inches(6cm) used for delivering
device drivers.

9. UNDERSTANDING THE CD: BUMPS
• A laser of wavelength 780 nm is used to ‘burn’ pits(bumps)
on CD track.
• The elongated bumps that make up the track are each 0.5
microns wide, a minimum of 0.83 microns long and 125
nm high.
• If you could life the data track off a CD and stretch it out
into a straight line, it would be 0.5 microns wide and
almost 3.5 miles(5km) ling!

10. DIGITAL VERSATILE DISC
• A DVD has almost 6 times (up to 4.7 GB) data storage
capacity then a CD.
• The more storage capacity of a DVD is due to less
separation between tracks and less size of track.

11. FUTURE TECHNOLOGY
Storage Devices
Helium Drive Technology
Ethernet Interface Kinetic Drives

12. THANK YOU