This presentation delves into the intricacies of external memory, shedding light on the concept of memory hierarchy and elucidating how hard disks operate within this framework. Through clear explanations and illustrative examples, the audience will gain a comprehensive understanding of the different levels of memory in computing systems, the role of external memory types like hard disks in data storage, and the underlying mechanisms that drive hard disk functionality. This presentation aims to demystify complex technical concepts and empower attendees with a deeper knowledge of memory management in modern computing environments.
3. Let’s get to
know
01
02 WHAT ARE THE EXTERNAL MEMORY DEVICES?
HOW DOES A MAGNETIC DISK WORKS ?
ADVANTAGES AND DISADVANTAGES?
WHY DO WE NEED EXTERNAL MEMORY?
03 MEMORY HIERARCHY? WITH EXAMPLE
04
4. WHY DO WE NEED EXTERNAL MEMORY?
Processor
Cache Memory Mapping
Main Memory
[ ROM ]
[ RAM ] 4 - 8 GB
4 - 8 MB
CACHE
Words Words
Or (Blocks)
Secondary memory
BIG PICTURE
RAM – volatile and writable
ROM – Non-volatile and non-writable
Virtual Memory Mapping
Main memory – process fast, but costly
Secondary memory – stores huge data but cheaper
and slower
7. MAGNETIC TAPES
• Developed in Germany in 1928.
• Recorded and read using Tape drivers
• Widely used in Mainframe computers.
• Used In Tape Vaulting.
• Storage: 148 GB per sqr inch -> 185
TB per cartige.
SONYCorporation in 2014
Backing up critical data
using magnetic tapes.
Cost-effective
10. • Debuted in 1960
8 inch
5.25inch
3.5 inch
FLOPPY DISKS
• 3 different form factors
11. 3.5 inch
FLOPPY DISKS
• 3 different form factors
Plastic
Housing
: 8 inch, 5.25-inch, 3.5 inch
• Capacity: 1.2 MB to 1.44 MB
Shutter
Polyster
Fabric
Plastic
Housing
Magnetic Disk
Magnetic Disk
12. FLOPPY DISKS
• 3 different form factors : 8 inch, 5.25-inch, 3.5 inch
• Capacity: 1.2 MB to 1.44 MB
• LEgacy: Icon for saving files
INTERESTING FACT…!
Do you know why our computer drive names start with C ……..?
Earlier, we used to have two floppy drives A & B in Computers and that’s why
the Hard Drive partition starts from C.
15. OPTICAL DISK: CD ROM
• It was introduced in 1983.
• Data can be read from and written to the optical disk by a
laser beam.
• They rely on a red or blue laser to record and read data.
• A Non erasable disk that stores digital audio.
• Size: 12 CM
• Records more than 60 minutes uninterrupted audio.
• Contain read only media like music.
• Capacity : 700 MB
16. OPTICAL DISK: CD-R, CD-RW AND DVD
• CD Recordable
• Write Once Read Multiple
• CD-Rewritable
• Writes multiple times
• Erase and write multiples times.
• Digital Versatile Disk
• Provides Video information
• And stores large volume of other digital data
• 8 and 12 cm are used with double sided capacity
• Size: 17gb
• Basic-Read only memory
17. OPTICAL DISK: DVD-R, DVD-RW AND BLUE-RAY DVD
• DVD Recordable
• Write only once
• They can read CD-ROM
and CD-R/RW addition to
reading DVD video and
audio discs.
• 20 times faster than CD
• DVD Rewritable
• Read and multiple write both
CD's and DVD's
• User can erase and rewrite
multiple times
• One sided discs can be used
• High definition
• Stores more data
• 25gb of data per layer
• Dual and triple layers which
hold more data
• Three versions: Read only (BD-
ROM),recordable once(BD-R),
recordable(BD-RE).
20. MEMORY CARD AND FLASH DRIVE
• An electronic storage device used
for storing digital media
• Small size but large data storage
capacity
• Cheaper
• Small, ultra-portable device unline an optical or hard drive has
no moving parts
• USB plug.
• Storage capacity: 8 GB to 64 GB
• Flash drives can be written and rewritten to an almost
unlimited number of times, similar to hard drives.
• They've replaced floppy drives
21. Main Memory
ROM
RAM
4 - 8 GB
4 - 8 MB
Processor
Secondary Memory
Hard Disk
Floppy Disk
Compactable Disk
Digital Versatile Disk
1 TB
1.44 MB
700 MB
4.7 GB
Let’s turn ON our system and play the movie TITANIC..
Switching ON process. . .
• ROM Programs
1. BIOS: Binary Input Output System
2. UEFI: Unified Extensible Firmware Interface
22. Let’s turn ON our system and play the movie TITANIC…
Main Memory
Cache
Bus
ROM
D RAM
Cache Memory
Mapping
External Memory
Hard Disk
Floppy Disk
Compactable Disk
Digital Versatile Disk
S RAM
2 - 4 MB
4 - 8 GB
4 - 8 MB
1 TB
1.44 MB
700 MB
4.7 GB
Processor
23. Main Memory
L2 Cache
Processor
Bus
ROM
D RAM
Cache Memory
Mapping
External Memory
Hard Disk
Floppy Disk
Compactable Disk
Digital Versatile Disk
S RAM
L1 Cache
8 KB
2 - 4 MB
4 - 8 GB
4 - 8 MB
1 TB
1.44 MB
700 MB
4.7 GB
Let’s turn ON our system and play the movie TITANIC….
26. HARD DISK DRIVE
Tracks
Sectors
Sectors size: 512 Bytes
• Recording Density
• Capacity of one disk = No. of Tracks x No. of Sectors per Track x Bytes per Sector
27. HOW TO READ OR WRITE IN A HARD DISK
Read Heads
Write Heads
Heating Coil
Changing the
polarity
• Write Head: Cobalt Chromium Tantalum
Alloy (120nm)
• Change in polarity
• Read Head: Giant Magnetoresistance (GMR)
• Change in resistivity
011011
28. ADVANCEMENTS IN HARD DISK
- Around 2010
• Orientation change from horizontal to vertical
• With that write and Read head also changed their
orientation
• Before 2020 – Classic Magnetic Recording
• 2020 - Shingled Magnetic Recording
Before 2010
After 2010
• Heat Assisted Magnetic Recording (HAMR)
• Not yet commercially available
• Laser is used to heat the region
30. THANK YOU
In 2016, Dutch scientists invented the world’s smallest hard
drive which can store all the books ever written on a hard
drive the size of a postage stamp!
DO YOU KNOW ..?
