1. What is Computer Storage
Refers to computer components and recording
media that retain digital data.
Categories of Computer Storage:
• Primary storage
• Secondary storage
• Tertiary storage or tertiary memory,
• Off-line storage

3. Primary Storage
 Four Main Types of Primary Storage
Processor registers are located inside the processor.
Processor cache is an intermediate stage between ultra-fast
registers and much slower main memory
RAM (Random Access Memory)- a volatile primary storage
and the main memory of a computer that is directly connected to
the cpu.
ROM (Read Only Memory) non-volatile primary
storage containing a small startup program (BIOS) is
used to bootstrap the computer,

4. Processor registers

5. Processor
cache

6. RAM
 SDRAM stands for Synchronous Dynamic
Random Access Memory.
 DDR is short for "DDR SDRAM" and
stands for Double Data Rate.
Nowadays to avoid misunderstandings SDRAM is often specified as SDR
SDRAM and SDR stands for Single Data Rate by analogy with DDR.
Therefore, the main difference between SDR and DDR memory the doubled
speed:

7. SDR SDRAM

8. RAM
DDR1
• DDR1 RAM, also known as simply DDR SDRAM, has 184 pins
that fit into the slot intended for it inside your computer on your
motherboard.
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9. RAM
DDR2
•DDR2 SDRAM has 240 pins, and a notch at the bottom that is in a
different location than the notch on DDR RAM.
9

10. RAM
DDR3
DDR3 SDRAM (Double Data Rate Three Synchronous Dynamic
Random Access Memory) is the third generation of DDR SDRAM
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11. RAM
Difference between SDR, DDR1, DDR2 and DDR3
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12. RAM
Desktop and Laptop DDR RAM

13. ROM
 Read-only memory (ROM): Type of primary storage where certain
critical instructions are safeguarded; the storage is nonvolatile and
retains the instructions when the power to the computer is turned off.
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14. Secondary Storage
What is Secondary Storage?
 Holds data, instructions, and information for future use
 Storage medium is physical material used for storage
 Also called secondary storage

15. Secondary Storage
What is capacity?
 Number of bytes (characters) a storage medium can hold
Kilobyte (KB) 1 thousand
Megabyte (MB) 1 million
Gigabyte (GB) 1 billion
Terabyte (TB) 1 trillion
Petabyte (PB) 1 quadrillion
Exabyte (EB) 1 quintillion

16. Secondary Storage
How does volatility compare?
 Storage medium is nonvolatile—contents retained when power is off
 Memory is volatile—holds data and instructions temporarily
ON OFF
Screen Display Display Display
Volatile
appears disappears
Memory Data and Data and
(most RAM) instructions instructions
(chips on motherboard) available to erased
Nonvolatile
user
Storage Medium Contents Contents
(floppy disks, Zip disks, available to retained
hard disks, CDs) user

17. Secondary Storage
What is a storage device?
Hardware that
Reading records and Writing
Process of transferring retrieves items Process of transferring
items from storage to and from items from memory
media to memory storage media to storage media
Functions as source Creates output
of input

18. Secondary Storage
What is access time?
 Time it takes storage device to locate item on storage medium
 Time required to deliver item from memory to processor
faster Stores
transfer
Primary Storage …
rates
Memory (most RAM) Items waiting to be interpreted
and executed by the processor
Secondary Storage
Hard Disk Operating system, application
software, user data and information
CDs and DVDs Software, backups, movies, music
Miniature Storage Media Digital pictures or small files to
be transported
Tape Backups
slower
transfer Floppy Disk Small files to be transported
rates

19. Floppy Disks
What is a floppy disk?
shutter
 Portable, inexpensive storage
medium (also called diskette)
shell
liner
magnetic
coating
Thin, circular, flexible film enclosed
in 3.5” wide plastic shell
metal hub
flexible thin film

20. Floppy Disks
What is a floppy disk drive?
 Device that reads from and
writes to floppy disk
 One floppy drive, named drive A Floppy disk drive built into
a desktop computer
 If two floppy drives, second
designated as drive B
 Also called secondary storage
External floppy disk drive attaches to
a computer with a cable

21. Zip® Disks
What is a Zip disk?
 Magnetic medium that stores 100 MB or 250 MB of
data
Zip disk
 Used to back up and to transfer files
 Backup is duplicate of file, program, or disk
in case original is lost
c
 Zip disks require a Zip drive — high capacity
c c
drive that reads from and writes on a Zip disk
External
Zip drive

22. Hard Disks hard disk installed
in system unit
What is a hard disk?
 High-capacity storage
 Consists of several inflexible,
circular platters that store items
electronically
 Components enclosed in airtight,
sealed case for protection

23. Hard Disks
What are external hard disks and removable hard disks?
 Used to back up or transfer files
External hard disk—freestanding
hard disk that connects to system unit
Removable hard disk—hard disk
that you insert and remove
from hard disk drive

24. CDs and DVDs
Push the button to
What are CDs and DVDs? slide out the tray.
 Flat, round, portable metal
discs with protective plastic
coating
 Can be read only or read/write
Insert the disc,
label side up.
 Most PCs include CD or DVD
drive, most play audio CDs
Push the same
button
to close the tray.

25. CDs and DVDs
What is a CD-ROM?
 Compact disc read-
only memory
 Cannot erase or
modify contents
 Typically holds
650 MB to 1 GB
 Commonly used
to distribute
multimedia and
complex
software

26. CDs and DVDs
What are CD-Rs and CD-RWs? Must have
CD recorder
or CD-R drive
CD-R (compact disc-readable)
— disc you can write on once
c
Cannot erase
disc’s contents
CD-RW (compact disc-rewritable)
— erasable disc you can write on
ce
multiple times
Must have
CD-RW software
and CD-RW drive

27. CDs and DVDs
What is a DVD-ROM (digital versatile
disc-ROM or digital video disc-ROM)?
 High capacity disc capable of storing 4.7
GB to 17 GB
 Must have DVD-ROM drive or DVD
player to read DVD-ROM
 Stores databases, music, complex software,
and movies
DVD
DVD drive

28. Tape
What is tape?
 Magnetically coated plastic ribbon
capable of storing large amounts
of data at low cost
 Primarily used for backup

29. Miniature Mobile Storage Media
What is miniature mobile storage media?
 Storage for small mobile devices
Miniature
mobile storage
media

30. Miniature Mobile Storage Media
What are common types of miniature mobile storage media?
CompactFlash Smart Media Secure Digital
Memory Stick ® Microdrive ™ USBDrive ™

31. Miniature Mobile Storage Media
What is a card reader?
 Reads information stored on miniature mobile storage media
 Type of card determines type of card reader needed

32. Microfilm and Microfiche
What are microfilm and microfiche?
Store microscopic images of
documents on roll or sheet of film
Images recorded using
computer output microfilm recorder
Microfilm — 100- to Microfiche — small sheet
215-foot roll of film of film, usually 4”  6”

33. Microfilm and Microfiche
How do life expectancies of various media compare?
 Microfilm and microfiche have longest life of any storage media
Media Life Expectancies
Media Type Guaranteed Life Potential Life
Expectancy Expectancy
Magnetic disks 3 to 5 years 20 to 30 years
CDs and DVDs discs 5 to 10 years 50 to 100 years
Microfilm 100 years 500 years

34. Tertiary Storage
A third level of storage. Typically it involves a robotic mechanism
which will mount (insert) and dismount removable mass storage
media into a storage device according to the system's demands.

35. Offline Storage
 is a computer data storage on a medium or
a device that is not under the control of a
processing unit.