This document discusses different types of computer storage. It describes primary storage, which stores data during operations like RAM and ROM, and secondary storage, which stores data permanently like hard disks, flash drives, and optical discs. Hard disks are discussed in detail, including their components, recording techniques, controllers, and different types. Other storage devices covered include solid state drives, memory cards, USB flash drives, cloud storage, optical discs, tape, magnetic stripe cards, smart cards, microfilm, and enterprise storage solutions.

3. Presented by
Muhammad Jawad Zafar (group leader)
Aiza
Ahsan
Laraib
Muqaddas
Saba
Minhal
Tooba
Mahjamal
Rabia

5. Introduction
 Storage holds data instructions and information for future
use.
Types:
 There are two types of storage
 Primary storage
This stores data during computer operations. For example,
 RAM (Static RAM, Dynamic RAM)
 ROM (PROM, EPROM, EEPROM)
 Processor registers (Programme register, Address register,
Accumulative register, Storage register)
 Processor cache

6. Secondary storage
This stores data permanently. For example,
 Hard disc,
 USB Flash,
 Optical Discs,
 Memory Cards.

7. Storage Devices
 These are hardware components used to store data
instructions and information permanently.
 They are non-volatile.
Examples: Hard disc, USB flash, Optical disc, smart
cards, Magnetic strip etc.

8.  Capacity: it is the number of bytes (characters) a
storage medium can hold.
Examples:
 USB flash drive store upto 4GB.
 Hard disc store upto 320GB.
 Writing: it is a process of transferring data
instructions and information from memory to storage
medium.
 Reading: it is a process of transferring items from
storage medium into memory.

9.  Access time: it is the time taken by the storage device
to locate items on storage medium.
 Access time of storage device is low as compared to the
access time of memory
 Speed of storage device is defined by access time.

10. Hard Disc
 Hard disc is a storage devise that contain one or more
inflexible circular platters that use magnetic particles
to store data.
 A system unit contain at least one hard disc.
 Current PC’s have storage capacity of 160GB to 2TB.

11. Characteristics of Hard disc:
 Capacity
 Platter
 Read/write heads
 Cylinders
 Sectors and tracks
 Revolution per minute
 Transfer rate
 Access time

12. Longitudinal recording:
In longitudinal recording magnetic particles are
aligned horizontally around the surface of disc.
Perpendicular recording:
in perpendicular recording magnetic particles are
aligned vertically to the disc surface. Which make
storage capacity.
Storage capacity in perpendicular recording is 10 times
greater than longitudinal recording

13. Working of Hard Disc
 Step 1: The circuit board controls the movement of the
head actuator and a small motor.
 Step 2: A small motor spins the platters while the
computer is running.
 Step 3: when software request a disc access the
read/write heads determinate the current or new
location of data.
 Step 4: The head actuator positions the read/write
head arms over the correct location on the platters to
read or write data.

15. Types:
 Fixed Hard disc: A hard disc that is mounted inside the
system unit.
 Portable Hard disc: A hard disc that can be removed from
one computed and can be placed in other computer.
 External hard disc: It is separate free standing hard disc
that connects with a cable to USB port on system SU. Its
storage capacity is upto 4TB or more.
 Removable Hard disc: It is a hard disc that can be
inserted and removed from a drive. They have storage
capacity upto 1TB or more.

16. Miniature hard disc:
 Devices such as portable media players digital
cameras and smart phones have miniature hard disc
which provide greater storage capacity.
Storage range from 4GB to 250GB

17. Hard disk controller
 It is an electronic circuit that control the transfer of
data instructions and information.
 It controls the interface between the hard disc and
system bus.
 Types:
 SATA
 EIDE
 SCSI
 SAS

18.  SATA (serial advanced technology attachment)
 it uses serial signals to transfer data, instructions and
information.
 It has thinner, longer, more flexible, and less
susceptible cables than parallel signals.
 It can support connection to optical disc driver.
 External disc use “e SATA” intereface.

19.  EIDE (enhanced integrated drive electronics)
 It is hard disc interface.
 It uses parallel signals to transfer data instructions and
information.
 It support upto 137GB.
 It also provide connection for optical disc and tape
drives.

20.  SCSI (small computer system interface)
 It uses parallel signals to transfer data instructions and
information.
 It can support upto 8 or 15 peripheral devises.
 Some computer use an adopter card to add a SCSI
interface.
 SAS (statical analysis system)
 It is newer type of SCSI.
 It uses serial signals to transfer data.

21. Advantages of SAS over parallel SCSI
 It have thinner longer cables
 Reduce interface.
 Less expensive
 Support many devices at once

22. Flash Memory Storage
 It is a type of non-volatile storage.
 Data can be erased electronically and rewritten.
 Types:
 Solid State Drive:
It uses flash memory to store data, intructions and
information.
With available size of 3.5 inches, 2.5 inches and 1.8 inches.
 Advantages of SSD:
 Access time of SSD are about 0.1 ms.
 It is 80 time faster than hard disc.
 SSD generate less heat and consume less power than hard
disc.

23.  Memory Card:
 It is removable flash memory device.
 Usually not bigger than 1.5 inches.
 Types:
Compact Flash
Secure Digital
Micro SD
Memory Stick
Memory Stick Micro

25.  USB Flash Drive:
 It is also called thumb drive.
 It can be plug into the USB port of the computer.
 Storage capacity ranges from 512MB to 64GB
 Express Card Module:
 It is removable device.
 About 75mm long and 34mm wide or L shaped with
width of 54mm that fits in express card slot.
 It is commonly used in notebook computers

27. Cloud Storage
 Cloud storage is an internet service that provides hard
disc storage to the computer users.
 Fee arrangements vary
 For example: One cloud storage service provides 25 GB
of storage free to registered users.
 For enterprises, cloud storage charges 15 cents per GB.

29.  Variety of Reasons:
 To access files on internet
 To allow others to access their files on internet.
 To view time-critical data and images. For example
doctor can view x-ray images from an other hospital.
 To store offsite backups of data.

30. Optical Disc:
 Optical disc is a type of optical storage media that
consist of flat, round, portable disc made of metal,
plastic and lacqouer.
 Size ranges from4.75 inches in diameter and less than
1/20th of an inch thick.
 Optical disc store software, data, digital
photos, movies and music.

31.  Types of ODD:
CD Drive:
It is a device used by computer to read and write data
from or to a CD.
Types of CD Drive:
1. CD-ROM: Read data from CD
2. CD-R Drive: Read data from CD and can also write to
CD
3. CD-RW Drive: Read, write and rewrite

32.  DVD drive:
 Sands for digital versatile/video disc.
 It is used to store music, videos, games and multimedia.
 It is similar to CD in appearance.
 Its storage capacity is 7 times greater than CD.
 Blue-Ray drive:
 It is the name of next generation optical disc format.
 It enable us to record upto 25 GB.
 It is 6 times the capacity of DVD.
 Single layer BD can store upto 25 GB data and double can
store upto 50 GB data.

33.  Types:
BD ROM: (Read Only)
 For pre-recorded contents.
BD-R: (Recordable)
 For PC data storage.
BD-RW: (Re-writable)
 For PC data storage.
 BD-RE: (Re-writable)
 For HDTV recording.

34. Tape
 One of the first storage media used with main frame
computer
 Tape:
 It is magnetically coated with ribbon of plastic capable of
storing large amount of data.
 Tape drive:
 Tape drive read and write data and information on tape.
 Tape cartridge:
 It is a small rectangular plastic housing of tape.
 Tape Library:
 On larger computers tape cartridge are mounted in
separate cabinet called tape library.

35. Magnetic strip cards and smart
cards
Magnetic Stripe Card:
It is a credit card, bank card, entertainment card or other
similar cards. With a strip that contain information
identifying you and the card.
Information stored in the strip include your name, account
number and expiration date.
 Smart Cards:
It is smaller in size to the credit card or ATM card.
It stores data on thin microprocessor embedded in the card
Smart card can double as an ID card.

36.  Uses of Smart Card :
 Storing medical record
 Vaccination data
 Tracking information
 Storing Prepaid amount of money
 Authenticating users.

37. Microfilm and Microfiche
 They both can store microscopic images of documents
on roll or sheet films
 Microfilm is 100 to 215 foot roll of film.
 Microfiche is small sheet of film about 4×6 inches.
 Uses:
 Use in library
 Large organizations
 Banks
 US Army for personal records.

38. Advantages:
 They reduce the amount of paper.
 They have longest life of any storage media

39. Enterprise Storage
 A large business refer as enterprise has thousands of
employs working all over the world.
 They use computer network to manage their data
(includes huge volume of information about employs,
customers and suppliers)
 They use hardware components for storage.
 one or more server has only work of providing storage
to connected users.
 Some systems have storage capacity of 185 TB