The document discusses various types of computer storage and memory. It describes primary storage such as RAM and cache memory that is directly accessible by the CPU. Secondary storage like hard drives and SSDs are non-volatile but not directly accessible. Tertiary storage provides very large scale storage through tape libraries and optical jukeboxes. Other storage types discussed include offline storage, network storage, flash memory, magnetic tape, solid state drives, hard drives, optical discs like CDs and Blu-rays, as well as various memory technologies.

1. MEMORY AND STORAGE
TAPAN KUMAR KHILAR

2. Hierarchy of storage
• Primary storage
• Secondary storage or external memory
• Tertiary storage
• Off-line storage
• Network Storage

3. Primary storage
• often referred to simply as memory, is the only one directly
accessible to the CPU .
• Primary storage devices are internal to the system and are the
fastest of the memory/storage device category.
• It is used to hold/store data and applications temporarily or for a
shorter period of time while the computer is running.
• Processor registers
• Processor cache
• random-access memory
• virtual memory

4. Secondary storage or external
memory
• it is not directly accessible by the CPU.
• it is non-volatile
• hard disk drive, SSD, CD , DVD,Blue Ray,
floppy disks, magnetic tape, paper tape,
punched cards are the example of this.
• It need to be formatted before they can
store data.

5. Secondary storage
 Auxiliary memory, also known as auxiliary storage, secondary
storage, secondarymemory or external memory, is a non-volatile
memory (does not lose stored data when the device is powered
down) that is not directly accessible by the CPU, because it is not
accessed via the input/output channels (it is an external device).
 Secondary storage is necessary because memory, or
primary storage, loses its data when a computer is turned off where
as secondary storage does not. Therefore, it is commonly known
as non-volatile storage.
 In modern personal computers, most secondary and tertiary storage
media are also used for off-line storage. Optical discs and flash
memory devices are most popular, and to much lesser extent
removable hard disk drives. In enterprise uses,magnetic tape is
predominant.

6. Fundamental storage technologies
• Semiconductor (dynamic random access
memory ,ROM,Cache Memory,Registers,Flash
memory)
• Magnetic (Floppy disk , Hard disk drive,
Magnetic tape data storage )
• Optical (CD, DVD,BLURAY)
• Paper (Paper tape, punch card)

7. Tertiary storage
• Provides a third level of storage .
• This is not a popular storage device
• Its main use is for storing data at a very large
scale.
• It require a database to organize the data that
are stored in them, and the computer needs to
go through the database to access those data.
• tape libraries , optical jukeboxes are the
example of this

8. Large tape library

9. Off-line storage
 Its another name is disconnected storage.
It is not directly connected to the computer and is used
as a transfer medium only.
Offline storage devices are remotely located and
accessed as per need only.
This storage devices also needs human intervention to
be read properly by the main computer system.
It serves as a good backup device since it is remotely
located.
It also provides good security for data since you can not
easily access it from a computer.

10. NETWORK STORAGE
• A NAS unit is a computer connected to a network that
provides only file based data storage services to other
devices on the network. Although it may technically be
possible to run other software on a NAS unit, it is not
designed to be a general purpose server. For example, NAS
units usually do not have a keyboard or display, and are
controlled and configured over the network, often using a
browser.

11. Magnetic storage
Magnetic storage or magnetic recording is the
storage of data on a magnetised medium. Magnetic
storage uses different patterns of magnetisation in a
magnetisable material to store data and is a form
Of nonvolatile memory. The information is accessed
using one or more read/write heads.
Example- hard disk , Solid state disk, Floopy disk,
Magnetic tape.

12. BLURAY DISK
What is Blu Ray technology?
• Blu-ray, also known as Blu-ray Disc (BD)
is the name of a next-generation optical disc
format. The format was developed to enable
recording, rewriting and playback of high-
definition television (HDTV). Blu-ray makes
it possible to record over 2 hours of HDTV,
or more than 13 hours of SDTV on a 27GB
disc. There are also plans for higher
capacity discs that are expected to hold up
to 54GB of data.

15. Hard disk
A hard disk drive (often shortened as hard disk, hard drive,
or HDD) is a non-volatile storage device.
A hard disk drive (HDD), hard disk, hard drive or fixed disk
is a data storage device used for storing and retrieving
digital information using one or more rigid ("hard") rapidly
rotating disks (platters) coated with magnetic material.
The platters are paired with magnetic heads arranged on a
moving actuator arm, which read and write data to the
platter surfaces. Data is accessed in a random access
manner, meaning that individual blocks of data can be
stored or retrieved in any order rather than sequentially.
HDDs retain stored data even when powered off.

16. Introduced by IBM in 1956,HDDs became the dominant
secondary storage device for general purpose computers
by the early 1960s. Continuously improved, HDDs have
maintained this position into the modern era of servers and
personal computers. More than 200 companies have
produced HDD units, though most current units are
manufactured by Seagate, Toshiba and Western Digital.
The primary characteristics of an HDD are its capacity and
performance. Capacity is specified in unit prefixes
corresponding to powers of 1000: a 1terabyte (TB) drive
has a capacity of 1,000 gigabytes (GB; where 1 gigabyte =
1 billion bytes).
Capacity – 80 GB,160 GB, 250 GB,320 GB,500 GB, 1 TB

17. The two most common form factors for modern HDDs are
3.5inch, for desktop computers, and 2.5inch, primarily for
laptops. HDDs are connected to systems by standard
interface cables such as SATA (Serial ATA), USB cables.

19. MECHANISM
HDDs record data by magnetizing ferromagnetic material
directionally, to represent either a 0 or a 1 binary digit. They
read the data back by detecting the magnetization of the
material. A typical HDD design consists of a spindle that holds
one or more flat circular disks called platters, onto which the
data is recorded. The platters are made from a non-magnetic
material, usually aluminum alloy or glass, and are coated with
a thin layer of magnetic material, typically 10–20 nm in
thickness with an outer layer of carbon for protection. Older
disks used iron(III) oxide as the magnetic material, but current
disks use a cobalt-based alloy.

20. SOLID STATE DISK
Solid state storage devices store computer data on non-
volatile "flash" memory chips rather than by changing the
surface properties of a magnetic or optical spinning disk.
With no moving parts solid state drives (SSDs) -- are also
very much the future for almost all forms of computer
storage.
As of 2014, most SSDs use NAND based flash memory,
which retains data without power. For applications requiring
fast access, but not necessarily data persistence after
power loss, SSDs may be constructed from random access
memory (RAM). Such devices may employ separate power
sources, such as batteries, to maintain data after power
loss.

22. Product description
1TB 5400RPM 64MB SATA 9,5MMLaptop Thin SSHD 8GB Flash
Product information
Technical Details
Brand Seagate
Series ST1000LM014
Item Height 7.1 Centimeters
Item Width 10 Millimeters
Screen Size 2.5 Inches
Item Weight 90.7 g
Product Dimensions 10.2 x 1 x 7.1 cm
Item model number ST1000LM014
RAM Size 1000 GB
Hard Drive Size 1 TB
Hard Drive Interface Serial ATA
Wattage 2.7 Watts
Hardware Platform PC, Mac OS
Included Components 7mm Laptop Thin SSHD or 9mm
Laptop SSHD, 3-year limited warranty

23. COMPARISION BETWEEN HDD AND SDD

24. Contd…

25. Magnetic tape
Magnetic tape is a medium for magnetic recording,
made of a thin magnetizable coating on a long,
narrow strip of plastic film. It was developed in
Germany, based on magnetic wire recording.
Devices that record and play back audio and video
using magnetic tape are tape recorders and video
tape recorders. A device that stores computer data
on magnetic tape is a tape drive (tape unit,
streamer).

26. Data storage
Magnetic tape was first used to record computer data
in 1951. The recording medium was a thin strip of one
half inch (12.65 mm) wide metal, consisting of nickel
plated bronze (called Vicalloy). Recording density was
128 characters per inch (198 micrometre/character) on
eight tracks.
Modern cartridge formats include LTO(LINEAR TAPE
OPEN), DLT(DIGITAL LINEAR TAPE), and
DAT(DIGITAL AUDIO TAPE).

28. FLASH MEMORY
• The flash memory is a type of chip that is called as the EEPROM.
• BIOS of computer, the memory stick that is found in the digital
cameras , USB pen drives , the memory cards of the mobiles etc
are the example of flash memory.
• The important properties of the flash memory are that it is much fast
and very much easier in use .
• Flash drive can be efficiently used for the purpose of a hard disk.

29. Advantages of flash memory
when used as a hard disk
• Advantage of the flash memory over the hard disk is that
it is compact and much efficient for the data transfer.
• There are no mobile parts in it As in the hard disk there
are the platters and the read write head moves over it.
• There is no such mechanical component in the flash
memory drive. Hence it is a purely electronic device.
• The flash memory is quite expensive as compared to the
hard disk drive, but it is light in weight

30. USB MEMORY STICKS
USB memory sticks (or USB memory keys, USB memory drives, or whatever
you choose to call them!) are basically a combination of a flash memory card
and a flash memory card reader in one handy and tiny package.
As with other storage devices, there are two key factors to consider when
selecting a USB memory stick: capacity and data transfer speed.
It is a function of the type of flash memory chips used to hold the data.
Without going into great technicalities, these chips come in two varieties
called single level cell (SLC) and multi level cell (MLC). Basically, MLC
flash chips store two or more bits of data in each memory cell, whilst SLC
chips store only one. MLC solid state disks are therefore cheaper to
produce than SLC disks at any given capacity, but due to storing more
than one bit of information in each memory cell take longer to write and
read data. If you need a fast USB key, memory card or indeed hard-disk
replacement SSD then you need to pay more to obtain an SLC device.

31. First commercial product
IBM's USB flash drive became available on December 15, 2000, and had a storage
capacity of 8 MB, more than five times the capacity of the then common floppy disks.
In 2000, Lexar introduced a Compact Flash (CF) card with a USB connection, and a
companion card read/writer and USB cable that eliminated the need for a USB hub.
Second generation
By 2013, most USB flash drives had USB 2.0 connectivity, which has 480 Mbit/s as
the transfer rate upper bound; after accounting for the protocol overhead that
translates to a 35 MB/s effective throughput.
Third generation
Like USB 2.0 before it, USB 3.0 dramatically improved data transfer rates compared
to its predecessor. It was announced in late 2008, but consumer devices were not
available until the beginning of 2010. The USB 3.0 interface specifies transfer rates
up to 5 Gbit/s (625 MB/s), compared to USB 2.0's 480 Mbit/s (60 MB/s).

32. Fourth generation
As of March 2015, some manufacturers have announced
USB 3.1 typeC flash drives with read/write speeds of
around 530 MB/s.
Storage capacity
The first USB flash drive appeared on the market in late
2000, providing a storage capacity of 8 MB. Later, the
maximum available storage capacity gradually doubled
(16 MB, 32 MB, etc.) all the way up to reaching capacities
of 512 GB and 1 TB by January 2013. However, as of
May 2014 flash drives with anywhere from 8 to 128 GB
are still frequently sold.

34. USB hub
A USB hub is a device that expands a single Universal Serial Bus (USB)
port into several so that there

35. SD CARDS
solid state storage devices come in two basic forms: flash memory
cards and USB memory sticks.
Flash memory cards were developed as a storage media for digital
cameras and mobile computers. They consist of a small plastic package
with a contact array that slots into a camera or other mobile
computing device, or an appropriate memory card reader.

36. U3
U3 was a joint venture between SanDisk and M-Systems, producing a
proprietary method of launching Windows applications from special USB flash
drives.
Flash drives adhering to the U3 specification are termed
"U3 smart drives".
U3 smart drives come preinstalled with the U3 Launchpad, which looks similar to
the Windows OS start menu and controls program installation.
Applications that comply with U3 specifications are allowed to write files or
registry information to the host computer, but they must remove this information
when the flash drive is ejected.
Customizations and settings are instead stored with the application on the flash
drive.
Microsoft and SanDisk created a successor called StartKey.

37. PROCESSOR REGISTERS
In computer architecture, a processor register is
a small amount of storage available as part of a
Digital processor, such as a central processing
unit (CPU). Such registers are typically
addressed by mechanisms other than main
memory and can be accessed faster.

38. Almost all computers, load store architecture or not,
load data from a larger memory into registers where
it is used for arithmetic, manipulated or tested by
machine instructions. Manipulated data is then often
stored back into main memory, either by the same
instruction or a subsequent one. Modern processors
use either static or dynamic RAM as main memory,
with the latter usually accessed via one or more
cache levels.

39. Processor registers are normally at the top of
the memory hierarchy, and provide the fastest
way to access data.
Registers are normally measured by the
number of bits they can hold, for example, an
"8bit register" or a "32bit register". A processor
often contains several kinds of registers, that
can be classified according to their content or
instructions that operate on them:

40. Cache memory
Cache memory is a small amount of fast memory
∗ Placed between two levels of memory hierarchy
» To bridge the gap in access times
– Between processor and main memory (our focus)
– Between main memory and disk (disk cache)
∗ Expected to behave like a large amount of fast memory

42. TYPES OF CACHE
Separate instruction and data caches
» Initial cache designs used unified caches
» Current trend is to use separate caches (for level 1)

43. Several reasons for preferring separate caches
∗ Locality tends to be stronger
∗ Can use different designs for data and instruction caches
» Instruction caches
– Read only, dominant sequential access
– No need for write policies
– Can use a simple direct mapped cache implementation
» Data caches
– Can use a set-associative cache
– Appropriate write policy can be implemented
∗ Disadvantage
» Rigid boundaries between data and instruction caches