kevalpatel2106@gmail.com

1. By:
Keval Patel(07)
Sandip Dobariya(13)

2.  A data recorder device is a device
for recording information.
 Electronic data storage requires electrical
power to store and retrieve that data.
 Electromagnetic data may be stored in either
an analog or digital format on a variety of
media.

3.  Floppy Disk
 CD(Compact Disk)
 DVD(Digital versatile disk)
 Hard Disk
 USB flash drive
 RAM(Random Accsess Memory)
 ROM(Read Only Memory)
 Other recorders

5.  The most common form of external storage device
used in a personal computer is a 3.5” & 5.5’’
FLOPPY DISK.
 A high density floppy disk can hold up to 1.4
megabytes of data.
 But some recent floppy disk can store up to
250MB of data.
 It can be read or write by using floppy drive.

6.  To protect the
magnetised, plastic
disk on which the data
is stored, a floppy disk
has a hard plastic
case.

7.  A sliding metal cover
protects the
magnetised, plastic
disk when it is not in
the floppy disk drive.

8. Floppy Disk

9.  A spindle motor in the drive rotates the
magnetic medium at a certain speed, while
a stepper motor-operated mechanism
moves the magnetic read/write head(s)
along the surface of the disk. Both read and
write operations require the media to be
rotating and the head to contact the disk
media, an action accomplished by a "disk
load" solenoid.

10. Floppy
Disk
Drive

11.  To write data, current is sent through a coil in
the head as the media rotates. The head's
magnetic field aligns the magnetic particles
directly below the head on the media.
 To read data, the magnetic particles in the
media induce a tiny voltage in the head coil as
they pass under it. This small signal is
amplified and sent to the floppy disk controller,
which converts the streams of pulses from the
media into data, checks it for errors, and sends
it to the host computer system.

13. How the
recorded data
looks like?

14. Media type Optical disc
Encoding Various
Capacity Typically up to
700 MB (up to
80 minutes
audio)
Read mechanism 780 nm wavele
ngth (infrared
and red edge)
semiconductor
laser, 1200
Kb/s (1×)
Write mechanism 1200 Kb/s (1×)
Developed by Philips, Sony
Usage Audio and data
storage

15.  The Compact Disc, or CD for short, is an optical
disc used to store digital data.
 Standard CDs have a diameter of 120 millimeters
(4.7 in) and can hold up to 80 minutes of
uncompressed audio or 700 MB (700 × 106 bytes)
of data. The Mini CD has various diameters ranging
from 60 to 80 millimeters (2.4 to 3.1 in); they are
sometimes used for CD singles, storing up to 24
minutes of audio or delivering device drivers.
 A CD is made from 1.2 millimeters (0.047 in)
thick, polycarbonate plastic and weighs 15–
20 grams.

16. CD
CD-ROM CD-R CD-RW

17.  This is the most common type of CD available,
and is the way in which most modern software is
supplied to individual personal computers.
 It is a memory storage device but because it can
not be ‘written to’ it can not be regarded as a
‘backing store’.

18.  These are supplied ‘blank’ and can be ‘written to’
by CD Writer drives.
 They can be used to store large amounts of data,
but once used, they can not be re-used.

19.  These are supplied ‘blank’ and can be ‘written to’
by CD Writer drives.
 They can be used to store large amounts of data,
and can be ‘written to’ many times, just like a hard
disk.

20.  CD data is stored as a series of tiny
indentations known as "pits", encoded in a
spiral track moulded into the top of the
polycarbonate layer. The areas between pits
are known as "lands". Each pit is
approximately 100 nm deep by 500 nm wide,
and varies from 850 nm to 3.5 µm in length.
The distance between the tracks, the pitch, is
1.6 µm

21.  A CD is read by focusing a
780 nm wavelength (near
infrared) semiconductor laser through the
bottom of the polycarbonate layer. The
change in height between pits and lands
results in a difference in the way the light is
reflected. By measuring the intensity change
with a photodiode, the data can be read from
the disc.

22. 1 0

23. Media type Optical disc
Capacity 4.7 GB (single-
sided, single-
layer – common)
8.5–8.7 GB (single-
sided, double-
layer)
9.4 GB (double-
sided, single-layer)
17.08 GB (double-
sided, double-
layer – rare)
Read mechanism 650 nm laser,
10.5 Mbit/s (1×)
Write mechanism 10.5 Mbit/s (1×)
Standard DVD Forum's DVD
Books and
DVD+RW Alliance
specifications

24.  The DVD is now beginning to replace the CD as
the main method of bulk saving data on personal
computers.
 The reason for this is that they are capable of
storing much larger amounts of data.
 A DVD can store 17 gigabytes of data
 This is equal to 26 CD-ROMs or 12,000 floppy
disks!

25.  DVD uses 650 nm wavelength laser
diode light as opposed to 780 nm for CD.
This permits a smaller pit to be etched on the
media surface compared to CDs (0.74 µm for
DVD versus 1.5 µm for CD), allowing in part
for DVD's increased storage capacity.
 In comparison, Blu-ray Disc, the successor to
the DVD format, uses a wavelength of
405 nm, and one dual-layer disc has a 50 GB
storage capacity.

26. Drive speed
Data rate ~Write time (minutes)
Mbit/s MB/s Single-Layer Dual-Layer
1× 11.08 1.39 57 103
2× 22.16 2.77 28 51
2.4× 26.59 3.32 24 43
2.6× 28.81 3.60 22 40
4× 44.32 5.54 14 26
6× 66.48 8.31 9 17
8× 88.64 11.08 7 13
10× 110.80 13.85 6 10
12× 132.96 16.62 5 9
16× 177.28 22.16 4 6
18× 199.44 24.93 3 6
20× 221.60 27.70 3 5
22× 243.76 30.47 3 5
24× 265.92 33.24 2 4

27.  In DVD the data can
be recorded & can
be read same as on
CD.
Path of recording data
On DVD.

28. Data tracks

30. Date invented 24 December
1954
Invented by IBM team led
by Rey Johnson

31.  A hard disk drive (HDD; also hard drive, hard
disk, or disk drive) is a device for storing and
retrieving digital information, primarily
computer data. It consists of one or more
rigid (hence "hard") rapidly rotating discs
coated with magnetic material, and with
magnetic heads arranged to write data to the
surfaces and read it from them.

32.  A typical HDD design
consists of
a spindle that holds flat
circular disks, also
called platters, which
hold the recorded data.
The platters are made
from a non-magnetic
material, usually
aluminum alloy, glass,
or ceramic, and are
coated with a shallow
layer of magnetic
material typically 10–
20 nm in depth, with an
outer layer of carbon for
protection.

33.  The factors that limit the time to access the
data on a hard disk drive (Access time) are
mostly related to the mechanical nature of
the
 Access time can be improved by increasing
rotational speed.
 Defragmentation is also a procedure used to
minimize delay in retrieving data by moving
related items to physically proximate areas
on the disk.

35.  A USB flash drive is a data storage device that
includes flash memory with an
integrated Universal Serial Bus (USB) interface.
USB flash drives are typically removable and
rewritable, and physically much smaller than
a floppy disk. Most weigh less than 30 g.

36.  A flash drive consists of a small printed circuit
board carrying the circuit elements and a USB
connector, insulated electrically and protected
inside a plastic, metal, or rubberized case.
1 USB Standard-A plug
2 USB mass storage controller device
3 Test points
4 Flash memory chip
5 Crystal oscillator
6 LED
7 Write-protect switch (Optional)
8 Space for second flash memory chip

37.  Compared to hard drives, flash drives
use little power, have no fragile moving
parts, and for most capacities are small
and light. These properties make them
suitable for transporting data from
place to place and keeping the data
readily at hand.
 Most personal computers
support USB as of 2012. Flash drives
implement the USB mass storage device
class so that most modern operating
systems can read and write to them
without installing device drivers.

38.  Like all flash memory devices, flash drives
can sustain only a limited number of write
and erase cycles before the drive fails.
 A drawback to the small size of flash drives is
that they are easily misplaced, left behind, or
otherwise lost.
 USB flash drives are more expensive per unit
of storage than large hard drives.

39. 1. Secure storage of data, application and
software files
2. Personal data transport
3. Application carriers
4. Booting operating systems
5. Media storage and marketing
6. Backup

40.  Read-only memory (ROM) is a class
of storage medium used in computers and other
electronic devices. Data stored in ROM cannot be
modified, or can be modified only slowly or with
difficulty, so it is mainly used to
distribute firmware.

41. MROM
PROM
EPROM
EEPROM
FLASH ROM

42.  Mask ROM (MROM) is a type of read-only
memory (ROM) whose contents are
programmed by the integrated
circuit manufacturer (rather than by the user).

43.  A programmable read-only memory (PROM) or field
programmable read-only memory (FPROM) or one-
time programmable non-volatile memory (OTP
NVM) is a form of digital memory where the setting
of each bit is locked by a fuse or antifuse. Such
PROMs are used to store programs permanently.
 A typical PROM comes with all bits reading as "1".
Burning a fuse bit during programming causes the
bit to read as "0". The memory can be programmed
just once after manufacturing by "blowing" the
fuses.

44.  An EPROM (rarely EROM), or erasable
programmable read only memory, is a type of
memory chip that retains its data when its
power supply is switched off. In other words,
it is non-volatile.
 Once programmed, an EPROM can be erased
by exposing it to strong ultraviolet light
source (such as from a mercury-vapor light).

45.  EPROMs are easily recognizable by the
transparent fused quartz window in the top
of the package, through which
the silicon chip is visible, and which permits
exposure to UV light during erasing.
Window

46.  EEPROM stands for Electrically Erasable
Programmable Read-Only Memory.
 EEPROM is user-modifiable read-only memory
(ROM) that can be erased and reprogrammed
(written to) repeatedly through the application of
higher than normal electrical voltage generated
externally or internally in the case of modern
EEPROMs.
 EPROM usually must be removed from the device
for erasing and programming, whereas EEPROMs
can be programmed and erased in-circuit.

47.  Flash memory is a non-volatile computer
storage chip that can be electrically erased
and reprogrammed. It was developed
from EEPROM and must be erased in fairly
large blocks before these can be rewritten
with new data.
 It is mainly use in USB flash drive mainly in
pen drives & sd cards.

48.  Random-access memory (RAM) is a form
of computer data storage. A random-access
device allows stored data to be accessed in
very nearly the same amount of time for any
storage location, so data can be accessed
quickly in any random order.
 One can read and over-write data in RAM.

49. RAM
SRAM DRAM

50.  Static random-access memory (SRAM) is a type
of semiconductor memory that
uses bistable latching circuitry to store each bit.
The term static differentiates it from dynamic RAM
(DRAM) which must be periodically refreshed.

51.  Each bit in an SRAM is stored
on four transistors (M1, M2,
M3, M4).
 Two additional
access transistors serve to
control the access to a
storage cell during read and
write operations.
 Thus a typical SRAM uses
six MOSFETs to store each
memory bit.
 So the size of SRAM is bigger
than DRAM.

52.  Advantages:
1. More faster than
DRAM.
2. Do not require to
refresh the data like
DRAM.
3. Less power
consumes.
 Disadvantages:
1. More costly than
DRAM.
2. Less dance than
DRAM.
3. More complex
structure than DRAM.
• Hence SRAM is generally not used for the computer as a RAM.
• But they are used as cache memory in PC.

53.  Dynamic random-access memory (DRAM) is a
type of random-access memory that stores
each bit of data in a separate capacitor within
an integrated circuit. The capacitor can be
either charged or discharged; these two
states are taken to represent the two values
of a bit, conventionally called 0 and 1.
 Since capacitors leak charge, the information
eventually fades unless the capacitor charge
is refreshed periodically.

55.  Advantages:
1. More cheaper than
SRAM.
2. More dance than
SRAM.
3. Less complex
structure than SRAM.
4. Compact in size
• Hence DRAM is generally used for the computer as a RAM.
Because they are suitable for large data capacity.
• The speed of DRAM is generally 633MHz.
 Disadvantages:
1. Less faster than
SRAM.
2. Require to refresh the
data as the charge on
capacitor leak.
3. More power
consumes.

56.  Magnetic Tape – this is a
cheap method of storing large
amounts of data (typically 26
gigabytes) and is often used
as a ‘backing store’ for large
and mainframe computers.
 Zip drives are similar to floppy
drives and use special (and
rather expensive) floppy disks
that can hold between 100
megabytes and 2 gigabytes of
data.

57. Thank You