Session B12
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FLASH MEMORY AS THE FUTURE FOR DATA STORAGE
Mason Kline, [email protected], Mena 1:00PM, Davis Kuhn, [email protected], Mena 1:00PM
long series of FGTs reading either “1” or “0,” thus providing
means of data storage. From the space station to the
smartphone, many mainstays of the modern world have been
invented or improved upon due to the inclusion of flash
memory. Flash memory’s lack of moving parts allows it to be
packed very tightly, which modern devices utilize to increase
performance. Through the implementation of NAND memory
cells containing FGTs, computing speeds have reached the
fastest they have ever been.
Abstract—In the last decade, flash memory and its
underlying NAND storage method (named after being the
opposite of an “and” logic gate) have made and continue to
make huge strides in data storage solutions with their
lightning fast speeds.
Flash memory can drastically improve computing
speeds, allowing a computer to run up to one hundred times
faster than the current standard, mechanical memory. These
blazing speeds are only achievable since flash memory has
no moving parts. They are composed of Floating Gate
Transistors, organized into arrays of memory cells. When an
electron is shot into a memory cell, it is read as either “1” or
“0,” which is translated into data storage.
However, flash memory has its place, just as
mechanical memory does. In mass storage systems, the cost
of the devices has a much higher priority than the access
speed of the data, which is when mechanical memory
prevails. In personal computing systems, the faster reading
and writing speeds of flash memory is crucial because
different applications are always being prompted, requiring
data to be accessed. From a quality of life perspective, flash
memory improves the sustainability of computing as a whole.
When it takes less time to read and write files to a storage
unit, the user can be more productive in a work environment.
Additionally, the longer life and improved reliability of flash
memory-based devices is environmentally conscious since it
preserves the resources dedicated to building these devices.
However, flash memory is not the standard for data storage
currently, but as they become more available in consumer
markets, the price will reach the point where it can be.
HOW IT ALL STARTED
As with most technologies, data storage did not start out
on at cutting edge speed and capacity it has today. The first
data storage solutions were massive enough to fill entire
rooms. They also only contained the storage capacity that,
today, would be filled by a few text files. However, as time
has progressed, so have data storage solutions. In modern
day, impressive amounts of data can be stored in handheld
devices with speeds that blow away technological
predecessors.
Magnetic Memory
The first steps in data storage were in the form of
magnetic memory, which gets its name from utilizing
magnets and mechanical parts to access the data. The earliest
viable data storage device was the magnetic tape drive.
According to the Computer History Museum, one of the
earliest forms of the magnetic tape drive was the “Univac
Uniservo tape drive,” introduced in 1951, which worked by
reading thick bands of rotating magnetic tape. Each Univac
tape weighed nearly three pounds and had a storage capacity
of 1,440,000 single digit numbers, which translates to a bit
larger than a single kilobyte [1]. To put this in perspective, a
single Microsoft Word document takes up 22 kilobytes of
memory today. Although it is a small amount of data to store,
the magnetic tape drive was revolutionary since it was the
first way to effectively store data.
The second major step in data storage solutions was the
floppy disk drive. According to the Computer History
Museum, the first floppy drive available for consumers was
the IBM “Minnow” floppy disk drive in 1968. It was a readonly drive with a capacity of 80 kilobytes [1]. At this point,
Key Words—Data storage, Flash memory, Floating gate
transistor, Hard Disk Drive, NAND, Solid State Drive.
THE BIG THING IN COMPUTING
Computers have been revolutionizing the way society
functions ever since they were first invented. The latest and
greatest improvement to computing speeds over the past
decade has been flash memory Specifically, floating gate
transistors (FGT) used inside of NAND (named after being
the opposite of an “and” logic gate) memory cells have
optimized the efficiency of computing speeds. Our focus will
be on NAND-based flash memory, which is comprised of
University of Pittsburgh Swanson School of Engineering
Submission Date 03.31.2017
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Mason Kline
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data storage solutions becoming sensible to store reasonable
amounts of information.
The third revolutionary step in data storage is a
precursor to a product that is still in use today. According to
the Computer History Museum, the first Hard Disk Drive
(HDD) was invented in 1980: “The disk held 5 megabytes of
data, five times as much as a standard floppy disk” [1]. Even
though this specific HDD was only able to hold five
megabytes, it is the predecessor of HDDs that are still used
today in computing systems.
The Compact Disk (CD) is the next major step in data
storage. According to the Computer History Museum, the CD
was developed in 1983 with the purpose of music
distribution. Later, in 1984, the CD-ROM was released,
improving on the CD. A single CD-ROM could store an
entire encyclopedia with over half of its storage space to
spare [1]. At this point, data storage is easily compatible with
computers to both read and write information.
There have been countless innovations to magnetic
memory since the CD-ROM. However, magnetic memory
has been approaching a point where it can no longer increase
computing speeds. Since it involves the use of moving parts,
a magnetic memory drive is only as fast as its slowest moving
component, which is where flash memory comes into play.
are considerably faster than HDD. To understand how flash
memory improves reading and writing speeds, it is important
to understand how the components that make it work.
THE FLOATING GATE TRANSISTOR
FIGURE 2 [2]
A visual representation of a normal transistor.
Early Flash
Flash memory is, in a broad sense, the most recent and
major improvement to data storage. The main idea behind
flash memory is that it has no moving parts, which allows for
considerably faster reading and writing speeds than magnetic
memory. Flash memory is a recent innovation, but it has
already gained the popularity to compete against the triedand-true HDD.
One of the first flash memory based innovations was the
SD (Secure Digital) card. According to the Computer History
Museum, the SD card was first introduced in 1994 with a tiny
size and a capacity of 64 megabytes [1]. This allowed the
cards to quickly become popular with cameras. Their small
size and reliable construction fit perfect inside of cameras,
giving them a greatly improved capacity to store photos and
videos.
A second major innovation that directly resulted from
flash memory is the USB flash drive. According to the
Computer History Museum, after being introduced to the
consumer market in 2000, they quickly became the preferred
method of transferring files between computers [1]. Since
they are not prone to scratching (like a CD) or corruption
from magnets (like a floppy disk), USB flash drives are a
very reliable method of storing information both in short and
long term settings.
The aforementioned flash memory based innovations
are both beneficial in various aspects of computing, but none
is as all-encompassing as the Solid State Drive (SSD). These
are the flash memory based counterpart to the HDD. Since
there are no moving parts in an SSD, the computing speeds
FIGURE [3]
A visual representation of a Floating Gate Transistor
The Technology
The Floating Gate Transistor (FGT) is the most basic
and integral part of modern flash memory. Without the
development of the FGT, neither NAND nor NOR flash
memory would exist. The NAND and NOR memory types
are named after the types of logic gates that they resemble,
NAND resembles a “Not AND” gate and NOR resembles a
“Not OR” gate. The FGT bears several differences from a
normal transistor; while a normal transistor is designed to
modulate an electric signal that passes through it by using
current passed through its source to increase the current that
flows through its emitter, the FGT is designed to both
modulate an electric signal like a transistor and contains the
eponymous floating gate. This floating gate is added by
taking a transistor’s original gate and completely insulating it
from the rest of the transistor with a dielectric material. After
the original gate is insulated, a second gate is added on top.
This new addition is not insulated and will function normally,
allowing the FGT to operate as a normal transistor, but now
with the added ability to store a charge within its floating
gate. By storing charge in the floating gate, the FGT can be
used as a storage system for binary code by having a device
read the voltage of what is stored within the floating gate.
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Then, having that device turn that reading into either a “0” or
“1.”
To store these electrons, the floating gate must be
constructed of a dielectric material that can both have a
voltage read from it and insulate the stored electrons from
any interference by which the FGT might be affected. This
interference can come from a variety of sources, including
external magnetic, electric fields, or other FGTs located
within the same device. Since the dielectric material needs to
be able to contain electrons effectively, this interference has
the consequence of making it very difficult to insert an
electron into the floating gate in the first place. There are two
methods by which the electron transfer is done.
The older, less used method of electron transfer is called
Hot Carrier Injection. It creates what are called hot electrons
that have a kinetic energy large enough to penetrate the
dielectric material shielding the floating gate. According to
the data collected by E. Takeda and N. Suzuki, of the Central
Research Laboratory in Tokyo, Japan, this method has
several drawbacks that have led to its discontinuation for
general use. First, this method can insert electrons, but is not
able to extract them from the floating gate. This means that
memory developed with the Hot Carrier Injection method is
only able to be programmed once [4]. Essentially, for later
uses of the device, it must be completely reset for the floating
gate to be reprogrammed. According to Dr. Thomas Shwarz,
professor of computer engineering at Santa Clara University,
this is done by shining UV light onto the chipset to energize
the electrons to the point where they exit the floating gate [5].
Second, the Hot Carrier Injection method causes the
dielectric material to experience a lot more wear, given the
fact that, to be programmed, an electron is essentially
smashed into the dielectric shell and forced inside [4]. The
more prevalent of the two methods in use is called FowlerNordheim tunneling [6]. Fowler-Nordheim tunneling is
performed by creating an extremely large potential difference
between the inside and outside of the dielectric shell, which
enables an electron to gather enough energy to pass through
what is normally a solid barrier. The same process in reverse
is used to extract the electrons from the floating gate.
FIGURE 3 [7]
A visual representation of the bit combinations that can
be stored in SLC, MLC, TLC, and QLC
In Microsoft Certified Systems Engineer, Scott Lowe’s
article, it is shown that making use of this property also has a
significant drawback. By adding more electrons, the read and
write speeds of the device that is reading memory will suffer
due to the increased difficulty of trying to fit the voltage
represented in the floating gate to a specific binary sequence
[8].
With the FGT’s ability to store a charge efficiently and
with little loss for large amounts of time, it was quickly
utilized by technology developers in non-volatile memory.
There were two main types of memory that were developed
using the properties of the FGT, Electrically Erasable
Programmable Read-Only Memory (EEPROM) and Erasable
Programmable Read-Only Memory (EPROM). These two
types of memory are different mostly in the fact that they
make use of differing methods of electron transfer. EEPROM
makes use of Fowler-Nordheim Tunneling, while EPROM
makes use of Hot Carrier Injection. In addition, EPROM
must be completely reset to be re-written, since Hot Carrier
Injection does not provide a way to extract electrons. These
two types of memory are outdated, as flash memory has
largely supplanted both due to its faster reading/writing
speeds and more efficient handling of the data.
INCORPORATING THE TECHNOLOGY
Later Developments
According to researchers at the Fraunhofer Institute of
Integrated Systems and Device Technology, flash memory is
the newest and most innovative implementation of the FGT
[9]. Flash memory is in use in millions of devices around the
world, and comes in two distinct versions: NOR and NAND.
NOR flash gets its name from the observation that the FGTs
are arranged so that they act similarly to, and resemble, the
NOR logic gate, which takes two inputs and creates one
output. NOR memory is very akin to the older EPROM
memory as both use Hot Carrier Injection to program their
floating gates. Although NOR flash memory does not need to
be completely erased to be reprogrammed, the FGTs
contained within the flash must be erased in large, connected
blocks. NAND flash is the other form of flash memory, and is
The originally developed FGT is referred to as a Single
Level Cell (SLC). In a SLC, only one electron can be stored.
Using singular electrons was found to be very inefficient
when designing memory cells based off the FGTs. As a
result, researchers and engineers developed what are called
Multi Level Cells (MLC), Triple Level Cells (TLC), and
Quadruple Level Cells (QLC), which can all be utilized to
store either two, three, or four electrons respectively. By
enabling the FGT to store more than one electron at a time,
the amount of binary code that can be represented by a single
cell is raised to another power of two for each added electron
(as shown in figure 3).
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the type of flash memory used in most modern technology.
NAND is formed from FGTs that are in the form of the
NAND logic gate, meaning that the FGTs are connected in
series instead of connected in parallel blocks like in NOR.
This allows for more exact operations to be performed on
each FGT, including reading, writing, and erasing the data
stored inside of the floating gate. NAND utilizes FowlerNordheim tunneling for both writing and erasing data,
meaning that each floating gate can be accessed individually
[9].
stacking allows for NAND cells to be laid on top of one
another without having to reconnect an entirely new bit line.
This is accomplished using charge trap flash, which works
similarly to a FGT. The one exception between the two is that
the charge trap is constructed mostly of an insulator
surrounded by an oxide, whereas the floating gate is
constructed of a conductor surrounded by oxide. According
to a paper by Woo Young Choi, Hyug Su Kwon, Yong Jun
Kim and various other members of the faculty at Sogang
University, this change of material is said to give the charge
trap extra insurance against defects, since any defect and
electron leaking will only affect that specific cell since there
is an insulator present. This extra insurance is taken
advantage of when stacking the NAND because it is an
imprecise process, and often leads to more defects and
problems than the regular horizontal NAND [11].
WORKING OUT THE KINKS
Data Seepage
As previously mentioned the floating gate of a FGT is a
conducting shell designed to encapsulate electrons and store
them as binary. To accommodate the Fowler-Nordheim
tunneling used to insert and extract electrons, the dielectric
material utilized for the floating gate is only a few
nanometers thick. Using this method of storing electrons in
NAND memory causes the floating gate’s dielectric material
to deteriorate slightly every time an electron is inserted or
extracted from the gate. Over time this small amount of
deterioration adds up, and eventually the floating gate is no
longer able to completely insulate its contained electrons
from outside interference. At even more advanced stages of
deterioration, the electrons held by the floating gate can leak
out completely, changing the data that is being stored inside
of the floating gate [12].
This deterioration and the resulting problems that stem
from it cause obvious issues with the longevity of any data
storage devices using the FGT. To increase performance,
many different dielectric materials have been investigated.
This research has become especially important with the
creation of Multi, Triple, and Quad level cells, which store
more than just one electron per floating gate. However, as a
result, the floating gates in these cells endure much more
wear and tear. To mitigate this problem, several
advancements have been made and there are quite a few
materials that have been proposed to work better than the
oxides that are commonly used now.
In his paper, “Dielectric Scaling Challenges and
Approaches in Floating Gate Non-Volatile Memories,”
Stephen Keeney introduces one such material that has been
proposed to replace the oxides, which is called a nanocrystal.
These nanocrystals would be used to store electrons in much
the same way that the crystals are used to store electrons in
quantum entanglement experiments [12]. Theoretically, if
done this way, there will be no deterioration of the crystals.
FIGURE 4 [10]
A diagram of NAND (on the right) and NOR (on the left)
flash memory.
NAND is much more prevalent in industry due to
its lower cost per memory unit and higher endurance with
respect to read and write cycles. The product in which NAND
memory is most heavily utilized is the Solid State Drive,
which is a form of secondary memory for computers and data
storage facilities. In NAND memory, the FGTs are placed
into a long series, all connected with the same bit line. This
allows the bit line to be pulled above or below the write
voltage and for each specific transistor as opposed to NOR
which has parallel blocks that only allow the bit line to be
pulled for each block of FGTs. This allows for increased
memory density compared to NOR flash, which has each of
its FGTs individually connected, thus taking up more space
[7].
VNAND is a relatively new development in flash
memory that has caused memory density and total storage
capacity to skyrocket. VNAND stands for Vertical NAND,
and not surprisingly, it has added a third dimension to the
previous two dimensional NAND memory. This memory
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However, in practice there is some slight damage, but it is
miniscule compared to the damage done by the presently
used Fowler-Nordheim tunneling. There are some large
drawbacks to the use of metallic nanocrystals though, the
biggest of which is the concern for metal contamination, this
is where semiconducting materials, such as those used in all
small chip and data storage drives, become affected by a
different material. An example of this would be the
intermixing of the nanocrystal material properties and the
properties of a new material, which would result as different
from the original. This causes a divergence from what the
expected performance is, and in extreme cases, it can cause
serious malfunctions in chips.
Since these FGT are being used to store data, it is not in
anyone’s best interest to have the chips working differently
than the way in which they were designed. If the chip works
in a way contrary to its design data stored on the memory
could be unintentionally corrupted. In addition, some studies
have called into question the effectiveness of metallic
nanocrystals as an insulator. If the nanocrystal cannot
properly insulate its stored electrons, there is no guarantee
that the data stored will remain uncorrupted from outside
sources.
The more important problem with metallic
nanocrystals, however, is that they are much more expensive
to produce and implement than the currently used oxides
[12].
expending the effort to sanitize a device would be satisfied
with this level of performance” [13].
The second option of wiping the memory from an entire
SSD is to “degauss” it. In this method, the drive and the
memory it contains are both destroyed. This process would be
effective if the user is trying to get rid of a drive they have
without having to worry about someone accessing the
memory it contained. Degaussing is performed by blasting
the drive with alternating magnetic fields of 8,000 and 20,000
gauss. However, when the researchers performed this on a
sample SSD, they found that the “data remained intact” [13].
However, it is quite rare that a user will need to erase all
the data stored on a SSD more than once in its lifetime. The
more common practice is to delete specific files to free-up
memory or get rid of sensitive information. In both cases
(especially the latter), it is very important that the desired
data be erased effectively.
When the researchers tested various methods to “scrub”
data files, they got back positive results. While some of the
methods to delete files were more time-effective than others,
they all could erase memory fairly quickly. They concluded
that, “the time to scrub 1 GB varies, but in all cases the
operation takes less than 30 seconds” [13]. Their results are
promising because it shows that although not all methods of
deleting single files worked, most of them were fast and
efficient.
From the University of California researchers’ findings,
it is apparent that SSD still need some improvement to catch
up to the HDD in terms of reliably erasing data. However, it
is promising that “commands are effective when
implemented correctly [13]. Not every method the
researchers tested worked, but with careful implementation
and development, improvements to the SSD’s data erasing
techniques will be able to securely delete the most sensitive
information.
Reliably Erasing Data
Although speed and reliability are important factors to
consider in analyzing a new technology, they take a back seat
when the security of the user is in question. For the HDD,
there are tried-and-true methods that have been developed to
overwrite single files and entire drives as well. When SSD
were making their first appearance in the consumer market in,
the University of California in San Diego took on the
question of whether the methods that work with the HDD
could be applied to reliably erase data from an SSD. They
published an essay that empirically investigates the
effectiveness of various methods of erasing data, which they
entitled, “Reliably Erasing Data from Flash-Based Solid State
Drives.” To summarize their findings briefly, they
determined that there is a greater risk to personal security
with the currently known methods to erase data on an SSD
[13].
In their investigation, the researchers began with
investigating techniques to wipe the memory from an entire
SSD, which fall under two categories: keeping the drive
usable and destroying it [13]. Most of the time, a user will
want to “overwrite” the data from their SSD and then
continue to use it. To accomplish this, the researchers tested
the drive’s on-board commands. After testing, they found that
“while overwriting appears to be effective in some cases
across a wide range of drives, it is clearly not universally
reliable. It seems unlikely that an individual or organization
A NEW TAKE ON OLD STORAGE
METHODS
Although NAND flash memory provides an insight into
more efficient computing solutions, it is not the answer to all
our problems just yet. The existing technology in the HDD is
still more effective in some areas of data storage. The main
comparison between the two data storage methods are cost
and computing power. The HDD is more cost effective, while
the SSD has greater computing power.
Benefits of HDD over SSD
In the area of mass data storage, the old technology is
still more desirable. For the most part, data access speeds are
not crucial when it comes to storing large amounts of
information, since the data is not being access very often.
Also, cost is a very important factor since it is going to take
many high-capacity units to store the necessary information.
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The most striking feature that separates the HDD from
the SSD is the price. On average, an SSD is four times more
expensive than a HDD [14]. Another distinct advantage of the
HDD is its ability to effortlessly overwrite information.
Unlike SSD, where the data needs to be erased before new
data can be input, the HDD is able to directly overwrite
information [15]. However, beyond these two benefits, the
HDD does not have any further distinct advantages. The
HDD is a technology that is readily available and costeffective, which is the main reason why it is still being used
for mass storage today. If large quantities of HDD need to be
purchased, the better price is almost always more alluring
than the increased speed and computing power of the SSD.
also require less power to function. In a study performed by
Tom’s Hardware in 2013, they explored the total bits of
information that could be read/written to a HDD using one
Watt of power. After analyzing dozens of HDD, they
concluded that the most efficient performed at 49.40 inputs
and outputs per Watt [16]. In a similar study also performed
by Tom’s Hardware in 2014, they studied the inputs and
outputs per Watt of dozens of SSDs. Once the tests were
complete, they found that the most efficient SSD performed
at 25,453.43 inputs and outputs per Watt [17]. Not only is the
SSD less power-hungry than the HHD, it is 515 times less
power-hungry. This substantial difference in energy
requirement alone makes a considerable difference in the
sustainability of SSDs.
Overall, while HDD have their applications, mainly in
mass storage, SSD have benefits that make them desirable for
most computing applications. The biggest roadblock from
utilizing SSD in all aspects of data storage is its higher cost.
The benefits are alluring, but for systems that are already
utilizing HDD in their operation, it might not be worth the
time and money to switch to the newer technology. When it
comes to new devices, however, SSD are necessary because
they improve computing speeds while also decreasing energy
usage.
Benefits of SSD over HDD
For most current high-tech devices, an HDD will no
longer cut it. Stemming from its lack of moving parts, the
SSD has improved speed and computing power over the
HDD, which makes it a necessity in everything from
cameras, to smartphones, to computers.
Arguably, the largest improvement that comes with the
SSD is its improved computing speeds. According to
computer engineers from Ajou University in Korea, an SLC
based drive can read data at 100 MB per second, a MLC
based drive clocks in at 220 MB per second, and the HDD
can read at 76.5 MB per second [15]. These numbers may
seem like a bit of a complicated comparison to make, but it is
important to note that the SSD is able to immediately access
files without having to move a mechanical arm to find the
correct location of the file. To access a single file, the SSD
can gain an 8.9 second advantage [15]. When it comes to
computing speeds, where multiple files are being accessed in
rapid fashion, the lack of time to seek the file gives the SSD a
huge speed advantage.
Another benefit of the SSD that is brought about by its
lack of moving parts is it improved reliability. From the same
article, the engineers analyze the Mean Time Between Failure
(MTBF) for SLC based, MLC based, and HDD memory
devices. The SLC and MLC based drives had MTBF of
2,000,000 and 1,000,000 hours, respectively, while the HDD
measured at 600,000 hours [15]. For personal computers and
devices, this statistic would not matter, since the existing
technology would be obsolete by the time the drive would hit
500,000 hours (about 57 years). However, this would have a
bigger impact in the application of mass storage. Since the
MTBF measures the mean between failures, it means there
will be failures that happen earlier in the time span while
others will happen later. When the MTBF really comes into
play is with data storage facilities that house thousands of
drives each, with each of those drives being susceptible to a
similar MTBF. A longer time between failures will allow the
mass data storage to minimize corrupted data files.
The final benefit of SSD is its improved sustainability in
the area of environmental friendliness. Not only do they
require less material to produce due to their smaller size, they
FLASH MEMORY BEYOND THE SSD
At this point, it is apparent that NAND based flash
memory has brought about great changes for personal and
industrial computing systems, but its effects are more farreaching than just that. The average person will most likely
interact with a device that uses flash memory several times a
day. There are all sorts of applications for flash memory in
consumer technology, but some of the most influential are the
smartphone, camera, and flash drive.
Smartphones
One of the most far-reaching modern devices that is
brought about by the invention of NAND flash memory is the
smartphone. Since these devices take up such a small space
and are constantly requiring memory to be accessed from
various locations, flash memory revolutionizes the size and
potency of technology inside of phones. According to a paper
presented at the Design Automation Conference in 2015,
smartphone applications are “switched much more frequently
than those in desktops or servers” [18]. Before flash memory
was created, it would not be possible to access these different
data locations in a timely manner. According to the same
paper, “while an application is accessing hot data in one
moment, another application might be launched in the next
moment access other data” [18]. If the smartphone were
developed using a mechanical hard drive for data storage, the
length of time for the drive’s arm to find the location of the
data would be unbearably slow. Since there are a lot of
people who use smartphones on a daily basis, it would not be
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a stretch to say that flash memory has improved many
people's’ lives.
with an 8 gigabyte SD card can hold 2288 pictures that are 8
megapixels each [20]. Along with the increased capacity,
digital cameras allow the user to transfer the taken pictures to
a computer before having them printed, which cuts down on
the required ink and paper to produce copies of photographs.
Along with the environmental friendliness associated with
less pictures being printed, it also saves the consumer money
since they do not need to print unwanted pictures.
Comparing flash memory-based cameras to non-flash
memory-based cameras, the benefits of flash memory are not
hard to spot. Improved photo capacity, sustainability, and
convenience of the digital camera all contribute to the
popularity of the digital camera.
Cameras
Obviously, cameras have existed for a much longer
length of time than flash memory, but it was not until the
invention of NAND-based flash memory that the digital
camera could be invented. With the old form of cameras, the
picture was either immediately printed out (an example
would be Polaroid cameras) or the picture was printed onto a
roll of film. With digital cameras, the pictures are stored on
an SD card, allowing the photographer to hold considerably
more pictures.
The chain of development for the digital camera goes as
follows: flash memory allowed for the creation of the SD
card, which allowed for the creation of the digital camera.
According to an article in the IEEE Consumer Electronics
Magazine, the SD card is made from a flash memory chip, a
controller, and an interface card. The flash memory chip acts
as the data storage portion of the device. The controller works
to control the flow of data in and out of the SD card as well
as help correct errors that come up. Finally, the interface card
is the portion that connects the SD card to the host machine,
allowing data to be exchanged freely [19]. A visual
representation of this process is shown in Figure 4.
Flash Drives
Another simple, yet effective innovation brought about
by the creation of flash memory is the flash drive (USB
stick). The main idea is this: flash drives work like small
SSDs. According to the same article in the IEEE Consumer
Electronics Magazine, flash drives are usually created from
3-bit memory cells, which “increase the storage capacity but
reduce the number of times the device can be written before
the cells wear out and no longer store new information” [19].
The fact that flash drives are built to maximize data storage
and minimize cost makes sense, since they are widely
available to consumers. The technology contained in the
small plastic drives is not revolutionary, but it considerably
improved the portability of consumer-level data transfer.
THE FUTURE OF FLASH MEMORY
From its greater reading and writing speeds and its
improved reliability over mechanical memory, flash memory
is where the future of data storage is headed. From a
sustainability
standpoint,
flash
memory
improves
productiveness and quality of life. The improved design over
the mechanical memory allows users in working and
recreational environments to spend less time waiting for files
to be accessed and edited. The improved design begins from
the smallest unit: the FGT. Based on the number of electrons
that are stored in the transistor, the flash memory device can
read either a “1” for occupied or a “0” for empty. The
transistors are then arranged into chains, which are translated
into longer lines of binary. This arrangement of FGTs is
considered NAND based flash memory, which is used in
SSD. Comparing the old standard for data storage, the HDD,
to the SDD, there are both benefits and downfalls. The main
disadvantage of the SSD is its greater price, which makes it a
less desirable choice for mass storage solutions. However, the
advantages of SSD include greater reading and writing
speeds, greater reliability, and lesser computing errors. All in
all, the benefits of flash memory far outweigh its downfalls.
When it comes to data storage in both personal and industrial
settings, NAND based flash memory is the future.
FIGURE 4 [19]
A dissection of an SD card with labels.
Another benefit associated with the usage of flash
memory in cameras is the reduction of waste produced, which
improves their overall sustainability. Older cameras came in
two variations: disposable and photographic film-based. The
disposable cameras could take a finite number of photos
before needing to go to the store to develop the pictures
taken. However, once the photos were developed, the entire
camera was thrown away. The second option was
photographic film-based cameras, which were loaded with
film canisters as their method to store photos. The film
canisters were small cylindrical units stored a finite number
of photos before needing replaced and the film developed. In
contrast, according to SanDisk’s website, a digital camera
7
Mason Kline
Davis Kuhn
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ADDITIONAL SOURCES
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ACKNOWLEDGEMENTS
We would like to thank Alyssa Srock, the co-chair for
our conference session, for her assistance in directing our
ideas and explaining the requirements of the conference paper
more clearly. Next, we would like to thank Professor Prymus
for her helpful comments and suggestions on improvements
we could make for the paper through each step of the process.
Then, we would like to thank our conference chair, Mr.
Wunderley, for his time and help throughout the writing
process of our paper. Finally, we would like to thank the
University of Pittsburgh’s Swanson School of Engineering
for allowing us to participate in the Seventeenth Annual
Freshman Conference.
9