there we go that's me I am a freelance
developer Advocate and one of my
previous jobs was at a cloud company a
cloud provider uh not one of the big
ones but we dealt quite a bit with a lot
of data you know um Code Media whatever
uh and I started learning about how and
why we store data in the way that we do
as an industry how we did it at my
particular employer at the time and I
went down a lot of lot of rabbit holes
and I came out with this talk so today
we are going to be talking about data
storage U before we get properly started
it's worth asking what is this concept
that I'm going to be talking about today
uh one of the ways I like to describe it
is in the Sherlock Holmes Stories the
titular detective says that he doesn't
know that the Earth revolves around the
Sun and he defends this lack of
knowledge by saying that like every
piece of knowledge he has is like a
piece of luggage taking up space in an
attic his brain is like an attic
crammed full of of knowledge and if he
wanted to keep knowledge uh about the
Sun going around the earth going around
the sun he would have to kick out
something that was more useful obviously
like our brains don't work quite like
that necessarily um but the general
principle stands we need to know more
things in our day-to-day life especially
as the world gets more and more
complicated than we can fit in our heads
so for example how many people in this
room would say they know three phone
numbers by heart
four five right um we need to know more
things than we can remember and that
means we need to store them somewhere
but you can't store ideas you can only
store objects so in order to store
information we have to turn it into a
physical object this talk is about how
we as a species have done that
historically how computers have impacted
the ways that we do that and the
problems that we went into doing that um
in terms of computers I'm going to talk
specifically about nonv memory so memory
that doesn't lose its state when it
loses its power so we're not talking
about for example
Ram one thing I'm also going to touch on
is the durability of data storage which
has two aspects to it two kind of
flavors obviously when you turn ideas
into objects the physical durability of
that object matters you know if you can
tear up a piece of paper or you know
snap a CD in half that's part of what
makes data durable or not durable but
the other half is about um the encoding
that we use the way that information is
transformed when we turn it into a
physical object if we lose the ability
to transform it back and forth we also
lose the data so who can tell me without
getting out their phones where this
leads so that's not very durable right
if you don't have your phone you can't
interpret this
data um so that's one of the things that
we need to be careful of when we talk
about storing data is not just how
what's the object that we're turning it
into but how we do that transformation
so what I'm going to talk about today is
um I'm going to go through old ways of
storing data so this is you no
electricity before we sort of harnessed
electricity how did we store data we've
got old things which did use electricity
so a l of the fun history of computing
we've got things that we use and know
and love and maybe hate today and then
for a bit of fun I'm going to talk about
things that we might use in the future
um I make no promises as to the ACC of
any of the things that I talk about in
this section but they are very cool so
let's get started old
stuff first up we've got clay tablets
these were traditionally not fired in a
Kil but instead they were left to air
dry and as a result we don't have a lot
of these um these uh the one that was up
here was actually found in the ruins of
a guy's house that had burned down and
the fire that burned his house down
fired the clay tablet and that's why we
still have it um this guy had a really
really bad time right because his house
burned down and as a result we now know
what's on this clay tablet which is a
complaint about how shitty of a copper
Merchant he was so you heard of Ian air
before yeah this is the Ian air tablet
um it is probably it's it's the oldest
known written customer complaint um it's
about this this guy's house that burned
down and it's one of the few that were
found in his house so the writing on
this tablet is aavan C form for a long
time we could not read this linguists in
the 18th and 19th century all got
together they went well this is clearly
language we'd like to be able to read it
and they got together and they sort of
reverse engineered the Acadian C form
that's on this tablet so now we can
decode it but for a long time that
decode that encipherment was lost so
while the object here is very durable
physically although that's only by
Chance the encoding of the data on it
wasn't durable we had we lost it for a
long long time um yeah tablets uh when I
said history of data storage I meant
like we're gone back to the BR Bronze
Age another thing that I'm going to talk
about is uh on the other end of the
physical durability Spectrum we've got
pen and paper um ink and parchment um
you know pigments on Papyrus you know so
on again the encoding here like with the
clay tablet is written language so to be
able to get data out of this thing you
have to know the language um the photo
of this photo is the first two pages of
the baywolf manuscript and we don't
actually know when this was written
sometime between 925 sorry 975 and 10 um
1,25 CE so about 3,000 years ago no
sorry 1,000 years ago sorry um yeah we
don't know when the poem itself was
originally composed this is the only
copy of it that we have now this is a
foundational text in the study of Old
English um and we only have the one copy
of
it this manuscript form part part of a
library called The Cotton library after
a guy called cotton who had a fondness
for old and weird stuff like me and for
a time this cotton library was stored in
a building called Ash Burnham house does
anyone want to guess what happened to
Ash Burnham
house like in Air's house it caught fire
and unlike with clay tablets fire is
very bad for the durability of paper and
parchment and
manuscripts and uh so the bearwolf
manuscript um it survived the fire but
it did suffer some damage and it's
continued to acre damage since then as a
result um so again you've got this very
not very durable physical medium but we
do have we can read Old English and we
can get the data back out of it and this
is all very interesting and you might be
thinking you know this is very cool but
this is supposed to be a tech talk um
what did any of this have to do with
technology well now I get to share one
of my favorite facts with you the
English word technology comes from the
same root uh European and Proto European
roote as the word for
textiles historically this makes a lot
of sense because as humans things that
we've needed to do in the past are like
find enough shelter so we don't die of
exposure grow enough food to eat and
produce enough cloth to make things like
clothing and sales for ships and bedding
so for a long time textiles were like
the site of technological advancement in
human societies for example if you spend
time looking at Medieval manuscripts as
I am known to do you will often see
women with drop spindles that's what
this woman is holding here this big long
stick um with the sort of pointy bit at
the top I have a laser yeah with a
pointy bit at the top um is called a
disf and then here she's got a drop
spindle and you can see her cat is
bothering her which if you do yarncrafts
you will know is absolutely true to life
and the thing about this illustration is
that it's you see so many of these
because as a woman in the you know the
12th century if you had five spare
minutes no you didn't you needed to
spend it spinning um fiber from your
sheep into yarn to be used in textiles
because that was like the single most
important thing you could be spending
your time doing we get the English idiom
to Spin A Yarn meaning to tell a story
or to tell a tale because women would
sit together with their drop spindles
and their disc offs and tell each other
stories while spinning
yarn
so how do we actually turn that yarn
into cloth well this is a loom in 2nd
Century China um they invented the draw
Loom which is a machine for weaving
thread into fabric which obviously
massively sped up this process of making
fabric which we definitely need and you
can see here that the fabric is like
it's not that fancy right it's got some
stripes and we needed fabric we do do
still need fabric um and we'll make do
with fabric that's like plain or not
that fancy but what we really like is
really fancy fabric but to make that
each of these individual threads both
the ones that go up and down and the
ones that are woven back and forth you
need to like select them very carefully
according to their color on each part of
you know passing some threads through
and some threads over right this is
labor intensive and time consuming and
very difficult to do without error if
only there was some way we could sort of
get that pattern information that we
know what it's going to be based on the
colors of the strings and like get some
way to encode that so that the loom
could do it automatically and this is
where we get Punch
Cards so how this works is as follows
like for each little thread you what it
is when you when you use a loom is you
have threads that like go up like sort
of you've got threads that go this way
and you separate them out right and then
you've got some other threads that go
back and forth so this is the warp these
are the warp threads and these are the
weft threads and for each thread in the
warp you want to decide which one goes
which ones go up and which ones Go Down
based on what color they are and so for
each pass what you can do is you can
have a little hook that comes down and
goes do I want to pull this thread up or
do I not want to pull this thread up and
the hook can pass through the punch card
if there is a hole there and pick up the
thread and it cannot pass through if
there is no hole there so depending on
whether or not there's a hole in your
punch C guard you will or will not
select a thread to go into the bit of
the warp that goes up or not ones and
zeros and so what you have here is you
have patent data encoded into binary and
this is called a jackard head um a loom
with a jackard head on it is called a
jackard loom and they let you get fancy
fabric with much much better Precision
much much lower labor costs fewer
children getting caught in the Machinery
of all the Looms and getting like
crushed to death which was genuinely a
problem um and also it gave rise to
computers but like fancy fabric fancy
fabric here is some fancy fabric that
was made with a jackard loom and the
ideas behind this technology were
developed by a few different artisans in
the 1700s in France um ending with the
guy called Joseph Marie jacard where it
gets its name and the patterns from
Punch Cards that were made in the 1700s
are still in use today so a big win for
data durability we know what that data
meant and we have the objects that we
used to encode it and we can still use
them that's super
cool right photography film photography
is anyone here like a film photography
buff like really into film photographs
okay cool um this will be new to all of
you then probably this is the earliest
image derived from a photographic
process whether or not you can call it a
photo photograph is sort of a bit up in
the air what's on the left is the
earliest photographic plate and on the
right is a colorized version of the
resulting image and this is this is a
building like that that's the Horizon
there and this is the view out of a
guy's window that he captured it was
created by a guy called um Nissa for NES
I'm probably mispronouncing that uh in
1826 and what he did was he used a
camera obscurer which is you take a
little pinhole in a Fab in a sort of a
surface and light filters through that
pin hole and ends up projecting an image
of whatever's on the other side onto a
surface and it will be um upside
down and the thing that he projected
that light onto was a photosensitive
substance um called bitamin of jir and
it hardened differently depending on
what kind of light hit it so what you
end up doing is encoding that light
information that's hitting the plate
into texture and then you can use that
texture to make prints that represent
the visuals of the light
that hit that plate um yeah I think
that's really really cool um it's really
interesting also as far as data storage
goes because the encoding itself has
very little human input it's a chemical
process there's no language involved
here there's not a lot of all of the
subjectivity of Photography is in what
you choose to capture rather or this
kind of Photography what you choose to
capture and not how the actual chemical
processes occur um that's I which I
think is that's unusual among all of the
kinds of data storage that I'm talking
about today pretty much apart from also
um vinyl discs which I'm talking about
next um but yeah film photography uh
cool little froid this is um a dear type
one of the slightly later forms of film
photography first publicly available
kind of film photography it kind of
democratized the entire thing and this
is very possibly the first candid photo
ever you can see just there um that you
can see a guy getting his shoe shined
and the person doing it the exposure
time for this kind of photograph or
deera type was about four or five
minutes and most people on this street
were weren't staying still for that long
right they were walking up and down and
they don't really show up in the
resulting image but this guy and the guy
shining his shoe do and they probably
never knew that they were the first
people ever to be the subjects of a
candid photograph which is really really
cool obviously film photography is
continued to progress as a discipline
thear types like this one here was
superseded by codian photograph s which
are still used by hobbyists and and
amateur well professional film
photographers today and um you know more
photosensitive substances have allowed
us to keep developing this
discipline right vinyl audio records
here we see the the first example of a
paradigm that's going to come up again
and again throughout this talk which is
you have a disc and it spins around and
round and then you have a head you have
like a needle here that reads data off
that disc as it spins and you encode
like data is sort of stored on the dis
in concentric circles or in a very sort
of very gradually increasing spiral so
here what the data is is it's audio and
it's en encoded as texture the arm goes
up and up and up and down and um in most
modern players what that does is it
translates to an electrical signal that
we then render into
audio so the head here just a little
needle is anyone here I should probably
ask this about a lot of the things I
talk about is anyone here a vinyl viny
collector okay a handful um yeah you
have a little needle and uh record T
players take the signal that it produces
and turns it into
audio so when we come to things about
thinking about data durability for this
kind of storage the data here is encoded
in the texture of the dis and the disc
itself doesn't have any kind of
protective layer over it it can't
because of the way that Nal needs to
read from it so you have to be super
careful when handling them we actually
get the phrase like a broken record
from what happens if you get a scratch
on the surface and the needle just like
skips back and then plays the previous
bit again that's why like a broken
record means repetitive because that's
what happens if you get a scratch on the
surface of one of these or what can
happen um physically they're pretty
fragile and they need pretty specialized
equipment to play so in terms of data
durability they're pretty fragile but
also they offer an incredible sort of um
high quality which is why they have
persisted as this sort of people collect
them and listen to them even though
they're acquire very specialist
equipment and they're quite difficult to
take care of
physically right we are now into the
wonderful world of computers electricity
magnetism and we're going to go back to
punch cards so Punch Cards round two uh
a guy called Herman holth in the he
developed machines for tabulating census
data for the US 1890 census all that
data was stored on Punch Cards and he
later founded a company that got merged
with a few other companies and
eventually became the entity that we
know and love today as IBM so IBM
essentially popularized Punch
Cards the concept here is with the same
as with the loom a hole in the card
allows some kind of connection to be
made that triggers a process in Herman's
um uh in Hol tabulating machines the
connection that's made is a spring that
drops down and dips into a pool of
liquid mercury allowing an electrical
connection to be made which is obviously
very safe and normal and healthy to be
around for long periods of time
something you might notice about this is
that there are 80 characters on on this
punch card sort of goes runs from 1 to
80 um just to do with like the physical
size of these things it was what how
they were manufactured and we see the
legacy of this today in systems that
assume that you want 80 characters in
your terminal or maybe 79 depending on
what kind of delimiter you're using um
80 characters per line comes from Punch
Cards Punch Cards were eventually
superseded um by
sorry uh yeah sorry they were eventually
superseded by magnetic storage of
various kinds in terms of long-term data
storage um there's a photo that I meant
to put in these slides of somebody with
a stack of data of of Punch Cards and
it's like their PHD thesis or something
they a Computing student um at some
point in I think the 70s and what
they've done is they've got this stack
of of cards and they've drawn a line
that goes diagonally across them like
you know sort of across the ends of each
of these and it's so so that if they get
out of order they know how to put them
back into order because if you got these
Punch Cards if you dropped them and they
shuffled everywhere it's like somebody
scrambled your code right it's uh you
lose you need to be able to put them
back into order and that was how they
chose to do it which I thought was
really cool so Punch Cards um and then
these were used in these are not
intrinsically electrical but they were
used in the electrical early Computing
context we now come on to drum memory
we've got more spinning things and now
the spinning things we are cooking with
magnets magnetic storage works like this
you have some kind of um ferromagnetic
material that's iron Cobalt nickel uh
certain rare earth metals um and you
arrange that that metal those those
pherom magnetic materials in some kind
of a crystalline structure and then you
can polarize that material um by using
magnets to polarize certain areas one
way or another to represent essentially
binary data which way around is this
area polarized drum memory works by
having a drum that's just a cylinder
coated in that magnetic material and
heads or or just a single head that can
read or write that material so it can
either detect the polarity or change the
polarity of the material at that point
data is stored in tracks which are like
circles around the surface of the drum
and uh various different types of drum
memory at various points have done so
here you can see actually I don't know
how many heads this has um but this is
the first one this I I think is
um yeah the best this is like the one of
the first bits of drum memory ever made
um but this one is called the Zam 41
this is a Polish one and the thing
that's interesting about this one is it
has one read right head for every track
because when you're dealing with your
spinning discs and heads that read and
write to them sometimes if your if your
surface is very large and you've just
got one head it'll take a long time to
physically move the head into the
position that it needs to be in order to
read data and this time is called the
seek time and you want generally to
minimize that because especially if
you're using these for like the working
memory of your computer that matters
like a lot but um if you want the one
way to minimize that is to have multiple
read write heads which is what this does
it has one per track so for every layer
that you're sort of storing data on your
drum there's a read right head
specifically dedicated to that one track
but it's really expensive to do um and
not many of these got made and they were
not did not become popular even though
they drastically reduced Computing time
um because it was just really expensive
to to build and maintain
these we now come on to Magnetic core
memory this was the dominant form of
random access memory storage for decades
and it was so ubiquitous that was often
just referred to as core memory or core
and the way that this works is it's also
magnets these ones don't spin though
each of these Rings is made of magnetic
material and what you've got running
through them is copper wire so generally
at least three bits of copper wire per
ring and by running currents through
those copper wires you can change the
magnet magnetism of each of those rings
so each of those Rings represents a
little bit um reading from a core also
requires running a current through or
generating a current um and what that
does is it wipes the magnetism from that
ring what that means is that when you
read data from memories that stored this
way you also destroy that data it's
destructive readout so you can't copy
data in this way what you have to do is
you have to read it out and then maybe
store it in two
places
um oh yeah one NE thing about this kind
of memory is that it was heated rather
than cooled in order to make it more
efficient the thing that makes this kind
of memory efficient is having a
consistent temperature and it's a lot
easier to manage that by heating
something up than by cooling it down so
if you are having you know problems with
your PC at home and it's getting too hot
and you maybe install some core memory
in it or just take advantage of all of
that heat using smaller and smaller
cores and wires um basically lets you
much more densely store information in
the same physical space but
manufacturing that as you get smaller
and smaller becomes very cost intensive
very labor intensive and this is a
process that had to be done by hand so
for working memory of your computer this
was eventually superseded by Ram which
is a volatile memory and I won't be
covering it but it's also very Qui cool
we get the phrase core dump from this
kind of memory because this kind of
memory does not lose its data when it
loses power this is not volatile memory
and so if your computer had an issue um
you could dump like this the working
memory the working state of the computer
at the time that it had that issue would
still be in here it would be dumped in
this core that's where you get a Core
dump
from this is one of my my favorite
things in the whole talk um this is this
is memory this is well this is memory
but this is actually a program this is
actually a a computer program this is
software and it's core rot memory and
it's readon memory and what happens here
is the process of writing to this memory
is done during its construction how you
thread that copper wire through these
Rings en codes information um yeah which
way around sort of ones and zeros you
can kind of see how that would map um to
update this software you've got to do
all kinds of complicated unthreading and
unthreading and rewiring
and this type of memory got the name LOL
memory or LOL memory for little old
ladies because the process of
manufacturing this and writing to it
looked like sort of some kind of
threadcraft like knitting or crochet or
whatever you look like little old ladies
doing it um the most famous usage of
this was in the Apollo missions and it
was used for that because it's really
hard for this to change like you you
can't it with core with core memory for
example you can imagine there might be
um and something else I come on to you
later when we talk about hard dis it's
sort of random effects that could maybe
flip a bit right and then suddenly you
have an error that's really hard for
that to happen here because it's about
how the wire is threaded through Rings
this is really really stable and durable
physically once it's been constructed so
if you want something that you know you
don't want to do updates to like your
software for your spacecraft once it's
already in flight and you want to make
sure that it stays stable this is great
for that so that's really cool I like
that I just like it's it's a piece of
software and it's just there physical um
right now we come on to something that I
feel very sad about putting in the old
section that is floppy
discs in the historical section seen
here in 8 in uh 5 and a/4 inch and 3 and
1/2 inch sizes these were the latest and
greatest in removable storage media from
about the mid 1970s to the early 2000s
and has anyone ever opened up a floppy
disc before yeah that's why they're
called floppy discs open them up um and
in the inside is magnetic sort of tape
film um sort of material and that's and
again it's a spinning disc it's a
spinning disc with stuff recorded on it
and tracks and when you put it in your
computer the disc spins and something
reads off it um this is what like a
naked floppy disc looks like this is the
innard of a 3.5 in floppy disc and if
you picked it up and shook it it goes It
goes and it's very satisfying but it
doesn't work again after that very
well uh here's what here's what it looks
like really close up and you can
actually see the way that it curves it
sort of Curves like this obviously much
less extreme than I'm doing with the
laser pointer um but yeah you can see
the tracks this was a uh photograph
taken with um what's called a magnetic
field camera and it detects
magnetization so the bright and dark
areas are areas of magnetic polarization
on the surface of this floppy disc um
yeah of course this means that if you
put a magnet near it you will destroy
the data that is encoded using magnetism
so don't don't do that one again one of
my favorite images on the internet um
one thing that's uh interesting about
floppy discs and the spinning disc kind
of method in general is when you think
about the way that data is encoded on
diss it's a bit like this here we can
see sort of two tracks right um and I've
sort of highlighted them in one sector
so memory would be addressed like per
track or per sector and then per track
um or vice versa it doesn't really
matter but you've got sort of the thing
that I wanted to point out is that each
of these lines would take the same time
to read from as the dis spins at a
constant rate you know the it's going to
your the head that hovers over here or
over here is going to be reading for the
same amount of time as it traverses here
or if it was traversing here and what
that means is that when you store data
if you want your head to be reading
every however many micros seconds or
whatever you get to store much data much
more densely towards the center that you
do on the edge because here the disc is
moving faster because it's the track is
longer so your data has to be much more
spread out and this is inefficient
you're not using the surface of the
magnetism here as efficiently as you are
towards the center um and if you care
very much about like optimizing the use
of your magnetic material you don't want
to do this You' like to store data much
more densely at the outside but what
that means is that when you're reading
from the outer edge of the disc your
disc has to be spinning more slowly you
can't have constant angular velocity
you'd have to have variable angular
velocity Apple tried to do this um they
tried to build floppy discs that worked
that way so that they could optimize the
amount of storage that they put on each
bit of the spinning disc but what this
meant is that discs encoded written to
in this way could not be read from in a
floppy disc drive that was not using the
same technology one that tried to read
from a disc written with this variable
angular velocity technology if you tried
to put it in a
uh standard constant angular velocity
disc drive you get garbage out because
it didn't it that's not how it was
written the encoding of the data was not
durable in that way it required very
specialized technology even more
specialized than the floppy desk drive
already is so it was expensive to
manufacture and to maintain and they
never caught on and so this is the model
that most spinning disc technology uses
is it's just less efficient at the outer
edge but it means that we have much more
simple technology and Hardware in order
to read and write these things
because the data the encoding of the
data being easy to you know read and
write to matters more than the physical
efficiency of the
medium so before computer environments
were regularly networked floppy discs
were the go-to way to like share data
between different computers and of
course this Legacy lives on with the
floppy discs being the global symbol for
the safe button while I've was been
writing this talk um back in last year
uh before NDC Oslo I think about 13
people came up to me looked at this
slide and went you're talking about the
save icon and these are like you know
50-year-old speakers who are like doing
it as a bit but it really is a sort of
thing it's like that's the save icon and
that's the the Legacy that it has
essentially because um they are now
Wikipedia calls them obsolescent uh in
February 2003 Dell announced that they
would no longer pre-install floppy disc
drives on their Flagship home computer
and by 2007 only 2% of Home computers or
computer sold in stores had um built-in
drives
um I grew up using floppy discs for like
up until I was about a teenager and then
USB thumb drives came became the thing
so I'm AG I'm sort of that that's how
old I am so it's you know they they are
still around you can still buy adapters
for them um the US nuclear weapons don't
use floppy discs anymore but this uh
this article came out in 2019 so it's
not it's not that uh it's not that far
into the past that these were still
being used in really really critical
systems um simply because they work and
if it ain't broke don't fix it and
another thing about floppy discs is that
the magnetism on them is very very
stable over time like a floppy disc that
you had written to 20 years ago if you
can find a way to plug it into something
today very likely to still be readable
and you can still do that today I went
on Amazon I looked for um external
floppy desk drives you can get them I
didn't find any that were us b c
connected but I did find lots that were
usba um so you know they haven't kept up
with the late like you don't have ones
that you can plug into your MacBook that
only has USBC you'll need an adapter but
you can still read data from a 3.5 in
floppy disc if you have one yeah
obsolescent which I think is just an
incredible
word
um oh and I have floppy disc stickers
actually after this don't let me forget
to give you your stickers um right
current stuff stuff that we know and
love and use
today first up we've got more spinning
discs Optical discs who here has um a
desktop to PC or a laptop with a CD
drive in
it okay a handful who has a gaming
console with a disc drive in it yeah
more right this is why they're in the
modern section it's like they're not
that widely used in day-to-day life the
except for you know your PS5 might still
have a disc drive so under this category
I'm grouping a bunch of things together
Optical discs include like CDs uh CD um
laser disc writable CDs Blu-rays DVDs um
they all work in pretty much the same
way they all use the same Paradigm as
vinyl and floppy discs and drum memory
you've got a thing that spins and a head
that reads from it or something Reading
day toare as it spins and uh Optical
media looks like this you've got um
bumps and dips in some polycarbonate
plastic that and that encodes ones and
zeros essentially then you've got a
reflective uh layer of usually aluminium
but not always depending on the type of
dis and then you've got some acrylic to
keep it flat and keep it safe and you
might have a label on the top and the
way that these work is that a laser
shines down onto this surface and how
reflective that surface is depends on
where it is in this kind of structure
and texture of the bumps and the laser
will be able to tell whether it's
looking at a bump or a dip this is a
detector um it's a lens from an ACA
laptop um CD D drive I think some kind
of optical disc drive and um yeah this
is a laser diode paired with a laser
detector and it's detecting the
reflectivity of the disc surface at each
point so CD ROMs ROM standing for readon
memory um they were developed by Sony in
1984 and it wasn't until 1997 that we
got rewritable CDs
now this is a rewritable CD and you can
notice that it's actually got a much
darker reflective surface than the read
only one that was the first image in
this section and that is because it's
not aluminium that's providing their
reflectivity there um it's actually uh
it's it's an alloy it is a silver indium
antimon torium alloy try saying that
three times fast after the party
tomorrow night and what this does is it
allows that laser diode in the the the
laptop disc Drive um to actually melt
That Metal Coating and what happens when
it does that is it does that is that the
Metal Coating goes from being this kind
of crystalline structure to being like
this kind of goopy just mess and then
it's you know it's it's solid but it's
it's lost a crystalline structure that
changes the reflectivity which is what
the laser diode reads and so it
interprets it in the same way that the
bumps and dips in a CD ROM are
interpreted so you can actually write
with the laser diode to this disc as
well as read from it
however in order to undo that process of
turning the crystalline structure into
goop you have to heat the disc up really
you have to heat it up quite hot and you
can't do that to like one specific point
at once really you have to heat the
whole disc up so if you want to erase
what you've written onto a rewritable CD
um you have to you have to do it all at
once um and that's what burning a CD
is reading data out of an optical this
requires it to be optically legible like
it has to look has has to look good it
has to be legible to that laser which
means that if you've got grease and dust
and whatever on the surface of these I
mean uh has anybody here not had the
experience of playing music on a CD and
it's got a fingerprint on it it goes all
weird yeah like you know exactly what
I'm talking about unlike floppy discs
these don't have protective cases to
protect them from that kind of thing um
you can also break them quite
dramatically this is a video of the
slow-mo guys who were some um I don't
know if they're still going but they did
um high-speed camera capture of just
like weird things like shooting a bullet
into jelly or you know doing oil
painting or whatever they span a CD so
fast that it just
shattered and something to note about
this kind of data storage and it's true
of the spinning discs in general is that
once something like this has happened to
it you cannot recover the data because
it would require like lining up all the
tracks and like you know reconciling all
the damage that's done at those edges
unlike for example shattering a clay
tablet where you could piece it back
together and maybe be able to read
what's been written there um so in terms
of the physical durability of these
media it's actually got a sort of a
different failure mode than some of the
more analog like you know pen and paper
clay tablets um I also really don't envy
them having to clean up all the little
tiny shards of CD room that they caused
by doing this um but it's a really cool
video I I encourage you to check it
out right something else that's still in
use today which you might not realize on
uh based off the image that I'm about to
show you is magnetic tapes so here we
have an example of a data storage medium
which is not random access read unlike
hard drives and flash memory where you
can kind of like well flash memory
haven't covered yet but unlike hard
drives for example where if you want to
read from a specific purp um part of the
surface you can move your head over and
it has a there's a fairly short maximum
seek time for that right it's not going
to take too long it's got good Random
Access but um magnetic tapes don't
because if you're 25% the way through
listening to Rick asley and you want to
go to 75% the way through you have to
scroll through that 50% it's linear seek
time in sort of in how far away your
data is how far away you are from where
you want to be um and this is true of
any kind of data stored on magnetic
tapes basically so we'll know how this
goes by now the tapes are made of a
ferromagnetic material it's polarized
ones and zeros and the hardware that
reads and writes to the tape is known as
a tape drive the first magnetic tapes
were used um to store uh record computer
data in 1951 for the univac one also an
IBM thing oh sorry no that wasn't an IBM
thing but IBM quickly followed suit and
set the standards for the industry when
use of magnetic tapes ever since um and
they have been in constant use since
then pretty much and despite the
drawback of that non that that slow
Random Access time or potentially very
slow Random Access time um they are very
durable magnetism wise I mentioned this
with floppy discs it's same thing um you
can shove these in a a cupboard for a
few years and nothing bad will happen to
the data that's stored on them they're
very easily removable from their
surroundings um you know you don't have
to keep them powered on you don't have
to keep them anywhere near the the
things that are used to read from them
um which means that also the data that's
stored on them is not vulnerable to
computational
attack um however if you've got data in
a data center that's stored on a tape
that is just sitting in a room and been
removed from the computer it's going to
take a while if you want that data CU
somebody has to physically go and get it
and put it in a machine and scroll to
the right bit of the tape so it's got
quite a a low sorry it's got quite a
high latency of access to these datas
when data is stored on these in for
example um Cloud companies store this
and this is one of the things that I
learned when I was working at the cloud
company that I worked for um last
year uh is that these are very often
used for Glacier storage if you've got
sort of blob storage that you've got
somewhere that you never look at and
it's in Cold Storage it's very there's a
very good chance it's stored our montic
tapes and slow access times then are in
acceptable constraint because if you're
using it to store legal data that you
need to keep for compliance reasons and
you don't need regularly it's fine that
it might take 24 hours for that to
become available to
you uh one note one last note on
magnetti tapes one of the most famous
examples of something called um the
digital Dark Age which is the idea that
if we lose access to our encodings we
lose all that data regardless if we
still have the physical objects um so
the failure mode of that second kind of
data durability that I talked about um
one of the most famous examples of this
happening is do is the NASA Mission uh
the Viking Lander on Mars here you can
see car Sega next to a model they did
not actually send him to Mars also
unfortunately that would have been
really cool um and this Rover um
recorded this Lander recorded a bunch of
data to Magnetic tapes um NASA got the
tapes back in 1976 or 7 I'm quite sure
um they got the tapes back and then they
put them in a cupboard for 10 years and
when they got around to trying to read
them they could have because all the
engineers who had worked on this project
originally had either left NASA or had
died and nobody knew what the ones and
zeros on the tapes meant and they um
they actually had to go and look at like
the physical Hardware of the Viking
Lander in order to try and reverse
engineer what it was doing in order to
put the data onto those tapes they lost
the encoding um yeah and uh if they had
looked at those tapes a little bit
earlier or if the people who had um
designed the encodings had written them
down somewhere that the people in 10
years time were able to find they would
have been able to avoid that so yeah the
loss of the encoding very nearly lost
the data that was gained from sending a
Rover to Mars or sending a Lander to
Mars um that's a lot of effort to
waste right more spinning discs can you
believe how many spinning discs we have
um hard drives we all use them know them
love them you get them belt into most
personal computers these days unless
you're an SSD only person and you can
get an external ones that you can fill
with lots of pirated media and I checked
the other day and it looks like about
like 20 terabytes is commercially
available now they expensive but like
that's a lot of movies right um
Wikipedia says that 26 terabytes are
available uh as of last year but I
couldn't find any on Amazon or CGA or
whoever so these again the same Paradigm
as floppy discs and Optical media this
metal disc um in the middle spins around
you have a head that reads and writes to
it and this is again uh stored pherom
magnetically this is a magnetized
material um but they've got cases around
them so you're unlikely to put a magnet
near enough to them that you're going to
damage the data that's stored on them
once again IBM who pioneered these and
the first one came out in
1957 and stored a whopping 3.75 of God's
Own megabytes of data here you can see
two of
them and these are each 3.57 3.75
megabytes um they had these had 52 discs
each holding two read write heads
and IBM kept iterating and improving and
we got to where we are
today um yeah um they also did so again
with the um on the theme of things being
technically better but too expensive to
maintain and produce IBM did toy with a
model called the um the yeah just the
IBM 2305 and that had one read WR head
per track of data again with tracks
being like those concentric circles um
and meant that you didn't have any seek
time basically basically minimal seek
time as good as you can get um again too
expensive to maintain they sto making
them over the 1980s hard drives went
from being very expensive as an add-on
to your to your home PC to be just the
standard
essentially here we can see again
magnetic field camera taking image of
the disc
surface here's one of my favorite facts
that I've ever learned we have got to
the stage where the areas that we are
magnetizing on this surface they've got
so small that they've become they start
to get get affected by a Quantum Effect
called super paramagnetism and what that
what that does what happens when super
paramagnetism happens is that um heat
can cause magnetized material to flip
its par polarity right the thing that I
was saying would never happen with the
corot memory it can happen with these we
it it's known to happen in magnetized
areas um smaller than 50 nanom so for
reference the thickness of a piece of
like copy paper like pred paper is
anywhere between 70,000 to 180,000
nanometers we're talking about areas
that are less than 50 here um like
really tiny we made the magnet so small
that the universe doesn't like
it it's so cool and the way that we
counter this is you actually have two of
these discs um next to each other
separated by a three atom thick layer of
ruthenium which is not ferromagnetic
it's not magnetically active and the two
discs sitting very very close to each
other are polarized oppositely and then
they attract to each other and reinforce
each other's magnetism and this
counteracts the effect of the super
paramagnetism which is just really
really cool um yeah and that's that's
hard drives so going back to this is
um these are some photos of a data
storage bunker underneath Paris this
belongs to my previous employer a cloud
company called scaleway and this is
their cold storage and it's not magnetic
tape storage they actually use hard
drives for this which is fairly unusual
this data bunker is 25 M underneath
Paris I don't know how close it is to
the catacombs um and these are like the
only photos I could find they keep this
stuff locked down um and the storage
mechanism they use here is they use
these hard drives in slightly different
ways than we use the ones that are on
say your laptop or in most data centers
that are using hard drives for anything
other than cold storage so when you
write data to a hard drive drive you
have a head that reads and a head that
writes and sometimes they the same head
and when you write to a hard drive you
write in like quite a wide circle like a
fat donut right but when you're reading
you don't need the entirety of the width
of that F fat donnut you could have a
fairly skinny donut that you're reading
from does that make sense like you the
width that you need in order to read
data is much narrower than the width
that is written to by the right head and
in everyday hard drift Drive
that's fine it's a little bit
inefficient you're writing more you're
writing to more of the surface than you
need to um but it's fine that's and
that's what is called um parallel
magnetic recording where the sort of the
right head and the read head just
operate on the same tracks and they're
just very
wide in this um cold storage facility
what they do instead is they do
something called shingled magnetic
recording so what happens is you start
in the center of the disc and you write
a fat donut and then you move a very
little bit outwards and you write
another Fat donut that almost entirely
covers the first one and leaves a thin
strip unedited that can still be read
from and then you do that and you do
that and you do that and it's sort of
like you're layering up these strips
like the shingles on a house and it's
called shingled magnetic recording and
what this does is it lets you be much
much denser with the information that
you store to your hard drive um much
much better data density but the
trade-off is that if you wanted to go
back into the middle of that and write
you'd suddenly be covering up a lot of
written tracks of data with your big
wide read head so you cannot do random
rights anymore with this but in a cold
storage facility that's probably an
acceptable trade-off because you don't
generally go and write to data in the
middle of your your cold store your cold
stored data you're generally writing
blobs all at once you know your legal
documents you're doing backups of video
security footage or something um and
that's an acceptable trade-off and I
just think that's really cool that
there's this way that you can move right
to hard drives that's only used in this
very specific
circumstances um so that's what scaleway
does um as far as no unless they've
changed it and they would not let me go
to the data bunker while I work there so
I don't have to be photos of my
own right flash memory last but not
least you have some of this in your
pocket probably it's in smartphones it's
in tablets if you've got a UB key or any
other kind of like hardware token that's
using flash memory and these work by
using a circuit component called a
mosfet the a floating gate mosfet it's
really complicated but essentially what
it does is it can hold charge or it
cannot hold charge one and zero um yeah
St it stores electrical charge and the
thing about these devices that made them
so handy for when I was a teenager and
writing homework and taking it school is
that they draw power directly from
whatever they're plugged into they do
not need their own power supply unlike
hard drives or well some hard drives
draw power from the ma machine they're
plugged into ones but like your big one
with 20 terab of pirated movies that
needs its own power source these don't
um yeah this is great because they just
sort of plug and
go however flash drives and this is ssds
are flash drives as well um they have a
few limitations for a given block of
storage you can really only write to it
all at once not in patches um they also
have a lifetime limit on how often they
can be written to because those Moss
fats if you fill them up and then drain
them and fill them up and drain them
they start to leak they start to they
start to wear out um to mitigate this
flash drives have something in them that
is called a memory controller which
essentially tries to spread the wear
across all of the sort of different bits
of the flash drive so that all of the
components give out at once rather than
one giving out way before everything
else and rendering the whole flash drive
unusable finally those mosfets also do
they do leak charge over time regardless
of how far through their lifetime they
are so unlike magnetic tapes or um
floppy discs if you put data onto one of
these and then leave it in a cupboard
for 10 years because you are NASA after
the Viking Land emission you might not
get usable data out at the other end um
yeah however if you have data on a a
hard drive sorry not a hard drive a
flash disc flash drive that you want to
make sure you don't lose just copy it
onto a new one it starts the clock all
over again so it's
fine
yep right we have learned all about the
history and current state of data
storage um we know a bit more about how
and why we use various types for various
purposes you know we use magnetic tapes
for Cold Storage um and we use hard
drives for every day and we use the
weird hard drives with the shingle mag
recording um if you're a weird data
center um all the current methods of
storage that I've just talked about are
going to get they're going to be
iterated on over time they're going to
get progressively better and better
we'll improve the lifetime wear of flash
drives and hard drives will keep getting
big bigger and bigger and we'll find
ways to make the universe okay with the
fact that we're making the really tiny
magnets but none of that is like
particularly cool or futuristic or sexy
um so let's talk about some stuff that
is DNA DNA is very very data dense
microscopically small cells um can hold
the entire genetic code for an entire
species a team at Los Alamos National
Laboratory has created an encoding um
the Adaptive DNA storage codex for
turning Compu comp friendly binary into
DNA friendly pairs of AC and G bases
there are other encodings out there that
are optimized for different things like
density of data storage or um error
correction and things like that um the
idea here is that you can create
synthetic DNA that represents your data
and then that DNA can be stored very
very durably at low temperatures for
decades and we can actually do this
today there's nothing stopping us doing
this today people are doing it today um
it's just not very efficient in terms of
time but in terms of data durability as
long as we know what those encodings are
that means that that data could still
persist for a very very long time there
is DNA data on the moon courtesy of the
be sheet Lander in April 2019 it did
crash so we don't know what status we
don't know what state that DNA data is
in but it had synthetic DNA data on it
and but if it isn't lost the arch
Mission Foundation who planned and
executed that mission
um they estimate it could still be
legible if somebody knew how to read it
in billions of years like billions of
years that's incredible that's really
really cool when I was first researching
this I thought it was talking about like
putting DNA into like plant DNA and then
it's like oh I can propagate this by
growing the plant that has the sort of
um in inserted DNA in it and apparently
that's not a thing and there's all kinds
of ethical concerns with doing that and
that we might bring about the end of the
world by creating a race of super plants
that I don't know but um uh that's not
that's not what this is this is still
very cool though um and there are lots
of different encodings being considered
and one of the things that people are
trying to consider when they're building
these encodings is how easy would it be
for somebody to reverse engineer this
because again if we lose that encoding
you lose all the data that's stored and
people do want to mitigate that another
type of data storage that being looked
at with an eye to data durability is
Superman storage also known as 5D
Optical data storage
um that's a bit of a marketing name I'll
talk about that in a bit um the idea
here is that you take a transparent
nonphotosensitive materials so something
like a bit of hardened glass or fused
quartz and you use a laser to engrave
data within the 3D sort of material that
you've got here it's called 5D because
it's it's a marketing thing but what
they're what they're sort of getting at
is like you have your three physical
dimensions like you know back and forth
up and down left to right and then you
have what the angle is is another degree
of freedom and how close you are to the
thing as another degree of freedom and
they say that's five Dimensions it's not
but it's a good name so um yeah so what
happens is that depending on how close
you are what angle you're looking at and
where in the in the crystal or material
you're looking you can read different
you can read data in different ways um
the photo here is the universal
Declaration of Human Rights engraved
into a piece of glass and you can see
they have done it in a way that it looks
like the UN symbol which is very cool
and cute um Hitachi and Microsoft are
both working on this concept and the
current bleeding edge stuff is being
done at Southampton here in the UK all
of those teams are working on this with
an i to data durability like the
explicit goal of data durability the
data isn't going anywhere unless you
drop the glass which you absolutely can
do but as long as the glass is not like
shattered this isn't this isn't charge
that's dissipating for mosfets this
isn't going to get erased by putting a
magnet too close to it you know this is
very very durable physically speaking
the encoding that's being used to turn
data into engraving isn't yet settled as
far as I can tell and that's the much
more philosophically interesting and
difficult problem um it maybe I I I
don't know what it is but maybe the
human rights declaration is all there in
just like seven bit asky or something as
long as we know what that is in like a
thousand years we'd be able to get the
UN Declaration of Human Rights back out
of this piece of glass which is really
really cool and it's very dense as well
you know you can just it's quite small
um yeah that's really really cool so the
last thing that I have to talk today
about today and the weirdest and the one
where I want to caveat very strongly
that um I'm not actually predicting this
this is going to go anywhere but it's
really cool is time
crystals do we have any condensed matter
physicists in the
room
good I have given this talk for when
people have put their hands up and I was
like I am so sorry for what I'm about to
do to your beautiful profession so this
up here isn't a Time Crystal there are
no good photos of them unfortunately it
is a space Crystal and like flash memory
you have some of this in your pocket
because silicon is this is silicon and
silicon is a space Crystal the thing
that makes it a space crystal is it has
a repeating structure in space you look
at it and then you move over a certain
bit and you look at it again and they
look the same a repeating structure in
space is a space Crystal time crystals
are the same but they have a repeating
structure in
time this is the best image I could kind
of think of to try and display the
concept that I'm talking about um a Time
crystal is an object whose lowest energy
state it sort of resting state is one of
motion this doesn't break the
conservation of energy because something
something quantum
physics they were first theorized to
exist in 2012 um by a theoretical
physicist called France wilchek
and or Frank wilchek sorry and in 2021
so only nine years later a team of
scientists in the University of Hamburg
made one in a lab it didn't look like
what you might expect um it was called
uh it's a Bose Einstein condensate and
that is a state of matter like you know
you've got liquid gas solid um plasma
and then there's like 13 others or
something and one of those is a Bose
Einstein condensate um it's what you get
when you super cool Bon gases I
personally hate when I open my freezer
and I've actually made a Bo accidentally
made Bose Einstein condensate again and
the reason that they're in this talk is
because some very clever people think
that we might be able to use them as
storage for quantum
computers and that's currently an open
problem as I understand it because in
quantum theory there's something called
the cloning theorem and what the cloning
theorem says is you cannot duplicate
Quantum State you can't copy it you can
only read it and by reading it you
destroy it like with for memory
destructive readout so any operation um
that reads from a Quantum memory store
is intrinsically
destructive um and that means you know
that that has certain implications for
what we can use in order to store
Quantum data um but maybe it's time
crystals and I read the I if you want to
go and read up up on time crystals it's
an absolute trip I think I briefly
understood them for about like 3 seconds
had an out of body experience and then
went back to just being like okay I
don't I don't know what this going on
here
um but they're really really cool and
the fact that we sort of went well the
laws of physics say that this should be
possible I guess and then it was only
from nine years from that moment that
people made one is incredible people are
incredible scientists are
incredible so on that note conclusions
we have uh we have learned about storing
data all the way from customer
complaints in the Bronze Age through to
encoding our data on DNA and putting it
on the moon um this has been an
incomplete and Whistle Stop tour and
most of what I wanted to impart with
this is that humans are really cool and
creative and we're very good at solving
problems in increasingly complicated
ways um if there's another takeaway from
it though it is that data is useless if
you can't read it data durability
matters when you encode data you need to
make sure that somebody is able to read
it otherwise there's no point in storing
it when we store data it has to be with
that Concept in mind and this isn't
something that in our day-to-day job as
software Engineers we get to deal with
directly but it does come into play
slightly when we think talk about things
like encoding Concepts into encoding
real world concept into code objects how
are we how are we serializing that is it
in a way that makes sense to the person
who's going to have to deal with it at
the other end um and you know we get
into all ideas of like demander of and
design when we start talking about those
things but it all interconnects and um
the way that we store data is absolutely
part of that too all of the data is
useless and another person in the future
which might be you knows how to get at
it um but mostly people are really cool
science is really cool time
crystals thank you so much for your time
today uh if you follow that QR code it's
not a Rick Roll unlike the first one
that will take you to a little uh
feedback form where you can leave
feedback for me if you're so inclined um
and if you would like to give me
feedback I really value it but more
crucially I have stickers and if anyone
would like stickers please come up to
the front and we have five minutes for
questions no sticker time oh
question
yeah oh good question so the question
was the core rope memory is that where
hard the term hardwire comes from
hardwired in I don't know I could see it
being from a lot of different places um
it would be cool though and it would
make sense yeah yeah I can add another
Linguistics uh atmology fact to my talk
yes
this uh SP uh same speed does that
happen with like CDs and other yes I
think CDs are generally um constant
angular velocity as well the question
was um spinning discs about spinning
discs and constant speed also have like
different uh densities of I believe so
that yeah they do they do thank
you
cool uh actually about the uh spinning
disc thing you were talking about how
Apple uh had this idea to do variable
angular velocities and it just occurred
to me that that would be a great way to
uh include you know exclusive content
only available that oh yeah yeah vendor
look in which is you know it gives its
own implications listen if anyone's
going to do it I think it would be apple
right yeah yeah no um exclusive uh you
know Apple only content that you can
only get by using their specific floppy
disc encoding if they're going to bring
back the floppy disc I wouldn't be
opposed right and that has its own
implications for um uh encod ability
what was the term you use like data data
durability data durability because if
you if you run around doing you know and
we've already had problems with DRM and
people can't get their own stuff so I I
named Dr the digital Dark Age that's a
whole thing you can go and research and
it's like a topic in its own right but
the concept there is that as we sort of
encode things in very in like
increasingly obscure ways
and do things like DRM and um things
like Netflix taking down movies before
they've even really been released and
just like those are never ever going to
be seen again or whatever like how do we
do digital preservation um in a way that
is actually going to be resistant to the
kind of things that go wrong over time
when we lose information and we lose
access to Hardware um yeah the digital
Dark Age it's it's a like scary idea but
lots of very clever people are working
on really interesting ways to try and
fix it circumvent it protect us against
it
yeah have two more question or two more
minutes for questions or we can just
go question is there a medium you didn't
have time to talk about that you want to
mention is there a medium I didn't have
time to mention so the one that I went
back and forth on whether I wanted to
put it in the talk is a um South
American and I can't remember which
South American country it is is kipo and
they are what a kipo is is a series of
it's It's a fiber
based writing system and it's strings or
like ropes that are knotted in order to
encode data and there are a couple
different kinds that people think that
they may have been used for like maths
and sort of going okay this is how much
grain you owe me in order for this but
they've also been used for narrative
recording and one of the things that's
really really cool about them is that
sometimes it's you need to see what the
fiber is in order to know data like
information about what it's telling you
you need to be able to see whether or
not it's knotted so there's a
topological aspect to it but sometimes
also you need to be able to touch the
fiber because your alpaca fiber and your
something else fiber I don't know I'm
blanking on South American animals that
give you fiber your your a pack of fiber
and your viconia fiber right for example
might look visually identical but they
mean different things and you will only
know if you touch it that's really cool
um and they were used um as a sort of
not back Channel isn't quite the right
word but they were used to encode secret
Communications during a Civil War I
think in Lima um but don't quote me on
that because I haven't got it in my
speaker notes but that's really cool
kipu um KH ipu is the search ter that
you want to look up and they're really
really cool Q I think it's either right
yeah yeah um yeah that would be the
thing that I would want to put in but
then I was like is it data if you're
recording like a narrative what
constitutes data and then I ended up
writing a whole separate talk about that
said yes because they used it to
transfer information regarding in the
whole empire because was really vast so
it was just to say like oh you know what
this province over there they are like
this amount of person this amount of
okay so it was very definitely like
quantifiable stuff we don't know for
sure how to read it because it was lost
in history but for examp the things that
we know is that for example red color
mhm isans an animal yeah so and depends
if you just do one not or two notes or
whatever the heck yeah like they books
just documenting all the types of notes
that they just made yeah like I I
started going down the rabbit hole of
researching this and then I went down a
separate Rabbit Hole of like what what
counts this data what am I going to
include like there's a reason I didn't
put cave paintings in here because what
they encode is not you get into what is
language and it's like specific
utterances and you have start having to
learn about Linguistics and semiotics
and that's a separate talk which I also
have but I'm not doing here at this
conference um it was Inc by the way
Incan okay yeah um like really like so
much fascinating stuff um I love all of
this all of the history of like stuff
and people and Technology it's
yeah um all right let me get you
stickers
[Applause]