A Case Study on Retrieval of Data from 8-inch Disks
Of the Importance of Hardware Repositories for Digital Preservation
Denise de Vries

Flinders University
GPO Box 2100
Adelaide, South Australia 5001
denise.devries@flinders.edu.au

Dirk von Suchodoletz
University of Freiburg
Hermann-Herder Str. 1079104 Freiburg, Germany
dirk.von.suchodoletz@rz.
uni-freiburg.de

ABSTRACT
There are still a significant number of born-digital artefacts whichhave yet to be received by memory institutions. These include
the works of famous or important authors, artists, politicians, andmusicians, some of which are stored on digital media dating back
30 years or more. Many digital objects have escaped the blight of bitrot, and legacy hardware, though rare, is still available for reading
the media. Assembling the required equipment and expertise ispossible but increasingly difficult.
This is an ongoing challenge which is not confined to floppy
disks or obsolete hard drives. The challenge is exacerbated by thereality that many artefacts are not considered for preservation until
the creator has passed away. In addition to the past 30 years’ worthof media, today’s storage media will also soon be superseded withnewer technology and form a new challenge for future archivists.
In order to preserve the content, or the look and feel of the original
objects, precautionary actions must be taken which require bothknowledge and the right equipment.
Creating disk images from obsolete magnetic media is not a simple task, especially when it concerns more obscure or older formats
such as 8-inch disks. There are many challenges to overcome, witheach small success leading to a new phase of discovery.
In this case study we recount our progress, through many stages,of dealing with the described challenges with regards to a set of
8-inch magnetic floppy disk media. At the beginning of this project,most requirements for recovering the data from this media were
unknown: the original hardware system, the original operating
system, and the disk format. In this paper, we describe our approachto uncovering this information, leading to a successful preliminary
outcome. This is a cautionary tale which aims to provide somelessons for use in related contexts.

CCS CONCEPTS•Information systems →Magnetic disks;

KEYWORDS
Digital preservation; disk imaging; disk format; digital heritage

1

INTRODUCTION

There is very little literature in the digital preservation discipline
regarding the challenges that must be overcome to retrieve datafrom obsolete media and render it accessible, complete and accurate.
For instance [20] has no use cases on 8-inch disks and the actual information referenced is often rather scarce [4]. Many practitioners

Willibald Meyer

University of Freiburg
Hermann-Herder Str. 1079104 Freiburg, Germany
willibald.meyer@rz.uni-freiburg.de

in digital libraries and archives presume that someone is aware of
the technological changes and takes the necessary action to mitigate it. But digital preservation is still a relatively young disciplineand many IT professionals have still not placed sufficient priority
on media migration. Additionally, well-established workflows tohand over materials from governance offices to archives still use
20–30 year pre-transfer retention periods, which were reasonable
for traditional paper-based records but are much too long for any
digital storage medium to be held without intervention by media
preservation experts. The situation is even worse in the personal
sphere: written documents of famous authors or politicians arestill valuable after their death [9] but there is little to no availability of standard processes or policies regarding the transfer of any
digital equipment and/or storage media at this difficult moment.
While organizational knowledge exists that There is little existentliterature that would recommend removal media of any type to be aworthy archival medium. [10], this is not necessarily the case forthe personal domain.
This case study presents the challenges and difficulties faced
when attempting to save research data from 8-inch disks and thedigital forensic methods needed to succeed. From the very startof this endeavour we had very little information from which toorganize our work.
The brief given to us was succinct. There is a set of 8-inch disks
from early- to mid-1980s which contain research data. These data are
required for current research. Retrieve the files from the disks andmake them available on current media.
The hand-over procedure did not generate much information,
seventeen 8-inch disks with some additional paper stuck in a few
of the disk sleeves were passed to us (Figure 1). The floppy labelsof the various brands (e.g. BASF and HP) did not provide any
information on the hardware or systems used to create them or on
the formatting used.
The few sheets of papers accompanying the disks seemed toindicate that no file system was used at all. It appeared to be head,sector and track information. While the column containing thehead information (0 for first side, 1 for the second side of a two sided
medium) was rather obvious to deduce, it took a few comparisons tounderstand the meaning of the sector and track information. Thereis no record within the university about the hardware systems usedat the time and inquiries within the organization only hinted thatthey had introduced office writers (electronic IBM typewriters) andlater CPM machines, both featuring 8-inch drives; Unfortunately,
nobody had a clear memory of the exact systems. Due to the number
of Hewlett-Packard (HP) disks in the set, it was presumed that an

Figure 2: Providing the 8-inch drive with 5V and 24V

Figure 1: Sample of the disks by different manufacturers
evaluated in the study
HP system could have been used and further investigation into thepart numbers was tried.
The sheets, with some of the disks, list information formatted as
NAME PROTYPE
REC/FILE
H8,0,1 148
ALT-A
DATA
1

BYTES/REC

ADDRESS

1188

0/1/0

The initial step was to find an appropriate machine which could
both connect an 8-inch floppy drive and host a recent operating
system to handle reading the data and transfer it to current media.
Two machines were evaluated: An older HP AMD CPU officedesktop machine (from approximately 2008) and a more recent
DELL Optiplex system, both still featuring a floppy controller. The
BIOS of the HP allows setting a single floppy to either 3.5-inch
1.44 Mbyte or 5.25-inch 1.2 Mbyte. The DELL BIOS made it moredifficult to configure for the older floppies, as only the 3.5-inch
option could be set. Additionally to make things more challenging,
actually attaching a 5.25-inch or 8-inch drive to the DELL machine
electrically required a power cable adaptor from the more recent 3.5inch SATA/HDD connectors to the old peripheral power connector
style 4 pin.
As no 8-inch disk drive was to be found in the university, a ”new”
one had to be bought. The market, in the 1980s, offered a wide rangeof drives each with their own special features. A half-height drive
not requiring AC power was chosen. A Mitsubishi (M2896-63) 8inch drive in mint condition was acquired for about 240 e from
eBay. In addition, a converter for the power supply of the 5/24V ofthe drive and a floppy disk adapter for 8-inch drives on PC floppy
controllers were procured from DBit [5] for a cost only marginallyless than the drive. The necessary cables were scavenged from oldsystems and recycling bins (e.g. a 50-pin ribbon SCSI cable andmultiple standard floppy attachment cables) and refitted to be usedwith the 34- and 50-pin connector of the drive [6] (Figure 3). The
power converter either plugged into a spare molex power connector
from the PC’s power supply or could be powered from a standard
ATX mainboard power input (Figure 2).
Both the 24V power supply and the cable adapter board havepower requirements and fit traditional PC power cable sockets.
To connect the 8-inch drive without external power supplies, themachine needed to have a 3.5-inch floppy disk power connector
and a standard molex power connector (for the 5.25-inch and 8-inch
drives, the latter one via the voltage adaptor). Having wired all
this, the setup for the 8-inch floppy reading experiment reached an
initial working status.

This we determined was from a HP CAT command, which isinterpreted as probably from an HP 984535 series. H is the drive
type, 8 the controller select code, 0 the drive address, and 1 the unit
address. The first entry, in this example, indicates a large data fileof 1188 bytes, file type unknown.
Extracting data from 5.25-inch and 3.5-inch floppy disks, whichwere used more recently and more commonly, is readily achievable
as it is still possible to find systems which feature a 3.5-inch driveand systems which have at least a floppy controller present. At
a computer centre it is still often possible to find all components
necessary in order to get working hardware set up to read DOS
formatted disks (MFM recording format, [12]), which was the mostcommon format.
The case for 8-inch disks is more complicated. Eight-inch floppy
disks were generally out of use by the beginning/mid-1990s andwere not a common part of typical office or personal computer
systems at that time; thus, they never obtained the interest of awider enthusiast scene as did the home computers of the sameera. The 8-inch disks have a completely different form factor anddifferent connectors for both data and power supply. Thus, there is
no standard support for them in most operating systems, and very
little general information on the Internet.

2

HARDWARE REQUIREMENTS

The status of the research data was not entirely clear and there
was some indication that the disks might contain private (clinical)
information on living persons. Thus, the disks could not be sent
off-site. As no service company or expert who was knowledgeable
about these disks could be found within the vicinity, we started ourstudy with the selection and acquisition of the hardware required
to capture the bits.
2

system(s). The same applied to the differences of the kernel configuration which only officially knows about 5.25-inch drives andhas no knowledge about 8-inch drives. Unfortunately, our research
revealed that there were multiple systems which used 8-inch drives
quite differently with regard to format, capacity and geometry (e.g.
just for IBM floppies of that format, [26]).
When doing these first trials, the kernel or tool messages indicated an ”active write protection”. The re-configuration of the drive
to WP (honour write protect) or NP (not protected) did not change
anything in the ongoing formatting tests with fdformat. Mysteriously, after a while the ”active write protection” disappeared for an
unknown reason.
It was possible to low-level format the test Nashua floppy disk
using a rather wide range of settings, but the verification failed forevery setting. It is known that these formatting tests run smoothly
on 5.25-inch floppy drives by a stepwise movement of the read/write
head. However, on the 8-inch drive some settings, especially thehigher density ones, produced strange jumps of the head and odd
sounds. The DBit controller displayed the same track number on
its two-digit seven-segment display as the fdformat gave for its
operation (Figure 3).
Finally we did a simple reading test by inserting the disk andexecuting a directory listing command (ls /dev/fd0 and mdir a:).
All “read” tests of different disks, including those from the archive,
failed as track 0 could not be read. This was a first indication that thedisks were not of DOS environments origin, possibly complicating
the access significantly.

Figure 3: Electrically adapting the drive and providing a
track readout

Checking the system
As no-one was really familiar with the drive, some preliminary
tests were run with standard floppy drives. To create a baseline
for the experiments, the two machines were checked with both3.5-inch and 5.25-inch drives and subsequent floppy reads (1.44 MB
floppies for 3.5-inch drive and both 360 KB and 1.2 MB floppies in
the 5.25-inch drive). We imaged 5.25-inch DOS formatted floppy
disks using the Linux dd rescue command and Linux mtools. The
drives and controllers were confirmed to be working properly.
The BIOS settings in the PC did not need to change as they can beoverridden when loading the Linux kernel. The only prerequisite isan enabled floppy controller. The Linux module floppy.ko takes(repeated) parameters in the form of floppy=0,1 (indicating thephysical floppy drive and the type of floppy respectively). Nevertheless, the Linux kernel is not aware of 8-inch drives and has no
specific settings for them in the module.
The 8-inch drive was connected and the BIOS of the machine
configured to 5.25-inch drive. It could be seen, by the flashing access
LED, that the drive reacted to commands issued by the controller,
for example, when loading the kernel module or running a program
which required access to the drive.

3

4

USING THE BITCURATOR LINUXENVIRONMENT

To rule out hardware-related issues such as cabling, the first suboptimal connection – a long cable with an open end which might leadto signal reflections – was shortened and a second edge connector
cable was produced. The new one avoided any malfunction of theconnector as it was an original 50pin.
A PC was then booted from a USB stick containing the BitCurator suite to avoid any hardware emulation a virtualization layer
might introduce. The number of tools in this particular setup was
limited to the command line floppy and raw IO tools available
with the Linux operating system, such as: getfdprm, setfdprm,
fdrawcmd, fdformat, mtools, dd, and dd rescue.
One of the major challenges was the lack of experience withthe 8-inch drives and floppy disks. Thus, trial and error was theapproach used. The knowledge needed to be unearthed step-bystep hoping to find the relevant bits and pieces to get everythingworking in the intended way.
For this task the web site of the Linux floppy disk utilities [25]was consulted as the Linux man (manual) page only explains thecommand line settings but does not give examples. We reproduced
various suggestions provided from the ”How to identify an unknown disk using Fdutils” section. ”Finding out the number ofsides (heads)” helped us to determine that the test disk we used
was actually single sided and that two sided formatting and verifying must fail. Further configuration parameters were checked
and tested using fdrawcmd and setfdprm, followed by a successful
low-level formatting tool. Error messages were checked from both

PRELIMINARY READING AND WRITINGTESTS

To conduct some preliminary experiments on the drive, an unused
8-inch floppy (manufactured by Nashua), of unknown quality, wastaken from a display case of obsolete media in the computer centre.
This was done to run some reading and writing experiments tosee if the floppy could be formatted and read without endangering
the original disks. One of the challenges was the unknown characteristics of both the floppies and the drive. For the latter there
was a specification sheet which came with the drive. It was notapparent to which degree the controller/drive combination would
be able to read floppies, which were created on completely different
3the tool’s printout and the kernel log file. The need within the wider
Linux community for floppy disk tools will diminish further andthe web site, last updated in May 2005, is in risk of disappearing at
some point leaving no or only a few traces.

Disk Geometry and other Parameters
For non-familiar users the options for the disk geometry remain a
bit opaque, apart from the recording mechanism which is presumed
to be MFM and cannot be changed. For example, typically the drive
supports 77 cylinders (should equal number of tracks), but the IBM
specification for type 2D (printed on the BASF disks) have a special
index cylinder and then 74 usable cylinders [26]. While the index
cylinder configuration remains the same, the remainder can differ
significantly.
The label on the Nashua test disk revealed very little. Thereis a part number (FD-1D-WP) which we were able to verify is asingle-sided double-density floppy disk. The specifications on theoriginal manufacturer’s box listed on the side of the carton are as
follows: FD-1D WP-R (the item number), S.S. / D.D. SOFT whichtranslates to single sided, double density, and soft sectors. This
explained the failures of the previous low-level formatting verification experiment: A single-sided disk can actually be formatted as
double sided, but reading from the empty side will fail. Changing
the parameters to single sided with setfdmprm progressed ourattempts at verification.
The fdrawcmd can issue raw floppy controller commands in order to discover the data transfer rate, the sector numbering scheme,
and the number of sides on a disk. We successfully ran this on
the test disk to confirm the geometry. Unfortunately, we were notsuccessful when trying the target disks. We had to rule out possible
problems such as:

Figure 4: Connecting an oscilloscope to verify magnetized
structures and check for patterns

on track 0 and started with the Nashua disk, using fdrawcmd to
produce read signals, which produced a visible pattern of different
frequencies on the oscilloscope. In further rounds, we looked forsimilar patterns on track 0 of the other disks. The picture obtained
was quite different and looked more like white noise compared tothe measurements on the Nashua.
Changing to a higher track number produced, for both classesof disks, patterns which were definitely visible. This could explain
why we were not able to read anything with the methods we had
been applying up to that point.
The oscilloscope setup had some limitations for the purpose ofdata interpretation. We were unable to store longer sequences ofsignal readings but could only freeze the content of the screen(Figure 5). For further stream interpretation a logic analyzer would
be useful, e.g. a Bitscope Micro with DSO Data Recorder software[1].
The readings from the disks did not imply that they were completely empty. We had confirmed that our hardware setup of the
8-inch drive and the adapters were working, and that the disks
seemed to contain something, our next step was to employ somemore advanced approaches, such as forensic floppy controllers.

• The disks were not formatted at all. Even though thesewere backup disks, as implied by the labels, that is no
guarantee that they had ever been verified.
• The disks may have been improperly stored before they
were transferred into the university archive, thus losing
most of the magnetic charge.
• The drive simply cannot interpret the recording format.

5

USING AN OSCILLOSCOPE

To identify if the disks contained any recorded information at all,an oscilloscope was connected to the analogue amplifier behindthe magnetic reading head. A GW Instek GDS-1022 oscilloscope
was linked to the disk drive at AD3 and AD4 on the read circuit(Figure 4). The signal was set to normal level 2.8V on TP-AD3 and2.75V on TP-AD4. Signal peaks for both channels were 800Vpp.
The rotational speed of the 8-inch floppy drive is rather slow
compared to modern equipment and the recording density is very
low. Even with just 26 sectors of 128 Bytes, a substantial number ofchanges in the magnetic flux are required to represent the data. It
was hoped that it would be possible to at least distinguish between
an unformatted disk (or demagnetized disk due to bit rot) and adisk containing data: white noise in the first case and some visible,
repeated changes in the second.
To trigger readings, the low-level program fdrawcmd was run
with different options on several disks [25]. Initially, we focused

6

KRYOFLUX AND CATWEASEL

Having established that the delivered disks were not empty, different approaches were chosen. These circumvented the use of
the standard floppy controller to allow a more direct access to themedium [13]. The KryoFlux and Catweasel floppy controllers are
add-in cards which were designed to read disks at a low-level approach and circumvent most of the built-in PC floppy disk controller
logic.
As the University of Freiburg does not have either of these devices, we asked for help from our colleagues at the Computerspielemuseum (Computer Games Museum), Berlin who have both
4

The KryoFlux Again
After connecting it all up, we powered up according to the KryoFlux
manual but the software reported that it did not recognize hardware.
This was strange as we did have it working earlier in the day.
Checking everything again, we noticed that the circuitry was
getting power from two sources and deduced that this was preventing the KryoFlux from resetting. We then unplugged power to allcomponents except the laptop, rebooted and then plugged in the
KryoFlux and then powered on all downstream components. This
was the correct way to do it. The KryoFlux recognized the drive
and we were able to start imaging.
The imaging was set to output KryoFlux Stream Files, preservation and all other settings to the default values. This meant that83 tracks were tried on each side of the disk, resulting in ”Error
reading stream device” from track 77 onwards (with tracks startingat 0).
We managed to get an image for each disk, albeit in so far uninterpreted stream files. The stream data contain two items of logical
data, the timing of flux transitions and timing of the index. This isjust a very low-level interpretation which does not translate at all
into human-readable form without further transformation. Eachdisk took around 4 to 5 minutes to image.

Figure 5: Oscilloscope screen capture

a KryoFlux and a Catweasel for their huge collection of magnetic
media from a wide range of computer and gaming systems.

7

ANALYZING THE MAGNETIC FLUXDiskettes are magnetic storage media on which small areas are more
weakly or more strongly magnetized. The magnetic read heads on
a disk drive operate by detecting the changes in the magnetic flux.
The encoding specifies how the bit is written to the disk surface,
and the disk format specifies the byte sequences to represent thestructure of the data, such as the cylinder, head number and sector
number.
A disk format is the organization of data on the disk whichenables the computer system to recognise and verify the data. The
bitstream (flux) is separated into addressable parts – sectors – withdata marks and address marks in order to tell different types of
information within the sector apart and to perform error checking.
The binary information is encoded as a pattern of magnetic flux
reversals, that is, changes from “0” to “1”.
Recordings are made on a single track at a time. A track consistsof a serial sequence of bits which are all interpreted as 8-bit bytes.
To ensure that there are changes in magnetisation, an encoding
method is used.
The read electronics must be able to get and maintain bit andbyte synchronization. Bit synchronization is achieved with a clock
bit, i.e., encodings have data bits separated by clock bits.
In MFM encoding, the first pulse period always contains a clock
pulse; the second pulse period may or may not contain a data pulse.
If the digital data is a “1”, a data pulse will be present in the second
pulse period. But, if the digital data is a “0” then there is no pulse
present (see Figure 6).
The KryoFlux stream format [16] is recorded in binary, andrecords only the changes in the magnetic flux of a given trackwith timing information and cannot reveal any bits directly. The
KryoFlux software suite contains stream analyzers for a wide rangeof different recording encodings for a variety of systems, e.g. FM,
MFM and so forth. It was unclear on which system the floppies

The KryoFlux
The KryoFlux card is built into a tower case containing a power supply unit (PSU), a 5.25-inch drive and a 3.5-inch drive. The Mitsubishi
drive was connected to the KryoFlux which in turn was connected
to a Dell laptop running Windows XP. The 50-pin data cable wasconnected to the fdadap floppy disk adapter, then the 34-pin to
the KryoFlux. The KryoFlux was connected via USB cable to thelaptop. The 5V/24V power supply to the disk drive was provided aspreviously described.
For our initial test of our setup we used our test disk, which failed
after reading only the first track. As this test disk has consistently
failed, we concluded that it is a dud disk. We then tried to calibrate
the drive. This was a bad move, as it calibrated only to track 0 and
subsequent attempts at imaging also failed.

The Catweasel
Please note that the Catweasel is no longer manufactured as thedemand and interest in magnetic floppy media has diminished. We
knew of software that worked with Catweasel to image 8-inch disks,
so we connected the Catweasel system to our disk drive and tried
to run the Catweasel software ImageTools 3. However, as there isno configuration for 8-inch disks this did not work out. We thentried cw2dmk [17], as the documentation mentions 8-inch disks andthat a variety of formats can be imaged. Unfortunately, this also
did not work, returning the error ”Failed to detect any drives”. To
make sure that the Catweasel device was in good working order,
the 5.25-inch drive was reconnected and we successfully imaged
a Commodore 64 disk. Retrying the 8-inch drive, cw2dmk failed
again with the same error. Later on it was discovered that cw2dmk
does not work with Windows XP. Another backwards step!
5

are clearly visible (in the cases evaluated). They are additional indicators for data written.
As some of these results contradicted the expected results, e.g.
recording format and sector size, continued analysis was necessary.
Statistical analyses on the KryoFlux streams established the numbers for each length of signal (ground truth). There were visible
clusters and only a few outliers (magnitudes less than the number
in clusters). The distortions in sector writing are some of them.
To reproduce data from the stream requires a correct clock signal,
which is challenging as a binary “1” is a changing phase in the
middle of a cycle (and then no additional clock signal is inserted);otherwise a clock is reproduced from mandatory phase changes ofconsecutive binary zeros.

Figure 6: MFM encoding
were actually written, so all options for different encodings weretried and all failed.
In the meantime, we had identified the drive type as an HP9895A
and researched the drive specifications from the resources at the HP
Computer Museum [3] and The HP 9845 Project [14]. It was discovered that this disk drive could read and write both Frequency Modulated (FM) and Modified Modified Frequency Modulated (MMFM or
M2FM [12]) encodings. The KryoFlux software had not recognized
an FM encoding, so we surmised that the encoding was possibly
M2FM, with Least Byte First and Least Bit First. While these sites
have a wealth of information, documentation of the M2FM format
is missing.

# snippets of Python code for KryoFlux stream analysis# distance of Data or Clock bits in M2FM multiples of 24
def genBitList() :for i in xrange( 300 ) :s = '1'i -= 24
while i > 24 :s += '0'i -= 24
if i >= 16 : s += '0'
bitList.append(s)# extract a byte 'Clock' and 'Data' of a byte
def pDataTakt(header , bits ) :# parse on BYTE DATA and CLOCk
Clock = 0
Data = 0
for i in xrange(8) :Clock *= 2
Data *= 2
if bits[(i)*2] == '1' : Clock |= 0x1
if bits[(i)*2+1] == '1' : Data |= 0x1
Clock = revOrder(T)Data = revOrder(D)return revBitOrder(Data),revBitOrder(Clock)# extract a complete sektor from bits
def pDataTaktData( header , bits ) :C = []T = 0
D = 0
c0 = ' 'c1 = ' 'for i in xrange(0,len(bits),16 ) :C.append(bits[i:i+16])
Sektor = []for i in xrange( len(bits)/2 ) :T *= 2
D *= 2
if bits[(i)*2] == '1' : T |= 0x1
if bits[(i)*2+1] == '1' : D |= 0x1
if (i%8) == 7 :c0 = B(c1)c1 = B(chr(revOrder(D)))
Sektor.append(revOrder(D))...

Creating Logic Analyzer Software
A small Python script was written to reproduce the recording patterns to be analyzed and visualized in logic analyzer software. A
major challenge was to derive the clock signal from the recording
as all possible encodings are self-clocked (Figure 6). While the lowlevel formatting creates quite clean recording patterns the actual
data written to sectors often implies tiny distortions (jitter) as it
is impossible for the mechanics of the drive to perfectly sync to
the clock. This step was really helpful as we were now able to scanalong the stream of each track. Our first interpretations were:• The recording format appeared to be FM (and not M2FM
or MFM as we expected to see).
• The low-level format of the system produced clearly visible synchronization patterns at regular distances. One
followed by a short block of data, the next one followed bya long block. These patterns were visible for every track.
• This was interpreted as possibly a kind of an information
header to the sector that follows, which presumably contains the actual data.
• Counting the zeros – which are easier to count, especiallyin an empty sector – in the graphical representation weestimated a sector size of 128 Bytes. This contradicts the
specifications for the HP drive which has 256-Byte sectors.
• Each information block seemed to contain data (a few nonzeros) which is different for each block. This information
seems to be created during the low-level formatting of the
disk.
• Some data blocks contain information (significant numberof non-zeros).
• If the data block contains information, it was presumably
put there later (after the low level formatting). There aretiny distortions visible at the end of the information block.
It is nearly impossible to perfectly synchronize with theoriginal recording [13]. This creates tiny distortions which

Taking this information into account and introducing a clock marker
into the visualization (Figure 7), it became clear that some of the visible code violations do not match the FM possibility. Additionally,
the statistical analysis on the phase-length FM could not completely
explain the reproduced pattern. We now concentrated on the M2FM
6

encoding possibility and put out a call for help on Internet fora andto other universities.
Our next step was to create an actual bit stream for each data
sector and read the sector information. The main challenge in thislay in the reassembling of the bitstream into bytes.

8

CONSOLIDATION

After three months of research, as well as trial and error experimentation, we received confirmation that the machine was an HP9845
with an external floppy drive, the HP9895A disk drive, attached.
The disks have 77 tracks or cylinders, and contain 30 sectors withan interleaving factor of 7. The machine was marketed for scientificpurposes and was popular in the university till the mid-1980s before
the IBM PCs were introduced. It offered a wide range of peripheralconnections and general programmed input/output (PIO).
Many of the floppy disks contained in the set appeared to havemostly data of clinical trials on them, judging from the file names
and brief descriptions on the disk labels. At this point, we still
did not know how these data were organized and if there was text
contained within the files. The reason for looking for text files was

Reassembling the Bitstream
At a well-timed moment, we received responses to our call forhelp which provided us with more information for a decoder andconfirmed the recording format as M2FM. With this knowledge,
we started decoding the header information (short ”sectors” after asynchronisation pattern) from the KryoFlux output.

Figure 7: Extract of bitstream showing identification markand track number
Sector information is not easily retrieved, as a track recording
does not necessarily start with sector ”0” and usually contains morethan a single rotation of the platter. This information is contained in
the short block after a sequence of 32 binary ones. We did a visualcount in the representation from the logic analyzer software (seeFigure 7). Directly after the pattern follows the identification markwhere we found the 0x70 hex address mark (after bit swapping andreading from right to left) and then the track address information.
The track (or cylinder) number 31 (0x1F hex) was displayed in thenext byte. Both bytes produced expected results which validated theapproach. Having established the proper byte boundaries, the flux
stream interpreter could now be completed. The simple structure of
the disks simplified the task, as no complex hierarchical filesystem
structure had to be taken into account to reassemble the files.
The proof for a properly working script was the reproductionof file names and occupied sectors which could be successfullycompared to the sheets available in some of the disk sleeves.
ETTX..<......... | TEXT...<........
OPEW.R=./....... | POWER..=./......
OR.M............ | ROM.............
RBTASI..K....... | BRATIS...K......
NIHFLD[.w....... | INFHDL.[.w......
HCBKLE..\....... | CHKBEL...\......
...

Figure 8: Decoded text from an 8-inch diskthat text was encoded in ASCII with each character taking one
byte of storage, while the numeric data was encoded with different
byte sizes dependent on whether they were full-precision numbers,
short-precision numbers or integers. One of the disks was labelled”Publications”, so this was selected to test our flux stream decoder.
An extract of the result of decoding one track is in Figure 8, whichshows the hexadecimal value of each byte, the ASCII character, andthe byte-swapped version.

9

IMPLICATIONS

Preservation projects that we and others have undertaken haveshown us that legacy hardware is still a significant part of thedigital universe [7, 8, 13, 23]. These projects may be in the formof complete systems or (removable) storage media. The last 30
years produced a plethora of magnetic, optical and more recently
electronic removable and fixed media including audio and video
cassettes, cartridges, floppy disks, ZIP disks, Syquest drives, harddisks, and so forth [11, 19], in a variety of formats. Many of themwere deployed as archival media, especially the cheaper ones. While
floppy disks and optical media such as CDROM, DVD (or Bluray Disks) might be more common, other items including ZIP,
Syquest, Jaz, LS-120, SparQ, Orb or MicroDrive might surface inthe legacies delivered to special collection libraries or digital arts
institutions. More recently, electronic media like CompactFlashcards, memory sticks or multimedia cards will complement thealready wide selection.
The drives to handle certain removable media have begun todisappear from the typical second-hand markets, e.g. it is much
more difficult to obtain a (confirmed working) 5.25-inch drive thanTEXT
60 - 61
POWER 61 - 108ROM925 - 1115
BRATIS 277 - 352
INFHDL 1115 - 1234
CHKBEL 465 - 557

During the different experiments, more facts about this floppy disk
format were gathered. The disks contain an unusual number of sectors compared to the typical structure of IBM- and PC-style disks:
30 sectors instead of the expected 26. These sectors are interleaved
and track numbers are not consecutive. The flux readings, createdby the KryoFlux tools, contain in their track readings approximately
five rotations of the platter. This offered the opportunity to compare different readings of the same sector to each other, and help
eliminate errors due to inconsistent timing (jitter).
7

it was just five years ago. In short Successful [media] migration
diminishes as the age of the medium, or hardware necessary to readit, increases. While most studies focuses [sic] on the longevity of themedium, no doubt fuelled by manufacturing marketing, the true risklies in the scarcity of hardware necessary to read these formats [10].
Compared to the ease of low-level analysis of 8-inch media, thechallenges will increase for most of the recent much more compact
and integrated storage peripherals. Some devices became much
more proprietary and were manufactured by just one company.
These developments increased the number of different standards,
but narrowed the amount of different media available for a particular device. Increasing capacities require more advanced technology
to squeeze data onto increasingly smaller media.
For many smaller institutions it does not necessarily make sense
to maintain a full collection of possible readers and peripherals.
For a range of once-popular formats, business models are wellestablished like media transfers from various magnetic tapes. Additionally, there is a selection of transfer peripherals available aslisted in the addendum of [13]. Nevertheless, some implementations, especially for USB, might be incomplete or erroneous.1
One strategy, especially for digital art collectors and memory
institutions, is to buy spare older equipment for backup or replacement parts, filling their storerooms and taking precious space without the guarantee of usefulness when required [2]. But, as ourstudies confirmed, there are certain gaps in the service domainchallenging memory institutions, such as Freiburg, Archives New
Zealand and others seeking to read old 8-inch disks.

many cases, the interfaces do not exist or have changed
significantly. An 8-inch drive had a 50-pin connector; forthe later 5.25-inch and 3.5-inch drives, these were replacedwith 34-pin connectors.
• Parallel connections were superseded by high-speed serial
connections as seen in the transition of IDE to SATA.
• The Universal Serial Bus (USB) standardised the connectionof commonly used computer peripherals to personal computers, both to supply electric power and to communicate.
Thus, it is possible to connect a RS232 serial cable or IDE
and SATA cables to USB via an interface adapter. However,the voltage supplied by the USB may not be high enoughfor older serial connections, and some IDE adaptors do
not comply with all aspects of the specification standard
making it difficult to properly image e.g. an early laptop
IDE hard drive.
• Lack of technical knowledge about connectors, unusual
sockets, and plugs cause difficulties: incorrect wiring candestroy well functioning, precious hardware.
• Small embedded components or a System-on-a-Chip (SoC)
can replace complete controllers, nonetheless at some pointa particular cable or power supply will still be required, as
well as the knowledge and expertise on how to connect it.
• Finally, some ”glue component” like a firmware or drivermight be required to make the peripheral accessible fromthe operating system.

Hardware and Documentation Repositories

Bridging the Technical Gap

The need for preserving hardware, software and documentation has
been raised for decades. In 1992, the Commission on Preservation
and Access [15] recommended that Computer museum operators
can be urged to maintain software as well as hardware, and to beable to operate old programs for purposes of translation. The samecall was made by McDonough et al. in 2010 [18] and Rieger et al.
in 2015 [21]. As Buskirk [2] put it … equally urgent is burgeoning
obsolescence that leaves orphaned media with no equipment on which
to be played or software that is incompatible with current platforms.
This aim has not yet been realised.
Dissemination of preservation techniques and workflows is wellestablished for tasks to be undertaken after a usable digital imageis acquired, and for popular formats, e.g. 8mm film or VHS to DVD,but little is available for older or rarer artefacts. Much of what isavailable is in the hands of hobbyists, enthusiasts and digital forensic scientists [10]. Although many hobbyists provide information
online, these sites are often not updated and if interest in the topic
wanes, the effort needed to maintain the site may outweigh the use
for the site owner(s). During this project, the website on which we
found the information for the Nashua disk disappeared. The National and State Libraries of Australasia [24] report that inhibitors
to data transfer include

A digital object is created in a physical and system environment[22]: the former with specific hardware components, the latterwith a specific operating system version and utilities. Specialised
software, such as digital art and video games, depend on particular
hardware for interaction or rendering. Peripherals and controllers
need hardware interfaces which become rare as computer technology evolves. While the development of system emulators is seen asa solution to some of these issues, original hardware is needed toprove that an emulator is working properly.
Preservation of born-digital objects necessitates links between
past, present and future hardware. A great deal of this can behandled via peripherals. As demonstrated in this 8-inch floppy disk
case, challenges are faced at different stages and technical levels.
While some of these challenges are unique to each specific type of
medium, others follow a pattern, and these will surely repeat forother storage media, such as the following:• A peripheral to read a particular storage medium must
be powered in a specific way. Previously, the voltage andpower requirements were much higher than today, 24V andalternating current (AC) connections are now uncommon.
In addition, the old types of connectors are no longer manufactured and their documentation of the pin assignment
does not typically come with the device.
• To transfer the data to new media, a peripheral or complete
computer system is connected to a current system. In• no in-house equipment and equipment is not easy to source• lacking the appropriate drives• no internal expertise or staff that have suitable skill set• no robust workflows for disk imaging
This paper has concentrated on 8-inch disks in M2FM format; data
retrieval methods for BTOS/CTOS formatted disks at Archives New

1 Challenges and solutions of imaging 20-plus-year-old IDE disks, http://openpreservation.org/blog/2013/03/20/challenges-dumpingimaging-old-ide-disks8

Zealand and the University of Freiburg are documented in [23].
Substantial personnel effort and time is invested in setting up theequipment for these projects, as well as financial costs. Often, theequipment is used for a single project, meaning that the return ofinvestment is low, and the acquired knowledge is lost over time.
There are many computer museums around the world, however
their primary mission is to preserve and display computer systems,
not the preservation of born-digital objects. There is a growing
need for there to be centres for the transfer of born-digital artefacts to current media which are hubs of expertise and resources,
who have a collection of obsolete computers, peripherals, softwareand manuals, such as the National Library of Australia, for theirdigital collection, and the Computer Archaeology Laboratory at
Flinders University, who undertake research into recovering datafrom obsolete media.
Technical documentation is a vital resource which is also rapidly
disappearing, hardcopy manuals and handbooks are seldomly digitised for online access, especially for devices that are currently
perceived by the general public to be out of use.

10

would benefit significantly from these repositories. Such activities
must be complemented with modified archival workflows to prevent items falling into limbo between becoming out of use within
the institution and being handed over for archiving. Research data
management will help to mitigate such challenges in the science
domain.

REFERENCES[1] BitScope. 2016. BitScope Micro. http://www.bitscope.com.
[2] Martha Buskirk. 2014. Bit Rot: The Limits of Conservation. Hyperallergic. http://hyperallergic.com/131304/bit-rot-the-limits-of-conservation.
[3] David Collins. 2016. HP Computer Museum. http://www.hpmuseum.net/.
[4] Jason Curtis. 2017. Museum Of Obsolete Media. http://www.obsoletemedia.org/
8-inch-floppy-disk/.
[5] D Bit. 2016. FDADAP floppy disk adapter. http://www.dbit.com/fdadap.html.
[6] Bart de Vries. 2016.
Digital Obsolescence:
Reproducing Floppy
Data Cables.
http://openpreservation.org/blog/2016/09/02/
digital-obsolescence-reproducing-data-cables.
[7] Denise de Vries and Craig Harrington. 2016. Recovery of heritage software
stored on magnetic tape for Commodore microcomputers. International Journalof Digital Curation 11, 22 (2016), 10.
[8] Denise de Vries and Melanie Swalwell. 2016. Creating Disk Images of Born
Digital Content: A Case Study Comparing Success Rates of Institutional Versus
Private Collections. New Review of Information Networking 21, 2 (2016), 129–140.
[9] Jürgen Enge and Heinz Werner Kramski. 2016. Exploring Friedrich Kittlerfis
Digital Legacy on Different Levels: Tools to Equip the Future Archivist. iPRES
2016 (2016).
[10] Miriely Guerrero. 2012.
Division Records-Digital Curation-PapersRemovable Media and the Use of Digital Forensics.
(2012).
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/96441/Guerrero IMLS
RemovableMediaReport 20120702.pdf Bentley Historical Library.
[11] David Christopher Harrill and Richard P Mislan. 2007. A small scale digital
device forensics ontology. Small Scale Digital Device Forensics Journal 1, 1 (2007),
242.
[12] John F Hoeppner and Larry H Wall. 1980. Encoding/Decoding Techniques Double
Floppy Disk Capacity. Computer Design 19, 2 (1980), 127–135.
[13] Matthew G Kirschenbaum, Richard Ovenden, Gabriela Redwine, and Rachel
Donahue. 2010. Digital forensics and born-digital content in cultural heritage
collections. Council on Library and Information Resources.
[14] Ansgar Kueckes. 2016. The HP 9845 Project. http://www.hp9845.net.
[15] Michael Lesk. 1992. Preservation of New Technology. A Report of the Technology
Assessment Advisory Committee to the Commission on Preservation and Access.
Commission on Preservation and Access, Washington DC, USA.
[16] Jean Louis-Guerin. 2013. KryoFlux Stream File Documentation. www.kryoflux.
com/download/kryoflux stream protocol rev1.1.pdf.
[17] Tim Mann. 2010. cw2dmk. https://github.com/ezrec/cw2dmk.
[18] Jerome McDonough, Robert Olendorf, Matthew Kirschenbaum, Kari Kraus, Doug
Reside, Rachel Donahue, Andrew Phelps, Christopher Egert, Henry Lowood,
Susan Rojo, and others. 2010. Preserving virtual worlds final report. University
of Illinois at Urbana-Champaign (2010).
[19] National Library of Australia. 2008. Mediapedia: Physical Format Carrier Resource.
http://mediapedia.nla.gov.au/.
[20] DPC Online. 2017. Digital Preservation Handbook Legacy Media. http://www.
dpconline.org/handbook/organisational-activities/legacy-media.
[21] Oya Y Rieger, Tim Murray, Madeleine Casad, Desiree Alexander, Dianne Dietrich, Jason Kovari, Liz Muller, Michelle Paolillo, and Danielle K Mericle. 2015.
Preserving and emulating digital art objects. (2015).
[22] Kenneth Thibodeau. 2002. Overview of technological approaches to digitalpreservation and challenges in coming years. The state of digital preservation: an
international perspective (2002), 4–31.
[23] Dirk von Suchodoletz, Richard Schneider, Euan Cochrane, and David Schmidt.
2012. Practical Floppy Disk Recovery Study. Preservation of Digital Objects (2012),
184.
[24] Scott Wajon, Somaya Langley, and Damien Cassidy. 2016. Collaboration on
Digital Infrastructure Project 3: Obsolete Physical Carriers in NSLA Collections.
National and State Libraries of Australasia. http://www.nsla.org.au/publication/
obsolete-physical-carriers-nsla-collections-stage-1.
[25] Webresource. 2005. Fdutils. https://fdutils.linux.lu/disk-id.html.
[26] Wikipedia. 2016. IBM 8-inch formats. https://en.wikipedia.org/wiki/List of
floppy disk formats.

CONCLUSION

Preservation of data from obsolete digital media is not a straightforward exercise. While many floppy disk formats have been studied
and have solutions available for them, there are still many, whichwere widely used, that have not yet been deciphered. This project
took a lot of patience, a lot of following hints and hunches to trackdown relevant information, and experimental analysis. We werealso aided enormously by the generosity of strangers.
Confirming the disk format and model of the original system
took quite a while, until we finally made contact with someone who
was involved with the scrapping of the system. Various different
levels of forensic science came into play: physical, logical, andhigher level information were all needed to identify the system, thedrive, the disk format so that we could finally extract some text.
Extracting other data content is much more complicated. We
now know that mostly scientific analysis work was carried out on
the system, with a large amount of the data being used in databases,
spreadsheets and custom-written analysis software. It is difficult tointerpret the non-textual data without the context or the software,and we cannot tell if we have the right numeric values, whereas it
is easier for ASCII text. We pretty much ended at the point of the
5.25-inch floppy disk recovery study being in need of the original
software of the system the data was created with [23]. Additionally,
it could be helpful to directly link KryoFlux images to special stream
readers built into emulators that interpret the streams directly as
disk drive sources, such as in the WinUAE Amiga emulator.
As seen in Figure 8, there are undecipherable characters within
the text, these could be word processor formatting codes for specificstyles or characteristics of the document, or something else entirely.
Our experiences have reinforced the importance of and needfor repositories of knowledge and resources for the initial steps ofdigital preservation – the creation of usable digital images – whichshould parallel the sharing of knowledge that has evolved aroundthe handling and future-proofing of artefacts held in galleries, libraries, archives and museums. Especially smaller institutions, lacking the resources for such special-purpose departments in-house,
9

ACKNOWLEDGMENTS
Many thanks to
Mick Crouch (Archives New Zealand) and Euan Cochrane (Yale
University Library) for advice and moral support,
Eric Smith for information about HP devices,
Christian Corti (Computer Center University of Stuttgart) for assistance with analyzing the M2FM encoding,
Konrad Meier (Computer Center University of Freiburg) for providing the oscilloscope and helping with the configuration of the experiment and interpretation of the readout, the Freiburg Emulationas-a-Service team to provide support and hardware, and finally
Jeannette Vollmer to proof read the paper.

10