
Recovering Fossil Data on IBM 8” Floppies [video] - zdw
https://www.youtube.com/watch?v=5FVwheTVWko
======
WalterBright
I retrieved my files off of old PDP-11 8" floppies by contacting a friend of
mine at cheshireeng.com who had an old 11 in a closet. He didn't know if it
still worked, but it did (yay for DEC quality!), and was able to transfer the
disk contents out via serial line. He was able to retrieve files and images
from all my disks, didn't lose a bit (yay for DEC floppy quality!). This was
after 30 years of sitting in a box.

Anyhow, I was able to retrieve my original 11 version of Empire this way:

[https://github.com/DigitalMars/Empire-for-
PDP-11](https://github.com/DigitalMars/Empire-for-PDP-11)

DEC made good machines. Not one of my machines from the 80s or 90s would power
up, though I stored them in working condition in warm and dry places. But the
30 year old DEC worked great.

~~~
dzdt
The typical thing that goes wrong with computers from the 80's and 90's is the
electrolytic capacitors dry out and go bad. This got even worse with the
"capacitor plague" of the late 90's/2000's.

I would guess the PDP-11 has fewer capacitors or of a different design.

~~~
Aloha
Higher quality caps

~~~
WalterBright
My vintage 1981 Carver amp still runs all day every day.

------
crmrc114
I love his videos he has a webpage with merch if you want to support him
[https://www.curiousmarc.com/](https://www.curiousmarc.com/)

If you are new to his channel I cannot recommend enough the Apollo AGC videos
[https://www.youtube.com/watch?v=2KSahAoOLdU&list=PL-_93BVApb...](https://www.youtube.com/watch?v=2KSahAoOLdU&list=PL-_93BVApb59FWrLZfdlisi_x7-Ut_-w7)

------
ggambetta
Somewhat related, I have a couple of tapes from the 80s that contained
software for the ZX Spectrum (mostly my first attempts at writing code). They
were written in a custom format by a custom device I no longer have, and of
which I have very little information (I managed to track down one of the
engineers who designed the thing some 30 years ago).

I have raw audio files of these tapes. I have managed to convert some other
tapes in standard ZX Spectrum format to readable files I can load in an
emulator. However, for the special tapes, there's no tooling available - all I
have is a waveform.

If I had an array of bits, I could start trying to figure out the format of
this thing. However, I have no idea how to go from a raw waveform to the zeros
and ones it encodes. My best idea so far is to write a small program that
looks for zero crossings, and depending on the timing output zeros or ones,
but I suspect there might exist some software that does this already? I have
next to no knowledge of signal processing.

Any suggestions on how to go about this?

~~~
tpmx
I'd recommend asking people at
[https://www.worldofspectrum.org/forums/](https://www.worldofspectrum.org/forums/).
This forum has been around since the 90s (iirc). I'd expect the kind of
detailed knowledge you're after to be present there.

~~~
vnchr
Interesting Q uestion you posed in your deleted comment. Unlikely to get
traction in this forum, but interesting nonetheless.

~~~
jacobush
Now I'm curious.

------
jhallenworld
They should try Dave Dunfield's ImageDisk:

[http://www.classiccmp.org/dunfield/img/index.htm](http://www.classiccmp.org/dunfield/img/index.htm)

This is used by bitsavers to preserve old data from 8 inch floppy disks. I was
able to write an emulator for a Motorola 6800 "Exorciser" that could boot
disks saved this way.

~~~
oneplane
I don't think it handles IBM formatted disks. You can use it with you have an
FDC that does some handling for you. Problem is that those disks are
practically 'punchcards-on-disk' for mainframes, not PC-based at all. Oddly
enough, it does know about paper tape.

Then again, OmniDisk can't autodetect it initially either, so perhaps the
whole concept of reading mainframe formatted disks and mainframe encoded data
on a non-mainframe system was rather problematic anyway.

~~~
jhallenworld
It does, IBM format is the most basic floppy standard (same for ASCII and
EBCDIC). I watched the video again- they did use ImageDisk for the bulk of the
transfer- you can see it flashed a few times (13:46 is one point). It's the
mostly blue screen with the red bar on the top.

------
kencausey
Part 1 for a more detailed introduction to the situation:
[https://www.youtube.com/watch?v=MPOYHQTMnf8](https://www.youtube.com/watch?v=MPOYHQTMnf8)

------
CaptArmchair
If you haven't seen this already, CuriousMarc has also done this awesome
series on the restoration of an original AGC - Apollo Guidance Computer last
year.

[https://www.youtube.com/watch?v=2KSahAoOLdU&list=PL-_93BVApb...](https://www.youtube.com/watch?v=2KSahAoOLdU&list=PL-_93BVApb59FWrLZfdlisi_x7-Ut_-w7)

And then there are real treats such as the restoration of a Teletype 33 ASR:

[https://www.youtube.com/watch?v=QzfjT1mCRww&list=PL-_93BVApb...](https://www.youtube.com/watch?v=QzfjT1mCRww&list=PL-_93BVApb5-84G5kmgfuu7TQduTMc73H)

Or them trying to get Fortran to compile on an IBM 1401 Mainframe dated 1959.
[https://www.youtube.com/watch?v=uFQ3sajIdaM](https://www.youtube.com/watch?v=uFQ3sajIdaM)

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thedance
This skewers the notion that old programmers were honed and refined by their
resource constraints. Whoever wrote these files was using a slow, expensive
physical format and wasting virtually all of it on padding.

~~~
fsh
All data was typed in by hand, and the entire dataset fit into a few boxes.
Resources were never an issue, so why optimize for them?

~~~
thedance
I think there's a practical difference between a folder full of data and a
wheelbarrow full of data.

------
sys32768
About six years ago I found several 8" floppies for the 1970s Ohio Scientific
system. These had been in storage since the late 1980s and contained games and
utilities. One disk label was dated 1/31/1979.

I sent them to the author of the OSI emulator and I believe all but one of
them were fully readable and dumped for emulation.

[http://osi.marks-lab.com/](http://osi.marks-lab.com/)

