[vcf-midatlantic] How To Geek article on floppy data recovery
hjohnson at retrotechnology.info
Sun May 10 14:21:47 EDT 2020
> Jack Rubin > Sat May 9 09:41:14 EDT 2020
> Hard to reply directly to your post since I only get the vcf digest, but a couple of points re new modes of disc (I'm an HP fan) imaging.
> 1) The flavor-of-the-day MCU or whatever isn't as important as maintaining accessible disk images and metadata. Flux level transcriptions weren't really practical when Dave Dunfield was building his ImageDisk system, so we should be thankful for all the extra CPU cycles available to us today, especially in a $15 package.
> 2) The approach is a little different but the philosophy is the same - for ImageDisk stuff, I still have a Dell 486 with all the right stuff, including an FDADAP and a Thinker Toys 8" floppy, but I also have a couple virtual machines with the proper toolchains installed to control a few Arduinos and PSoCs for the new stuff that demands a full software ecosystem beyond the hardware. More important, today's cutting edge developers can still read (and write?) .imd files.
> I was thinking about this last night as I was installing and configuring all the stuff necessary to start working on my first Verilog project. It took me a lot longer to get the point where I could blink a light on the demo board than it would have to reconfigure a CP/M bios for a new serial card and sysgen a new system.
> Be well and stay safe,
Always good to hear from Jack Rubin, an old friend. I'm going to reply
back in the previous thread, and include Jacks' post there. And I've not
decided I'm being a curmudgeon, yet. My responses focus on the tech, not
my attitudes. Unless of course, being technical is old-school now. ;)
Again, this argument takes awhile. For the impatient: Jack has not
convinced me of the merits of short-term disk-imaging solutions. I'm
focused on the delivery hardware; Jack on the imaged disk results. In
effect, he's conceding to the modern reality of what I call "popsicle
stick computers". But I think he misses something, in not focusing on
the problem of non-persistent tech, and ignores problems with
flux-imaged file formats. I end by pointing to the irony that interest
in keeping old stuff around is called "curmudgeon" in a vintage
Jack's point 1 says, accessible disk images and metadata matter. That is
correct. But that's not all that matters. Of course, if we are voting on
what matters: then a million for-free emulator users, outnumber the
hundreds who create the disc images. But whose role is critical?
The problem I point at, is disk imaging hardware and software which
becomes obsolete. The fact it's $15 technology makes it more LIKELY to
become obsolete. And when the hardware is obsolete, you can't add more
imaged discs, and at some point the already-imaged content become less
accessible as the software falls out of favor, off-line. And developers
of new-tech, often enough start from scratch.
This consideration has occurred with a more expensive tech - the
Catweasel. Only persons who bought those decades ago, can exercise the
hardware; the software has persisted but many people are unfamiliar with
the device or its flux image formats. That's what obsolete looks like.
An aside: Dunfield didn't need to flux-image diskettes, because almost
all the 1980's and 70's diskettes in question, were accessible with many
available ISA based PC-compatible floppy controllers. Dunfield's genius,
was to identify appropriate floppy controllers!(Some stuff got left
behind: Intel Multibus M2FM format disks took decades to be recovered
for reuse. That history I know.)
And: he came up with means to native floppy controllers which were
incompatible. Namely, one injects into the native machine a downloader,
which can then download a native program to format and fill a
diskette-image - COLD. And: Dave stored his .IMG images as BYTE data in
sector/track order, in a specific format.
The .IMD format became a defacto emulated-disk format for many emulators
of 1970's and 80's computers in the PC-compatible enviroment (of the
1990's forward). Those emulators would have gone nuts, decoding fluxes.
As Jack points out in his point 2, many developers today still support
.IMD format. It's hard to avoid: it's essentially as-recorded
I dwell on those points, because all those features of Dunfield's work,
have been reinvented by other people - or forgotten by other people - as
they reinvent disk imaging technology.
Jack's point 2. He says "the philosophy is the same" between using a
1990's PC and IMAGEDSK and physical drives, versus use of a modern
desktop computer with "the proper toolchains" and "software ecosystems"
for arduinos and PSoCs.
Well, that's *almost* the problem I call out. What Jack neglects to
mention explicitly, is that for *each* Arduino or programmable system on
a chip, one needs *another ecosystem*. My point is: if one wants to
maintain or recreate an "old" (five years ago) Arduino or PSOC, one has
to have or find that old ecosystem, and find that old piece of hardware.
Jack appears to be saying, one doesn't have to "maintain". One ignores
obsolescence, simply keeps the data, and moves along to the next "flavor
of the day MCU". He doesn't say how flavor A's flux-images are
reinterpreted by flavor B's flux-imager device. Or how
computer-emulators might be obliged to support several flux-imaged
formats. In fact he leans on the obvious choice for emulators,
byte-correct formats including .IMG. I"ve all but explained why that is.
I'm aware, Jack, these popsicle-stick computers don't and can't stay
around long. They aren't built for that purpose. The world most of those
MCUs are produced for, is a short-life world. Think cell phones.
But: the Arduino world, is a meta-environment created and supported to
solve that problem. It EXACTLY allows Arduino-class devices to come and
go: one keeps the Arduino environment but changes the libraries to match
the popsicle flavor desired AND available. There's consequences that are
off-topic to discuss, but Arduino has persisted as a working solution to
obsolescence and transient technology.
But for this topic: not all Arduinos or MCUs or PSOCs have sufficient
hardware to perform rapid bit sampling of 100K-bit data streams. So,
some of the "flavored" disc-imaging hardware solutions, are not in the
Arduino universe. That makes hardware obsolescence a *worse* and
To Jack's point as I see it. To developers of these of these
flux-sampling disc-samplers and producer devices, they just hop to
current products and platforms for them. No problem - of course they
self select, we only pay attention to the successful results.
To the "customers", all my considerations are techno-babble. They aren't
developing anything. They buy what is available. The disc libraries are
there, for free. They are consumers and outnumber the producers, if it
comes down to a popularity contest.
In between, is the tough part: the people who image found diskettes.
They don't likely have technical skills, much less PSOC developer
skills. They will buy and run, whatever disk-imaging hardware they can
get today; or pass their discs along to whomever has such stuff. Or the
disks are lost. And, contrary to prior discussion, disks are still
found, and still lost.
Now: there's people who want to restore and run the vintage hardware.
Like me, like many that's part of the audience in this email list. Are
they all required to be PSOC developers? No. Are they all required to be
1980's 90's digital engineers? No. They make choices about what old-tech
to have and what new-tech to have.
But they choose between a $500 CP/M machine (or Amiga, or Mac) and a
zero-cost emulator on their laptop - who wins that? And so they choose
USB devices for $10, $20, over some clunky floppy drive that needs $100
of additional hardware for either domain. Again - who wins the vote for
modern over vintage, even among vintage-computing enthusiasts?
In closing: It's funny to use the word "curmudgeon", in an email list
exclusive to those interested in 1980's and 90's (and earlier, maybe
later) computers. Because, it references age, and the subject is
old-stuff. But the actual reference, is to old *people*, and the
consequences of having accumulated knowledge and experience, versus
(pardon me) a larger world where those are lost in normal practice.
My regards to Jack and all,
Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
preserve, recover, restore 1970's computing
email: hjohnson AT retrotechnology DOT com
or try later herbjohnson AT retrotechnology DOT info
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