[Intel-devsys] disk formats (was: irmx-80 diskettes)

Jon Hales jonhales at gmail.com
Sat Aug 17 03:05:14 MDT 2019

Herb, cc others

Here's a link to a useful discussion (posted in 2015, but mostly valid
today) of devices and software for archiving data from floppy disks:


The author uses the name 'Someguy' and appears to be a moderator on the
Winworldpc forum.

The advice seems soundly-based and experience-based.

I'll sort out some photos of the arrangements I use for connecting a
Shugart drive to a PC - for a future message.

I noticed that MS-DOS 2.0 supported 8 inch drives with several IBM formats.
However, this support wasn't present in later versions of DOS.

Best regards


On Fri, 16 Aug 2019 at 21:31, Herb Johnson <hjohnson at retrotechnology.com>

> Well, Roger Arrick, for a single Web page on how to deal with Intel
> class floppy diskettes; I have a few Web pages on the subject. Then
> below, a little lecture on the concept. This doesn't have much to do
> with irmx80, so I changed the subject-line.
> Do a Web search on "intel diskettes site:retrotechnology.com". or "M2FM
> site:retrotechnology.com". It's not one Web page, because efforts
> occurred over two or three decades. I covered things for different
> reasons at different times.  While I'm not the only person who reported
> on reading "funny" diskettes, I think I was early and persistent,
> particularly on the Intel Multibus side of disk images. Of course, Al
> Kossow had the persistent archive for diskette images, thanks Al!
> But in the end, I think there's three ways now to process Intel-class
> diskettes. Here's a lecture about that, with my opinions. I'm not
> arguing, I'm just laying out the landscape, answering Roger's question.
> + Obviously the first is: native systems, restored Intel development
> systems. Especially for M2FM diskettes. That's a recent achievement,
> mostly by people on this Intel-dev list! Thanks, buddies!
> + The second way, was use of what I'll arbitrarily call "MS-DOS boxes".
> Those use either IBM-PC compatible floppy controllers with Dunfield's
> imagedisk suite; or early customized disk-sampling ISA (later PCI) cards
> with specialized programs.
> Premier among the "customs" is/was the "catweasel" in various versions.
> That controller is no longer in production, and was never widely
> available. Development of software for it, forked and divided among
> maybe six developers including the producer. I tried to 'cover' that for
> years, at the time. It's time has mostly passed, but it's an option if
> you have the board. Again - Google my Web site for "catweasel".
> On "PC compatible floppy controllers", the limiting factor is
> single-density format support. One either finds a 486/386/286 DOS
> computer with its on-board floppy controller; or one uses an Adaptec ISA
> board, a SCSI/floppy ISA card. Dave Dunfield himself, documented how to
> do all that with imagedsk, has a test program for floppy controllers.
> There's a few predecessor MS-DOS programs like Teledisk.; many CP/M
> reader programs. Discussions on the Web, confirm which models of Adaptec
> boards do the job of single-density. And a search of my Web domain will
> find some of THOSE references.
> There's a few old-days ISA floppy boards to read copy-protected disks
> with MS-DOS programs. Rare and not cheap now.
> + The third way, is what Jon Hales just posted about. Devices, embedded
> controllers really, which do bit-sampling and which operate floppy
> drives. Most are USB-based. As Jon points out, there are several. I'll
> tell you immediately - my Web site doesn't cover those. The *makers*
> have to cover those. Here's why.
> There's several of these devices, which have been produced by (mostly)
> "hobbyists" since about the 1990's. In my general opinion, they come and
> go over several years. They often target specific vintage computers.
> Some are for industrial purposes: sewing machines with nonstandard
> floppy drives.
> However: it's possible there's now a few which have either persisted, or
> which can be replicated if they are out-of-production. And some support
> general vintage-computing use. But I - don't - know. I gave up trying to
> keep up with them. They are part of modern 21st century hobby computing
> tech: items on github, posted with Gerber files, you-want-one,
> you-make-one, send to China/East Asia for the PC boards. But a few may
> be "commercialized", in some kind of production, some kind of support
> which may or may not be "open".
> Roger, that's my "read" of your request for "one Web page to rule them,
> one Page to find them". That ring already fell down the volcano. Google
> is your friend now. But if you find such a Web page, let me know, I'd be
> curious.
> regards
> Herb Johnson
> On 8/16/2019 3:15 PM, Roger Arrick wrote:
> > Really enjoying this thread.
> > Would love for there to be a single webpage for how to deal with MDS
> > 1/2/etc floppies.  With specifics on hooking up an 8" drive to a PC,
> > links to archives, etc.  Would go a long way to keeping these old
> > systems going.
> >
> > _______________________________________________
> > Roger Arrick
> > Roger at Arrick.com
> > Tyler, TX
> >
> >
> >
> >
> > Bill Beech (NJ7P) wrote:
> >>
> >>
> >> Jon,
> >>
> >> Good discussion.  I was kind of out of it during some of this.  I
> >> vaguely remember the filling of a matrix of programs in the 95 and 97
> >> series.
> >>
> >> Attached is a picture of the disk label for 9500018-03.
> >> I think we are going to need to document the hardware, software, and
> >> method used to pull the images off the floppies.  I would be glad to
> >> place these "howtos" on the web and in the google drive.
> >>
> >> I seem to be way behind on the imaging stuff with Dave's tools.  I am
> >> glad to see Mark has transitioned from Dave's C to a VS implementation
> >> on some of the tools.  This is good.  I need to get a box running with
> >> an FDC that will read SD and DD disk sectors.  I have NEVER had any PC
> >> that would do SD and work with Dave's tools! I believe I have an
> >> Adaptec board that will do it.  We will see over the weekend.
> >>
> >> Bill
> --
> 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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