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

Herb Johnson hjohnson at retrotechnology.com
Fri Aug 16 14:30:29 MDT 2019

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 

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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