PDA

View Full Version : Extracting files off “unknown” 8 inch disks. Any thoughts…



tezza
March 22nd, 2017, 02:46 PM
Hi


I’d be grateful for any guidance or comments anyone could give me on this problem.


Guys in the building next door to me (a Science lab) have found some 8 inch floppy disks. They want to see what’s on them, or at least to archive them. They have no idea what machine these disks were used with, or the software was used to write the files. They may be CP/M, or some other format entirely.


I’ve got little experience with 8 inch drives or disk formats. However I have got a bare 8 inch floppy drive (a Mitsubishi M2896-63 Half Height 8inch DSDD), and also a CP/M computer with 8 inch drives (A Panasonic JD-850M). I’m thinking it might be an interesting challenge/project to see if I can read these disks and get files off.


However, I imagine given all the unknowns it won’t be easy…perhaps even impossible.


I see two possible approaches. One is to wire up the 8 inch drive to an MS-DOS machine. I’ll have to build/get a PSU for the drive so it can supply the necessary 24 Volts required. I’ll also have to make up a special drive cable. That info is available. In fact, Chuck gave me some tips a year or so ago. However, once I’ve got the drive successfully wired up, I then need to somehow analysis the disks to see what format they are in. Does anyone know of any software that will do this? I’m aware of disk22, for reading KNOWN CP/M formats but is there anything out there that will analyse a disk from scratch? Search the web has thrown up a few possibilies (MMCPC, Cpmtools) but I haven’t explored them at all.


The second approach is to use the Panasonic JD-850M, and find a CP/M program that will analyse an “unknown” 8 inch disk and read files from said disks into the CP/M environment. I’d somehow get the program into one of my Panasonic 8 inch disks (just how, I’ll need to figure out). I’d also need to figure out how to get the files out of that environment also.


Anyway, has anyone else faced this kind of challenge and what are your thoughts? I don’t want to start unless I at least have some chance of success. I’m not hopeful. The more I read the more you seem to need real forensic skills and something like Kyroflux that works at low-level.


Thanks


Tez

Chuck(G)
March 22nd, 2017, 02:52 PM
Single- or Double-sided, soft- or hard-sectored?

The methods differ for each.

new_castle_j
March 22nd, 2017, 03:38 PM
I purchased 22Disk and have worked with Chuck on getting several previously unknown disk formats de-coded, he's an absolute wizard! I've got a DOS machine with an Adaptec 1522A SCSI card that has an onboard floppy controller. This is connected by ribbon cable to a D-Bit FDADAP board (http://www.dbit.com/fdadap.html) and from there it goes to an 8" floppy drive. I use Dave Dunfield's IMGdsk program to capture the unknown floppy to an image file and I send the image to Chuck. He's been a real hero in getting a new disk definition created. Hats off to Chuck, Huzzah!

Chuck(G)
March 22nd, 2017, 04:43 PM
Thanks, for the upvote!

A couple of weeks ago, I was contacted by a customer who asked if I could get the files from a bunch of floppies. She said she had images.

Piece of cake, I thought. Those images turned out to be photos of the disks.... :)

SomeGuy
March 22nd, 2017, 07:26 PM
This is the sort of time a device like a Kryoflux can come in handy. Assuming the media matches the drive, it will archive all of the bits, and you can analyze the image later without putting wear on the disks.

When hooked to a PC, you MAY be able to use ImageDisk to determine the encoding and sector geometry to create an ImageDisk sector file. But you run the risk of missing something since you don't really know what those are supposed to be. If the disks happen to use FM encoding instead of MFM you will need a floppy disk controller that supports FM encoding - many don't.

Now, once you have an image file, either decoded from a Kryoflux stream or an ImageDisk file, you still face the problem of extracting files. That is where tools like 22disk come in. And you may be able to get some idea of the system it was used in just by looking at the image files in a hex editor.

And, of course, the entire time you have to be careful that the disks don't fall to shreds. What brand(s) are the disks? Hopefully none of them are Wabash. :)

tezza
March 22nd, 2017, 07:45 PM
>Hopefully none of them are Wabash

Hahaha. I agree. What a load of crap that brand is. I had most of my original System 80 collection on Wabash disks. Big mistake.

Anyway, thanks for the comments and ideas. If I can get the 8 inch drive attached and running to a DOS machine I'll take a look. If there is nothing I can do...and these guys have a budget and are desperate to get the files off, I'll point them in Chuck's direction.

Tez

Druid6900
March 23rd, 2017, 05:32 AM
Tez, if you get the drive hooked up to a MS-DOS machine, there are a couple of programs that may help you figure out what you have by analyzing the diskette.

One is AnaDisk and the other is OmniDisk. I use them a lot for this type of work.

If you can't find them "out in the wild", let me know.....

Dwight Elvey
March 23rd, 2017, 06:10 AM
Being out of a science lab, they could be from things like a Varian or a Nicolet.
Your not going to read those with a PC disk controller.
Dwight

archeocomp
March 24th, 2017, 04:43 AM
I believe DEC PDP format is also unreadable by PC floppy controler.

Chuck(G)
March 24th, 2017, 08:33 AM
DEC RX01 is standard single-density (FM) and quite readable on a PC equipped with a controller that can do FM (TestFDC will tell you that).

DEC RX02 format is not readable on a standard PC. Single density headers with a modified MFM encoding for data. Sui generis--I don't know of another manufacturer using the same system. An RX02 drive can read and write RX01 floppies.

Al Kossow
March 24th, 2017, 08:46 AM
An RX02 drive can read and write RX01 floppies.

or a Catweasel with Tim Mann's software.

3rd party rx02 qbus floppy controllers are easier to find if you need one, and work with ordinary shugart drives
the mxv21
http://www.ebay.com/itm/MTI-MICRO-TECHNOLOGY-MXV21-Q-BUS-8-FLOPPY-DRIVE-CONTROLLER-BOARD-/201859336541
is a good one.

Chuck(G)
March 24th, 2017, 09:21 AM
Sure Al, but the topic was "what can I do with a standard PC?"

Catweasels are getting harder to locate nowadays. But if you're willing to build your own, a cheap microcontroller with a bit of support logic and some programming will do just fine. I suspect that even an Arduino board with some added memory can be coaxed to read RX02 floppies. The STM32F1 boards, such as the "blue pill" or "maple mini" certainly can be made to do that--and they cost, what, less than $5 each.

All it takes is a little bit of work.

Al Kossow
March 24th, 2017, 09:30 AM
All it takes is a little bit of work.

And you've done it before, hearing crickets when asking about interest.

People seem content to forget about what has been said, over and over again, on a couple of different forums.

archeocomp
March 24th, 2017, 12:02 PM
DEC RX01 is standard single-density (FM) and quite readable on a PC equipped with a controller that can do FM (TestFDC will tell you that).

DEC RX02 format is not readable on a standard PC. Single density headers with a modified MFM encoding for data. Sui generis--I don't know of another manufacturer using the same system. An RX02 drive can read and write RX01 floppies.

I tried to read some 30 and more years old (probably) 250kB PDP floppies with my CP/M machine. I have set parameters as IBM FM 77/26 drive but I could not read anything, no sector was ever found. That's why I assumed DEC must have used some deviation. And the floppies were actually not real PDP floppies but east European clone, but I assume they copied the PDP11 including drives and format used properly..

Chuck(G)
March 24th, 2017, 12:16 PM
And you've done it before, hearing crickets when asking about interest.

People seem content to forget about what has been said, over and over again, on a couple of different forums.

George Santayana had a good point. :sigh:

tezza
March 24th, 2017, 04:51 PM
Tez, if you get the drive hooked up to a MS-DOS machine, there are a couple of programs that may help you figure out what you have by analyzing the diskette.

One is AnaDisk and the other is OmniDisk. I use them a lot for this type of work.

If you can't find them "out in the wild", let me know.....

Thanks Druid. I was familiar with omindisk and (by coincidence) took a look at Anadisk last night. It looks like it will be highly useful all right.

I've decided to buy the necessary hardware which will allow me to connect the drive this 486 I've got earmarked for the project.
http://www.dbit.com/fdadap.html
http://www.dbit.com/fddc.html

Now it's a matter of waiting for the mailman to row the boat from the US to deliver. Looking forward to tackling the challenge.

Tez

SomeGuy
March 24th, 2017, 06:10 PM
Well, if you are going to all the trouble to get those devices, you really aught to seriously consider a Kryoflux or perhaps a SuperCard Pro. (Those will plug in to the fdadap board).

I also have a Mitsubishi M2896-63 floppy drive, but since I only needed it for one batch of disks, I cheaped out using an old crufty 24v power supply and wired my own interface cable adapter since the M2896-63 doesn't need the TG43 line support (Actually just reading a disk doesn't need that).

Both projects have some politics surrounding them, but functionally the Kryoflux and Supercard Pro are pre-built microcontrollers that simply record the drives raw Data Out and save it to a file. Once the stream is saved to disk, it becomes entirely a software problem to decode and verify the image. The Kryoflux software comes with some decoding capabilities, but several third party tools have additional decoding capabilities. Note that the Kryoflux does not support hard sectored disks (but neither does a PC FDC).

If you are interested in more details comparing PC FDCs, Kryoflux, and SuperCard Pro, see this writeup: https://winworldpc.com/winboards/viewtopic.php?t=7877

MikeS
March 25th, 2017, 10:24 AM
Well, if you are going to all the trouble to get those devices, you really aught to seriously consider a Kryoflux or perhaps a SuperCard Pro. (Those will plug in to the fdadap board).
Nothing wrong with those of course, especially if you're going to deal with lots of different formats, but in most cases that's overkill.

If your disks use 'normal' modulation (FM, MFM) which most disks do, and especially if you're only reading the disks then all you usually need is a $4.00 24V boost supply and a cable (documented on the Imagedisk site and elsewhere) that should only take about an hour at most to make. And of course one or more of the various software apps to analyze and read 'foreign' formats on a PC, some of the better ones written by one of our members who will usually even help out (if you actually paid for the software! ;-) )

As a matter of fact 8" diskettes did not use nearly the wide variety of formats that 5.25" versions did in the CP/M heyday, and many used the 241Kb 'standard' IBM 3740 format: SSSD, 77 tracks, 26 x 128 byte sectors per track with a skew of six.

m

Chuck(G)
March 25th, 2017, 11:39 AM
As a matter of fact 8" diskettes did not use nearly the wide variety of formats that 5.25" versions did in the CP/M heyday, and many used the 241Kb 'standard' IBM 3740 format: SSSD, 77 tracks, 26 x 128 byte sectors per track with a skew of six.

There I'll disagree with you a bit. About all that you didn't see in 8" floppies is varying numbers (e.g. 8, 10, 16) of hard-sector varieties (8" uses 32-sector universally, choosing to use a divider to get 16 and 8 sectors; there are the very early utterly incompatible floppies with 8 sector holes punched on the outer circumference of the disk, but I'm not counting those) and varying radial track spacing (5.25" has 48, 96 and 100 tpi, though there is also a 192 tpi used by Drivetec). Otherwise, whacky encoding and modulation (FM, MFM, MMFM, GCR) are all represented; reverse bit ordering, nonstandard (or absent) headers, etc. How about 132-byte sectors as used on the Zilog development systems?

No, I'll say that if it could be done with 5.25" disks, it probably was also done on 8".

The

MikeS
March 25th, 2017, 12:18 PM
There I'll disagree with you a bit. About all that you didn't see in 8" floppies is varying numbers (e.g. 8, 10, 16) of hard-sector varieties (8" uses 32-sector universally, choosing to use a divider to get 16 and 8 sectors; there are the very early utterly incompatible floppies with 8 sector holes punched on the outer circumference of the disk, but I'm not counting those) and varying radial track spacing (5.25" has 48, 96 and 100 tpi, though there is also a 192 tpi used by Drivetec). Otherwise, whacky encoding and modulation (FM, MFM, MMFM, GCR) are all represented; reverse bit ordering, nonstandard (or absent) headers, etc. How about 132-byte sectors as used on the Zilog development systems?

No, I'll say that if it could be done with 5.25" disks, it probably was also done on 8".

Well, I'm certainly not going to disagree with you ;-)

There were certainly totally non-standard diskettes in the early days, but I'd think that among the diskettes folks in this hobby are likely to run across there'd be less variety among 8" formats than 5.25", partly because there was a standard (such as it was) used for many software distributions etc. (even some Commodore disks) and also because the real explosion of different CP/M boxes and proprietary 5 1/4" formats came along when 8" disks were already becoming obsolescent. Quite a few systems using proprietary 5.25" formats could also read 3740 format 8" disks

I'm going to have to look it up: how many definitions are there in 22disk for 8" disks vs. 5.25"?

m

Chuck(G)
March 25th, 2017, 12:23 PM
I'll have to check, but 8" are in the minority--but that's mostly a matter of timing and the nature of the home computer market. About the time that floppy drives became affordable for home computers, the much much cheaper 5.25" drives had begun to make an appearance. I remember setting a friend up with a KIM-1 board with a single-sided Shugart 5.25" floppy drive.

Admit it--if someone walked in with a batch of Lanier hard-sectored 8" disks, you'd be at a loss...

MikeS
March 25th, 2017, 12:30 PM
I'll have to check, but 8" are in the minority--but that's mostly a matter of timing and the nature of the home computer market. About the time that floppy drives became affordable for home computers, the much much cheaper 5.25" drives had begun to make an appearance. I remember setting a friend up with a KIM-1 board with a single-sided Shugart 5.25" floppy drive.

Admit it--if someone walked in with a batch of Lanier hard-sectored 8" disks, you'd be at a loss...
Heck, I'd be at a loss with 95% of the diskettes that you've managed to decode in your time.

Let's hope that that's not what Tez is trying to read... ;-)

Nama
March 25th, 2017, 01:09 PM
Hi Terry, I have basically the same setup that you are aiming to get. However, one thing you may find you need is a decent/versatile floppy controller. I opted for the recommended Adaptec AHA-1522A, and it seems to work very well.

Chuck(G)
March 25th, 2017, 01:13 PM
If the controller passes TestFDC(), then it's neither better nor worse than the Adaptec unit.

A lot of Future Domain, Adaptec and DTC SCSI controllers used the National Semi 8473 FDC, which is among the best for "tweeners". What many people don't know is that it can directly support 4 drives. I turned my Future Domain ISA controller into supporting 3 drives on the same cable with only a short jumper wire. Some DTC controllers had the option to support 4 drives on the same "flat" cable--if one motor ran, they all did and drive selects had to be consecutive.

Some Ultrastor ISA controllers also used this FDC.