IBM PC DOS 3.5" disks - parsing files from MFM sector image?

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adamsabi
Posts: 19
Joined: Thu Feb 09, 2017 9:30 pm

IBM PC DOS 3.5" disks - parsing files from MFM sector image?

Post by adamsabi » Tue Jun 06, 2017 4:25 pm

I have a set of 3.5" floppy disks that I created MFM sector images for with the KryoFlux. I can tell the files were created with a Panasonic KX-W1510 Personal Word Processor so the OS seems to be IBM PC DOS. The problem is that although I can read each file on the sector image in a text editor, I cannot find a program that will parse out the files from the image. FTK Imager does not work. I also tried mtools, which I found instructions for at http://journal.code4lib.org/articles/11986 but since these are PC DOS, not MS-DOS, that does not seem to work, either. Here is a link to the sector image: https://utexas.box.com/s/sh9oez12ck06un ... xf3pv7u6yg. Could anyone give me some guidance on this?

Thanks, Abby

SomeGuy
Posts: 218
Joined: Wed Feb 18, 2015 8:18 pm

Re: IBM PC DOS 3.5" disks - parsing files from MFM sector image?

Post by SomeGuy » Tue Jun 06, 2017 11:02 pm

Well, there are a couple of issues with this disk image. First of all, there is no Bios Parameter Block in the boot sector. I really wish disk tool makers would get it through their skulls that a BPB is not actually required under MS-DOS. I run in to disks like that all the time. Even though BPBs were introduced with DOS 2.0, they were not actually used at all until 3.2. And even then, DOS all the way up to at least 6.22 can usually still deal with bad/missing BPB info.

In this case, one solution is to copy and paste the first 32-bytes from a normal 720k disk:

Code: Select all

00000000  EB 34 90 4D 53 44 4F 53-33 2E 33 00 02 02 01 00    .4.MSDOS3.3.....
00000010  02 70 00 A0 05 F9 03 00-09 00 02 00 00 00 00 00    .p..............
Some tools might let you manually specify the sectors, heads, tracks, sectors per cluster, and other PBP info.

The other problem is that the filenames have spaces in them. It was possible to get away with all kinds of naming murder in earlier versions of DOS. Under real DOS you can do a mass rename to get rid of the spaces. Otherwise you need a tool that can handle oddball file names.

With the above copy-paste, I was able to extract files with WinImage, although it didn't get the file names exactly right.

Otherwise yea, it is a valid MS-DOS disk and readable under genuine MS-DOS.

adamsabi
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Joined: Thu Feb 09, 2017 9:30 pm

Re: IBM PC DOS 3.5" disks - parsing files from MFM sector image?

Post by adamsabi » Fri Jun 09, 2017 10:19 pm

Thank you. This worked!

BarryB
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Joined: Thu Aug 02, 2012 8:15 pm

Re: IBM PC DOS 3.5" disks - parsing files from MFM sector image?

Post by BarryB » Sun Jun 11, 2017 12:24 am

I think 7-Zip can also open most MS-DOS IMG files too.

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mr.vince
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Re: IBM PC DOS 3.5" disks - parsing files from MFM sector image?

Post by mr.vince » Sun Jun 18, 2017 2:14 pm

We recommend TotalCommander with the plugins available.

anormal
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Joined: Sat Jul 19, 2014 1:44 pm

Re: IBM PC DOS 3.5" disks - parsing files from MFM sector image?

Post by anormal » Mon Jul 24, 2017 12:03 pm

Check FarManager with observer plugin.

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