Test image for an 8" drive?

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baford
Posts: 14
Joined: Sun Jun 06, 2021 9:43 pm

Test image for an 8" drive?

Post by baford »

Hi. I've got an 8" floppy drive that I believe to be in good shape, and I've got the necessary widgets to power it up and convert the cabling... the FDADAP and power converter products from DBit. I've also got a KryoFlux, of course, :-) and I've got a question... I'd like to test out my setup in a practical way with the equipment I have. The easiest thing to do would be to write a KryoFlux image of a FAT12 diskette to a floppy, read it back and mount it. I've imaged the old diskettes I've picked up on eBay... I can't identify the type of diskettes they are, and KryoFlux wasn't finding a formatted filesystem on any of the diskettes. They were written in the early to mid 1980's, according to the labeling. So could someone help me out with a KryoFlux stream of a DOS filesystem that I can write and read back? Any help much appreciated. Thanks,

-Bret Ford
brightcaster
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Joined: Fri Nov 08, 2013 10:48 pm

Re: Test image for an 8" drive?

Post by brightcaster »

As far as I know there are only 3 DOS FAT format for 8inch drives:

Formatted Capacity 250K 500K 1.2 MB
-----------------------------------------------
# of Heads (Sides) 1 2 2
# of Cyls (Tracks) 77 77 77
# of Sectors/Track 26 26 8
Total # of Sectors 2002 4004 1232
# of Bytes/Sector 128 128 1024
# of Bytes/Cluster 512 512 1024
# Sectors/Cluster 4 4 1
Total # of Clusters 497 997 1227
# Reserved Sectors 1 4 1
# of Hidden Sectors 3 0 0
# Sectors/FAT 6 6 2
# of FAT Copies 2 2 2
# Root Dir Entries 68 68 192
Media Descriptor FE FD FE
Recorded Density Single Single Double
MS-DOS Version Began 1.00 2.00 2.00
Change-Line Support NO NO NO

So it's important what kind of drive you have. Is it single or double sided and is it single or double density?

You should also be aware that even if these formats are some kind of standard, you can't read them with MSDOS as the sectors size is either 128 or 1024 byte where DOS only works with 512 byte!

So even if the above formats exist in theory they are not compatible with MSDOS. I think 8inch drives have never been in common use with MSDOS!

https://retrocmp.de/fdd/8inch/general.htm

I guess it would be much easier to upload a sample of the raw files (you already dumped) to some web space and provide a link here for further examination...


David
baford
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Joined: Sun Jun 06, 2021 9:43 pm

Re: Test image for an 8" drive?

Post by baford »

Thanks for the reply. The drive is a Mitsubishi M2896. It can read and write single and double sided, and single and double density diskettes.

Here's a Box link to my streams:

https://app.box.com/s/09gva20k3n4sg0xg98obt93xtqgapbhi

I'd really appreciate any assistance anybody can offer. My technical tools aren't my sharpest implements. :-)

-Bret.
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IFW
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Re: Test image for an 8" drive?

Post by IFW »

I just checked disk 1, haven't downloaded the rest.
You can use the following parameters to decode the disk or use as a guide format:
-v360 -z3 -i4
e.g.
dtc -m1 -f< stream filename or pattern> -i -f<image filename> v360 -z3 -i4 -l8
-l8 at the end will restrict the information on the console to format check only.
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IFW
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Re: Test image for an 8" drive?

Post by IFW »

The very first sector has "APOLLO" in it, not sure what logical format/file system is that... could be e.g. a backup archive too, some of those did something similar to ID their own disks quickly.
Attachments
apollo.png
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IFW
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Re: Test image for an 8" drive?

Post by IFW »

It's research work, honest :D
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apollo2.png
baford
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Joined: Sun Jun 06, 2021 9:43 pm

Re: Test image for an 8" drive?

Post by baford »

Thanks. :-) I checked the rest of the disks with the DTC parameters you suggested, and only disks 8 and 9 failed to deliver usable results. Disks 2-4 and 6 were also "APOLLO" 'format.' Disk 10 appears to contain BSD 4.3 code for /usr/games/trek. :-) I've apparently got a functional 8" drive.

-Bret.
brightcaster
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Joined: Fri Nov 08, 2013 10:48 pm

Re: Test image for an 8" drive?

Post by brightcaster »

Disk 9 claims to be space quest II for MSDOS 3.3 with a FAT12 filesystem (8sectors, 1024 byte). But sector 8 each track on both sides shows a bad data checksum!

I guess it's a copy from a 5,25inch 1,2MB floppy...

Disk 8 is very weird with FM parts on it. Will look at it tomorrow.

David
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IFW
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Re: Test image for an 8" drive?

Post by IFW »

Disk 8 is 360 RPM, FM, single sided, 77 tracks, sector size 1024, 4 sectors, but the sector headers show a sector size of 128 instead of 1024.
No idea if this is just copy-protection, or a legit format from some unknown 8'' dos...
I've attached the decoded image, but it does not seem to contain anything useful, maybe some database?
Just a hunch, but... each record is 128 bytes, 0x40 means valid, 0x60 deleted, then the record number/offset etc. record itself is gibberish, maybe byte order is scrambled or has some simple encryption.
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is_this_a_database.png
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IFW
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Re: Test image for an 8" drive?

Post by IFW »

The disk image
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dec.zip
(8.92 KiB) Downloaded 2 times
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