Kryoflux, Shugart and M2FM

All questions about how to use KryoFlux go here.
Post Reply
hansliss
Posts: 11
Joined: Sun Mar 18, 2018 10:31 am

Kryoflux, Shugart and M2FM

Post by hansliss » Fri Apr 20, 2018 9:26 pm

I posted a question a while ago about my Shugart 850 being built for 60Hz spindle AC, while I can only provide 50Hz. I'm reading disks with the drive now, using a DBit FDADAP + FDDC and a Kryoflux, but I've yet to extract anything that looks like data. Part of the problem is that most of my floppies is from an iNTEL MDS system, which apparently uses a custom M2FM format (http://www.retrotechnology.com/herbs_st ... html#isis1).

I found a program that can supposedly decode M2FM but I'm wondering if the bit rate issue from the original post could cause trouble. Will I have to do something manually to compensate for the lower spindle speed, or should the information in the track files be enough for any program reading the file to be able to interpret the data correctly?

/H

hansliss
Posts: 11
Joined: Sun Mar 18, 2018 10:31 am

Re: Kryoflux, Shugart and M2FM

Post by hansliss » Fri Apr 20, 2018 10:04 pm

Followup: I just managed to read a Cromemco FM disk using this floppy drive, by setting the RPM to 330 and sector size to 128. So at least something works!

ZrX
Posts: 483
Joined: Tue Dec 06, 2011 9:09 pm

Re: Kryoflux, Shugart and M2FM

Post by ZrX » Sat Apr 21, 2018 8:39 am

Could you post the raw files of one of those M2FM disk for study?

hansliss
Posts: 11
Joined: Sun Mar 18, 2018 10:31 am

Re: Kryoflux, Shugart and M2FM

Post by hansliss » Sat Apr 21, 2018 7:07 pm

Sure! Can I send it to you rather than posting it here?

Best regards,

Hans

ZrX
Posts: 483
Joined: Tue Dec 06, 2011 9:09 pm

Re: Kryoflux, Shugart and M2FM

Post by ZrX » Sun Apr 22, 2018 9:05 am

Upload to sendspace or some other service and send the link as private message.

hansliss
Posts: 11
Joined: Sun Mar 18, 2018 10:31 am

Re: Kryoflux, Shugart and M2FM

Post by hansliss » Sun Apr 22, 2018 9:11 am

Actually, I think there's no need. I had missed that the bit rate was supposed to be 500kbps, and I was trying the tool with bit rates around 250-360. I'm currently testing every integer between 200 and 601, and from 494 to 499, where it's currently at, I'm getting consistent, readable data. I'm getting a lot of CRC errors in the tool's output so I'm going to let it run to see if there's more or better results at higher values, but it looks promising. The tool is here: https://github.com/brouhaha/fluxtoimd

Code: Select all

00000c40  00 00 00 00 00 00 00 00  00 00 00 00 00 00 02 c7  |................|
00000c50  01 00 49 53 49 53 00 00  44 49 52 81 80 19 00 01  |..ISIS..DIR.....|
00000c60  01 00 49 53 49 53 00 00  4d 41 50 81 80 04 00 01  |..ISIS..MAP.....|
00000c70  02 00 49 53 49 53 00 00  54 30 00 81 80 17 00 18  |..ISIS..T0......|
00000c80  00 00 49 53 49 53 00 00  4c 41 42 81 80 35 00 19  |..ISIS..LAB..5..|
00000c90  00 00 49 53 49 53 00 00  42 49 4e 83 7d 62 00 06  |..ISIS..BIN.}b..|
00000ca0  02 00 49 53 49 53 00 00  43 4c 49 83 44 24 00 02  |..ISIS..CLI.D$..|
00000cb0  04 00 49 53 49 53 00 00  4f 56 30 83 25 0e 00 27  |..ISIS..OV0.%..'|
00000cc0  04 00 42 41 4d 44 53 00  4f 42 4a 00 1d 01 00 13  |..BAMDS.OBJ.....|
00000cd0  0e 01 7f 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000ce0  00 00 7f 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
(the tool adds a 30 byte text header, to make an "IMD" file, so the offsets are incorrect)

Post Reply