MFM Controllers and Data Recovery \ VOGONS

MFM Controllers and Data Recovery

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First post, by Droidekafan

Posted on 2025-04-22, 09:21

Droidekafan Offline

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Hi all, looking for some advice on MFM hard disks and controller compatibility.

So I do some work in data recovery and we occasionally still get MFM hard disks in which we don't have the hardware to recover at the moment. I have my personal vintage machines lying around and out of curiosity I want to attempt to recover some of these disks.

However as you all likely know, controller compatibility can be an issue with MFM/RLL drives. I don't have much experience in this area so I wanted to know if anyone has ideas as to what controller would be the best option for the widest compatibility and ability to recover the most types of drives? I was planning on using spinrite and sending data over laplink to a more modern PC if I can get the drive working on a compatible controller.

I only have 1 MFM drive controller in my collection at the moment, in my PC AT 5170 with a functioning MFM drive. However I'm not sure how compatible the stock IBM storage controller would be especially with newer/larger drives.

There's also the MFM hard disk emulator; https://decromancer.ca/mfm-emulator/
Anyone have experience with one of these?

Thanks all

Reply 1 of 3, by maxtherabbit

Posted on 2025-04-22, 13:02

maxtherabbit Offline

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For professional data recovery you're better off using the gesswein emulator to image the disk instead of connecting the drive to a real vintage controller. The emulator can image MFM encoded drives from any controller type. The only issue would be if the drive was RLL, which I believe it doesn't support.

Reply 2 of 3, by Droidekafan

Posted on 2025-04-22, 13:46

Droidekafan Offline

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Posts: 28
Joined: 2021-03-15, 13:13
Location: Cymru

maxtherabbit wrote on 2025-04-22, 13:02:

For professional data recovery you're better off using the gesswein emulator to image the disk instead of connecting the drive to a real vintage controller. The emulator can image MFM encoded drives from any controller type. The only issue would be if the drive was RLL, which I believe it doesn't support.

That was my thought too, any experience with them especially regarding compatibility? Also I don't believe these are compatible with RLL drives, is there any option on that front?

Cheers

Reply 3 of 3, by digger

Posted on 2025-04-22, 18:21

digger Offline

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I can wholeheartedly recommend this video by Adrian Black (of the YouTube channel "Adrian's Digital Basement") about this topic.

He shows how such a device can be used both to back up data from a physical MFM drive, as well as emulate an MFM drive in a host computer.

The MFM Hard Disk Reader/Emulator that he uses in the video is a different one than the one you linked to. You can find more info about that device here: https://www.pdp8online.com/mfm/

Not sure how the two different hardware emulation solutions compare.

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