Jump to content
webdeck

Update on hard drive recovery

Recommended Posts

I believe I have managed to recover the majority of data off my 20MB hard drive from over 30 years ago.  I worked with the creator of the MFM emulator to add support for drives formatted by the HFDC, after digging up low level docs on the chipset the HFDC uses.  The latest release of the MFM Emulator software includes the HFDC support, so if you are looking for a cheaper alternative to the DREM, the MFM emulator is now an option.  Knowing your way around a linux command line is required to get the emulator setup and working, however.  I plugged in a USB WiFi dongle to the emulator so that I can make backups easily.

 

The cool thing about the MFM Emulator is that you can connect it to a hard drive and do a raw read of it.  I performed multiple read passes and assembled them together into one image that was mostly complete with only a few bad sectors remaining.  You can tweak the number of retries, and I also enabled micro-stepping the drive heads between read attempts, which helped recover more data.  The final trick was to use a plastic stylus and put pressure on the shaft of the stepper motor (wiggling the stylus back and forth while pressing fairly firmly), which helped the drive read better.  Now that I have the image, I no longer need the dying drive.  I switched the cabling on the emulator, put it into emulation mode, and now it pretends to be up to 3 hard drives (2 read/write, 1 readonly.)

 

Next, I wrote some python code to walk through the disk structures and flag all the problems.  I'm happy to share the code if anyone wants to play with it.  I had to do some manual sector editing to fix up some corrupted filesystem structures.  TI Image Tool was a great help in flagging problems as well.  Ultimately, once I fixed everything I could, I used TI Image Tool to create a new blank hard drive image, copied all the files over to the new image to have a nice, pristine copy, and then copied that over to the emulator to use going forward.

 

I tested it both with the Geneve and the TI with the HFDC, and it works well and is much faster than the original hard drive.

 

Sadly, I thought this hard drive had way more data on it than it actually does.  Apparently, a lot of my early work was still on floppies, and I have no idea where those floppies are after 30+ years.  As it was, I had to make a number of eBay, Arcade Shopper, and Shift838 purchases just to get this far, not to mention repairs to the HFDC, Geneve, and a TI Power Supply, since a lot of my original equipment has been lost to time and many moves.  Along the way, I added a TIPI/32K and a FinalGROM, which I would consider essential upgrades these days.

 

I will be uploading my old source code to the developer forum as I have time, to share back to the community.  It's all 30+ years old, but maybe there is something that someone will find worth playing with.  One thing I did notice is that my Geneve was on version 0.98 of MDOS, and when I tried using the newer version TI Image Tool installed, none of the software I wrote would launch, so I guess things have changed in the MDOS world since I was last developing for it.  The programs do run okay in MDOS version 0.98 though.

 

A huge thank you to everyone in the community who helped me get back up and running!

 

-Mike

  • Like 6
  • Thanks 1

Share this post


Link to post
Share on other sites
I believe I have managed to recover the majority of data off my 20MB hard drive from over 30 years ago.  I worked with the creator of the MFM emulator to add support for drives formatted by the HFDC, after digging up low level docs on the chipset the HFDC uses.  The latest release of the MFM Emulator software includes the HFDC support, so if you are looking for a cheaper alternative to the DREM, the MFM emulator is now an option.  Knowing your way around a linux command line is required to get the emulator setup and working, however.  I plugged in a USB WiFi dongle to the emulator so that I can make backups easily.
 
The cool thing about the MFM Emulator is that you can connect it to a hard drive and do a raw read of it.  I performed multiple read passes and assembled them together into one image that was mostly complete with only a few bad sectors remaining.  You can tweak the number of retries, and I also enabled micro-stepping the drive heads between read attempts, which helped recover more data.  The final trick was to use a plastic stylus and put pressure on the shaft of the stepper motor (wiggling the stylus back and forth while pressing fairly firmly), which helped the drive read better.  Now that I have the image, I no longer need the dying drive.  I switched the cabling on the emulator, put it into emulation mode, and now it pretends to be up to 3 hard drives (2 read/write, 1 readonly.)
 
Next, I wrote some python code to walk through the disk structures and flag all the problems.  I'm happy to share the code if anyone wants to play with it.  I had to do some manual sector editing to fix up some corrupted filesystem structures.  TI Image Tool was a great help in flagging problems as well.  Ultimately, once I fixed everything I could, I used TI Image Tool to create a new blank hard drive image, copied all the files over to the new image to have a nice, pristine copy, and then copied that over to the emulator to use going forward.
 
I tested it both with the Geneve and the TI with the HFDC, and it works well and is much faster than the original hard drive.
 
Sadly, I thought this hard drive had way more data on it than it actually does.  Apparently, a lot of my early work was still on floppies, and I have no idea where those floppies are after 30+ years.  As it was, I had to make a number of eBay, Arcade Shopper, and Shift838 purchases just to get this far, not to mention repairs to the HFDC, Geneve, and a TI Power Supply, since a lot of my original equipment has been lost to time and many moves.  Along the way, I added a TIPI/32K and a FinalGROM, which I would consider essential upgrades these days.
 
I will be uploading my old source code to the developer forum as I have time, to share back to the community.  It's all 30+ years old, but maybe there is something that someone will find worth playing with.  One thing I did notice is that my Geneve was on version 0.98 of MDOS, and when I tried using the newer version TI Image Tool installed, none of the software I wrote would launch, so I guess things have changed in the MDOS world since I was last developing for it.  The programs do run okay in MDOS version 0.98 though.
 
A huge thank you to everyone in the community who helped me get back up and running!
 
-Mike
Cool I have one of these and will have to see about updating the sw..

Thanks for doing the hard work :)

Sent from my LM-V600 using Tapatalk

Share this post


Link to post
Share on other sites

Two quick corrections to my original post:

 

The emulator emulates two read/write drives.  It does not emulate a third drive.  I got confused with the HFDC's capability to have a third read-only drive.

 

This is a better link to the MFM Emulator site.

 

And here is a link to the Decromancer version of the emulator that I purchased fully assembled.

 

-Mike

Edited by webdeck

Share this post


Link to post
Share on other sites
23 minutes ago, webdeck said:

Two quick corrections to my original post:

 

The emulator emulates two read/write drives.  It does not emulate a third drive.  I got confused with the HFDC's capability to have a third read-only drive.

 

This is a better link to the MFM Emulator site.

 

And here is a link to the Decromancer version of the emulator that I purchased fully assembled.

 

-Mike

The Decromancer version you purchased was fully assembled and came with a BeagleBone Green also for $125 USD?

 

 

Share this post


Link to post
Share on other sites
11 minutes ago, Shift838 said:

The Decromancer version you purchased was fully assembled and came with a BeagleBone Green also for $125 USD?

Yes, plus shipping.  I don't know if he is still selling them - I got one of the last ones from the batch he was making earlier this year.

 

Learn from my painful and expensive lesson - I didn't check the voltage on the power supply I was using and it was putting out over 14V on the 12V line, which fried the DC/DC power converter on the card and the entire BeagleBone Green, so I had to replace the BBG and power converter on mine.

Share this post


Link to post
Share on other sites
1 hour ago, webdeck said:

Two quick corrections to my original post:

 

The emulator emulates two read/write drives.  It does not emulate a third drive.  I got confused with the HFDC's capability to have a third read-only drive.

Quick question -  have you been using the Decromancer to write to your emulated drive(s) or have you just been using it primarily for read operations?  I'm curious as to the write stability.  this looks like a good alternative for my repair system, where my last two real MFM drives are starting to really show their age.  I need to keep those drives in good shape for testing the HFDCs, particularly for termination and some of the connecting logic glue that acts differently for certain drives. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...