Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

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ZrX
Posts: 642
Joined: Tue Dec 06, 2011 9:09 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by ZrX »

The new dump looks just like unformatted floppy with steady "background noise" and nothing else.
exidyboy
Posts: 26
Joined: Wed Jul 24, 2019 2:11 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by exidyboy »

Thanks for your insightful comments Someguy. That is one mystery solved regarding not reading beyond 40 tracks.
I will have a go a creating a custom preservation stream profile to overcome this and I will observe the movement of the carriage of 'C' and also whether it differs from 'B'.
The drives are different models and although mechanically similar the controller boards are slightly different. B is I presume an earlier revision and doesn't even have the standard 4 pin power connector. It is possible the track-to-track step time of 'B' is a few ms less than 'C' and just under the default step rate.
exidyboy
Posts: 26
Joined: Wed Jul 24, 2019 2:11 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by exidyboy »

Thanks ZrX I will give the heads a clean as there is definitely data on the disk. Cleaning requires dismantling the drive as my nice Verbatim cleaning disk with the removable biscuits won't fit in the drive.

I think this is because of the extra thickness caused by covering the 2nd head aperture in the jacket with the included sticker that stops the felt pressure pad riding on the cleaning media and getting contaminated with solvent.

I'll be back in a few days.
exidyboy
Posts: 26
Joined: Wed Jul 24, 2019 2:11 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by exidyboy »

I have finally taken receipt today of the imperial nutdrivers that I needed to open up the drive and clean the heads. I've PMd you a link to the preservation streams from the 77 track single sided drive. This is an attempted read of the same disk we were looking at back in April. I would be interested in finding out if cleaning the heads made any difference - is there a way I can tell as an end user?

The Kryoflux still gives an Error: Could not communicate with floppy drive when I try to calibrate the 77 track driv but that is a minor consideration.
ZrX
Posts: 642
Joined: Tue Dec 06, 2011 9:09 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by ZrX »

DTC now detects some sectors from the first few tracks, but looking at the scatter plot everything turns into noise/nothingness very quickly.

So either something gets released from the surface contaminating the head or there's still more cleaning to do.
exidyboy
Posts: 26
Joined: Wed Jul 24, 2019 2:11 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by exidyboy »

I rechecked the head and the disk surface is coming away in little flakes that look like black fish food. That probably explains what you were seeing in the preservation stream.

I cleaned the head again and imaged two newer disks and the client saw sectors when I fed the preservation stream back through against the 'MFM sector image' template. It issued a "Warning Sector found but not in image. Try different sector size" if I hover over the yellow "N".

It still won't calibrate as anything other than maxtrack=0 drive (which explains earlier errors reported above where it aborts after one track) but if I manually set for 77 tracks I can image the entire disk.
ZrX
Posts: 642
Joined: Tue Dec 06, 2011 9:09 pm

Re: Imaging 100TPI 77 track Exidy Sorcerer disks on a Micropolis 100TPI

Post by ZrX »

There's a good chance the disk is self-destructing if any more attempts to read it is made unless the disk is throughly cleaned (and the drive head too again).

Best would be to cut open the disk, remove the platter and carfully wash it in warm soapy water while scrubbing it with your fingers and then rinsed and carefully wiped dry with a towel. As the 8" is so large you'd have to be very careful not to get any dents, bends or creases on it.

The second best option is to have a microfiber cloth and some 50/50 water/isopropyl mix you put on the cloth and without too much pressure hold the cloth between your fingers and the floppy between the cloth and then keep wiping both sides at the same time while slowly rotating the platter, which is a bit difficult to do.
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