DaveDDS wrote on Yesterday, 20:41:

I just double-checked on "Daves Old Computers", and under Software/Images ImageDisk shows as 1.20 I also downloaded the IMD120.Z […]
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I just double-checked on "Daves Old Computers", and under Software/Images ImageDisk shows as 1.20
I also downloaded the IMD120.ZIP it points at an when I run that IMD.COM it shows itself as 1.20

Sometimes browsers cache a LOT - that why I recommend flushing your browsers cache before downloading.
If you have an old page cached which points at IMD119.ZIP, that archive may still be on the site.

I downloaded it from here: http://dunfield.classiccmp.org/dos/index.htm

the file was called imd.zip, not imd20.zip. I wonder if I managed to find the wrong page?

DaveDDS wrote on Yesterday, 20:41:

You should feel some resistance - not much, but you should be able to tell the head is being pressed on the paper. If you use a […]
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You should feel some resistance - not much, but you should be able to tell the head is being pressed on the paper.
If you use a thin strip which can fall to the side with the drive vertical and heads open - is it still that loose when the heads are
closed on it (and make sure you are getting it under the head - some drives have shielding which makes it tricky to get
it in the right place.

If there is no output from 'A'lign/tests = it would seem there's no data from the FDC.

When you 'E'rase, does it step over the whole disk?
Can you 'E'rase with no disk in the drive?

Erase did step over the whole disk. I am about to go to bed now (in UK), but will check erasing with no disk tomorrow and also try the paper test again.

edit: ok, I have found 1.20 under software/images.

DaveDDS wrote on Yesterday, 20:41:

I just double-checked on "Daves Old Computers", and under Software/Images ImageDisk shows as 1.20 I also downloaded the IMD120.Z […]
Show full quote

I just double-checked on "Daves Old Computers", and under Software/Images ImageDisk shows as 1.20
I also downloaded the IMD120.ZIP it points at an when I run that IMD.COM it shows itself as 1.20

Sometimes browsers cache a LOT - that why I recommend flushing your browsers cache before downloading.
If you have an old page cached which points at IMD119.ZIP, that archive may still be on the site.

You should feel some resistance - not much, but you should be able to tell the head is being pressed on the paper.
If you use a thin strip which can fall to the side with the drive vertical and heads open - is it still that loose when the heads are
closed on it (and make sure you are getting it under the head - some drives have shielding which makes it tricky to get
it in the right place.

If there is no output from 'A'lign/tests = it would seem there's no data from the FDC.

When you 'E'rase, does it step over the whole disk?
Can you 'E'rase with no disk in the drive?

If I try to erase with no disk in the drive I get this:

I have one disk now that seems to be showing something on track 0 head 0. But no other track on that disk with either head:

I don't know what the numbers mean, but at least its a sign of life.

I then used erase disk function of IMD and then the Align method. This time it was giving ??? again. So no data. I then went back to dos and tried an unconditional 1.2mb format. It reported error "Invalid Media or Track 0 bad - disk unusable". I then went back to IMD again and find the same kind of data showing on T0 H0, but nowhere else. So it would appear that the format command can write to T0 H0, and IMD can read from that track and head.

I have done a test where I put a small strip of paper between the disk and the head, then held drive vertically. The paper didn't fall out. So head does appear to be making contact with it.

A quick follow up. I tried writing a disk image again using IMD. It gave same errors as before (NoData) but I left it longer and could see it started moving the head and was going track by track. Still reporting NoData. I stopped it after 3 tracks and then did Align test again. It is showing data from both heads from the first 3 tracks.

So, clearly, the drive is able to read and write from the heads. But clearly its not doing it correctly, as IMD and Format command both complain.

My apologies, I didn't realize an older IMD.ZIP was still available under "DOS widgets"
- I have removed it from there, and added a note under "Special purpose packages"
to indicate that it is available and where to find it.
(btw, if you found/downloaded it from somewhere else on the site, please let me know)

--

I should mention that the PC FDC (Nec765) does NOT have an "erase" function,
IMD does an effective erase by formatting the disk with an unreasnably large sector
size - which actually fails (IMD does not report this) and overwrites the entire
track with an unreadable partial sector.

In other words, 'E'rase is essentially doing a 'F'ormat, which does need the index
pulse to know where to start on the track - in other words, this means that your
index sensor is indeed working!

--

Align/Test is one of the more unusual funcitons offered by ImageDisk, and kinda
requires you to know a fair but about floppy disk internals in order to make full
use if it's capabilities. The ImageDisk documentation and interactive help do describe
what the number indicate ...

Also be aware that as described above, 'E'rase intentionally makes unreadable
sectors.

It might be worth trying 'F'ormat .. this won't create a disk that an OS can read
(it won't have a filesystem), but will low-level format a diskette, which you can
then read/align/test within ImageDisk.

--

Also, have you tried giving the drive heads a good cleaning?
A common problem with older floppy drives is that the heads get crud on them which
prevents them from reading/writing sectors correctly ... given that you are seeing
some data transfer, this seems quite likely.

The best way to clean a drive is to disassemble it to the point where you can
use an aicohol swab to give a good (and gentle) cleaning... This can be fairly
difficult on some drives...

You used to be able to get "cleaning disks" which would allow you "scrub" the
disks with an alcohol solution - unfortunately OS's don't include a function to
properly perform this, so you end up just trying to access the disk (which will
fail) and only uses the first 1-2 tracks of the cleaning media.

ImageDisk has a 'C'lean function which will scrub the head over all tracks of such
cleaning media.

I've not seen such "cleaning disks" available for a long time - I've made my own 5.25
by carefully cutting the very back edge of a diskette casing, removing the original
media, and using it as a template to carefully/accurately cut out a replacement
from thick paper. Sometimes I use the center "circle" from the original media to re-
enforce that ring at the center - FWIW