Strange Teledisk question

[Warner Losh]

On Sat, Jun 23, 2018 at 5:53 PM, Fred Cisin via cctalk <
cctalk at classiccmp.org> wrote:

> All the disk images for the Waveterm have been created using programs
>>> written by PPG users. For some reason any disk we wrote with them
>>> wouldn’t read correctly in the machine itself UNTIL we made a new
>>> image of that disk using Teledisk 2.15 then re-wrote it back to the
>>> same floppy. My question is why should that make so much of a
>>> difference between working and non-working disks?
>>>
>> On Sat, 23 Jun 2018, Chuck Guzis via cctalk wrote:
>
>> I'd love to be able to tell you, but I really haven't fooled with the
>> thing for something like 17 years.
>>
>
> I had hoped that Chuck would have an answer.
>
> If you have two disks that are nominally the same, and one works and the
> other doesn't, then there is obviously something different.
>
> If the sector contents are the same, then the next step would be to
> examine the headers, gaps, and addressmarks.
>

Also, sector ordering can be an issue with more obscure formats... Though
most drives can cope with non-consecutive ordering...

In some cases, track width may also matter, especially for 40 track formats.


> For example,
> if the gap after index pulse, before the first sector ofeach track is too
> short, then it may not be able to read the sector header of the first
> sector.  (A serious and common problem with NEC-style FDC, not usually a
> prolem with WD-style FDC)
>
> Do you have a way to examine the raw track encoding?
> I used a track read with a WD 179x (slightly modified "Trakcess" on TRS80
> Model 3), and "TE" with the Central Point Option Board.
>

I used to mess around with different drives on different machines. These
days I find that kyroflux just works (on the right drive) and I don't have
to mess with weird things. It has a small learning curve, but it allowed
me, through brute force, to read the Rainbow Venix disks that were
otherwise not readable... It was ~$100 well spent...

Warner