Re: format difference between a 4040 and a 1541

On Tue, Sep 30, 2025 at 4:15 PM Rhialto <rhialto_at_falu.nl> wrote:
>
> On Mon 29 Sep 2025 at 09:32:01 +0200, Francesco Messineo wrote:
> > On Sun, Sep 28, 2025 at 10:37?PM André Fachat <afachat_at_gmx.de> wrote:
> > >
> > >
> > > It could very well be that there is a difference in gap length between formatting a disk and writing a sector. Those are two different code paths IIRC.
> >
> > yes, this is what I'm observing on the 4040 formatted floppy. I was
> > just curious to know if someone can identify what is going on on the
> > actual code.
>
> I tried looking for the source code at https://github.com/mist64/cbmsrc,
> but even though there is the controller code for 8250
> (https://github.com/mist64/cbmsrc/blob/master/CONTROLLER_8250/cmds for
> the code that writes a sector) (which seems to use variable gap sizes,
> so looking at just the source code there isn't even telling what the gap
> sizes are), there is no CONTROLLER_4040 directory.

so if I understand correctly, 8250 does use a variable Header gap? Not
the end of data sector gap?
What I have observed on 154x/4040 is that only the end of data gap is
variable (as it has been pointed out, this
is calculated at format time).
I have the SFD-1001 drive but no current way of dumping flux data from
the 100tpi formatted floppies.

Frank IZ8DWF